YEAR 12 BIOLOGY

MODULE 5 – HEREDITY

Sections Covered:
Reproduction
Cell Replication
DNA and Polypeptide Synthesis
Genetic Variation
Inheritance Patterns in a Population
 MODULE 5 – SECTION 1: Reproduction

Syllabus Dot-point:
• Explain the mechanisms of reproduction that ensure the continuity of a species, by analysing sexual and asexual
methods of reproduction in a variety of organisms, including but not limited to: Animals: advantages of external and
internal fertilisation. Plants: asexual and sexual reproduction. Fungi: budding, spores. Bacteria: binary fission.
Protists: binary fission, budding

ASEXUAL REPRODUCTION vs SEXUAL REPRODUCTION:

Asexual Reproduction (e.g. Sexual Reproduction
Parthenogenesis)
How many parents? 1 parent 2 parents
Offspring identity? Genetically identical to parent Offspring inherit different genetic traits from
both parents
Increases variation? Only from random mutations of DNA to their Increases genetic variation due to different
offspring. combination of genes in offspring.
Advantages • Energy is minimal • Genetic variation
• No need to find mates • Offspring better able to adapt to
• Reproduction is at a faster rate environments.
Disadvantages • No genetic variation • Takes longer
• Offspring may not be able to adapt • Requires more energy
to environment. • Requires a mate.
Similarities • Produces offspring, both pass
genetic info.

ANIMALS: INTERNAL AND EXTERNAL FERTILISATION (SEXUAL REPRODUCTION):

Internal Fertilisation Advantages Successful fertilisation Examples:
more likely.
• Humans
More offspring survival • Cows
(parental care). • Hens
Disadvantages Fewer offspring produced.

Much more energy

required to find a mate.
External Fertilisation Advantages Large offspring produced. Examples:

Not that much energy • Fish

required to find a mate. • Frog
• Starfish
Disadvantages Many eggs will not be
fertilised.

Offspring survival
decreases (little parental
care).
Similarities
• Male and female gametes
required
• Parental investment
indirectly proportional to
number of gametes
produced.
 PLANTS (ASEXUAL AND SEXUAL REPRODUCTION):
Asexual Reproduction Sexual Reproduction
VEGETATIVE PROPOGATION: POLLINATION:
• Reproduction without seeds. • Pollination – pollen from the anther of the stamen (male
• Using vegetative parts of a plant e.g. stem, roots, leaves, parts of flower) to the stigma (a part of the carpel or the
to propagate new plants. female parts of the flower).
• Advantages: Can produce the same plant over again. • Can occur by cross-pollination where pollen from one
Speed to maturity is relatively quick. flower transferred to stigma of another, or self-
• Disadvantages: Little chances of new variety to uprise. pollination where pollen is carried from anther to stigma
Each plant has to be individually propagated. in same flower.
• External agents carry pollen (wind, birds etc.)
• Ovules in plant develop into seeds after fertilisation
(pollen and egg cell meet), ovary will mature into fruit
and enclose seeds.
• Advantage: Helps maintain genetic diversity within a
population.
• Disadvantage: High wastage of pollen grains which need
to be produced to ensure successful fertilisation.

FUNGI: BUDDING AND SPORES:

Asexual Reproduction Sexual Reproduction
BUDDING: 3 STAGES OF SEXUAL REPRODUCTION:
• Occurs in single-celled organisms and simple multi-cellular • Many variations of fungal sexual reproduction → all consist
organisms e.g. hydra and yeast of 3 stages: plasmogamy, karyogamy, meiosis.
• A small bud grows on the surface of the organism, part of
the nucleus will split and enter the new bud. When bud is Plasmogamy – protoplasm of two parent cells fuses together without
big enough, breaks off organism. fusion of nuclei.

Karyogamy – nuclei fuse together

Meiosis – Nucleus will undergo meiosis to produce spores.

SPORULATION (SPORES):
• Spores - Reproductive cell able to develop into a new
individual.
• Sporulation – cells of an organism produces one or more
spores inside its cell wall.
• Spores released and carried to a favourable environment to
grow into an adult organism.
• Example is Cyanobacteria.

FRAGMENTATION:
• Organism is split into fragments, each which mature
individually into the same copy of the parent organism.
BACTERIA: BINARY FISSION (ONLY ASEXUAL):
• Cells increase in size until they divide into two new cells
• Firstly, DNA of bacteria divides into two, then the cell splits into two daughter cells with
identical DNA to the parent cell.
• Examples of organisms which produce through binary fission include protozoans like
Amoeba and Paramecium.

PROTISTS: BINARY FISSION AND BUDDING (ASEXUAL):

Binary fission – single protist divides its nucleus and then divides itself into two organisms.
Budding:
• Parent protozoan produces a bud which is a daughter nucleus created based on a replica
of DNA.
• Then there is nucleus division and separation of parent’s cytoplasm.
• Over time daughter nucleus undergoes further cell division via mitosis to grow and mature, which
results in protists with identical DNA.

Syllabus Dot-point:
• Analyse the features of fertilisation, implantation and hormonal control of pregnancy and birth in mammals

FERTILISATION:

• Requires gametes (sperm and egg) to meet and combine to form zygote (fertilised egg)

• Gametogenesis (the gamete formation process) can be divided into:

➢ Spermatogenesis – production of sperm
➢ Oogenesis (matured egg cells)

• Hormones:
➢ Testosterone: Produced in testes of male and plays a part in
spermatogenesis.
➢ Oestrogen: Helps with maturing of sperm cells in males.

• Fusion of gametes/fertilisation process happens in fallopian tube of

female’s body. Zygote will develop into a living organism that has
mixed genetic info from parents.

• During fusion of gametes:

➢ Head of sperm cell detaches from tail
➢ Sperm-egg species then goes down the female’s uterus.
➢ Sperm cell activates egg cell – results in cell division of egg cell development. Resulting product is a blastocyst
(structure formed in early development of mammals).

• Gametes must be from the same species for successful fertilisation.

IMPLANTATION:

• Process of adhering fertilised egg to stick to walls of reproductive tract (providing suitable environment for zygote). This
is a crucial phase for successful fertilisation.
• Blastocyst implanted on walls of reproductive tract – successful implantation = pregnancy. Implantation gives blastocyst
access to nutrients and to develop into an embryo.
• Embryo develops into a foetus (5-11 weeks), then becomes a new organism upon release from female’s body.
HORMONAL CONTROL:

Hormonal Control of Pregnancy:

• Hormones are released into blood by endocrine glands.

• Promotes changes in cells and tissues (i.e. increased growth, development of secondary sexual characteristics, control of
menstrual cycle)
• E.g. Placental mammals, which have extended gestation (time between conception and birth) require a complex
hormonal coordination which can ensure development of embryo and foetus.

Table of hormones which control pregnancy

Hormone Where is it produced in the body? Role

Progesterone Placenta Prohibits muscle contractions in uterus
which would otherwise cause body to reject
an egg.
Oestrogen Placenta Development and regulation of female
reproductive system.
Follicle stimulating hormone (FSH) Pituitary gland Stimulates maturation of follicles.
Luteinizing hormone (LH) Pituitary gland Stimulates ovulation and development of
corpus luteum.

Hormonal Control of Birth:

• Progesterone and oestrogen drop – maintains lining.

• Pressure from baby’s head stimulates production of oxytocin (hormone
which stimulates more contractions and more pressure)
• When cervix is pushed 10cm wide, oxytocin and adrenaline hormones
work together to start final series of muscular contractions.
• Baby is delivered – uterine contractions controlled by oxytocin until
placenta is pushed out and uterus shrinks to normal size.

Syllabus Dot-point:
• Evaluate the impact of scientific knowledge on the manipulation of plant and animal reproduction in agriculture.

SELECTIVE BREEDING:

• Humans use animal/plant breeding to selectively develop characteristics – choosing which typical plant or animal males
and females will sexually reproduce and have offspring.
• Advantage – can produce animals with desirable traits. Disadvantage: Decreases the gene pool – less genetic diversity
with more of those that have favourable traits.
• Example: Labradoodles – bred by crossing Labrador x Poodles to produce new variety with different combination of
characteristics.

ARTIFICIAL INSEMINATION:

• Process of collecting sperm cells from a male animal with desirable characteristics and inserting into uterus of women,
thus more females being impregnated, and large numbers of offspring produced with desirable characteristics.
• Advantages: Improves cross breeding of males and females with desirable traits. Disadvantages: Requires expensive
equipment and well-trained operations.

ARTIFICIAL POLLINATION:

• Taking pollen from one selected plant and dusting it onto another selected parent. Gives control over which plants
become parents of the next generation.
CLONING:

• Type of asexual reproduction which creates offspring genetically identical to the parent.
• Plant cloning – cutting section of mother’s plant which contains one stem cell, cutting planted in same environment
which develops same characteristics as mother plant.
• Animal cloning – Genetic material from unfertilised egg removed and replacing it with complete genetic material from
an animal which is subject to cloning. Egg is then implanted into mother who gives birth to a clone of that said animal.

OVERVIEW OF DOTPOINT:

The impact of the scientific knowledge of inheritance has enabled people to develop animals and plants with desirable traits such
as animals who can produce increased quantities of milk, or animals which have a particular quality of wool.

MODULE 5 – SECTION 2: Cell Replication

Syllabus Dot-point:
• Model the processes involved in cell replication, including but not limited to mitosis and meiosis, DNA replication
using the Watson and Crick DNA model, including nucleotide composition, pairing and bonding.

DNA STRUCTURE – WATSON AND CRICK DNA MODEL:

• DNA molecule: two chains or strands of small building blocks (monomers)

called nucleotides - consisting of phosphate, sugar, and nitrogenous base.
• 4 types of nitrogenous bases, each nucleotide named after base that it carries
➢ A – Adenine
➢ T – Thymine
➢ G – Guanine
➢ C – Cytosine
• Bases arranged in a sequence along each strand of DNA, each DNA molecule is
thousands of bases long.
• Strands held by weak hydrogen bonds in the centre. Two strands in double-helix
model have an ‘antiparallel’ arrangement (running in opposite direction).
• Two strands form a ‘ladder’ in spirals known as a ‘double helix’ – chains of DNA
could unzip (opens line of hydrogen bonds) between base pairs allowing them to
replicate.
• DNA is found in chromosomes inside eukaryotic cells – chromosomes contain 2
chemicals: DNA and proteins.

CHROMOSOMES:

• For a cell to divide, chromosomes must replicate.

• A chromosome with one copy of DNA is made up of a chromatid.
• Replicated chromosomes with two sets of DNAs are made up of two
chromatids joined at the centromere.
• In humans → each cell normally contains 23 pairs of chromosomes for a
total of 46. One of each pair comes from mother, the other from the
father.
DNA REPLICATION:

• Forms two identical strands of DNA from a single one.

PROCESS OF DNA REPLICATION:

Step 1 - Unzipping:

• Topoisomerase (enzyme) relaxes DNA from its coiled structure

• DNA helicase (requiring ATP to move) unzips double helix into two
single strands by breaking hydrogen bonds of A-T and G-C pairs.
• Single stranded DNA binding protein (SSB) prevents DNA from
becoming a double helix again until replication is done.

Step 1.1 – Replication Fork:

• Helicase forms a fork-like structure. Strands are antiparallel to each other, which is signified by a 5’ and 3’ end.
• One strand is oriented in 3’ to 5’ direction (leading strand) and one in 5’ to 3’ direction (lagging strand).

