ADDIS ABABA CITY ADMINISTRATION EDUCATION BUREAU, ADDIS

ABEBA

GRADE 12 BIOLOGY MODEL EXAMINATION

GINBOT 2012/MAY 2020

NUMBER OF QUESTIONS: 100 TIME ALLOWED:- 2 HOURS

GENERAL DIRECTIONS

THIS BOOKLET CONTAINS BIOLOGY EXAMINATION. IN THIS EXAMINATION,

THERE ARE A TOTAL OF 100 MULTIPLE CHOICE QUESTIONS. CAREFULLY SELECT
THE BEST ANSWER AND BLACKEN ONLY THE LETTER OF YOUR CHOICE ON THE
SEPARATE ANSWER SHEET PROVIDED. FOLLOW THE INSTRUCTIONS ON THE
ANSWER SHEET AND THE EXAMINATION PAPER CAREFULLY. USE ONLY PENCIL
TO MARK YOUR ANSWERS. YOUR ANSWER MARK SHOULD BE HEAVY AND DARK,
COVERING THE ANSWER SPACE COMPLETELY. PLEASE ERASE ALL UNNECESSARY
MARKS COMPLETELY FROM YOUR ANSWER SHEET.

YOU ARE ALLOWED TO WORK ON THE EXAM FOR 2 HOURS. WHEN TIME IS
CALLED, YOU MUST IMMEDIATELY STOP WORKING, PUT YOUR PENCIL DOWN,
AND WAIT FOR FURTHER INSTRUCTIONS.

ANY FORM OF CHEATING OR AN ATTEMPT TO CHEAT IN THE EXAMINATION WILL

RESULT IN AN AUTOMATIC DISMISSAL FROM THE EXAMINATION HALL AND
CANCELLATION OF YOUR SCORE (S).

PLEASE MAKE SURE THAT YOU HAVE WRITTEN ALL THE REQUIRED
INFORMATION ON THE ANSWER SHEET BEFORE YOU START TO WORK ON THE
EXAMINATION.

DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO.

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DIRECTION: Each of the following questions is followed by four possible alternatives. Read
each question carefully and BLACKEN the letter of your choice on the answer sheet
provided.

1) Which one of the following is used to find out the way in which life begin on earth from
simple life form into more complex one?
A. Paleontology C. Physiology
B. Oncology D. Entomology
2) In scientific method, what is the importance of a background of research for a given
problem?
A. To make a prediction C. To formulate hypothesis
B. To prepare report of the result D. To make a conclusion
3) Which of the following tools is used by biologist to study the internal anatomy of
experimental animals?
A. Dissecting kit C. Hand lens
B. Petri dish D. Microscope
4) A straight line across an expanse of ground along with ecological measurements are taken
continuously at a regular intervals is called_____.
A. quadrant C. flow meter
B. pitfall traps D. transect
5) What is the independent variable, if we want to measure the effect of tutor on students’
academic success?
A. Academic success C. Tutor
B. Class size D. Number of students.
6) Which one of the following is TRUE in relation to transmission electron microscope?
A. Show the three-dimensional surface of cell
B. Use beams of light to produce magnified images
C. Shows the inside details of a cell structure
D. It has less magnification and resolution power
7) Suppose an experimenter conduct the effect of oxygen on seed germination and divided the
seeds into two groups, supplied sufficient oxygen to group “A” and absence of oxygen to
group “B”. What is group “B” seed called?
A. Test group C. Control group
B. Variable group D. Experimental group

