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Grade 12 Biology national exam, 2008 E.C. (2016 G.C.)
93 questions · 120 minutes. The first 5 answers are shown with explanations; sit the whole paper timed in the app to get your score and the textbook page behind every question.
- 1.Which of the following food types would most likely give a negative result upon addition of iodine solution?
- A. Bread
- B. Butter
- C. Biscuit
- D. Potato
Answer: B. Iodine tests for starch, which turns blue-black when present. Butter is mostly fat, so it has no starch and gives a negative result. Bread, biscuit, and potato contain starch, so each can give a positive result. Textbook: Grade 10, unit 3 · section 3.1.3. - 2.Which process produced mRNA during protein synthesis?
- A. Translation
- B. Replication
- C. Mutation
- D. Transcription
Answer: D. The key idea is that mRNA is made by transcription. During transcription, a cell copies a gene’s code from DNA into mRNA. Translation uses mRNA to build a protein; replication copies DNA; mutation is a change in genetic material. Textbook: Grade 11, unit 4 · section 4.4. - 3.What is the molecule in plant cells that first captures the radiant energy from the sun light?
- A. ATP
- B. DNA
- C. Chlorophyll
- D. Carbon dioxide
Answer: C. The key idea is that a photosynthetic pigment first absorbs light energy. Chlorophyll absorbs light, exciting electrons that begin the energy-capturing process. ATP stores energy, DNA carries genetic information, and carbon dioxide is a raw material for photosynthesis. Textbook: Grade 12, unit 3 · section 3.2.1. - 4.Of the following functions, which one do triglycerides accomplish in cells?
- A. Increase density of tissues and cells
- B. Increase thermal insulation of cells
- C. Yield limited amount of ATP for cells
- D. Facilitate entry of excess water in to cells
Answer: B. Triglycerides stored in body tissues help reduce heat loss. This thermal insulation is the function listed in B. A is wrong because triglycerides do not increase tissue density; C is wrong because fats can yield a large, not limited, amount of energy; D is wrong because they do not help excess water enter cells. Textbook: Grade 10, unit 3 · section 3.1.3. - 5.Which of the following laboratory glassware is used for culturing bacteria?
- A. Petri-dish
- B. Test tube
- C. Filter paper
- D. Measuring cylinder
Answer: A. Bacteria are commonly grown on a nutrient medium in a Petri dish. The dish holds the medium and lets bacteria grow in a visible colony. A test tube can hold liquid or samples, filter paper separates materials, and a measuring cylinder measures liquid volume. Textbook: Grade 10, unit 3 · section 3.1.3. - 6.of the following, which one is the main source form which plants get the nutrients necessary for their growth and development?
- A. Light
- B. Chlorophyll
- C. Atmosphere
- D. Soil
Answer, explanation and textbook page: open in the app. - 7.Which of the following is the correct sequence of the steps in scientific research?
- A. Hypothesis formulation----> Conclusion---->experiment---->question
- B. question----> Hypothesis formulation---->experiment---->Conclusion
- C. Hypothesis formulation---->question ---->experiment---->Conclusion
- D. question---->Hypothesis formulation ---->Conclusion---->experiment
Answer, explanation and textbook page: open in the app. - 8.Which of the following types of cancer is known to mostly develop in AIDS patients?
- A. Cervical cancer
- B. Stomach cancer
- C. Kaposi's sarcoma
- D. Breast cancer
Answer, explanation and textbook page: open in the app. - 9.How many fatty acids would a cell need to form a molecule of triglyceride
- A. Two
- B. Four
- C. Five
- D. Three
Answer, explanation and textbook page: open in the app. - 10.Which part of the human elementary canal contains digestive enzymes that function at acidic pH?
- A. Stomach
- B. Mouth
- C. Esophagus
- D. Small intestine
Answer, explanation and textbook page: open in the app. - 11.Which of the following is the correct constitution of the sex chromosome of a normal woman?
- A. XY
- B. XX
- C. XO
- D. XXY
Answer, explanation and textbook page: open in the app. - 12.From which of the following does the $O_2$ released during the process of photosynthesis originate?
