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MELKA TEJO SPECIAL SECONDARY SCHOOL SECOND ROUND BIOLOGY MOK

MODEL EXAM FOR GRADE 12 STUDENTS DECEMBER 2017 BATU (ZEWAY)
TIME ALLOWED 2:00HRS
I.CHOOSE THE BEST ANSWER FROM THE GIVEN ALTERNATIVES
1. Assume a boy was diagnosed to have less hemoglobin in his blood cells. A doctor predicts the
problem to be within his bone marrow. What would be the possible justification for the problem the boy
has?
A. The boy has less blood in his body thus the less blood the less the hemoglobin will be.
B. The bone marrow has nothing to do with the boys’ problem and the less hemoglobin.
C. The bone marrow may let the blood cells leave before maturation that causes less hemoglobin.
D. The bone marrow may not release the blood cells as needed in the body and cause less
hemoglobin.
2. How would you differentiate between afferent neurons and efferent neurons?
A. Afferent neurons carry information from the central nervous system (CNS) to different parts of the
body.
B. Efferent neurons carry information from receptors to the CNS.
C. Afferent neurons stimulate effector organs, usually muscles or glands.
D. Efferent neurons carry messages from the CNS to different parts of the body to make muscles
contract and/or organs respond to changes in the surroundings.
3. One of the following is a correct match about the parts of the human eye and their color
A. Sclera vs. Blue B. Choroid vs. White C. Iris Vs. various D. Cornea Vs. Black
4. Analyze the relationship between insulin and blood glucose levels in diabetic individuals. One of the
following is the most accurate scenario:
A. Blood sugar levels remain constantly high throughout the day, with no significant fluctuations.
B. Blood sugar levels are higher before meals but tend to normalize after eating due to other regulatory
mechanisms.
C. Blood sugar levels are consistently high regardless of food intake due to the lack of insulin
regulation.
D. Blood sugar levels are higher both before and after meals due to insufficient insulin to regulate
glucose after eating.
5. Analyze the hormonal changes that lead to the disintegration of the uterus lining if pregnancy does not
occur. Which hormone change directly causes this disintegration?
A. The increase in FSH. B. The reduction of the oestrogen and progesterone hormones.
C. The increase in LH. D. The increase in LH and FSH.
6. Assume one of the cells in your body needs energy for an important chemical reaction. Once the cell
utilizes the energy the energy provider will end up to be?
A.ADP B. Lactic-acid C. Adenosine tri phosphate D. ATP
7. STDs are caused by various microbes and the treatment is challenged by various factors. Which one
of the following is a challenge related to the timely diagnosis?
A. People with STDs don’t come to hospitals even when they are very sick.
B. People with STDs are afraid of stigma. C.STDs often has no symptoms. D. STDs lack treatment.
8. One of the following is true about DNA
A.DNA is a helical structure containing two parallel strands that are connected at the phosphate base.
B.DNA is a helical structure containing two parallel strands that are connected at the sugar base.
C.DNA is a helical structure containing two parallel strands that are connected at their base.
D.DNA is a helical structure containing two parallel strands that are connected by bases.
9. How would you interpret the role of meiosis in reducing the chromosome number in sex cells?
A. Meiosis increases the chromosome number in sex cells.
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B. Meiosis divides the chromosome number in body cell.