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8) Which of the following is a rarely clinical method to test for HIV infection?
A. Testing for human anti-HIV antibodies
B. Microscopic examination of the viruse
C. Measuring the amount of hemoglobin
D. Counting the number of white blood cells
9) The asymptomatic period following the initial acute stage caused by HIV infection is
characterized by: _____.
A. The body is susceptible to opportunistic infection. C. High level of HIV-antibodies.
B. The number of HIV in the blood is high. D. High level of T-lymphocytes.
10) One of the following decreases the reliability of an experiment?
A. Repeat experiment many times C. Minimizing personal judgment
B. Working as quickly as possible D. Use the most appropriate apparatus
11) What are the two most abundant elements in the body of an organism?
A. Hydrogen and Carbon C. Hydrogen and Oxygen
B. Carbon and Oxygen D. Hydrogen and Nitrogen
12) Which property of water allows organisms to resist change in temperature in cells and
aquatic habitat?
A. High surface tension C. Low density when frozen
B. High specific heat D. Solvent property
13) Which one of the following linkage, links glucose and fructose molecule in making sucrose?
A. α-1,4 glycosidic bond C.β-1,6 glycosidic bond
B. α-1,2 glycosidic bond D. β-1,4 glycosidic bond
14) In the process of condensation reaction making a double sugar, which one of the following
happens?
A. Water is used up C. Two oxygen molecules is released
B. Carbon dioxide is released D. Water is released as byproduct
15) Which of the following group of monosaccharaides are all ketose?
A. Dihydroxy acetone, Fructose and Ribose
B. Glyceraldehyde, Ribose and Glucose
C. Dihydroxy acetone, Ribulose and Fructose
D. Glyceraldehyde, Ribulose and Glucose

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16) What makes phospholipids molecules arrange themselves into bilayer in a water molecule?
A. The double bond of fatty acid C. The high solubility of water
B. The length of fatty acid chain D. The amphipathic nature of lipids
17) What hold and stabilizes secondary structure of protein?
A. Ionic bonding C. Disulphide Bridge
B. Hydrogen bonding D. Hydrophobic interaction
18) One of the following is correct about tertiary structure of a protein.
A. Liner sequence of amino acid chain C. Three dimensional structure of protein
B. Helical structure of protein D. Sub unit structure of protein
19) Which of the following organic compound is most abundant in animal tissue?
A. Carbohydrates C. Lipids
B. Protein D. Nucleic acid
20) Which organic molecule in a cell is the constituent of gene?
A. Nucleic acid C. Protein
C. Lipids D. Carbohydrates
21) When enzyme is denature by extreme temperature, which one of the following does it lost?
A. The peptide bond C. Primary structure
B. Tertiary structure D. Secondary structure
22) Identify the statement that correctly explains why a small amount of enzyme can bring about
a change in a large amount of its substrate.
A. Enzymes consumed during chemical reaction. C. Enzymes specific to their substrate.
B. Enzymes reused over and over again. D. Enzymes easily synthesized in the cell.
23) In which area of enzyme application invertase injected to sucrose paste in order to produce
liquid chocolate?
A. Detergent making industry C. Food processing industry
B. Pulp and paper industry D. pharmaceutical industry
24) In which of the following does the induced fit model of enzyme action differ from the lock
and key model?
A. Enzymes lower the energy of activation
B. Substrate binds at the active site of the enzyme
C. During the reaction an enzyme substrate complex is formed
D. Active site moulded to a precise conformation

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25) Which type of enzyme inhibition its effect is reversed by increasing substrate concentration?
A. Allosteric inhibition C. Non-competitive inhibition
B. Competitive inhibition D. End product inhibition
26) What is the cause of tomato fruits to ripen much more slowly when kept in a refrigerator than
on a table at room temperature?
A. Enzyme produce by bacteria normally inhibit ripening
B. Humidity accelerates enzyme activity and ripening process
C. Room temperature arrest the action of ripening enzymes
D. Low temperature slow the normal action of ripening enzymes
27) If a cell fails to modify proteins and distributes them to the appropriate part of the cell, which
one of its organelle is most likely not functioning?
A. Ribosomes C. Mitochondria
B. Golgi bodies D. Vacuole
28) Which of the following organelle are likely to be more abundant in phagocytic white blood
cells?
A. Lysosomes C. Mitochondria
B. Endoplasmic reticulum D. Vacuole
29) What is the importance of turgor pressure?
A. Prevent loss of water from plant C. Make plant cells plasmolysis
B. Helps the root to loss excess water D. Supporting young plant stems.
30) If a homogenate of eukaryotic cells spun in a centrifuge, which of the cellular organelles settle
out last?
A. Chloroplast C. Nucleus
B. Ribosome D. chloroplast
31) Which of the following cell is an example of a cell formed by reduction division?
A. Bone cell C. Egg cell
B. Nerve cell D. Skin cell
32) Suppose a cell was kept in a solution of unknown concentration and found to have lost its water
content after an hour. Which of the following is correct explanation about the solution and the
cell?
A. Cell is hypertonic to the solution C. The cell is isotonic to solution
B. Solution is hypotonic to the cell D. Solution is hypertonic to the cell