- A. Pyruvic acid
- B. $CO_2$
- C. Sugar
- D. Water
Answer, explanation and textbook page: open in the app. - 13.What is the best term that expresses the movement of substances in cells against their concentration gradient?
- A. Active transport
- B. Passive transport
- C. Osmosis
- D. Water
Answer, explanation and textbook page: open in the app. - 14.In cell division, what is the phase that comes following the metaphase called?
- A. Extraphase
- B. Prophase
- C. Anaphase
- D. Telophase
Answer, explanation and textbook page: open in the app. - 15.Who was the person that first observed living cells moving around when he examined drops of water under the microscope?
- A. Robert Brown
- B. Robert Hook
- C. Anton van leeuwenhoek
- D. Theodor schwann
Answer, explanation and textbook page: open in the app. - 16.Which of the following is true about gene mutation?
- A. Altering the DNA sequence of a gene
- B. Change in the position of a block of genes
- C. Addition of genes to a chromosome
- D. Loss of genes from a chromosome
Answer, explanation and textbook page: open in the app. - 17.What is the circumstance that causes the health condition known as sickl-cell anaemia?
- A. DNA denaturation
- B. Haemoglobin mutation
- C. RNA mutation and decay
- D. Phosphate mutagenesis
Answer, explanation and textbook page: open in the app. - 18.Based on similarity in number of amino acids found in haemoglobin, which one of the following animals has closer phylogenetic relations to human beings?
- A. Chicken
- B. Horse
- C. Frog
- D. Gibbon
Answer, explanation and textbook page: open in the app. - 19.In which of the following groups of living organisms do the cells lack organized nuclei?
- A. Fungi
- B. Protozoa
- C. Bacteria
- D. Algae
Answer, explanation and textbook page: open in the app. - 20.Which one of the following terms refers to the failure of sister chromatids to separate from one another during anaphase?
- A. Non-disjunction
- B. Replication
- C. Deletion
- D. Double inversion
Answer, explanation and textbook page: open in the app. - 21.If two species are known to belong to the same order ,they must also belong to the same which taxonomic categories?
- A. Class
- B. Family
- C. Species
- D. Genus
Answer, explanation and textbook page: open in the app. - 22.What happens in first reaction of the Krebs cycle during energy transformation?
- A. A 2-C compound is produced.
- B. A 6-C compound is produced.
- C. A 4-C compound is produced.
- D. A 5-C compound is produced.
Answer, explanation and textbook page: open in the app. - 23.What do you call structure that have the same evolutionary origin even though they may now have different structural make-ups or functions?
- A. Endemic
- B. Analogous
- C. Homologous
- D. Indigenous
Answer, explanation and textbook page: open in the app. - 24.For what purpose do biologists use the GPS receiver?
- A. To produce area maps
- B. To measure tree height
- C. To estimate tree ages
- D. To count tree rings
Answer, explanation and textbook page: open in the app. - 25.Which of the following organisms usually forms the pioneer community in the primary biological succession?
- A. Annual herbs
- B. Lichens
- C. Trees
- D. Ferns
Answer, explanation and textbook page: open in the app. - 26.In an experiment designed to study the effect of temperature on the rate of seed germination ,which of the following should the experiment vary?
- A. Seed number
- B. Water quality
- C. Temperature
- D. Seed size
Answer, explanation and textbook page: open in the app. - 27.In the carbon cycle, which of the following processes removes carbon dioxide from the atmosphere?
- A. Respiration
- B. Decomposition
- C. Combustion
- D. Photosynthesis
Answer, explanation and textbook page: open in the app. - 28.Which of the the following sequences represents the correct change in number of chromosomes during fertilization?
- A. n+n 2n
- B. 2n --> 2n
- C. n --> n
- D. 2n---->n+n
Answer, explanation and textbook page: open in the app. - 29."Rats can be produced by keeping rags and grains at a corner of a room". Which of the following thinking supports this statement?
- A. Darwinian evolution
- B. Spontaneous generation
- C. Alternation of generation
- D. Sexual reproduction
Answer, explanation and textbook page: open in the app. - 30.What is the specific name of biological scientists who do research that tries to find evidence of life on other planets in the solar system?