Step 2 – Primer Binding:

• Primers (made by the enzyme Primase) binds to 3’ end of the strand, and acts as a starting point for replication.

Step 3 – DNA Synthesis:

• Enzyme DNA Polymerase adds nucleotides to continue synthesis of the new strand.
• Free nucleotides (found in the nucleus) are always on hand when required by Polymerase.
• On the leading strand (3’ to 5’ direction), DNA is synthesised in the same direction as the replication fork.
• On the lagging strand (5’ to 3’ direction), DNA is synthesised in the opposite direction and is a much harder process.

Step 3.1 – DNA Synthesis on the Lagging Strand and Okazaki Fragments:

• Lagging strand synthesised in short and separated segments.

• RNA primers are constantly being formed on the lagging strand for the polymerase to start at that point.
• DNA polymerase adds pieces of DNA, “Okazaki Fragments”, to the strand between primers.

Step 4: Re-formation of Double Helix:

• The enzyme Ligase joins the two strands together of each new double helix and reconnects hydrogen bonds of base pairs.
MITOSIS AND MEIOSIS:

MITOSIS (animal and plants):

• Cells are created through cell division – mitosis is an

important part of this process (creates identical copies of
cells).
• Important for growth and repair eukaryotic organisms.

MITOSIS STAGES:

Interphase:

➢ DNA replicated and is in the form of chromatin.

➢ Synthesis – makes new organelles
➢ Cell increases in size.

Prophase (longest phase in mitosis):

➢ Chromatin condenses into

chromosomes
➢ Centrioles separate, spindles form.
➢ Nuclear membrane disappears.

Metaphase (shortest phase of mitosis):

➢ Chromosomes line up at middle of

cell
➢ Spindle fibres attach to
chromosomes at centromere.

Anaphase:

➢ Spindle fibres pull chromosomes

apart
➢ ½ of each chromosome
(chromatid) moves towards
centrioles.

Telophase:

➢ 2 nuclei form
➢ DNA uncoils – appears as
chromatin again.
➢ In animal cells, cell membrane
pinches in to form 2 daughter
cells. In plant cells, cell wall
forms between two nuclei to form
2 daughter cells.

Cytokinesis:

➢ Division of cytoplasm creates 2

new cells (begins in telophase).
➢ In animals – looks for cleavage furrow
➢ In plants – looks for a cell plate.
MEIOSIS:

• Process where a single cell divides twice – produces four cells containing half the original number of chromosomes.
• Maintains a constant chromosome number from one generation to the next
• Meiosis occurs in two stages – Meiosis I and Meiosis II

Meiosis I (Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis):

• Chromosomes duplicate themselves (e.g. if there was 1 chromosome and it duplicated, there would still be 1
chromosome or 2 chromatids).
• Chromosomes line up in pairs – crossing over (Prophase I) which increases genetic variety, random assortment in
Metaphase I which also increases genetic variety. Chromosome has some genes from father and some from mother.
• Pairs of chromosomes separate, halving chromosome number in
gametes.

Meiosis II (Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis):

• Centromere divides, chromatids separate from each other.

• Nuclear membrane forms around each set of chromosomes.
• Cytokinesis follows, resulting in four daughter cells each with half the
original chromosome number.
 Syllabus Dot-point:
• Assess the effect of the cell replication processes on the continuity of species

• Cell replication allows favourable characteristics to be passed onto offspring, allowing a higher chance for survival for
that offspring.
• Crossing-over in Meiosis I increases genetic variability in offspring and species population, can also reduce chance for an
extinction event in case an external factor affects the environment.
• Random assortment during Meiosis also increases genetic variation.

MODULE 5 – SECTION 3: DNA and Polypeptide Synthesis

Syllabus Dot-point:
• Construct appropriate representations to model and compare the forms in which DNA exists in eukaryotes and
prokaryotes

PROKARYOTES VS EUKARYOTES – DNA:

PROKARYOTES EUKARYOTES
Location of DNA? Nucleoid (in the cell’s cytoplasm) Nucleus, mitochondria, chloroplast etc.
Shape of DNA? Circular chromosome (contains DNA). Linear chromosomes in nucleus and
chloroplast. Can be circular in mitochondria
and chloroplast.
Protein synthesis – where and when? Transcription/translation happen Transcription (occurs in nucleus) and
simultaneously in cytoplasm. Translation (occurs in cytoplasm) does NOT
occur simultaneously.
Alleles per gene? 1 allele per gene. 2 alleles per gene.
Presence of plasmids (smaller rings Contains plasmids Generally, no. Although some may contain
of DNA which carry limited genes)? plasmids e.g. fungi.
Diagram

Syllabus Dot-point:
• model the process of polypeptide synthesis, including:
– transcription and translation
– assessing the importance of mRNA and tRNA in transcription and translation
– analysing the function and importance of polypeptide synthesis
– assessing how genes and environment affect phenotypic expression

TRANSCRIPTION AND TRANSLATION:

• TRANSCRIPTION – Gene’s DNA sequence is copied to make an RNA molecule.

• TRANSLATION – Process where mRNA is decoded to build a protein that contains a specific series of amino acids.
STEPS OF POLYPEPTIDE SYNTHESIS:

TRANSCRIPTION:

Initiation:
• RNA Polymerase binds to the promoter region of DNA (short sequence of
DNA) and the DNA unwinds.

Elongation:
• RNA Polymerase adds nucleotides to growing mRNA strands.
• RNA Polymerase synthesises mRNA starting from 5’ to 3’, but RNA
polymerase reads DNA strands in 3’ to 5’ direction.
• Template strand used to synthesise DNA; Coding strand is not used but
sequence matches up with the mRNA.

Termination:

• RNA polymerase reaches terminator and mRNA is released from DNA

template strand.

PRE mRNA/RNA SPLICING:

• After termination in Transcription, a pre-mRNA (messenger

RNA) strand is formed.
• Pre-mRNA consists of introns (non-coding long sequences of
nucleotides) and exons (coding sections).
• Introns are removed and exons are “spliced” or joint together.
• mRNA is transported out of the nucleus into the ribosomes for
translation.

TRANSLATION (in the ribosome):

Initiation:
• Small subunit binds to a starting codon AUG (a codon is a sequence of 3 nucleotides). Codons represent a single amino
acid.
• tRNA (transfer RNA) carrying the amino acid Met attaches to the “P site” (holds polypeptide chain). A large subunit is
then placed on top.
Elongation:
• tRNA for second amino acid binds to mRNA within the second ribosomal binding site, the “A site”. Covalent bond is
formed between the two amino acids (e.g. Met - *amino acid*)
• As process continues and ribosome moves down mRNA, the tRNA moves to the “E site” (exit site for tRNA) and loses
its amino acid.
Termination:
• A stop codon is read (release factor), tRNA and mRNA are released from the ribosome and the polypeptide is folded into
a 3-dimensional structure.
GENOTYPE, PHENOTYPE, AND THE ENVIRONMENT:

• A gene is a section of DNA which codes for a polypeptide. A gene can come in different variants (alleles).
• The genetic code specific to us as individuals is our genotype.
• Physical appearance, physiology, behaviours etc. are phenotype. This results primarily from genotype, but the
environment can impact expression of genes and resulting phenotype.

Expression of a gene is complex. Six steps along the path from DNA to protein can be distinguished as possible points of control
of gene expression.

Some environmental factors that can influence gene expression are temperature, light, diet, and pH.

Example of Temperature: Siamese cats – colder temperature turns on genes which in turn allow the cat to grow a pigment.

Example of Light: Tanning in humans – light increases tanning which changes colour of skin.

IMPORTANCE OF POLYPEPTIDE SYNTHESIS:

• Creates proteins which carry out different functions in our body, such as enzymes.
• Proteins control characteristics of all organisms – gene expression is hence a part of polypeptide synthesis.

IMPORTANCE OF MRNA AND TRNA:

mRNA
• Part of transcription involves creation of mRNA strand with nucleotides complementary to the nucleotides on the coding
strand.
• mRNA is important in ensuring organisms’ genes code for correct mRNA codon.
• This allows tRNA molecule with anticodons that correct the amino acid which corresponds to the mRNA codon to form
the correct sequencing.

tRNA
• Ensures anticodon specifies and binds to correct amino acid – ensures polypeptide chain has the correct amino acid
sequencing allowing the protein folding process to occur correctly.
• If this is not done correctly protein may have different shape (primary structure) not suitable for function where it is
needed.

Syllabus Dot-point:
• Investigate the structure and function of proteins in living things

FUNCTION OF PROTEINS:
They are determined by our genotype and have important functions in our body:
• Controls metabolic reactions as enzymes
• Some send intracellular signals
• Some groups, e.g. antibodies, are involved in the adaptive immune system
• Transmembrane proteins alter permeability of cell’s membrane
• Some proteins are directly involved in building, structure, and mechanics of a whole organism e.g. collagen, elastin,
keratin.
 PROTEIN STRUCTURE:

PRIMARY STRUCTURE SECONDARY STRUCTURE TERTIARY STRUCTURE QUARTERNARY

STRUCTURE
The primary structure is the • Refers to local folded • Overall three-dimensional • Many proteins are
sequencing of amino acids. structure that form structure of a polypeptide made up of single
within protein due to • Structure due to various types polypeptide chains
interactions between of interactions between the R and have three
atoms of R-group. groups of amino acids that levels of structure.
• Common types of make up protein. • Some are made of
secondary structures multiple
are alpha helix and the polypeptide
beta pleated sheet. chains, subunits.
• Structures held in • When subunits
shape by hydrogen come together –
bonds – formed gives protein
between carbonyl O of quaternary
one amino acid and structure.
amino H of another.

MODULE 5 – SECTION 4: Genetic Variation

Syllabus Dot-point:
• model the formation of new combinations of genotypes produced during meiosis, including but not limited to:
– interpreting examples of autosomal, sex-linkage, co-dominance, incomplete dominance, and multiple alleles
– constructing and interpreting information and data from pedigrees and Punnett squares

SEX LINKAGE:

SEX DETERMINATION
• Every cell in human body contains 23 pairs of chromosomes (22 pairs of autosomes – chromosomes coding for general
traits in body) and 1 pair of sex chromosomes.
• Sex of an individual is determined by sex chromosomes contributed to the zygote by sperm and egg.
• Egg can donate an X. Sperm can donate X or Y and determines the sex of a child.

SEX-LINKED INHERITANCE
• Sex chromosomes carry genes which determine sexual characteristics and ultimately the sex of a person.
• Other traits are located on sex chromosomes – males only have one X-chromosome, which leads to inheritance patterns
which differ from autosomal inheritance.
• This was first documented and explained by Thomas Morgan in 1910 while he performed a series of experiments with
fruit flies.

INCOMPLETE DOMINANCE:
• A third physical type can occur when an individual is heterozygous.
Usually a phenotype which is in between both alleles is shown. E.g.
flower colour.
CO-DOMINANCE:

• Both alleles expressed equally.

• E.g. roan cattle are red and white.
• If codominance was seen in flowers, it
would result in flowers that had both red
and white.

MULTIPLE ALLELES:

• More than two alleles for a trait.

• Example: Blood type in humans
• Blood types: Type A, B, AB, O
• Alleles: IA, IB, i.