C. Meiosis reduces the chromosome number in cells.
D. Meiosis does not affect the chromosome number in sex cells.
10. How would you distinguish between mitosis and meiosis in terms of chromosome number?
A. Mitosis results in an increase in chromosome number while meiosis results in a decrease.
B. Mitosis results in a decrease in chromosome number while meiosis results in an increase.
C. Mitosis and meiosis both maintain the same chromosome number.
D. Meiosis results in a decrease in chromosome number while mitosis maintains the same number.
11. What would happen if meiosis does not occur in the reproductive organs?
A. The sperm cell would have 23 chromosomes
B. At fertilization the new cell would have 46 chromosomes
C. At fertilization the new cell would have 92 chromosomes
D. At fertilization the new cells will end up having twins
12. Albinism is characterized by a lack of melanin production in the skin, hair, and eyes. If a mother is
homozygous normal and a father is homozygous albino how many of the children in the F1 generation
will be albino?
A. All B. Two C. None D. One
13. There are significant difference between meiosis I and meiosis II. Because during meiosis II:
A. There is crossing over in prophase B. There is separation of sister chromatids
C. There is separation of homologous pair of chromosome D. Chromosomes line up side by side
14. Suppose 75% of the molecules of an enzyme are inhibited by noncompetitive inhibitors. Which of
the following would happen if the amount of substrate is increased by 50%?
A. The rate of the reaction would increase by 50%. B. The reaction rate would double.
C. The rate of the reaction would remain unchanged D. The rate of the reaction would increase by
75%.
15. Which of the following events occurs during prophase I of meiosis I?
A. Duplication of chromatids B. Separation of homologous chromatids
C. Formation of nuclear envelope & Dispersion of spindle fibers D. exchanging of genetic material
between non sisters chromatids
16. Which of the following is not true about the lock-&-key and induced fit model?
A. Lock-&-key model visualize weakening of substrate bond, whereas induced fit model not.
B. Lock -&-key model doesn't explain development of transition state, while the induced fit model
does.
C. In both cases active site of an enzyme is bind to the substrate.
D. Both express the mechanism of competitive inhibitor
17. All of the followings are non Mendelian inheritance EXCEPT
A. Multiple allelism B. Codominance C. Complete dominance D. Incomplete dominance
18. Which of the following factor does not result in high blood glucose level?
A. Production of low level of insulin B. Loss of response to insulin in target cells
C. Having regular physical exercise D. Over consumption of carbohydrate rich food
19. Why sweating is referred to be best mechanism of cooling down?
A. It raises the temperature of the body B. It is a means by which heat is released
C. It is a means by which sweat glands are arrested D. It is a means by which the body is hydrated
20. Why small animals eat more when compared to their body size?
A. Because they loss much heat compared to their body size B. Because their body weight is small
C. Because their skin is more porous as compared to other animals D. Their skin is covered by thick fat
layer
21. Identify the rightly matched cause and effect.
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A. Increased body temperature- vasodilatation B. Sweating-increase in temperature

C. Increased insulin-shot in blood sugar D. Vasoconstriction- cooling
22. According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
A. The binding of the substrate depends on the shape of the active site.
B. Some enzymes change their structure when activators bind to the enzyme.
C. A competitive inhibitor outcompete the substrate for the active site.
D. The binding of the substrate changes the shape of the enzyme’s active site.
23. A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA
molecule could be composed of
A. 120 thymine and 120 adenine molecules. B. 120 cytosine and 120 thymine molecules.
C. 240 adenine and 240 cytosine molecules. D. 240 guanine and 240 thymine molecules.
24. Which of the following statement about double-stranded DNA is false?
A. The backbone contains deoxy ribose sugars and phosphate groups.
B. The strands are formed by nucleotides linked together via phosphodiester linkage
C. The two strands have an anti parallel orientation
D. The bases are on the outside of the helix and connect the two strands together
25. Which of the following is true of the figure given below? It shows