- A. Neurobiologists
- B. Paleontologists
- C. Astrobiologists
- D. Biogeographers
Answer, explanation and textbook page: open in the app. - 31.Which of the following is made of globular proteins?
- A. Enzyme
- B. Keratin
- C. Collagen
- D. Glycogen
Answer, explanation and textbook page: open in the app. - 32.Which of the following events happened before all the others?
- A. The cell theory was proposed .
- B. The protozoa were discovered
- C. The compound microscope was invented .
- D. The structure of DNA was discovered.
Answer, explanation and textbook page: open in the app. - 33.Which of the following is NOT a universal property of all living things?
- A. Heritable characters
- B. Reproduction
- C. Photosynthesis
- D. Growth and development
Answer, explanation and textbook page: open in the app. - 34.In which area of enzyme application is invertase injected to sucrose paste in order to produce liquid chocolates?
- A. Detergent making industry
- B. pulp and paper industry
- C. Pharmaceutical industry
- D. Food processing industry
Answer, explanation and textbook page: open in the app. - 35.Which of the following function best at higher optimum pH than all the rest?
- A. Pepsin
- B. Salivary amylase
- C. Trypsin
- D. Enzymes in the stomach
Answer, explanation and textbook page: open in the app. - 36.Which class of enzymes joins to molecule together by formation of new bonds?
- A. Ligase
- B. Isomerase
- C. Lyase
- D. Hydrolase
Answer, explanation and textbook page: open in the app. - 37.Which of the following has a bigger size than all the other?
- A. A ribosome taken from animal cell
- B. A mitochondrion take from plant cell
- C. A nerve cell taken from a human brain
- D. A glucose molecule taken from a plant cell
Answer, explanation and textbook page: open in the app. - 38.How does a simple microscope differ from a compound microscope?
- A. A simple microscope has no lens.
- B. A simple microscope has got two lenses
- C. A simple microscope uses mirror as lens.
- D. A simple microscope has only one lens.
Answer, explanation and textbook page: open in the app. - 39.Which of the following molecules can serve as a raw material for industries that produce glucose?
- A. Nucleic acids
- B. Proteins
- C. Lipids
- D. Starch
Answer, explanation and textbook page: open in the app. - 40.In enzymes that contain non-protein organic molecules, in addition to the protein component, what is the protein component called?
- A. Apoenzyme
- B. Coenzyme
- C. Holoenzyme
- D. Cofactor
Answer, explanation and textbook page: open in the app. - 41.Which of the following should be done in order to remove an enzyme inhibition caused by a competitive inhibitor?
- A. Remove affected enzyme molecule
- B. Add more substrate to the enzyme
- C. Remove the end product of the reaction
- D. Add more inhibitor to the system
Answer, explanation and textbook page: open in the app. - 42.Which of the following parts of the plant cell is NOT a living component of the cell?
- A. Cell membrane
- B. Cell wall
- C. Cytoplasm
- D. Nucleus
Answer, explanation and textbook page: open in the app. - 43.What are the possible consequences of deforestation of the tropic rain forest?
- A. An increase in existing ecological niches
- B. Reduction in species diversity of an area
- C. Increased removal of $\mathrm{CO_2}$ from the atmosphere
- D. An increase in the amount of nitrogen in the soil
Answer, explanation and textbook page: open in the app. - 44.Which of the following processes releases in to the atmosphere?
- A. Respiration
- B. Assimilation
- C. Feeding
- D. Photosynthesis
Answer, explanation and textbook page: open in the app. - 45.If an area is dominated by just one species having very many individuals, what would be its index of diversity?
- A. Fluctuating
- B. High
- C. Low
- D. Unpredictable
Answer, explanation and textbook page: open in the app. - 46.Which of the following is true about sex determination in birds?
- A. They have heterozygotic ?X and Y chromosomes
- B. Males have ᓼheterozygotic ᓼW and Z chromosomes
- C. Females have the homozygotic WW chromosomes
- D. They have the heterozygotic ᓸW and Z chromosomes
Answer, explanation and textbook page: open in the app. - 47.How many amino acids are there in all known proteins?