RULES FOR BLOOD TYPE:

A and B are codominant:

• IAIA = Type A
• IBIB = Type B
• IAIB = Type AB

A and B are dominant over O:

• IAi = Type A
• IBi = Type B
• ii = Type O

DIHYBRID CROSSES:

• Crosses where the inheritance of two characteristics at the same time are considered.

PEDIGREES:

• A record of the family of an individual.

• Used to study transmission of hereditary condition
• Useful when there are large families and there is a good family record over several generations.

RULES FOR PEDIGREE CHARTS:

 RULES FOR PEDIGREE CHARTS (Continued):

Autosomal Dominant Autosomal Recessive

• Trait is common in pedigrees • Trait is rare in pedigree
• Found in every generation • Can skip generations.
• Generally, trait is passed on to roughly ½ of the children. • Will affect males and females equally

X-Linked Dominant X-Linked Recessive

• Trait is common in pedigrees • Trait is rare in pedigrees
• Affected fathers pass to all their daughters • Can skip generations
• Males and females equally affected • Affected fathers don’t pass to sons
• Males more often affected than females.

Syllabus Dot-point:
• collect, record and present data to represent frequencies of characteristics in a population, in order to identify trends, patterns,
relationships and limitations in data, for example:
– examining frequency data
– analysing single nucleotide polymorphism (SNP)

ALLELE FREQUENCY:

• Genetic variability in populations can be determined by analysing relative proportions of given phenotypes, genotypes, or
alleles within that population.
• Measure of how common an allele is within a population. For a gene with 2 alleles:
Number of copies of allele G in the population
Frequency of allele G =
Total number of copies of the gene (G + g) in the population

If a gene had more than two alleles, add and divide by the total number of each allele.
SINGLE NUCLEOTIDE POLYMORPHISM (SNP'S):

• Single nucleotide substitutions of one base for another.

• Not all single-nucleotide changes are SNP's – two or more versions of a
sequence must each be present in at least 1% of the general population.
• Can affect gene/protein function but often in non-coding sections of DNA
• Used as genetic markers (to distinguish individuals and identify things such as
disease susceptibility in individuals).
• Approx 10 million SNP's in the human genome.

SHORT TANDEM REPEATS (STR'S):

• Non-coding DNA that has strings of repeating

nucleotides (AGAGAGAGAG for example.
• Number of repeats vary between individuals.
• Analysis of the size of STR's allows for
comparison between individuals and is used for
paternity tests and crime investigations.

MODULE 5 – SECTION 5: Inheritance Patterns within a Population

Syllabus Dot-point:
• Investigate the use of technologies to determine inheritance patterns in a population using, for example:
- DNA sequencing and profiling

DNA SEQUENCING:

• Exact nucleotide sequence of a gene on

a chromosome is identified.
• The compilation of large amounts of
sequencing data allows us to model
changes in frequencies of genes and
alleles in population over space and
time.
• Methods of sequencing include the
Sanger method and the Maxam-Gilbert
method.

Sanger Method:
• Target DNA is copied many times to
make fragments of different lengths.
• Fluorescent “chain terminator”
nucleotides mark ends of fragments and
allow sequences to be determined.

PCR (Polymerase Chain Reaction):

• Referring to the amplification of specific DNA segments. A single copy can make thousands or millions of the one DNA
segment.
• There are three stages of PCR: Denaturing (DNA heated and separated into strands), Annealing (temperature lowered
allowing the DNA primers to attach to DNA), Extending (temperature raised and new strand of DNA made by
polymerase).
DNA PROFILING:

• Used to identify and compare individuals by their

characteristics in their DNA.

Gel Electrophoresis:

• Technique used to separate DNA fragments

according to their size. This can then be used to
investigate crime scenes.
• Also can be used to analyse results of a PCR.

END OF MODULE 5!
 YEAR 12 BIOLOGY
MODULE 6 – GENETIC CHANGE

Sections Covered:
Mutation
Biotechnology
Genetic Technologies
MODULE 6 – SECTION 1: Mutation

Syllabus Dot-point:
• explain how a range of mutagens operate, including but not limited to:
– electromagnetic radiation sources
– chemicals
– naturally occurring mutagens

WHAT ARE MUTATIONS AND MUTAGENS?

• Mutations – permanent change in DNA structure which alters genetic sequencing of a gene.
• Amino acid sequencing of proteins may also be modified such that it's effectiveness is lowered or removed completely.
• Mutations can be spontaneous due to errors in meiosis or mitosis, or from natural degradation over time. They can also
be induced from environmental agents known as mutagens.

PHYSICAL MUTAGENS – ELECTROMAGNETIC RADIATION SOURCES:

• Gamma rays and X-rays etc. are ionising radiation which can directly damage the chemicals that make up DNA and
produce free radicals (reactive molecules).
• UV is non-ionising – produces formation of thymine dimer → two T-bases next to each other absorb UV light and bond
together causing bulges in DNA that will block replication, which will therefore cause errors.

CHEMICAL MUTAGENS:

• Intercalating agents – chemicals slip in between two base pairs and alter
morphology of DNA at that point, which will higher the chances of replication
errors, and will cause mutations.
• Base analogue – morphologically similar to normal nitrogen bases. During
replication these molecules are implemented instead of normal nitrogen bases
which causes mutation.
• Reacting chemicals – Chemical mutagens react directly with nitrogen bases of
DNA and chemically modify the DNA to cause mutation.

BIOLOGICAL MUTAGENS – NATURALLY OCCURING MUTAGENS:

• Living molecules which cause mutation and cancer.

• Retroviruses – viruses which can insert genetic material in the DNA of a host cell, causing a mutation in the cell (causes
cancers such as HPV).

• Transposable genetics elements – Discrete sections of DNA which can move around among chromosomes.
• Can transfer genes to a structurally unrelated part of DNA or another chromosome.
• Process of inserting into the genome or removing them "cut and paste", can interrupt normal sequencing of DNA and
cause mutation.
 Syllabus Dot-point:
• Compare the causes, processes, and effects of different types of mutation, including but not limited to:
– point mutation
– chromosomal mutation

POINT MUTATIONS:

• Involves changes in one or few nucleotides – occurs at single point in DNA and can occur during replication.
• Includes different types: substitution, insertion, deletion.

SUBSTITUTION:
• One base is changed to a different base.
• Usually affect only one amino acid – may not even have an effect at all.

FRAMESHIFT MUTATIONS (INSERTIONS AND DELETIONS):

• Insertion is when one base is added to DNA sequence, deletion is when one base is removed from the DNA sequence.
• Also called frameshift mutations – shifts “reading frame” of DNA sequence.
• Can change all amino acids following the mutation which can alter a protein to make it unable to carry out functions.

TABLE OF POINT MUTATIONS AND EFFECTS

TYPE OF POINT MUTATION EFFECT OF POINT MUTATION

Silent DNA change does not alter amino acid sequence (certain codons
coding for same amino acid).
Missense DNA change alters single amino acid in DNA sequence such as
in sickle cell anaemia.
Changes level and activity of protein.
Nonsense DNA change which creates premature stop codon and truncates
polypeptide e.g. Cystic Fibrosis
Protein becomes dysfunctional.
Frameshift DNA change affects every codon beyond point of mutation –
changes the amino acid sequencing significantly.
Results in a non-functional protein.

CHROMOSOMAL MUTATIONS:

CHANGES IN CHROMOSOMAL NUMBERS:

• Nondisjunction of chromosomes during meiosis – chromosomes line up in centre of cell but fail to separate to two sides
of the cell.
• Results in mutant gametes (sperm cells) – some contain extra chromosomes, and some contain less. E.g. in karyotypes if
there is a nondisjunction of C-21, when gametes are produced one has two C-21’s while other is missing chromosome.
When double chromosome fuses with one chromosome, result is 3 chromosomes which causes down-syndrome.

REARRANGEMENTS OF GENES ON CHROMOSOMES:

• Mutations occur when chromosomes break and reform but altered in the process – 4 types of rearrangement: Deletion,
replication, inversion, translocation.
TABLE OF REARRANGEMENTS OF GENES ON CHROMOSOMES

Type of Rearrangement What is it?

Deletion Loss of part or all of chromosome.

Effect: Disrupted or missing genes – effect on growth and

development of organism.

Replication Copy of all or part of chromosome.

Effect: Increases gene expression, may be either beneficial or

harmful depending on the gene.

Inversion Reverses direction of parts of chromosome.

Effect: Lowered fertility due to production of unbalanced

gametes.

Translocation Part of chromosome breaks off and attaches to another.

Alternatively, two chromosomes exchange segments with
Effect: Interrupts gene regulation – causes of some forms of each other.
cancer.

POLYPLOIDY:

• In some cases, entire set of chromosomes can be inherited → mutant diploid gene fuses with normal haploid gene,
creating a triploid cell.
• Can cause disruption of chromosome pairing during meiosis – results in production of unbalanced gametes and hence
infertility.
 Syllabus Dot-point:
• Distinguish between somatic mutations and germ-line mutations and their effect on an organism.

SOMATIC MUTATIONS:

• Somatic cells – body cells.

• Somatic mutations occur in somatic cells – usually a result
of environmental factors such as radiation.
• Mutation occurs during normal process of mitotic cell
division and growth.
• Mutations in somatic cells not passed onto next generation
of offspring and thus don’t affect gene pool.

GERM-LINE MUTATIONS:

• Germ line cells produces gametes – egg and sperm cells.

• Mutation in germ line cell can be passed onto next
generation – offspring has possibility of carrying the
mutation.
• Mutation becomes a part of the gene pool – affects
population and increases chance for evolution.

Syllabus Dot-point:
• Assess the significance of ‘coding’ and ‘non-coding’ DNA segments in the process of mutation.

SIGNIFICANCE OF CODING DNA IN PROCESS OF MUTATION:

• Coding DNA – DNA which codes for proteins (responsible for mRNA sequence during transcription).
• Mutations in coding genes affect type or sequencing of amino acids in a protein end-product.
• In eukaryotes – could affect gene splicing and modify function or levels of the protein.

SIGNIFICANCE OF NON-CODING DNA IN PROCESS OF MUTATION:

• DNA sequences in non-coding region of DNA control gene expression – controls where and when genes are expressed,
location of splicing to remove introns, and location for ribosome to bind to mRNA.
• If mutation occurs in a DNA segment located in this region – production of small nuclear RNA responsible for DNA
splicing may be affected. Small nuclear RNA might therefore lose function and hence some introns might not be spliced
before translation.
• Intron which is not spliced away could signal for a stop codon during translation – affects sequencing of polypeptide
chain.

Syllabus Dot-point:
• Investigate the causes of genetic variation relating to the processes of fertilisation, meiosis, and mutation.

FERTILISATION:

• 1 gamete from each parent forms zygote – increases genetic diversity since every gamete contains a different set of DNA
(due to independent assortment and random segregation in meiosis), producing a unique combination of genes in zygote.

MEIOSIS:

• Crossing over – exchanging of genes between homologous chromosomes.

• Random segregation – Two chromosomes separated randomly to reproductive cells’ gametes.

MUTATIONS:

• Changes to organism’s DNA will increase genetic diversity by introduction of new alleles.
 Syllabus Dot-point:
• Evaluate the effect of mutation, gene flow and genetic drift on the gene pool of populations.

EFFECT OF MUTATION ON GENE POOL:

• Rate of mutation of DNA in germ-line cells decreases → frequency of alleles being passed on to new generations will
decrease which results in a decrease in the gene pool.
• If rate of mutation of DNA in germ-line cells increases → frequency of alleles being passed on to new generations will
increase which results in an increase in the gene pool.