A. End product inhibition. B. Irreversible inhibition C. Enzyme Denaturation. D. competitive

inhibition
26. Some bacteria are metabolically active in hot springs because
A. They are able to maintain a cooler internal temperature. B. High temperatures make catalysis
unnecessary. C. Their enzymes have high optimal temperatures. D. their enzymes are completely
insensitive to temperature
27. Increasing the substrate concentration in an enzymatic reaction could overcome which of the
following?
A. Denaturiation of the enzyme B. Allosteric inhibition C. Competitive inhibition D. Saturation of
the enzyme activity
28. Which one of the following is true of allosteric inhibition?
A. Enzymes are activated when activator attached on the active site.
B. Inhibition by uncompetitive inhibitor when it affect enzyme action
C. Inhibition by competitive inhibitors when it interacts on the allosteric site
D. It occurred when inhibitors attached on the active site
29. Consider the following chemical reactions below.
I. X+H2O----------X+Y II. APO4- + B---------A+BPO4
The enzymes catalyze the reactions I,II represent respectively
A. Lyases and Hydrolases B. Ligases and Transferases C. Transferases and Hydrolases
D. Hydrolases and Transferases
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30. Which statement is incorrect about the factors that influence the rate of enzymatic action?
A. When sufficient substrate is available the active site almost always occupied.
B. An enzymes activity is generally reduced by an increase in substrate concentration.
C. A change in an extreme PH causes an enzyme to be inactivated.
D. As temperature increases so the rates of an enzyme activity up to optimum point
31. Zinc, an essential trace element for most organisms, is present in the active site of the enzyme
carboxypeptidase. The zinc most likely functions as a
A. Cofactor necessary for enzyme activity. B. Coenzyme derived from a vitamin.
C. Competitive inhibitor of the enzyme. D. Allosteric activator of the enzyme
32. Which type of interaction stabilizes the alpha (α) helix and the beta (β) pleated sheet structures of
proteins?
A. Hydrophobic interactions B. Peptide bonds C. Ionic bonds D. Hydrogen bonds
33. The bases in the template strand of DNA are 5ʹ AGGCTAGGC 3ʹ. The corresponding codon for the
mRNA transcribed is
A. 3ʹ UCCGAUCCG 5ʹ. B. 5ʹUCCGAUCCG 3ʹ C. 5ʹUGCGAUCCG 3ʹ D. 3ʹ UCCGAUCCC 5ʹ.
34. Which of the following stages of cell cycle correctly matched with events involved?
A. G1 Phase - the cell replenishes its energy stores that exhausted & cytoskeleton disintegrates
B. G0 phase - the cell accumulates the building blocks of chromosomal DNA, the associated proteins
and energy to complete the task
C. G2 Phase- the cell is neither dividing nor preparing to divide but performs regulatory and basic
cellular functions
D. M phase - DNA replication proceeds to form identical pairs of DNA molecules that are firmly
attached to the centromeric region.
35. A cell having 32 chromosomes (2n) undergoes meiotic cell division. Then it results in
A. 2 daughter cells each with 32 chromosomes B. 4 daughter cells each with 16chromosomes
C. 4daughter cells each with 32 chromosomes D. 2 daughter cells each with 16 chromosomes
36. A cross between two true breeding lines one with dark blue flowers and one with bright white
flowers produces F1 offspring that are light blue. When the F1 progeny are selfed a 1:2:1 ratio of dark
blue to light blue to white flowers is observed. What genetic phenomenon is consistent with these
results?
A. Incomplete dominance B. codominance C. Random mating D. Complete dominance
37. In cattle, roan skin color occurs in the heterozygous (Rr), offspring of red (RR) and white (rr)
homozygotes. Which of the following crosses would produce offspring in the ratio of 1red:2roan:1
white?
A. Red X white B. roan X roan C .white X roan D. red X roan
38. Regarding seed traits, suppose a heterozygous round yellow pea plant of RrYy genotype is crossed
and produced 256 seeds, how many of the seeds are expected to be round yellow?
A. 72 B. 36 C. 144 D. 48
39.A woman with type B blood has a child with type B blood; one of the following men couldn’t be the
father of the child?
A. AO B.AA C. OO D. BB
40. What is the Role of tRNA in translation?
A. Assembling the amino acids into polypeptide chain
B. Acting as a template for converting a genetic code into sequences of amino acids
C. Carrying genetic information from DNA in the nucleus to cytoplasm
D. Recognizing the codon of mRNA & brings the correct amino acid to the ribosome
41. Which of the following is alternative contains the correct description of stage of meiosis?
A. Prophase I -chromosomes begin to condense and spindle fibers appear.
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B. Anaphase II - the pair of chromosomes are then pulled apart by the meiotic spindle.
C. Metaphase II- pairs of chromosome align next to each other along the center equator of the cell
D. Anaphase I -sister chromatids are pulled to opposite pole
42. Which of the following crosses is result in offspring that only display the dominant phenotype?
A. Homozygous dominant &heterozygous recessive B. Homozygous dominant & homozygous
recessive
C. Heterozygous dominant &heterozygous recessive D. Heterozygous dominant & Homozygous
dominant
43. How does crossing over during meiosis bring variation in species?
A. Creating genes that are not found in both parents due to meiosis
B. Increasing the number of genes in one of the parents during meiosis
C. Combining of genes is gamete that are not found in either parent
D. Combining the segment of DNA on sex chromosome and auto some
44. Which of the following genotypic ratio is not expected in the offspring if two tall pea plants are
Mated? When tall is dominant over short
A. 100%TT B. 50%TT, 50% tt C. 50%Tt, 50%TT D. 25%TT,50%Tt, 25%tt
45. Which one of the following belongs to non-renewable natural resource?
A. Salt B. Water C. Wind D. Sun
46. Food security is ensured only if
A. large technology is used C. garden plantation is applied
B. barrier exist to access food D. enough food is available for all
47. Which one of the following belongs to social equity in a model for sustainable development?
A. Preserving biodiversity C. Income quality
B. Demand satisfaction D. Viability of companies
48. Biology has a vital role in creating conscious citizen by
A. expanding awareness of the society C. minimizing practical applications
B. initiating citizens to negative impact D avoiding the use of modern technology
49. Which is the most useful change made to crops using applications of biotechnology?
A. Crops use more nutrients C. Crops resist more disease
B. Crops need more fertilizer D. Crops take more time to grow
50. Which area of biotechnology would most likely create ethical issues with human society?
A. Insulin production by bacteria B. Genetic engineering to improve agriculture yields
C. Organ cloning for use in trans plants D. DNA and forensic testing of crime scene evidence
51. When DNA is manipulated and moved from one source to another it is known as
A. genetic engineering C. genetically modified organisms
B. gene therapy D. electrophoresis
52. Organism that contains genes from other organisms are called.
A. Polygenic B. Mutagenic C. Transgenic D. Donors
53. One of the following is the example of an antibiotic.
A. Vaccine B. Pathogen C. Penicillin D. Antibody
54. One of the following is used to investigate crime by using blood, saliva and hair.
A. Health science B. Physical science C. Forensic science D. Ecology
55. Waste water is best described as
A. Water that you can cook with B. Water that goes down your drain or toilet
C. Water in a local pond D. River water