- A. About 10
- B. About 35
- C. About 20
- D. About 46
Answer, explanation and textbook page: open in the app. - 48.What percentage of the $F_2$ progeny of a monohybrid cross is expected to have the recessive phenotype?
- A. 100 %
- B. 75 %
- C. 25%
- D. 50 %
Answer, explanation and textbook page: open in the app. - 49.Which of the following is NOT true about innate behaviours?
- A. Can be improved by trial and error
- B. Common to all members of the species
- C. Present at birth or on hatching
- D. Do not have to be learned
Answer, explanation and textbook page: open in the app. - 50.To which one the following classes of stimuli do pheromones belong?
- A. Auditory
- B. Smell
- C. Visual
- D. Touch
Answer, explanation and textbook page: open in the app. - 51.Which of the following types of microscope is most suitable for a detailed study of the surface structure of an object ?
- A. Filed microscope
- B. Optical microscope
- C. Scanning electron microscope
- D. Dissecting microscope
Answer, explanation and textbook page: open in the app. - 52.According to the fluid-mosaic model of the plasma membrane, what does the word 'mosaic' refer to?
- A. The hydrophobic property of fatty acids
- B. The bilayer nature of the membrane
- C. The arrangement of the proteins
- D. The movement of the phospholipids
Answer, explanation and textbook page: open in the app. - 53.Which of the following diseases is correctly matched with its causative agent?
- A. Malaria - fungus
- B. AIDS - virus
- C. Ringworm - protozoa
- D. Syphilis - worm
Answer, explanation and textbook page: open in the app. - 54.Which of the following organic compounds would release both nitrogen and sulphur to the ecosystem when decomposed?
- A. Polysaccharides
- B. Sucrose
- C. Proteins
- D. Lipids
Answer, explanation and textbook page: open in the app. - 55.Among the vertebrate found In ethiopia, which class has the highest percentage of endemic species?
- A. Amphibians
- B. Reptiles
- C. Birds
- D. Mammals
Answer, explanation and textbook page: open in the app. - 56.Which of the following terms refers to the movement of individual out of a population?
- A. Mortality
- B. Immigration
- C. Emigration
- D. Natality
Answer, explanation and textbook page: open in the app. - 57.Which of the following crosses will produce progeny with phenotypic ratio of 3:1?
- A. Crossing the $F_1$ to the dominant parent
- B. Crossing two homozygote individuals
- C. Crossing the $F_1$ to the recessive parent
- D. Crossing two heterozygote individuals
Answer, explanation and textbook page: open in the app. - 58.Which of the following changes that happened during human evolution had the most contribution to the evolutionary success of Homo sapience?
- A. Proportionately big brain size to body mass
- B. Big body parts and big overall body mass
- C. Long legs, arms and more upright body posture
- D. Fast running ability and overall physical strength
Answer, explanation and textbook page: open in the app. - 59.In Ethiopia animal diversity ,which group is presented by the highest number of orders, families, genera and species
- A. Birds
- B. Amphibians
- C. Fish
- D. Mammals
Answer, explanation and textbook page: open in the app. - 60.Why mutations are important in evolution
- A. They are related to the environment.
- B. They contribute to new variation in organisms.
- C. They are always beneficial to the organism
- D. They become causes for species migrations
Answer, explanation and textbook page: open in the app. - 61.Which of the following processes involved in the water cycle is carried out by green plants?
- A. Evaporation
- B. Precipitation
- C. Condensation
- D. Transpiration
Answer, explanation and textbook page: open in the app. - 62.Deficiency of which of the following nutrients in human diet is likely to result in deficiency of some co-enzyme like FAD?
- A. Essential amino acids
- B. Vitamins
- C. Carbohydrate
- D. Saturated fatty acids
Answer, explanation and textbook page: open in the app. - 63.If someone suddenly removes his/her hand from a very hot object, which of the following types of behavior is manifested?
- A. Reflex action
- B. Imprinting
- C. Learned behaviour
- D. Sensitization
Answer, explanation and textbook page: open in the app. - 64.Which step in the HIV life cycle is disrupted by antiretroviral drug that competitively inhibits the reverse transcriptase enzyme?