EFFECT OF GENE FLOW ON GENE POOL:

• Gene flow – transfer of genetic material from one population to another.

• Immigration of species from one subpopulation to another will allow gene flow amongst species in both populations.
• As species from two populations mate with each other and exchange genetic material, exchange of alleles increases allele
frequency in population, hence increasing genetic variation which results in an increase in gene flow.

EFFECT OF GENETIC DRIFT ON GENE POOL:

• Genetic drift – one or more alleles are lost in a population due to random events which may happen by chance – hence
allele frequency of gene pool will decrease.

BOTTLENECK EFFECT:

• Chance of sudden decline in population due to random

events such as an ice age or natural disasters result in loss
of one or more alleles for a gene in population of concern.
• Decrease in allele freq., lowers genetic variation, and thus
decreases gene pool.

FOUNDER EFFECT:

• Refers to separation of some species from original population to another location.

• Species which are separated are “founders” of new population established in new location. By random chance, new
population has different allele freq. compared to old population which lowers genetic variation in gene pool compared to
old population (founders may not carry all genetic variation of old population).
MODULE 6 – SECTION 2: Biotechnology

Syllabus Dot-point:
• investigate the uses and applications of biotechnology (past, present, and future), including:
– analysing the social implications and ethical uses of biotechnology, including plant and animal examples
– researching future directions of the use of biotechnology
– evaluating the potential benefits for society of research using genetic technologies
– evaluating the changes to the Earth’s biodiversity due to genetic techniques

USES AND APPLICATIONS OF BIOTECHNOLOGY (PAST, PRESENT, FUTURE):

PAST BIOTECHNOLOGY USES/APPLICATIONS:

• Fermentation – occurs when microorganisms break down sugars during aerobic respiration. Commonly used to produce
bread, wine, cheese, tofu, yoghurt etc.
• Medicines – also used biological processes and organisms e.g. ancient Egyptians used honey to treat wounds and
infections.
• Selective breeding – humans choose plants or animal individuals to breed together in order to yield offspring with
desirable traits (e.g. cattle could be high beef yield).
• Artificial insemination – involves taking sperm from male and artificially inserting it into females.

MODERN BIOTECHNOLOGY USES/APPLICATIONS

• Continues to use biological processes such as fermentation.

• Polymerase chain reactions (PCR) – genetic technology used to amplify large amounts of DNA, making it available for
other applications such as gel electrophoresis.
• Gel electrophoresis – Used to analyse genetic relationships in a range of applications, including familial relationships and
forensic investigations.
• Gene cloning – occurs at a cellular level and involves identical copes of one or more genes.
• Whole organism cloning – entire new identical organism is created.

FUTURE BIOTECHNOLOGY USES/APPLICATIONS:

• More widespread use of cloning and recombinant DNA technology e.g. gene therapy (inserting or replacing genes to
prevent or treat disease).

SOCIAL IMPLICATIONS AND ETHICAL USES:

POSITIVE SOCIAL AND ETHICAL USES:

• Genetic diversity: potential to create new arrangements of genes to increase diversity of traits. Has a positive impact
upon course of evolution as traits continue to be recombined to best survive in the environment.
• Open-source directions: Keeping scientific information within the public sphere by creating open-access databases to
create a more democratic process such that scientists can work on projects they find to be important.

CONCERNS WITH SOCIAL AND ETHICAL USES:

• Ownership – personal and private information is valuable to large companies who will pay large amounts of money for
this information. Gene sequencing can allow people to understand more about themselves as humans however there is a
potential for this information to be exploited (e.g. companies who use genetic information to discriminate).
• Intellectual property – Allows for certain processes and products to be patented so that people who invented them can
make profit. With biotechnology this becomes more complicated, for example questioning the rights a person has to a
gene or claiming ownership of a DNA sequencing in a person’s body.

FUTURE DIRECTIONS:

• Synthetic biology – combines engineering principles with biotechnology.

• Movement started out aiming to characterise the fundamental building blocks of biology, DNA, genes, proteins.
• Progress in this field has been helped by establishment of international research competitions such as iGEM
(international genetically engineered machines). Capitalises vast creative energy of researchers at the university level and
directs them toward developing technologies to address world issues.
BENEFITS OF BIOTECHNOLOGY:

• Pharmaceuticals such as vaccines which use understanding of how the immune system responds to invasion of foreign
materials such as viruses, or antibiotics which target certain proteins in bacteria.
• Stem cell treatments – therapeutic cloning to harness stem cells to create skin grafts and treat certain cancers or
autoimmune diseases.
• Agriculture – transgenesis: used to produce genetically modified crops improving the plants ability to survive and
increasing nutritional value.
• Biodegradable plastics – helped to address pollution and improve living systems due to increased biocompatibility.

EFFECT ON BIODIVERSITY:

• Creation of monocultures – favouring genes so as to wipe competitive alleles from species gene pools.
• Horizontal gene transfer – acquisition of genetic information by transfer of a member of different species. As traits
escape into ecosystems, this may pose competition to other naturally occurring alleles.

MODULE 6 – SECTION 3: Genetic Technologies:

Syllabus Dot-point:
• Investigate the uses and advantages of current genetic technologies that induce genetic change.

REPRODUCTIVE TECHNOLOGY:

Method Uses Advantages

Artificial Insemination Animal production and fertility Efficient, makes remote mating
treatment possible, can bypass fertility issues.
IVF – In vitro Fertilisation Fertility treatment Can help patients who otherwise would
not be able to conceive, helps women in
case they have blocked fallopian tubes.
Artificial Pollination Pollination of crops Controlled inheritance of genetic traits.

CLONING TECHNIQUES:

Method Uses Advantages

Whole-organism Cloning Production of genetically identical Definite inheritance of desirable traits.
offspring.
Therapeutic Cloning Medicine – stem cell technologies Stem cells can differentiate into any
cell.
Gene Cloning Medicine and industry Production of biologically relevant
proteins.

RECOMBINANT DNA TECHNIQUES:

Method Uses Advantages

Transgenesis Agriculture (development of pest Creation of organisms with multiple
resistant crops etc.) functions, transference of favourable
traits, reduction of pesticide use.
Gene Sequencing Medicine, genetic research. Identification of genetic disorders and
risk factors.
Gene Therapy Medicine Treatment of diseases e.g. cystic
fibrosis.
ELISA Medicine Can identify infections.
CRISPR Molecular Biology Treatment of infections and can modify
DNA with exceptional precision.
Syllabus Dot-point:
• compare the processes and outcomes of reproductive technologies, including but not limited to:
– artificial insemination
– artificial pollination

Technology Process Outcomes

Artificial Insemination 1. Extraction of sperm. • Favourable genes passed onto
2. Insertion into uterus of females. offspring (pro).
• Limits genetic variation (con).

In-vitro Fertilisation 1. Hormone treatment – stimulates egg • Favourable genes passed onto
production. offspring (pro)
2. Removal of multiple eggs from • Expensive (con)
ovaries
3. Fertilisation (egg and sperm
combination)
4. Incubation (leading to production of
embryo)
5. If successful, embryo is implanted
into the uterus or frozen.

Artificial Pollination 1. Pollen removed from stamen of one • Selection of desirable traits
plant. (pro)
2. Applied to stigma of another plant. • Creation of new plant species
3. Pollen fertilises ovum. (pro)
• Loss of biodiversity (con).
 Syllabus Dot-point:
• Investigate and assess the effectiveness of cloning, including but not limited to:
– whole organism cloning
– gene cloning.

WHOLE ORGANISM CLONING:

• Creation of new organisms which are genetically identical to their parent.
• Occurs through somatic cell nuclear transfer (creation of a viable embryo from somatic cells and egg cells)

PROCESS:
1. Somatic cell removal from organism in interest of cloning –
contains genetic material which is wanted in the offspring.
2. Unfertilised egg removed from a donor organism; DNA is
removed from this.
3. Egg and somatic cell are fused.
4. The resulting cell is cultured so that it begins to divide and
become an embryo.
5. Embryo implanted into a surrogate organism.
6. Surrogate gives birth to an organism which is genetically
identical to donor.

EFFECTIVENESS:
• Clone produced is not strictly identical to parent – if there is a mutation in the somatic cell this is passed onto the
offspring.
• Mitochondria present in cytoplasm of donor egg contains DNA which will be passed on to the clone, meaning the cloned
organism will have a different mitochondrial genome from its parent.
• Expensive and time consuming.

GENE CLONING:
• Production of multiple copies of a specific DNA sequence to produce multiple copies of identical DNA molecules.
• In other words, to assemble recombinant DNA containing a gene of interest, and then directing this DNA into a host
organism which will replicate the gene and produce the target protein in large amounts.

PROCESS (e.g. For duplication of DNA by bacteria):

1. A target gene is identified.
2. Plasmids (circular DNA) are isolated from bacteria.
3. Bacterial plasmid and DNA containing the target gene are treated using a restriction enzyme – cuts DNA and creates sticky
ends or sequences of overhanging single stranded DNA.
4. Complementary stick ends of target gene and plasmid come together and recombined using DNA ligase.
5. The new recombinant plasmid is re-inserted into the host bacteria, so that it expresses many copies of the target gene and
producing more of the target protein. The protein can be extracted and then used for its purpose.

EFFECTIVENESS:
• Fast and cheap.
• Harder to produce large amounts of protein on an industrial scale.
 Syllabus Dot-point:
• Describe techniques and applications used in recombinant DNA technology, for example:
– the development of transgenic organisms in agricultural and medical applications

TRANSGENESIS:
• Introduction of DNA from an external source or a different organism into a living organism, and as a result organism
exhibit new traits which are transferred onto offspring.

METHODS OF PRODUCING TRANSGENIC ORGANISMS:

Plasmids – gene editing in bacteria, facilitated by availability of naturally occurring plasmids into which genes may be easily
inserted.

Retroviral vectors – retroviruses being exploited to deliver foreign genetic material to a cell. They insert RNA into host cells,
which then reverse-transcribe them into their genomes.

DNA Microinjection - Gene of interest is injected into a reproductive cell by a fine glass needle, which is then cultured in vitro
until it develops into an embryo. Then this is implanted into the uterus.

GENE THERAPY:
• A medical treatment (correction of genetic disorders)
whereby a healthy copy of a gene is inserted into a non-
germline tissue in a developed organism.
• Can be transported directly into a cell or via an adeno-
associated viral vector which causes no diseases and a
minor immune response.

ELISA (ENZYME LINKED IMMUNOABSORBENT ASSAY):

• Diagnostic tool – exploits the natural binding affinity of antigens and antibodies. During immune responses, the body
produces antibodies specific to invasive antigens.
• By fixing antigens or antibodies to a surface, this can detect whether a corresponding molecule is present in a sample.
• Can be used to test if individuals have produced antibodies specific to an antigen, indicating their exposure to a disease.
Can also be used to test presence of antigens in a sample.