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33) When athletes take a part in a short distance running, how do the cells generate most of the
energy that is needed?
A. Oxidative phosphorylation in muscle cell C. Lactate fermentation in muscle cell
B. Alcoholic fermentation in muscle cell D. Aerobic respiration in muscle cell
34) Under normal condition as electron flow down the electron transport chain of mitochondria,
one of the following could not happen?
A. NAD and FAD are reduced C. Chemiosmosis synthesis of ATP
B. The electron lose free energy D. Proton chemical gradient is formed
35) Which of the following stages of respiration occur in the cytoplasm of the cell?
A. Glycolysis C. Acetyl CoA formation
B. Krebs cycle D. Electron transport chain
36) During aerobic respiration, from which process does most of the ATP molecule is produced?
A. Krebs cycle. C. Conversion of glucose to pyruvate.
B. Substrate level phosphorylation. D. Chemiosmotic phosphorylation.
37) One of the following could happen in the Calvin-Benison cycle of photosynthesis?
A. Photolysis of water C. NADP is reduced
B. ATP is synthesis D. Carbon dioxide is reduced
38) Which of the following happen in both cyclic and non-cyclic phosphorylation?
A. Water is splitting C. NADP is the last electron acceptor
B. Formation of ATP D. Oxygen is evolved as by product
39) In which part of chloroplast does light dependent reaction of photosynthesis take place?
A. In the inter membrane space C. In the thylakoid
B. In the stroma D. On the inner membrane surface
40) Which of the following is true about CAM plants such as cacti?
A. Carbon dioxide fixation takes place in bundle sheath cell
B. Photorespiration occur during high light intensity
C. Chloroplast of bundle sheath cell lack thylakoids
D. Carbon dioxide harvested during the night time
41) Which of the following microorganism is not an example of protozoa?
A. Amoeba C. Euglena
B. Plasmodium D. Chlamydomonas

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42) Surface appendages used by bacteria to attach to one another and to host organisms are
A. cell wall. C. flagella.
B. pilli. D. capsule.
43) Gram positive and Gram negative bacteria are differentially stained by Gram's stain due to the
structure difference in their ___.
A. cell membrane. C. capsule.
B. ribosome. D. cell wall.
44) Which of the following bacterial structure is found in all bacteria?
A. Plasmid. C. DNA.
B. capsule. D. flagella.
45) What is the disease caused by pathogenic microorganisms?
A. Degenerative C. Functional
B. Infectious D. Human induced
46) Which of the following human disease is NOT correctly matched with its mode of
transmission?
A. Sleeping sickness - Physical contact C. Malaria - vector born
B. Cholera - contaminated water D. Influenza - droplet infection
47) One of the following statements is true about Gram-positive bacteria?
A. stained pink by Gram’s stain.
B. have thick peptidoglycan in their cell walls.
C. Take the color of secondary stain safranin .
D. have a membrane outside the peptidoglycan.
48) "Farmer's lung" which results in an allergy in the lung is caused by ___.
A. bacteria. C. virus.
B. fungus. D. protozoa.
49) Which bacterial species is used to transfer recombinant DNA to plants?
A. Escherichia coli C. Nitrogen fixing bacteria
B. Agrobacterium D. Denitrifying bacteria
50) Which of the following can be taken as a good example a cell that lacks nuclear membrane and
mitochondria?
A. Algal cell C. Bacterial cell
B. Fungal cell D. Protozoan cells

