Biology Unit 1 Module 3 - Question and Answers 2013 To 2016
Biology Unit 1 Module 3 - Question and Answers 2013 To 2016
Biology Unit 1 Module 3 - Question and Answers 2013 To 2016
2013
4 1
FSH:
LH:
The ovary wall becomes the fruit/The ovary wall X becomes the pericarp (fruit
wall)
The ovule walls (integument) becomes the testa; the ovule becomes the seed; the
egg when fertilized forms the zygote which becomes the embryo; the polar nulei
when fused with the male nuclei becomes the endosperm; Nucellus (Y)
disintegrates (nourishes embryo)/ provides nutritive support
Biology U1 Module 3 Q&A 2013-2016
Acrosome reaction- outer surface of sperm membrane and acrosome membrane rupture to
release hydrolytic enzymes.
Released enzymes digest a path through layer of follicle cells/ granulosa cells (corona radiate)
that surrounds the oocyte.
Sperm use tails (to swim) and reach outer surface of zona pellucida.
Another acrosomal enzyme digests a path through the zona pellucida (jelly coat).
Sperm moves to the surface of secondary oocyte (leaves tail)
Head of sperm fuses with microvilli surrounding secondary oocyte
Sperm penetrates into cytoplasm
Once sperm penetrates oocyte- fertilization membrane forms (cortical reaction)
Secondary oocyte stimulated to complete meiosis
Male nucleus fuses with female nucleus (to form zygote)
Bii) Nutrition
Proper nutrition e.g. foliate and folic acid – prevents spina bifida, calcium, protein and iron are
important for foetal growth – prevents birth defects and low birth weight.
N.B. Spina bifida is a birth defect where there is incomplete closing of the backbone and membranes around the spinal cord.
Spina bifida is best prevented by taking 400 micrograms (mcg) of folic acid every day. Studies have shown that if
all women who could become pregnant were to take a multivitamin with the B-vitamin folic acid, the risk of neural
tube defects could be reduced by up to 70%.
Smoking
(Including second hand smoke)- can contribute to low birth weight, preterm delivery, stillbirth and
chronic health problems for the baby, including cerebral palsy, mental retardation or learning
disabilities, intra uterine growth retardation.
Smoking can cause problems during pregnancy, such as placenta previa and placenta abruption.
Using alcohol during pregnancy can cause behavioural and physical problems to the baby (foetal alcohol
syndrome)
Use of illegal/illicit drugs during pregnancy can result in the baby having low birth weight, birth defects
or symptoms of withdrawal at birth.
Maternal self-care
2014
- Detailed drawing
NOT PLAN!
- Cellular details
correct
Accurate relative
proportions.
- Any three structures
labelled correctly (2
marks) germinal
epithelium, primary
spermatocyte,
secondary
spermatocyte,
spermatid, lumen of
tubule, Sertoli cell.
- Neat and tidy.
Biology U1 Module 3 Q&A 2013-2016
Ai) Explanation:
No gamete formation
No fertilization of gametes
No meiosis
Offspring genetically identical to parents
Only one parent involved.
Definition: Ability of plants to reproduce (asexually/ without sexual reproduction) by producing new plants from
existing vegetative structures (specialized stems, leaves and roots, buds)
Method of plant propogation (not through pollination or via seeds or spores) where new plant individuals develop
from parts such as specialized stems, leaves and roots)
Can be used to grow crops like bananas, seedless grapes and oranges, and sugarcane that do not produce
viable seeds (seedless varieties of fruits are also a result of vegetative propogation)
Since offspring produced are generally identical, more beneficial/ aesthetically desirable/ unique
characteristics can be preserved- best crop/variety (greater control over genetic make-up)
More economical- produced on a large scales/ only one parent/ no need for special mechanisms of
fertilization.
Faster than seed propagation e.g. tissue culture
May allow elimination of the non- fruiting, juvenile phase of the plant’s life when plants will not flower or
produce fruit or take long to do so (speed up time of maturation)
Permits physical/ physiological joining of separate plants for economic advantage- good qualities of two
varieties can be combined in one plant e.g. tissue culture, grafting.
Propagate plants that are difficult to germinate/ crops may be introduced into areas where seed
germination has failed.
Easy to do e.g. from cuttings for garden plants/some crops/ on a large scale/ can be done from one
parent.