CRISPR-Cas9:

• The CRISPR-Cas9 system is composed of a guide RNA

containing a nucleotide sequence complementary to the gene
you want to edit, which is bound to a Cas9 protein which can
cut DNA.
• Can be directed to a specific part of a genome with high
accuracy to cut and edit the gene of interest. This can
substitute, insert, or delete up to 20 base pairs and can
improve targeted gene therapy or reversing point mutations.
• Efficient and relatively low cost, can improve gene cloning
and production of transgenic species.
 Syllabus Dot-point:
• Evaluate the benefits of using genetic technologies in agricultural, medical and industrial applications

Application Technique Benefit

Agriculture • Selective breeding • Creation of crop and livestock
• Artificial pollination species which exhibit
• Transgenesis favourable traits
• Creation of organisms which
do not require uses of
herbicides or insecticides, thus
decreasing impact on
environment
Medicine • Gene cloning • Personalised medicine –
• Gene sequencing diagnosis of disorders for better
• Gene therapy treatment.
• ELISA • Improved creation of important
• CRISPR biological molecules for
treatment of disease.
Industry • Gene cloning • Creation of organisms which
• Transgenesis produce industrially significant
products (biofuels, energy etc.)

Syllabus Dot-point:
• Evaluate the effect on biodiversity of using biotechnology in agriculture

EXAMPLE: GOLDEN RICE

• Golden rice – strain of rice developed through genetic engineering techniques.

• Has been designed to produce beta-carotene.
• Intended to be grown in areas whose populations have a shortage in dietary Vitamin A.

Advantages Disadvantages
• Public health benefits (aid with vitamin A • Potential loss of biodiversity in surrounding areas
deficiency) due to unsustainable monoculture practices.
• Introduction of new alleles into the gene pool which • Risks of introducing new molecules into a person's
increases variation across rice species. diet.
• Development of this tech outlines ways for future • Fears of widespread use diverting attention away
research into nutritionally augmented food. from continuing structural inequalities causing
Vitamin A deficiency.
 YEAR 12 BIOLOGY
MODULE 7 – INFECTIOUS DISEASE

Sections Covered:
Causes of Infectious Disease
Response to Pathogens
Immunity
Prevention, Treatment, and Control
 MODULE 7 – SECTION 1: Causes of Infectious Disease

Syllabus Dot-point:
• describe a variety of infectious diseases caused by pathogens, including microorganisms, macroorganisms and non-
cellular pathogens, and collect primary and secondary-sourced data and information relating to disease transmission,
including:
– classifying different pathogens that cause disease in plants and animals
– investigating the transmission of a disease during an epidemic
– design and conduct a practical investigation relating to the microbial testing of water or food samples
– investigate modes of transmission of infectious diseases, including direct contact, indirect contact and vector
transmission
WHAT ARE PATHOGENS?

• Organisms/biogenic molecules that cause disease – infectious

agents.
• Specific for their hosts and can cause disease in a specific or
closely related group of species.

TYPES OF PATHOGENS WHICH CAUSE DISEASE:

Name Description Picture Example

Prions • Proteins capable of causing disease and doesn't contain
genetic material.
• Normal prion proteins are coded for by genes in an Mad Cow
organism's DNA, doesn't cause disease and can be Disease
destroyed by heat.
• Infectious prions can multiply when in contact with normal
proteins.

Viruses • Non cellular pathogens with both living and nonliving

characteristics.
• Contains genetic material and made of a protective coat
enclosing genetic material.
• Viruses attach themselves to host cells and inject genetic Influenza A
material into cell. The cell eventually bursts after replication
of many viruses.

Bacteria • Single celled prokaryotes (no nucleus).

• Disease-causing bacteria produce toxins or chemicals
harmful to the host's body. Cholera

Protozoans • Single-celled eukaryotes.

• Only some types are pathogenic
• Some possess a flagellum to move about (flagellates). Malaria
• Amoeba possess projections of cytoplasm to move them
around (pseudopods)

Fungi • Eukaryotes possessing a cell wall but different to plant cell

walls.
• Most are composed of a system of filaments (hyphae) which Athlete's Foot
spread to form a structure called mycelium.

Parasites • Multicellular and very in size, can cause disease or act as

vectors in transmission.
• Different types of parasites include:
- Endoparasites: lives inside hosts body and included Tapeworms
flatworms and roundworms.
- Ectoparasites: lives on the outside of the body, usually
sucking blood.
TRANSMISSION OF DISEASES DURING EPIDEMICS:

For a disease:
• If more people are infected than usual, it is an epidemic. Occurs when the occurrence of the disease in a given area increases
among the population.
• If disease occurrences increase at a global level and across continents it is a pandemic.

For a disease to occur there must be a pathogen, a host, and a favourable environment for which the pathogen can reproduce or
replicate.

Example: Cholera Outbreak – John Snow

• Cholera is a disease characterized by diarrhoea, cramps, vomiting, and dehydration.
• Mid-19th century – cholera epidemics were hitting London in waves.
• Most people in London obtained water from water pumps which drew contaminated
water from underground sources.
• Although Snow could trace many cases of cholera around the town, places such as the
brewery were found to have had people which didn't contract the disease. This was
due to the establishment having its own well of water.

MODES OF TRANSMISSION:

Direct Transmission – directly contacts the uninfected organism through methods such as kissing, biting, touching, sexual
contact, blood contact.

Indirect Transmission – transfer of an infectious agent from a reservoir to a host through methods such as airborne transmission,
touching infected surfaces, contamination of ingested substances e.g., water, vector transmission.

Syllabus Dot-point:
• Investigate the work of Robert Koch and Louis Pasteur, to explain the causes and transmission of infectious
diseases, including:
– Koch’s postulates
– Pasteur’s experiments on microbial contamination

KOCH'S POSTULATES:

• Robert Koch – German scientist who made many contributions to microbiology.

Koch's Experiment:
• Provided proof that microscopic pathogens cause disease.
• In sheep infected with anthrax (caused by bacteria), Koch found bacteria which he isolated. He then placed the bacteria on agar
places and allowed them to culture. Then he injected the bacteria back into healthy sheep and noticed they were infected as
well.
Kosh's Postulates:
• A way of determining if a particular microorganism causes diseases. This is done as follows:
1. The microorganism should be found in all organisms suffering from disease, but not found in healthy organisms.
2. The microorganism must be isolated from said organism and cultured.
3. The cultured agent must cause the same disease when injected into a healthy organism.
4. The cultured agent must be reisolated from the experimental host and identified as being identical to the original agent.

LOUIE PASTEUR:
• French biologist and chemist – determined that beer and wine sometimes
turn sour due to microbes causing chemical changes to produce alcohol
and lactic acid.
• Referred to spoilage of beer and wine as 'diseases – called the Germ Theory
of Diseases.
• Suggested a solution of heating wine between 50 to 60 degrees to kill off
microbes (nowadays called pasteurisation – used in milk today to increase
longevity of milk before it 'goes off' or becomes contaminated).
• Created vaccines for anthrax and rabies.
 Syllabus Dot-point:
• Assess the causes and effects of diseases on agricultural production, including but not limited to:
– plant diseases
– animal diseases

PLANT DISEASES – PANAMA DISEASE IN BANANAS:

• Panama disease is caused by a parasitic fungus and has bananas as its hosts.
• The disease causes yellowing and wilting of leaves, as well as the splitting
of stems, resulting in damage to the plant tissues and thus it is starved of
food or water.
• In 2014-2015 when this was prevalent, farming operations ceased where
such fields were contaminated – the fungus affects soil permanently and
remains a biosecurity risk. Banana's rose in price due to this as there was a
decrease in production of bananas.

ANIMAL DISEASES – GASTROINTESTINAL WORMS:

• Commonly found in goats, cattle, and sheep.
• Can form in high rainfall or irrigation conditions.
• Parasites have more of an advantage to infect such hosts when farmers selectively breed for desired traits such as increased
wool production as genes for parasitic resistance aren't part of the selection process (often reduced in the population).

OTHER CAUSES/EFFECTS:

• Changing patterns of land use – Deforestation and irrigation practices may change the distribution of organisms, bringing
species together than may not have previously lived in close proximity.
• Pesticide Resistance - Increased presence of pathogens will resistance to pesticides increases the risk of disease transmission
• Loss of genetic diversity – Monocultures for example, results from inbreeding or cloning in agriculture which decreases
genetic variation and increases vulnerability of crops or animals to disease.

Syllabus Dot-point:
• Compare the adaptations of different pathogens that facilitate their entry into and transmission between hosts.

Pathogen Type of Pathogen Adaptations How it assists

entry/transmission
Ticks Parasite Can sense odours, CO2 of Mouthparts – allow ticks to
hosts, humidity of their secure the spikes into their
climate. Sharp spikes on their host while feeding.
mouthparts. Four pairs of Legs – Upper legs used to
legs. reach up and grab onto a
host.
Cordyceps Fungus
Malaria Protozoan
Bubonic Plague Bacteria
 MODULE 7 – SECTION 2: Responses to Pathogens

Syllabus Dot-point:
• Investigate the response of a named Australian plant to a named pathogen through practical and/or secondary-
sourced investigation, for example:
– fungal pathogens
– viral pathogens

EUCALYPTUS TREES AND PROTOZOA – WATER MOULD:

• Water moulds are protists which have devastated Eucalyptus (jarrah) forests in WA – the mould lives in soil and attacks the
roots of the plant to absorb nutrients. '
• Upon examination, jarrah roots reveal lesions where water mould activity has damaged the root tissue, however a similar
Eucalyptus tree (marri gum) which grows amongst the jarrah (demonstrating resistance to the pathogen) reveals healthy roots
with increased lignin development.
• Lignin protects the cell wall of plant cells from damage by pathogens – in some plants the presence of a pathogen increases
lignin production such as in the marri gum.
• PAL (Phenylalanine Ammonia Lyase) is an enzyme associated with lignin production and is thus caused by the presence of a
pathogen.

Syllabus Dot-point:
• Analyse responses to the presence of pathogens by assessing the physical and chemical changes that occur in the
host animal cells and tissues

FIRST LINE OF DEFENCE – INNATE IMMUNE RESPONSE AND PASSIVE BARRIERS:

• Passive innate barrier or first line of defence are physical barriers preventing pathogen entry. They are passive as no energy is
required from the body for the barriers to function. Different physical barriers include:

Barrier Description Image

Skin • Large physical barrier protecting cells from pathogens
• Surface of skin is waterproof – thus can stay in a dry state to hinder
growth of pathogens.
• Bacteria can break down through sweat produced from sweat
glands, also hindering growth of other pathogens.

Mucous Membranes • On surface of respiratory and digestive tracts, producing mucous to

trap pathogens.
• Saliva travelling across the membranes contain enzymes to break
down pathogens.
• The environment of the membranes support growth of chemical-
producing microbes capable of hindering growth of pathogens.
Cilia • Tiny structures located in respiratory tract, the vibrations they cause
allow for mucus (containing trapped pathogens) to be coughed or
sneezed up.
Chemical Barriers • The stomach contains HCl, such high acidity can dissolve mucus
containing pathogens.
• The alkaline environment in intestines can also kill pathogens.
Body Secretions • Urine for example passes through walls of the bladder, helping to
wash the walls to hinder growth of pathogens.
• Saliva contains lysozymes capable of decomposing the cell walls of
bacteria, thus preventing infection from pathogens.
• Tears also contain lysozymes to flush pathogens off the eyes.
 SECOND LINE OF DEFENCE (NON-SPECIFIC ACTIVE IMMUNITY):
• Activated in the case that the passive immune barriers are breached by the pathogen.
• Antigens are molecules which hosts recognise as foreign, thus initiating the production of antibodies to destroy the antigens
and to initiate an immune response (e.g. phagocytosis).
• Phagocytes are types of white blood cells responsible for phagocytosis – when phagocytes
engulf antigens, it combines with lysosomes to break down the antigens.