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56. One of the following is the use of living organism or their products for the detoxification and degradation
of environmental pollutants
A. Bioengineering B. Bioremediation C. Biotransformation D. Biosensors
57. One of the following is the application of using living organism or their products from
another living organism for the development of products that benefit humans.
A. Biotechnology B. Genetic engineering C. Cell biology D. Biosensors
58. The main goal of using biological warfare in modern conflict is to
A. promote peace and cooperation. B. improves public health in the affected area.
C. provide medical aid to the enemy. D. kill the enemy using disease- causing microorganisms or their
toxins.
59. What is nutrition? It is
A. obtaining food only from micronutrients B. obtaining food to carry out life processes
C. getting food only from macronutrients D. getting food simply to prevent from hunger
60. The blue color of diclorophenol indophenol (DCPIP) reagent turned colorless up on addition to un
known sample. This confirms that the unknown food sample is A. Protein B. starch C. Fat D.
Vitamin C
61. Which of the following is true about balance diet?
A. Eating only fruit is sufficient in order to get a balanced diet.
B. Eating injera every day is enough in order to get a balanced diet.
C. taking only very few foods is enough in order to get a balanced diet
D. Getting enough food from major food classes is required in order to a balance diet.
62. Which of the following digestion activities takes place in the mouth?
A. production of hydrochloric acid by salivation glands B. Absorption of carbohydrates as glucose
C. Breaking down of food into smaller pieces D. Digestion of proteins to amino acids
63. The two human teeth types that are used for biting are
A. canines and premolars B. Incisors and premolars C. molars and premolars D. incisors ad canines
64. Which of the following enzymes uses to digest carbohydrates in the mouth?
A. Lipase B. Amylase C. Trypsin D. Maltose
65. A greenish- yellow alkaline fluid which is produced in the liver is
A. Trypsin B. Saliva C. Pepsin D. Bile
66. In human digestive system, where does absorption of food take place? In the
A. large intestine B. mouth C. small intestine D. stomach
67. The digestion of proteins takes place in the
A. Small intestine only B. Stomach and small intestine. C. Mouth and stomach D. Stomach only
68. Which of the following statements is true about enzymes? They are
A. protein that speed up specific reactions B. found only in the small intestine
C. free from the effect of different pH levels D. important to absorb digested food
69. A biology student did an observation using a microscope and a piece of specimen from the structure
of human breathing system. He put the specimen on the microscope stage and looked at the cilia on the
epithelium tissue and the cartilage rings on the specimen. The specimen he observed was
A. diaphragm B. esophagus C. larynx D. trachea