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51) Which statement is not true about bacteria? Bacteria have ___.
A. circular DNA. C. prokaryotic cells.
B. cell wall which made from peptidoglycan. D. linear DNA in chromosome.
52) During Genetic engineering process, the genes that can be inserted into another DNA using:
A. restriction endonucleases. C. ligase enzyme.
B. vectors. D. polymerase enzyme.
53) In DNA cloning technology, which of the following molecules serves as a vector of gene of
interest to be transferred to bacterial host?
A. Bacterial DNA C. Nuclear DNA
B. Plasmid DNA D. Mitochondrial DNA
54) Which part of bacteriophage become incorporated into a bacterium and instructs the bacteria
to produce more viruses?
A. DNA C. Envelope
B. RNA D. Peptidoglycan
55) HIV virus inserts its RNA into the host cell and converts its RNA into DNA by using ___.
A. reverse transcriptase. C. gp-120.
B. restriction endonuclease. D. CD4.
56) In the stages of virus infection of cells, the replication in enveloped DNA virus takes place at
______.
A. nucleus. C. cell membrane.
B. cytoplasm. D. mitochondria.
57) Which of the following features makes human T-lymphocyte cells more vulnerable to HIV
attack? The presence of___.
A. cell membrane C. CD4 on the membrane surface
B. DNA on the chromosomes surface D. pores in the cell membrane
58) If a new anti-HIV drug is to be developed to prevent the virus from entering the host cell,
which one of the following processes should the drug target?
A. Reverse transcription C. Integration of viral DNA into host DNA
B. Binding of Gp120 and CD4 D. Assembly of viral parts into a whole virus
59) Which one of the following principles are most of the anti-HIV drugs currently in use working?
A. Inhibition of enzyme action C. Digesting of the viral particles
B. Degradation of viral RNA D. Phagocytosis of the virus

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60) Which of the following is the major killer of AIDs patient?
A. Pneumonia C. Malnutrition
B. Anaemia D. Opportunistic infection
61) One of the following is true about viruses except.
A. all virions contain a protein shell or capsid.
B. all virions contain either DNA or RNA as the genetic material but no chromosomes.
C. all virions contain enzymes inside the capsid.
D. all viruses are obligate intracellular parasites.
62) In nitrogen cycle, what is the bacteria that increase free nitrogen gas in the atmosphere?
A. nitrogen-fixing bacteria. C. nitrifying bacteria.
B. ammonifying bacteria. D. denitrifying bacteria.
63) During carbon cycle process, the amount of carbon dioxide in the atmosphere is reduced by_.
A. photosynthesis. C. fossilisation.
B. respiration. D. combustion.
64) What is the important role played by bacteria and fungi in the ecosystem?
A. Antibiotic reproduction C. Recycling of nutrients
B. Forming organic substances D. Supplying energy to the ecosystem
65) Which component of soil fertility is improved when farmers grow legumes in crop rotation?
A. Phosphorus C. Sulphur
B. Nitrogen D. Carbon
66) Which form of nitrogen absorbed from the soil by plants?
A. Nitrite C. Ammonia
B. Nitrate D. Protein
67) Which of the following microorganism obtain their food from other dead or living organisms
using extracellular digestion?
A. Bacteria C. Viruses
B. Fungi D. Protozoa
68) Which one of the following has a unidirectional flow in an ecosystem?
A. Nitrogen C. water
B. Carbon dioxide D. Energy
69) Which of the following plants would likely colonize bare land first?
A. Annual herbs C. Lichens
B. Mosses D. Perennial herbs

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70) Which of the following term is most appropriate to collectively refer to all the plants, animals
and microorganisms found in Addis Ababa botanical garden forest?
A. Ecology C. Population
B. Ecosystem D. Community
71) What is the term that refers to all parts of the earth where living things are found?
A. Population C. Biosphere
B. Ecosystem D. Environment
72) What is the main reason for the high species richness of plants and animals observed in
Ethiopia?
A. Efficient management of ecological resources C. Lack of disturbance
B. Presence of several biomes D. Lack of predators
73) Suppose sites A, B, C and D have Simpson`s index of diversity (d) values are 10, 8, 6 and 3
respectively, which site is High species diversity and stable ecosystem?
A. site A C. site C
B. site D. site D
74) Intera-specific competition is competition between members of ___.
A. different species in the same ecosystem.
B. the same species in the same ecosystem.
C. the same species in the same habitat.
D. different species in the same habitat.
75) In which phase of population growths of population size increase rapidly due to plentiful
resources and adaptation to the environment?
A. Lag phase C. Log phase
B. Stationary phase D. Decline phase
76) Global human population increase or a decrease does not depend on:
A. natality. C. mortality.
B. access to contraception. D. migration.
77) Gregor Mendel concludes his results as:
A. not all traits are determined by two factors.
B. linked genes do not assort independently
C. genes are not always dominant or recessive.
D. alleles separate when the gametes are formed