LYMPHATIC SYSTEM:
• Filters and returns intercellular fluid to the blood using lymph nodes connected by lymph
vessels.
• The lymph nodes (where B and T lymphocytes are formed) can filter and trap antigens –
essentially facilitating lymphocytes to bind with antigens to initiate immune responses.

COMPLEMENT SYSTEM:
• Group of proteins assisting other defence mechanism in destroying extracurricular pathogens.
• Stimulates phagocytes to become more active, attracts phagocytes to site of infection, or destroys membranes of invading
pathogens.

INFLAMMATION:
• Initiated by infected cells releasing chemicals, acting on blood cells resulting in higher blood flow within infection site
(infection site will therefore be hot and red).
• Increase in temperature slows rates at which pathogens reproduce enzymes and proteins crucial for pathogenic invasion and
survival.

CELL DEATH:
• Neighbouring cells die in order to form a structure called granuloma which surrounds infected cells.
• Since pathogens are deprived from food supply by being contained in the wall, they will die whilst preventing the
transmission to other healthy cells.

WHITE BLOOD CELLS IN THE SECOND LINE OF DEFENCE:

Name Description Function

Neutrophil • Most common type of white blood cell found in • Born in the bone marrow and circulates in blood before
blood smear. entering tissues.
• Consists of a single nucleus and can have between • Phagocytes – they destroy bacteria in infected cells.
2-5 lobes.
Eosinophils • Rarely found in blood smears. • Born in bone marrow – migrates from peripheral blood
• Only 2 lobes to their nucleus system to lose connective tissue.
• Contains granules which consist of toxic and • They phagocytose antigen-antibody complexes and produce
destructive proteins Histaminase/Aryl Suphatase B (enzymes which deactivate
inflammatory agents).
• Kills parasites such as worms.
Basophils • Rarest type of WBC contains lots of blue granules • Involved in immune responses to parasites
and a bi-lobed nucleus. • Accumulate at sites of infection, release of serotonin and
• Granules contain heparin, serotonin, histamine etc. histamine increase blood flow to infection site.
Lymphocytes • Second most common type of WBC, most are small • B-lymphocytes develop into plasma cells to make
and slightly bigger than RBC's. antibodies whilst T-lymphocytes attack viruses and cancer
• Consists of a small spherical nucleus. cells.
MODULE 7 – SECTION 3: Immunity

Syllabus Dot-point:
• Investigate and model the innate and adaptive immune systems in the human body

THIRD LINE OF DEFENCE:

• Adaptive immunity – resistance against pathogens which develop

during the course of one’s life.
• Specific response involving WBC’s called lymphocytes: B cells
and T cells.

T-CELLS (Thymus-derived Cell):

• Control’s cell-mediated immunity, protecting the body against:

- Bacteria and viruses inside cell wall
- Protozoa, fungi, parasites (worms etc.)
- Cancerous cells and transplanted foreign tissue.

4 types of T-cells:

T-CELL MEDIATED IMMUNE RESPONSE (does not require antibodies):

1. A pathogen is engulfed and destroyed by a phagocyte, leaving an

antigen sticking on the surface of the phagocyte (APC – antigen presenting
cell).

2. As this moves to the lymph node, the specific receptors of Helper T-

cells attach to matching antigens on the APC’s.

3. Once attached, this promotes TH-cells to divide by mitosis to replicate

and make large numbers of clones.

4. The cloned TH-cells differentiate into other types of T-cells:

- Some remain as TH-cells.
- Some cells become TM-cells (memory T-cells), remembering the specific
antigens so that once exposed to the antigen again, they can produce
multiple cytotoxic T-cells which are also specific.
- Some cells become TC-cells (cytotoxic T-cells) to migrate to infected
cells, attaching their receptors to antigens displayed on other infected
cells and releasing chemicals destroying the cell and pathogens in it.

5. Once infection is defeated, TS-cells (suppressor T-cells) are activated to

stop production and action of TC-cells.

How do TC-cells work?

TC cells detect infected cells and releases chemicals, creating pores in the
membrane and breaking down proteins. Ultimately this causes cell death.
B-CELLS (Bone-marrow maturing cells):
• Control’s antibody-mediated immune responses defending the body against toxin-producing bacteria and viruses outside the
cell.
• Produces antibodies (proteins) which are specific to antigens – antibodies move to site of infection to bind and deactivate
antigens.
• Once antibody-antigen complex is activated, B-cells will clone itself forming many B-plasma cells and fewer memory cells.

FLOW-CHART OF INTERACTIONS BETWEEN B-CELLS AND T-CELLS:

MHC’S (Major Histocompatibility Complex):

• Appears on the surface of cells – glycoprotein molecules (allows the recognition of cells from the body).
• MHCI molecules – present on all cells that possess a nucleus and involved in recognition of antigens by T-cells. For example,
infected cells hold antigens on the MHCI molecule on the surface for T C cells to identify and destroy it.
• MHCII molecules – present in APC’s e.g., macrophages.

Antibody Methods of Destroying Pathogens:

 Syllabus Dot-point:
• Explain how the immune system responds after primary exposure to a pathogen, including innate and acquired
immunity
• Primary exposure – requires the individual to suffer all the
symptoms caused by infection and takes a long time to implement
and succeed.
• Secondary exposure – TM-cells and B-cells respond within hours
well before symptoms appear. After antigen presentation, T H cells
send cytokines to lymph systems, activating TM-cells and B-cells
(main role of innate immune response upon secondary exposure).
• Antibodies levels peak within 2-3 days at higher plasma levels than
primary response.
• Activated B-cell clones generate antibodies which exhibit higher
binding affinity, and plasma antibody levels remain high for weeks
to months after exposure, with 100-1000 more antigens produced than during primary exposure.

MODULE 7 – SECTION 4: Prevention, Treatment, and Control

Syllabus Dot-point:
• Investigate and analyse the wide range of interrelated factors involved in limiting local, regional, and global spread
of a named infectious disease.

LOCAL, REGIONAL, AND GLOBAL FACTORS – INFLUENZA A:

Factor Spread of Disease Measures for limiting spread

Local • Local environments such as schools and • Availability of healthcare clinics/facilities including
hospitals. hospitals or medical centres to access vaccinations
• Suburbs with many schools may have higher against viruses.
incidences of Influenza A due to a large • Social distancing.
number of people students come into contact • Covering mouth/nose.
with. • Wash hands.
• Suburbs with large population density will also • Regional or global surveillance of strains of Influenza
have higher incidences. (e.g., reporting from World Health Organisation)
• Animal husbandry practices.
Regional • Transmission can occur through airplanes,
through transporting both infected and non-
infected individuals to different regions.
• Individuals living in isolated regions are less
likely than those in the city (a higher populated
area) to come in contact with an affected
person.
• Climatic conditions – in colder weather there
will be increased transmission depending on
the virus.
Global • Transmission can also occur on airplanes
through transporting infected people to
different countries, giving Influenza a chance
to spread to another country on a massive
scale.
• Some countries might not provide valuable
information on how to prevent or control the
spread of disease – access to information via
internet in third-world countries are limited in
comparison to first-world countries.
• Misuse of antibiotics and antimicrobial
medication – led to a rise in resistant bacteria.
Syllabus Dot-point:
• Investigate procedures that can be employed to prevent the spread of disease, including but not limited to:
– hygiene practices
– quarantine
– vaccination, including passive and active immunity
– public health campaigns
– use of pesticides
– genetic engineering

Procedure What is the procedure?

Hygiene • Can be divided into personal hygiene and community hygiene.
• Personal hygiene – washing hands before and after the consumption of food and use of the toilet.
Prevents spread of pathogens which cause symptoms such as diarrhoea. Body and hair should be washed
regularly and cleaned to prevent build up of pathogens.
• Community hygiene – Sewage and garbage disposal reduce risk of pathogen numbers increasing and
spreading throughout community e.g., sewage treatment plants use a UV disinfection for the management
of pathogens in water.
Quarantine • Involves the isolation of diseased organisms – a strategy which has been used for a long time to control
the spread of disease.
• Minimising risk of exotic pests and diseases which enter Australia (e.g. Animal quarantine which
involves animals to be quarantined to ensure they are free of disease).
• Plant quarantine – examining all plants, parts of plants and plant products brought into Australia.
• Captains of aircraft and ships are required to notify authorities if any passengers or crew are displaying
symptoms.
Vaccination • Refers to the administration of a vaccine (injection). Immunisation is what happens after vaccination,
stimulates the immune system so that it may recognize the disease in the future and prevent an individual
from future infection from said disease.
Passive Immunity:
• Transfer of antibodies from another source. Effects however are only temporary and memory cells are
not involved.
• Used because a susceptible person could be exposed to disease which could cause immediate
complications (time is important).
Active Immunity:
• Contains cultures of microorganisms which could be living but weakened (harmless) or dead.

Public Health • Government regulations and laws which are followed in hospitals and preparation of food etc.
Campaigns • Childhood immunisation schedules.
• Public educational programs which aim to increase awareness of lifestyle related risk factors to prevent
occurrence of disease (e.g. Slip, Slop, Slap and the “Quit” smoking ads).
Pesticides • Used to kill plants and animals which could be involved in transmission of disease.
• E.g. DDT was an insecticide which was used to kill mosquitoes, but more specifically mosquitoes which
carried malaria.
• Pesticides are also used for any items entering Australia to kill any insects or other types of organisms
present.
Genetic • Involves altering the genetic composition of an organism to make them resistant to disease.
Engineering • GMO’s have been accepted worldwide, however concerns are raised about the effects the organisms may
have on biodiversity.
 Syllabus Dot-point:
• Investigate and assess the effectiveness of pharmaceuticals as treatment strategies for the control of infectious disease,
for example:
– antivirals
– antibiotics

ANTIBIOTICS:
• Chemicals used to treat bacterial diseases, sourced from chemicals which are naturally produced by organisms.
• Different types of antibiotics have different effects on bacteria – vancomycin disrupts cell wall synthesis in some types of
bacteria.
• Antibiotics can treat certain types of fungal and protozoan diseases but cannot be used against viral infections.
• Antibiotic sensitivity tests are conducted by pathology labs to determine the best antibiotic to use, thus improving the
treatment outcomes.

ANTIVIRALS:
• For most diseases caused by viruses there are no drugs which can kill the virus.
• Treatments include the management of the symptoms – antiviral drugs however do exist.
• They do not cure disease but rather help to prevent death from disease and help to manage symptoms.

Syllabus Dot-point:
• Investigate and evaluate environmental management and quarantine methods used to control an epidemic or pandemic.

• Managing the environment during an epidemic reduces the pool of available pathogens.
• Quarantine measures are designed to reduce possibility of transmission of pathogens from infected to non-infected hosts.
• Planning is part of epidemic and pandemic management – includes education and training for all staff involved.
• Successful management requires goodwill and cooperation between population and health workers.

Example – Ebola:
• Ebola virus is a severe infectious disease which is extremely contagious and can cause rapid death.
• Management of the disease is supportive with oral fluids to replace losses in blood volume and antibiotics to manage
potential secondary bacterial infections.
• Environmental management – Provision of facilities for barrier nursing, water and hygiene control, hand hygiene and
safe waste management, provision of personal protective equipment.
• Quarantine methods – Isolation of patients or providing a space of 3m between patient beds, same clinical staff assigned
to a single patient and the medical equipment for their care, visits were restricted, any exposed person was monitored and
isolated for 21 days.