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70. The black substance found in tobacco smoke which causes chronic obstructive pulmonary disease is
A. Caffeine B. Carbon monoxide. C. Tar. D. Nicotine.
71. Which of the following occurs during inhalation of air?
A. Movement of the ribs up and out B. The diaphragm becomes dome shaped
C. Relaxation of the diaphragm D. Relaxation of the external inter coastal muscles
72Which of the following comparisons about aerobic and anaerobic respiration is correct?
A. aerobic respiration occurs in animal cells while anaerobic respiration occurs in plant cells
B. aerobic respiration occurs in the cytoplasm while anaerobic respiration occurs is the mitochondria
C. Energy produced by aerobic respiration is much higher than that produced by anaerobic
respiration
D. the waste products of anaerobic respiration are CO2 and H2O while that of aerobic respiration is
lactic acid
73. The reaction that is the immediate source of energy for cellular activities is
A. ADP +P +Energy -->ATP +H2O B. ATP +H2O --> ADP +P +Energy
C. Glucose --> Lactic acid +Energy D. Glucose +Oxygen -->CO2 +H2O+Energy
74. Why is double circulation so important for warm blooded animals like us? Because it
A. supplies fully oxygenated blood to all body cells B. increase the pumping efficiency of the heart
C. carries blood directly from the lungs to the body cells D. supplies all cells with sufficient amount of
nutrition
75. What are antigens? They are proteins which
A. play regulatory role in cells B. recognize cells from different organisms
C. allow red blood cells to accommodate more oxygen D. destroy foreign cells to the body
76. The main components of human blood are
A. Plasma, white blood cells, heart and red blood cells.
B. Plasma, red blood cells, white blood cells and platelets
C. Red blood cells, plasma, heart and lymph vessels
D. Red blood cells, platelets, heart and lymph vessels
77. The transportation of oxygen and nutrients within the human body is facilitated by the
A. Excretory system B. Nervous system C. Respiratory system D. Circulatory system
78Which of the following structures of the heart is correctly matched with its function?
A. Left ventricle- contracts and forced the blood out to the lungs
B. Right ventricle- receives deoxygenated blood from the body
C. Left atrium- receives oxygenated blood from the lungs
D. Right atrium- contracts and forces blood out to the body
79. Someone, who has blood group "A" has got a car accident and lost a lot of blood. Therefore, he
needs blood transfusion. Which of the following blood groups is used during the transfusion?
A. O B. B C. AB D. OB
80. The correct pathway of the incoming sound in the ear ossicle is:

A.Stapes Incus Malleus C. Stapes Malleus Incus

B.Malleus Incus Stapes D.Malleus Stapes Incus

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81. All of the following glands secrete their product through the duct except?
A. Mammary glands B. Salivary glands C. Sweat glands D. Adrenal gland
82. Which of the gland and the hormone it secretes is not correctly matched?
A. Thyroid ---Thyroxin C. Pancreas---Insulin
B. Pancreas---adrenaline D. Pituitary---Growth stimulating hormone
83. Which one of the following contraceptive method is only used by human male?
A. Hormonal injection B. IUD C. Vasectomy D. Tubectomy
84. Which one of the following statement is true about nervous system?
A. CNS contain brain and spinal cord
B. Impulse in unmyelinated axon is faster than myelinated axon
C. The nervous system involves the movement of chemical message around the body
D. Neurons are bundles of nerves
Based on the following given item answer question number 65.
1. Relay neuron 2. Sensory receptors 3. Brain 4. Afferent neuron 5. Efferent neuron 6. Effectors
organs
85. The correct pathway of impulses in the voluntary action is;
A. 1,4,5,3,2,6 B. 2,5,3,4,6,1 C, 2,4,3,5,6 D. 6,5,3,4,2
86. Which microorganism is used to produce Mycoprotein, a meat substitute?
A. Spirulina B. Saccharomyces cerevisiae C. Fusarium venenatum D. Methylophilus methylotrophus
87. What is Single-cell protein (SCP)?
A. Protein derived from plant cells B. Protein derived from cells of microorganisms
C. Protein extracted from animal muscle cells D. Protein produced synthetically in a laboratory
88. Which microorganism is used in the production of yoghurt?
A. Streptococcus thermophilus B. Lactobacillus acidophilus
C. Saccharomyces cerevisiae D. Methylophilus methylotrophus
89. Which microorganism is used for fermenting all alcoholic beverages?
A. Lactobacillus B. Saccharomyces C. Escherichia coli D. Pseudomonas
90.What is the primary distinction between spirits and other alcoholic beverages like beerand wine?
A. Spirits undergo fermentation without distillation.
B. Spirits undergo both fermentation and distillation.
C. Spirits are made exclusively from fruit juices.
D. Spirits have lower alcoholic content than beer and wine.
91. Biosensors can be used for
A. detecting glucose and ethanol B. producing growth hormones
C. gene therapy D. mining uranium
92. Gene therapy is used to
A. replace defective genes with healthy ones B. amplify DNA sequences
C. measure specific components in beer D. produce antibiotics
93. Biomining involves the use of microorganisms to
A. amplify DNA B. propagate plants
C. extract valuable metals from low-grade ore D. produce antibiotics
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94. Which microorganism is known for its role in biomining copper and other metals?
A. Saccharomyces cerevisiae B. Thiobacillus ferrooxidan C. Streptomyces
D. Penicillium notatum
95. During composting, organic matter is primarily broken down by
A. fungi and bacteria B. transgenic plants C. producers and consumers D. algae and viruses
96. Which of the following is not a component of biogas?
A. Methane B. Carbon dioxide C. Oxygen D. Hydrogen
97. What is the purpose of using the polymerase chain reaction (PCR) in forensic science?
A. To create transgenic organisms B. To amplify DNA sequences
C. To measure biochemical oxygen demand D. To produce antibiotics
98. During secondary treatment of wastewater, what process is primarily used?
A. Physical filtration B. Chemical precipitation C. Bacterial decomposition D. Thermal oxidation
99. Which one of the following birth control method is correctly matched with its function?
A. Hormonal method -prevents follicle development and ovulation.
B. Physical method – Reduce the lining the uterus.
C. Surgical method-avoids early embryo implantation
D. Natural method-prevent the ovum from reaching to the uterus
100. Which one of the following is the main function of Bowman’s capsule of the human kidney?
A. Mineral reabsorption B. Prevent back flow of urine
C. Ultrafiltiration of blood D. Water preservation

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