- Changes body’s hormonal balance (secondary oocyte not released from ovary)
- No egg available to be fertilized by sperm
- Thinning of uterine linint- deceases probability of feriilsed egg being implanted
- Causes cervical mucus to thicken and form a mucous plug- makes it difficult for sperm to get
through to uterus to fertilise egg
ii)
Client is most likely on or near day 14 of the menstrua cycle hence ovarian follicle has begun to develop
Starting use of combined oral contraceptives (COC) immediately now may not stop ovulation
Best to start COC on the first day of menstrual cyclce (or at least within first 5 days)
COC needs to be taken evey day for 21 days of the cycle with a seven day break
For complete effectiveness, COC must be taken consistently at the same time every day
Inconsistent use of COC may cause failure rate (alter hormonal balance)
Advisable to use some other method of protection e.g. husband using a condom/ abstaining from
intercourse until COC can be started.
Biology U1 Module 3 Q&A 2013-2016
2015
Microscopic/canno
t be seen with
naked eye (about
0.05mm in length)
Spherical/round/oval
Differentiated into
region (head, neck,
middle piece tail-
flagellum)
Endosperm
Ovary (wall )
Increased seed dispersal- eaten by far-ranging animals who then excrete/ scater
the seeds.
Biology U1 Module 3 Q&A 2013-2016
Dioecious plants — male and female flowers on separate plants (self-pollination and hence
self-fertilization cannot occur)
Non-synchronous maturation:
-Dichogamy — stamens and carpels do not open at same time - protandry (male before female);
protogyny (female before male)
Heterostyly — different types of flowers within the species — position of male and female
flower parts can vary among plants encouraging cross pollination
Self-incompatibility — germination and/or growth of pollen grain reduced or inhibited if it
lands on a stigma of the same plant
Male sterility – failure of plant to produce viable pollen grains
Special floral structures — that favour dispersal of pollen by insects or wind
Genetic consequences
Self-fertilization (inbreeding)
Fertilization involving self-pollinated flowers
Reduces genetic variation in population
Can lead to inbreeding depression (less vigorous individuals/increasing
homozygosity/increase in deleterious genes)
Decreases likelihood that at least some individuals will have resistance to stresses
May be more reliable where populations are low or under adverse environmental
conditions
Cross-fertilization (outbreeding)
Fertilization occurs between different plants of the same species
Increases the amount of genetic variation in the population
More vigorous offspring( increase in heterozygosity)
Increases likelihood that at least some individuals will have resistance to stresses (better
adapted to change)
May be less reliable where populations are low or under adverse environmental conditions
Increase likelihood of speciation
Biology U1 Module 3 Q&A 2013-2016
2016
Plan done
Representative
Should show
anther after
dehiscence
Title given e.g.
Cross-section of a
mature anther
Magnification
given (in relation
to
photomicrograph
Villus Foetal
Sinus/lacuna/intervillus space/
placental lakes
Maternal
Endometrium Maternal
1. Protection/Acts as a barrier (separation of circulatory systems) for pathogens, blood cells, some
proteins, maternal blood pressure increases etc.
2. Secretion of hormones (oestrogen, progesterone) important for physiological changes during
pregnancy – production
3. Metabolite and energy storage (some fats, glycogen)
4. Exchange of substances facilitated by large surface area of villi
- Nutrients and antibodies
- Gases (O2, CO2)
- Waste products, for example, urea
5. Reservoir of blood in case of low blood pressure (hypotension) in the foetus
Biology U1 Module 3 Q&A 2013-2016
1. Supports developing foetus. Low levels of amniotic fluid — reduced support and shock-
absorbing properties; possible physical damage to foetus
2. Mitigates effects of gravity. Low levels — reduced isolation from gravity (foetus floats in
amniotic fluid); foetal muscles unable to cope with gravitational forces in early stages;
possible deformities
3. Amniotic fluid acts as temperature buffer (due to high heat capacity of water). Low
levels — greater temperature fluctuations.
4. Amniotic fluid serves as receptacle for urea excreted by foetus (passed to mother’s
blood for excretion) – low amniotic fluid levels can expose foetus to higher concentrations
of waste products
5. Amniotic fluid is swallowed by foetus allowing for muscles to develop for swallowing
and moving materials through alimentary canal – low levels can cause underdevelopment
of the muscles.
Biology U1 Module 3 Q&A 2013-2016
B. Example 2: Penicillin
(5 marks)
Biology U1 Module 3 Q&A 2013-2016
1. Proliferative/follicular phase
- repair and growth of endometrium /thickening of glandular endometrium and blood vessels
develop/ endometrium becomes vascularized and glandular
2. Secretory/Luteal phase
(7 marks)