Syllabus Dot-point:
• interpret data relating to the incidence and prevalence of infectious disease in populations, for example:
– mobility of individuals and the portion that are immune or immunised
– Malaria or Dengue Fever in South East Asia.

INCIDENCE:

• Number of new cases occurring during a specified time. Can be thought of as the infection rate.
• Infection rate = (New instance of disease in population) / (Duration or period of time of disease).
• Limitations: incidence rate assumes that the rate is constant throughout the duration of disease.

PREVALENCE:

• Proportion of the population that have the specific disease AT THE TIME.
• The difference between incidence and prevalence is that incidence refers to new cases, prevalence refers to all cases both
previous and current.
• Prevalence rate = (Total instance – old + new cases at some time t) / population of individuals at risk.
 Syllabus Dot-point:
• Evaluate historical and culturally diverse and current strategies to predict and control the spread of disease.

HISTORICAL STRATEGIES:

• Middle ages – infectious diseases and parasites were common such as head lice and worms. Poor hygiene meant skin, if cut,
could be affected with gangrene.
• Was believed the body had four ‘humours’ – blood, yellow and black bile, as well as phlegm.
• Humours needed to be balanced by the withdrawal of blood – an imbalance in the humours could cause sickness.
• Not very effective as it was later on disproved by germ theory, which showed that many diseases which were thought to be
humoral were caused by pathogens.

CULTURAL STRATEGIES:

• Chinese medicine – involves many strategies such as acupuncture, herbal medicine, maintaining a specific diet, Tai-chi etc.
• Chinese medical books provide herbal formulas to treat and control many types of illnesses i.e. ‘warm diseases’ which went
from one person to another and from street to street were treated with bitter and cold herb diseases.
• Medicine has antibiotic properties – ginseng, honeysuckle, Forsythia suspensa (Weeping forsythia - plant).
• Effective as it has been tested for centuries.

CURRENT STRATEGIES:

• Immunisation programs, public health campaigns, provision of fresh water and good sewage treatment and disposal.
• National Framework for Communicable Disease Control (The Australian Government) – developed with assistance of the
states and territories and provides strategies for communicable disease control and prevention, detection, and response.

Syllabus Dot-point:
• Investigate the contemporary application of Aboriginal protocols in the development of particular medicines and
biological materials in Australia and how recognition and protection of Indigenous cultural and intellectual property is
important, for example:
– bush medicine
– smoke bush in Western Australia

• Indigenous cultures around the world have used methods to treat diseases, usually they lived healthy lives however on
occasion there may have been a need for curing of wounds from burns, stings, and bites.

DIFFERENT TYPES OF MEDICINES:

Emu Bush Leaves Used as a decoction, for sores and wounds, an infusion for
colds, headaches, chest pains and diarrhoea treatment.
Tea Tree One of the most widely known antiseptics in the world and
has been used as a mainstream pharmaceutical. Has anti-
microbial and anti-fungal properties. Can treat acne or
blemishes.
Kakadu Plum Highest source of Vitamin C in the world and rich in
antioxidants. Involved in tissue repair and building collagen.
Rich in iron and Vitamin E. Antibacterial, antifungal, and an
antiviral agent.

ABORIGINAL INTELLECTUAL PROPERTY:

• Smoke bush – investigated in the 1980’s and patented as a medication for HIV.
• Healing properties of smoke bush were known to Aboriginals, however the State Government awarded the institute a licence
to conduct research into smoke bush with no financial returns for the traditional custodians.
 YEAR 12 BIOLOGY
MODULE 8 – NON-INFECTIOUS DISEASES AND DISORDERS

Sections Covered:
Homeostasis
Causes and Effects
Epidemiology
Prevention
Technologies and Disorders
MODULE 8 – SECTION 1: Homeostasis

Syllabus Dot-point:
• Construct and interpret negative feedback loops that show homeostasis by using a range of sources, including but not
limited to:
– temperature
– glucose

HOMEOSTASIS AND FEEDBACK LOOPS:

• Homeostasis – maintenance of a constant or almost constant internal environment (body) despite changes in the external
environment.
• Negative feedback loops are used to show homeostasis through detecting the change from the stable state and then
counteraction of the change to return back to a stable state (positive feedback loops do the opposite by moving the body away
from a stable state).

Steps of negative feedback loop:

1. A change occurs
2. The change is detected by an
appropriate receptor
3. Receptor sends a signal to the
control centre
4. Control centre sends a signal to an
appropriate effector
5. Effector responds to the signal.

Temperature – thermoregulation:
• A type of homeostasis mechanism expected to be found in endotherms.

If the body’s temperature rises above or below

37 degrees, thermoreceptors in the
hypothalamus (small region of the brain) detect
the change and respond accordingly.

Responding to cold:
- Vasoconstriction (blood moving close to
surface is reduced)
- Seeking shelter
- Shivering
- Increased metabolism

Responding to heat:
- Sweating
-Vasodilation (more blood is sent to
extremities) – capillaries are flushed with warm
blood.
Blood Glucose Level (BGL):
• Increases and decreases based on intake of foods and
physical activity.
• More carbohydrates = more insulin. Less carbohydrates
= more glucagon.
• If BGL is too high, hyperglycaemia can develop. If
BGL is too low, hypoglycaemia can develop.
• Normal blood glucose level should be regulated at
around 3.5-8mmol/L.

Syllabus Dot-point:
• Investigate the various mechanisms used by organisms to maintain their internal environment within tolerance limits,
including:
– trends and patterns in behavioural, structural, and physiological adaptations in endotherms that assist in maintaining
homeostasis
– internal coordination systems that allow homeostasis to be maintained, including hormones and neural pathways
– mechanisms in plants that allow water balance to be maintained

BEHAVIOURAL, STRUCTURAL, AND PHYSIOLOGICAL ADAPTATIONS OF ENDOTHERMS FOR HOMEOSTASIS:

• Endotherms – organisms which use internal mechanisms (such as the generation of heat energy) to maintain their core body
temperature within a narrow range.

Example – Fairy Penguins:

• Structural adaptation – Short legs and round body, does not have external ear flaps to minimise contact or exposure with cool
surroundings to maintain its body temp.
• Physiological adaptation – Able to thermoregulate their body temperature as their muscle glands is activated, resulting in
shivering to produce heat energy.
• Behavioural adaptation – Able to move into the cool water to lower their body temp in the case that they might overheat.
Penguins also hug each other to minimise penguin’s surface area exposure to cold environment.
INTERNAL COORDINATION SYSTEMS FOR THE MAINTENANCE OF HOMEOSTASIS:
• Nervous system and endocrine systems are internal coordination systems in our body to achieve and maintain homeostasis.

Nervous System (transmits signals between different parts of the body):

• Utilises electrochemical impulses to relay messages regarding information
such as a stimulus detected by a receptor and the appropriate reaction to be
performed by the effectors to counteract the stimulus.
• Involves reception of stimulus, transmission of messages, interpretation,
and generation of responses.
• CNS and PNS (Central/Peripheral Nervous System) make up the nervous
system which provides neural pathways through which receptors can
coordinate with effectors to maintain homeostasis.
• The CNS consists of the Hypothalamus (control centre for regulation,
directs effectors to carry out responses) and the spinal cord (conduction
pathway for nerve impulses, coordinates reflex actions).

Endocrine System (produces hormones for metabolism, growth etc.):

Consists of:

• Hormones (chemical messenger molecules which are transported by the

bloodstream)
• Endocrine glands (pituitary glands which release hormones on direction of
hypothalamus to regulate activity of other glands, thyroid glands, adrenal
glands, pancreas).
• Hypothalamus joins this system with the nervous system as in the
endocrine system, the hypothalamus is responsible for controlling the
endocrine glands as it connects to the pituitary gland.

HOMEOSTASIS MECHANISMS IN PLANTS:

• Controlled stomata opening and closing – in early morning and late afternoon when temperature is cool and sunlight is less
intense, can open stomata for CO2 necessary to carry out photosynthesis. Prevents dehydration.
• Thick and waxy cuticle – Insulates water from excessive sunlight as it reduces internal temperature, therefore decreasing the
evaporation rate.
• Shiny leaves – Shiny leaves help to reflect sunlight and therefore help to reduce the spike in internal temperature due to heat
energy from sunlight, minimising rate of transpiration.
MODULE 8 – SECTION 2: Causes and Effects

Syllabus Dot-point:
• Investigate the causes and effects of non-infectious diseases in humans, including but not limited to:
– genetic diseases
– diseases caused by environmental exposure
– nutritional diseases
– cancer

Type of Disease Disease Name Cause and Effect

Genetic Disease Cystic Fibrosis Cause: Mutation involving deletion of
three base (CCT) in CF gene.
Effect: Effects cells responsible for
secretion of mucus, sweat, digestive
fluids. Individual may have problems
with breathing or performing exercise.
Disease caused by Environmental Skin cancer Cause: Thymine dimer – bonding of
Exposure thymine bases on same DNA strand.
Effect: Discoloured area of skin, yellow
discolouration. Dilation of blood
vessels. Destruction of elastic tissue.
Nutritional Diseases Iron deficiency Cause: Insufficient intake of iron.
Effect: Tiredness and muscle weakness,
pale skin, headache, dizziness, light-
headedness.

Syllabus Dot-point:
• Collect and represent data to show the incidence, prevalence, and mortality rates of non-infectious diseases, for example:
– nutritional diseases.
– diseases caused by environmental exposure

Example – Melanoma:

Incidence: In Australia, there were an estimated 14320 cases diagnosed in 2018 (10.4% of all new cancers which were diagnosed
that year).

Prevalence: In Australia, Melanoma has high reported rates 37 per 100000.

Mortality rates: 1905 deaths in 2018 (3.9% of all cancer deaths in 2018).

Data collected from such scenarios is very useful in many ways including:
• Trends associated with particular diseases.
• Whether certain groups are more susceptible to particular disease.
• Provides pathways for areas in need of further research.
MODULE 8 – SECTION 3: Epidemiology

Syllabus Dot-point:
• Analyse patterns of non-infectious diseases in populations, including their incidence and prevalence, including but not
limited to:
– nutritional diseases
– diseases caused by environmental exposure

NUTRITIONAL DISEASE – OBESITY:

• In 2016, 650 million adults were obese (13% of these over the age of 18)
• 41 million children over 5 were obese or overweight.
• 340 million children/adolescents within the age bracket of 5-19 were overweight or obese.

DISEASE CAUSED BY ENVIRONMENTAL EXPOSURE – CANCER:

• One in two Australian men and women are diagnosed with cancer by the age of 85.
• Leading cause of death – 50000 deaths from cancer est. in 2019.
• 25000 more people die from cancer in comparison to 1982.
• In 2016, 679 Australians died from non-melanoma skin cancer.

Syllabus Dot-point:
• Investigate the treatment/management, and possible future directions for further research, of a non-infectious disease
using an example from one of the non-infectious diseases’ categories listed above.