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78) In which stages of meiosis crossing over occurs and genetic material is exchanged?
A. Prophase I C. Metaphase I
B. Anaphase II D. Anaphase I
79) A plant has a genotype AABb. There is no linkage of the genes. The gametes it will produce:
A. AB & ab C. AB, Ab, AB & Ab
B. B. Aa & Bb D. AB, Ab, aB & ab
80) In a cross between heterozygous, what proportion is expected to be homozygous recessive?
A. 25% C. 75%
B. 50% D.100%
81) Which of the following is not true about the gene called SRY?
A. Testes develop in its presence C. It is found on the Y-chromosome
B. It determine maleness D. Females have two copies of this gene
82) One of the four siblings is blood group A, the second is B, the third is O, and the fourth is AB.
Their parents must have blood type is ___.
A. A and B C. AB and AB
B. AB and O D. A and AB
83) Before making crosses, which part of flower did Mendel remove to avoid self-pollination?
A. Stigma C. Ovary
B. Ovule D. Stamens
84) Which of the following is not an example of codominance?
A. A child of parents with blood type A and B, who has AB blood type
B. A calf of a red cow & a white cow, which has a roan coat consisting of red & white hairs
C. A child of a parent with blue eyes and a parent with brown eyes, who has brown eyes
D. A flower offspring of red and white flowers, which has both red white petals
85) Genes found only on the "Y" chromosome determine:
A. degenerative retinitis pigmentosa.
B. a gene controlling red-green colour blindness.
C. a gene controlling one form of haemophilia.
D. they are more common among males than in female.
86) Suppose in monohybrid cross 200 F2 plants were produced, what is the number of plants that
are expected to have the dominant and recessive phenotypes respectively?
A. 150 dominant, 50 recessive C. 80 dominant, 120 recessive
B. 160 dominant, 40 recessive D. 100 dominant, 100 recessive

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87) DNA is a very stable molecule at normal temperatures due to:
A. hydrogen bond and Phosphodiaster bond. C. peptide bond and ionic bond.
B. hydrogen bond and glycosidic bond. D. single strand of nucleotides.
88) If it is known that the total number of the purine bases account for 50% of a DNA molecule
and if each of the remaining bases are known to have the same proportion, what proportion is
accounted for by thymine alone in the same molecule?
A. 25% C. 75%
B. 50% D. 100%
89) Which of the following is a recently developed active area of research in biology?
A. Taxonomic study C. Ecological research
B. Study about the cell theory D. Stem cell research
90) Which process produces mRNA during protein synthesis?
A. Translation C. Mutation
B. Replication D. Transcription
91) Which characteristic of RNA makes it suitable for moving out of the nucleus?
A. Inability to replicate C. Its unstable nature
B. Absence of thymine D. smallness of its size
92) If the genetic code on DNA triplets’ base is GTA, what is the complementary codon on
mRNA?
A. CAT C.CAU
B. CUA D. GUA
93) If a cell having 80 chromosomes divides by meiosis, how many chromosomes are expected in
the daughter cells?
A. 60 C. 40
B. 30 D.30
94) In DNA replication, enzyme breaks hydrogen bonds and ‘unwinds’ part of the helix of the
DNA by:
A. DNA helicase enzyme. C. ligase enzyme.
B. DNA polymerase. D. transcriptase.
95) Suppose the amino acid coding region in mRNA is 2400 nucleotides long. How long is the
protein interms of amino acid number?
A. 1200 amino acids C. 800 amino acids
B. 600 amino acids D.400 amino acids

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96) Which of the following is removed from eukaryotic mRNA during post transcriptional
modification?
A. Intron C. promoter
B. Transcriptase D. Exon
97) Which of the ff terms refers to the failure of sister chromatids to separate from one another
during anaphase?
A. Non-disjunction C. Deletion
B. Replication D. Double inversion
98) What is the process called when the plasmid is absorbed from a dead bacterium and exchange
their genetic information?
A. Conjugation C. Co-transformation
B. Transformation D. Transduction
99) Which of the type of mutation is responsible for sickle cell Anaemia?
A. Addition of a base pair C. Deletion a base pair
B. Substitution a base pair D. Frameshift of genetic code
100) What is the type of mutation that arises from a change in the nucleotide sequence of the
DNA at a particular locus of the chromosome?
A. Gene mutation C. structural mutation
B. numerical mutation D. chromosomal mutation

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