- A. Entry into the host cell
- B. Assembly of viral parts in to a virus
- C. Formation of DNA from RNA
- D. Integration of viral DNA into host DNA
Answer, explanation and textbook page: open in the app. - 65.During which of the following processes in cellular respiration are most of the ATPs formed?
- A. Glycolysis
- B. Chemiosmosis
- C. Link reaction
- D. Krebs cycle
Answer, explanation and textbook page: open in the app. - 66.Which of the following pairs are ANALOGOUS structures?
- A. The human arm and the front leg of a mule
- B. The front leg of a frog and the wing of a bat
- C. The wing of a bird and the wing of a butterfly
- D. They wing of a bat and the wing of bird
Answer, explanation and textbook page: open in the app. - 67.Which of the following is the adaptation by $C_4$ plants that helps them to avoid photorespiration?
- A. Harvesting of carbon dioxide at night
- B. Using separate cells for light and dark reaction
- C. Storing carbon dioxide in the vacuole
- D. Keeping the stomata closed during the day
Answer, explanation and textbook page: open in the app. - 68.If a codon on a messenger RNA is UUU, what is the complementary anticodon on the transfer RNA?
- A. UUU
- B. GGG
- C. CCC
- D. AAA
Answer, explanation and textbook page: open in the app. - 69.If a clone is produced by transferring a nucleus of animal A to an enucleated egg of animal B and the egg is then implanted in the uterus of animal C, which animal would the clone resemble most?
- A. Animal C
- B. Animal B
- C. Animal A
- D. Other animal
Answer, explanation and textbook page: open in the app. - 70.Which of the following classes of fatty acids is without carbon-carbon double bond?
- A. Monosaturated fatty acids
- B. Unsaturated fatty acids
- C. Saturated fatty acids
- D. Polyunsaturated fatty acids
Answer, explanation and textbook page: open in the app. - 71.Choose the one that had the LEAST contribution to human evolution?
- A. Development of bipedalism
- B. Adaptation to flight
- C. Attaining opposable thumb
- D. increasing brain size
Answer, explanation and textbook page: open in the app. - 72.In which biome are epiphytes typically present as a characteristics element ?
- A. Tropical montane forests
- B. Cold desert woodlands
- C. The Tundra environment
- D. Boreal deciduous forests
Answer, explanation and textbook page: open in the app. - 73.If it is known that the total amount of DNA in a cell is 300 units and that adenine contributes 70 of these units, how many units go to cytosine?
- A. 40 units
- B. 70 units
- C. 80 units
- D. 35 units
Answer, explanation and textbook page: open in the app. - 74.which of the following substance is NOT formed when yeasts ferment glucose?
- A. Alcohol
- B. ATP
- C. Lactic acid
- D. Carbon dioxide
Answer, explanation and textbook page: open in the app. - 75.Which phosphate bond of the ATP is broken when the energy it contain is needed for cellular activity?
- A. The first bond
- B. The C- C bond
- C. The second bound
- D. The third bond
Answer, explanation and textbook page: open in the app. - 76.What is the advantage that a photosystem containing molecules of different types of light sensitive pigments have?
- A. To absorb light of different wavelengths
- B. To increase the size of photosystem
- C. To increase the complexity of the photosystem
- D. To increase the surface area for the light absoption
Answer, explanation and textbook page: open in the app. - 77.How many years have passed since Darwin's book on the theory of evolution was published?
- A. About 50 years
- B. About 160 years
- C. About 120 years
- D. About 100 years
Answer, explanation and textbook page: open in the app. - 78.Which of the following can be understood about living things from the study of how breeders improve domesticated plants and animals?
- A. Living things tend to over-reproduce
- B. Natural resources are of limited supply
- C. Living things can be improved through selection
- D. Individuals compete for resources
Answer, explanation and textbook page: open in the app. - 79.Which of the following is responsible for the bending of a young plant towards a unidirectional source of light?