TREATMENT AND MANAGEMENT OF SKIN CANCER:

• Chemotherapy – drugs which eliminate cancer cells which is injected or consumed in tablets by a patient. Can reduce
symptoms however may also reduce lifetime of a patient.
• Target drug therapy – reduces or stops development of cancerous cells (for example Tafinlar is a substance which prevents a
certain protein functioning, which said protein is responsible for growth of cells.
• Surgery – Localised melanoma cells can be cut out. Not viable when cancer has spread to other parts of body.

FUTURE DIRECTIONS:

• Gene therapy – extracting the affected T-cells and then genetically modified so that it contains a gene specified for a receptor
that are unique to the antigens present in the skin cancer cells which cause melanoma.
• More research is required in the case of unexpected results such as mutation of other genes which result for development of
other forms of cancer than skin cancer.
• Ethical issues – availability to anyone or only rich people?

Syllabus Dot-point:
• Evaluate the method used in an example of an epidemiological study.

• Epidemiology is the study of the cause, distribution, and frequency of a disease in specific populations in order to establish
measures to prevent and control the spread of disease.
• Types of epidemiological studies include descriptive, analytical, and interventional.

Descriptive Epidemiology:

• Person (age, gender, ethnicity, diet, physical activity), place (presence of vectors, climate, geology, population density), and
time (calendar time, time since an event, seasonality) as the main characteristics of disease. Can generate a hypothesis
through this: who has the disease, where is the disease found, what groups was the disease found etc.
• How many people the disease affects?

Analytical Epidemiology:

• How is the disease caused and transmitted? Why?

• Examining the host (traits and behaviour), environment (change in environments that result in changes of transmission) and
agent (biological, physical, and chemical features) is involved.
General Evaluation of an Epidemiological Study:

• Identifies nature/cause of disease WITHIN a population.

• Identifies trends, patterns, and thus priority population groups to implement strategies.
• Results obtained are essential to decisions about campaigns such as public health programs.
• Compares changes over time.
• Downsides: Time-consuming and costly, can only be used for a common disease, without longitudinal data it is hard to
establish cause and effect.

Syllabus Dot-point:
• Evaluate, using examples, the benefits of engaging in an epidemiological study

BENEFITS OF EPIDEMIOLOGICAL STUDIES:

• Identification of disease cause – epidemiology provides public health professionals with information to strategize plans or
public health campaigns to help with the prevention of disease. Also allows professionals to understand where to direct
research.
• At a national, regional, and global health level, organisations such as the World Health Organisation are able to develop
strategies and tools to address global health.
• Descriptive epidemiological studies e.g. – "Who has the disease?" or "Where is the disease found" are questions answered
within this field of study, as well as how many people the disease affects.
MODULE 8 – SECTION 4: Prevention

Syllabus Dot-point:
• Use secondary sources to evaluate the effectiveness of current disease-prevention methods and develop strategies for the
prevention of a non-infectious disease, including but not limited to:
– educational programs and campaigns
– genetic engineering

EDUCATIONAL PROGRAMS AND CAMPAIGNS:

Slip, Slop, Slap! – Skin Cancer

• Addresses how skin cancer is prevented and any recommended products i.e., sunscreen, how individuals determine initial
signs of skin cancer, and any recommended treatments for skin cancer.
• Effectiveness: effective and yielded positive results in decreasing the incident rate skin cancer (for example Melanoma
Research Victoria reports that the rate of melanoma cases fell from 25 per 100000 in 1996 to 14 per 100000 in 2010). This is
also recognized in other countries besides Australia and New Zealand.

GENETIC ENGINEERING – GENE THERAPY:

Kymriah

• Suitable for treating B-cell acute lymphoblastic leukemia.

• Cost is $475000 for a single treatment, not including hospital fees, conditioning chemotherapy, or treatment of side-effects.
• Success rate: In its trial stages, within 3 months of treatment, 83% of the 63 patients involved were removed from signals of
cancer. After 6 months, 89% of the infected individuals who received treatment survived.
MODULE 8 – SECTION 5: Technologies and Disorders

Syllabus Dot-point:
• Explain a range of causes of disorders by investigating the structures and functions of the relevant organs, for example:
– hearing loss
– visual disorders
– loss of kidney function

HEARING LOSS – STRUCTURE AND FUNCTION OF EAR:

Region of Ear Structure Structural Feature/Function

Outer ear Pinna Flesh section of ear. Gathers and directs
sound into the ear canal in the
appropriate direction.
Outer ear Ear Canal Connects pinna to tympanic membrane.
Directs sound to tympanic membrane.
Manufacturing ear-wax.
Outer ear Tympanic Membrane Converts pressurised sound waves into
mechanical energy, protects middle ear
from substances in outer ear.
Middle ear Ear ossicles Small bones located in the middle ear.
Convert mechanical energy of the
tympanic membrane to the oval
window.
Middle ear Oval window Thin membrane between inner and
middle ear. Transfers the mechanical
energy from ossicles to fluid in the
cochlea.
Middle ear Round window Located below the oval window. Moves
in and out to adjust for pressure
differences (mechanical energy in
cochlea).
Inner ear Cochlea Circular chamber with fluids. The fluid
is a medium converting mechanical
energy received from oval window into
electrochemical energy.
Inner ear Organ of Corti Composed of cochlear hair cell
receptors located in cochlea. Receptors
are responsive and active when exposed
to electrochemical energy, transfers
electrochemical signals to auditory
nerve.
Inner ear Auditory nerve Bundle of nerve fibres. Carries
electrochemical signals to auditory
cortex brain.

Hearing Loss – causes:

• Causes of conductive hearing loss are, for example, ear

infections or wax build-up.
• Causes of sensorineural hearing loss are, for example, the
exposure to loud noise which can kill cochlear hair cells.
SIGHT LOSS – STRUCTURE AND FUNCTION OF EYE:

Component of Eye Structural Feature/Function

Conjunctiva Mucous membrane shielding sclera. Protects internal
structures of eye, helps lubricate & nourish the eyes with
mucus.
Cornea Dome shaped tissue wrapping the front of the eye. Protection
of the internals of the eyes and refracting light towards the
eye's retina.
Scelera White part of the eye. Protects inner parts of eye and
maintains its shape.
Choroid Dark pigmented layer comprised of blood vessel between
retina and sclera. Nourishes cells in inner parts of eye.
Pupil Circular opening controlled by iris muscles. Responsible for
permitting light to travel through retina.
Retina Innermost layer, composed of photoreceptors. Converts light
stimuli into electrochemical messages to be interpreted by the
brain.
Iris Coloured part of the eye. Iris muscles control size of pupil and
amount of light able to travel through retina.
Lens Transparent protein disc situated behind the pupil, responsible
for refracting light towards retina.
Aqueous humour Watery fluid located between cornea and lens. Provides and
maintains curved shape of eye.
Vitreous humour Jelly-like fluid located in lens and retina. Provides
environment to help prevent infection of eye.
Ciliary Body Made up of ciliary muscles. Control's curvature of lens.
Optic Nerve Bundle of nerve fibres. Conveys electrochemical message
from photoreceptors to visual cortex of the brain.

Sight loss – causes:

• Colour-blindness – Individual experiences difficulties in distinguishing between colours. This is due to the dysfunctional
pigment in red or green cone cells. Caused by injury to eyes, sex linked recessive alleles responsible for colour blindness.
• Cataracts – Light is prevented from striking the retina, caused by ageing.
KIDNEY FAILURE – STRUCTURE AND FUNCTION OF KIDNEY:

Structure Structural Feature/Function

Glomerulus Network of blood vessels surrounded by the Bowman's
capsule. Creates regions of high blood pressure for filtration
of blood.

Bowman's capsule Cup-shaped structure. Collects filtrate exiting blood from

glomerulus.
Proximal tubule Tube attached to Bowman's capsule. Responsible for active
and passive transport of various components of filtrate from
blood.

Distal tubule Tube attached to ascending loop of Henle. Also responsible

for active and passive transport of components filtered out
from blood.

Loop of henle Loop in the nephron which dips into medulla. Allows salts
and water to be reabsorbed
Collecting duct Large tube at end of nephron which connects to renal pelvis
and the ureter. Transports remaining filtrate (urine) to renal
pelvis.

Kidney failure – causes:

• Caused by high blood pressure, physical trauma, infections, inflammation to the kidney etc.
• Complete loss of kidney function promotes build-up of urea (waste product).
 Syllabus Dot-point:
• Investigate technologies that are used to assist with the effects of a disorder, including but not limited to:
– hearing loss: cochlear implants, bone conduction implants, hearing aids
– visual disorders: spectacles, laser surgery
– loss of kidney function: dialysis

TECHNOLOGY FOR HEARING LOSS:

Hearing Aids
• Electrical devices which amplify sound in the environment for an individual to hear better.
• Directs sound into the ear canal.
• Consists of a microphone, amplifier, and receiver.
• Can restore hearing with cochlear hair cells having low sensitivity.
• Limitations are that it doesn't heal hearing-impaired individuals. If cochlear hair cell receptors are dead, no amplification will
help.

Bionic Ear
• Can directly stimulate the auditory nerve itself and bypass the activation of hair cell receptors.
• Requires surgical implantation.
• Consists of a microphone, speech processor, transmitter, receiver/stimulator, electrodes.
• Limitations are that the surgery is costly from $30k-50k, sound frequencies are also different to environment so it will take a
while to learn new sounds.

Bone Conduction Implants

• Helps when the person's outer and middle ear structures are not functioning normally to detect sound waves.
• Consists of a microphone and a sound processor – transforms sound waves into vibrations which are then sent to the implant.
Sound waves then travel to cochlea.
• Background noise received by external sound processor is lower than normal microphones, good as it removes unwanted
noises. The limitation is that sometimes this might not be wanted in case of small sounds produced during dangerous events.

TECHNOLOGY FOR SIGHT LOSS:

Spectacles
• Adjusts refraction of light prior to radiation striking the eye and undergoing refraction.
• Light strikes cornea and passes through to the lens of the individuals' eyes, resulting in light being refracted more towards
retina.
• Made out of glass once but now plastic, light in weight and less of a chance of being broken.
• Contact lenses are also used to correct vision, are convex in shape and are fitted to match the curvature of the eyeball. These
can be used for cosmetic purposes, sport, entertainment industry, and they can block UV radiation.

Refractive Laser Eye Surgery

• Involves use of lasers to change curvature of cornea to alter refractive power to compensate for any visual defect in the eye.
Lasers are computer operated.

TECHNOLOGY FOR KIDNEY FUNCTION LOSS:

Renal Dialysis
• Semi-permeable dialysis tubing is attached to an artery where patient's blood is pumped into tubing.
• Runs through dialysis fluid inside a machine, urea is not present in fluid.
• Salts are removed from blood during the process.
• Fluid flows in opposite of blood present in dialysing tubing, facilitates diffusion of urea out of the blood.
 Syllabus Dot-point:
• Evaluate the effectiveness of a technology that is used to manage and assist with the effects of a disorder.

TECHNOLOGY – RENAL DIALYSIS:

• Performed two to three times per week at a hospital or home. Helps drive salt and water balance to a normal level on a
frequent basis to avoid accumulation of nitrogenous waste toxic to cells.
• Limitations: Slow process requiring several hours and takes time away from daily life, required to undergo dialysis on a
regular basis as removal of nitrogenous waste occurs only when connected to the dialysis machine. Does not restore kidney
function.
• Effectiveness: Effective in acting as an artificial kidney. Allows the patient to continue to perform everyday functions, such
as breathing normally, without experiencing many symptoms.

END OF HSC BIOLOGY!!!