- A. Reduced photosynthesis on dark side
- B. Faster growth rate on the dark side
- C. Reduced auxin concentration on dark side
- D. Increased rate of cell division on the light side
Answer, explanation and textbook page: open in the app. - 80.In what way would AIDS patients benefit from the treatment with anti-retroviral drugs?
- A. Reduction of HIV replication
- B. Provision of cure for AIDS
- C. Immunizing against HIV
- D. Killing of opportunistic infections agents
Answer, explanation and textbook page: open in the app. - 81.If a country has a large number of young people relative to the number of old people, to which category of countries does it belong?
- A. Industrial
- B. Hunter - gatherer
- C. Post - industrial
- D. Developing
Answer, explanation and textbook page: open in the app. - 82.Which of the following is the best collective name for all bacteria with spherical shape?
- A. Spirochaetes
- B. Bacilli
- C. Cocci
- D. Streptococci
Answer, explanation and textbook page: open in the app. - 83.Suppose two heterozygous round yellow (RrYy x RrYy) pea plants wear crossed and 128 seeds were produced, how many of the seeds are expected to be heterozygous around yellow?
- A. 64 seeds
- B. 32 seeds
- C. 96 seeds
- D. 128 seeds
Answer, explanation and textbook page: open in the app. - 84.Which of the following way is an important way by which green plants mitigate the green house effect?
- A. Use of fire wood to replace coal
- B. Remove $\mathrm{CO_2}$ from the atmosphere
- C. Releasing water to the atmosphere
- D. Releasing oxygen to the atmosphere
Answer, explanation and textbook page: open in the app. - 85.What causes tomato fruits to ripen much more slowly when kept in a refrigerator than if left on a table at room temperature?
- A. Low temperature slows the normal action of ripening enzymes.
- B. Enzymes produced by bacteria normally inhibit ripening.
- C. Humidity accelerates enzyme activity and ripening process.
- D. Normal temperature arrests the action of ripening enzymes.
Answer, explanation and textbook page: open in the app. - 86.Which characteristics of RNA makes it suitable for moving out of the nucleus?
- A. Inability to replicate
- B. Absence of thymine
- C. Its unstable nature
- D. Smallness of its size
Answer, explanation and textbook page: open in the app. - 87.Why does sucrose give a negative result when mixed and heated with Benedict's solution?
- A. Because it is not a sugar molecule.
- B. Because it is a reducing sugar.
- C. Because it is a non-reducing sugar.
- D. Because it is not a monosaccharide.
Answer, explanation and textbook page: open in the app. - 88.What does an evolutionary selective pressure that acts around the mean do?
- A. It stabilizes
- B. It terminates
- C. It converges
- D. It disrupts
Answer, explanation and textbook page: open in the app. - 89.Which of the following is consistent with science?
- A. Proof by investigation of the causes of a phenomenon
- B. Proof by reference to a respected leader
- C. Proof by reference to an unknown object
- D. Proof based on lessons from a person one believe
Answer, explanation and textbook page: open in the app. - 90.In his theory of evolution, the cause of which of the following concepts was MISSING in Darwin's explanation
- A. Ove-reproduction
- B. Struggle for survival
- C. Hereditary variation
- D. Survival of the fittest
Answer, explanation and textbook page: open in the app. - 91.which of the following is a learned behaviour?
- A. Suckling of the newborn at mothers breasts
- B. Salivation by conditioned dogs at the sound of a bell
- C. Withdrawal of hands suddenly from hot objects
- D. Blinking the eyes when something gets into them
Answer, explanation and textbook page: open in the app. - 92.Which of the following diseases is transmitted by mosquitoes?
- A. Diabetes mellitus
- B. Kaposi's cancer
- C. Rabies
- D. Malaria
Answer, explanation and textbook page: open in the app. - 93.In which of the following are all the tools mainly used in the laboratory rather than in the field situation?
- A. Centrifuge, microscopes, measuring cylinder, petri dishes
- B. Flow meters ,centrifuge, theodolites, microscopes
- C. Centrifuges, plant presses, flow meters, microscopes
- D. Theodolites, petri dishes, GPS receivers ,measuring cylinder
Answer, explanation and textbook page: open in the app.