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Grade 12 Biology national exam, 2010 E.C. (2018 G.C.)
82 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 tools is used by a biologist to study the internal anatomy of experimental animals?
- A. Dissecting kit
- B. Hand lens
- C. Petri dish
- D. Microscope
Answer: A. The question tests which tool is used to open an animal and examine its internal parts. A dissecting kit contains tools for cutting and examining an animal, so A is correct. B is wrong because a hand lens only magnifies small objects. C is wrong because a Petri dish is used to hold or grow samples. D is wrong because a microscope magnifies small structures rather than opening an animal. Textbook: Grade 9, unit 3 · section 3.6. - 2.Which of the following is NOT a characteristic of an enzyme?
- A. It is a globular protein
- B. It function as a catalyst
- C. It lowers the energy of activation
- D. It converted to products
Answer: D. The question tests which statement is not a feature of an enzyme. Enzymes are not converted into products; they help reactions happen and remain available afterward. Enzymes are generally globular proteins; they act as catalysts, which speed reactions; they lower activation energy, the energy needed to start a reaction. Textbook: Grade 11, unit 3 · section 3.11. - 3.Who was the first person who believed to have seen moving cells under a microscope?
- A. Robert Hooke
- B. Rene Dutrochet
- C. Anton van Leeuwenhoek
- D. Theodor Schwann
Answer: C. The key idea is to remember the early observer of living, moving cells under a microscope. Anton van Leeuwenhoek observed living microscopic organisms, including moving cells. A is wrong because Robert Hooke described dead cells in cork; B is wrong because Rene Dutrochet is not credited with this early observation; D is wrong because Theodor Schwann later helped develop cell theory. Textbook: Grade 9, unit 3 · section 3.2. - 4.Why do micro-organisms decompose dead organic matters?
- A. To release mineral nutrients for the plants
- B. To clean up the ecosystem
- C. To drive energy for their own uses
- D. To keep the balance of atmospheric gases
Answer: C. The question tests why decomposers break down dead organic matter. Micro-organisms obtain energy from the material for their own life processes. Releasing minerals for plants and cleaning the ecosystem can be results of decomposition, not its purpose; maintaining atmospheric gases is not the main reason. Therefore, C is correct. Textbook: Grade 10, unit 6 · section 6.2. - 5.The practice of modern agriculture that reduces crop biodiversity is:
- A. Overgrazing
- B. Forest clearing
- C. growing land races
- D. growing few high yielding varieties
Answer: D. The question tests which farming practice lowers the variety of crops grown. Growing only a few high-yielding varieties reduces crop biodiversity, so D is correct. A is wrong because overgrazing damages land but is not the practice described. B is wrong because forest clearing removes habitat rather than directly describing reduced crop variety. C is wrong because growing land races helps maintain crop diversity. Textbook: Grade 11, unit 6 · section 6.6. - 6.Of the following organic molecules which one includes a pentose sugar?
- A. Glucose
- B. Fructose
- C. Galactose
- D. Deoxyribose
Answer, explanation and textbook page: open in the app. - 7.What dose an enzyme do to a chemical reaction that allows it to proceed optimally?
- A. It lower the required activation energy .
- B. It increases the amount of the substrate.
- C. It increases the required activation energy .
- D. It modifies both th Ph and the temperature.
Answer, explanation and textbook page: open in the app. - 8.Which of the following is lacking in prokaryotic cells?
- A. Cytosol
- B. Ribosome
- C. DNA strand
- D. Cellulose
Answer, explanation and textbook page: open in the app. - 9.What is the name of a major group of eukaryotic organisms that obtain their nutrition using extracellular digestion?
- A. Viruses
- B. Bacteria
- C. Fungi
- D. Algae
Answer, explanation and textbook page: open in the app. - 10.What kind of nutrition do most of the decomposers have in general?
- A. Auto trophic nutrition
- B. Saprobiotic nutrition
- C. Endosymbiont nutrition
- D. Chemosynthetic nurtition
Answer, explanation and textbook page: open in the app. - 11.To which genus of primates are the Neanderthal humans classified?
- A. The genus Ardipithecus
- B. The genus Australopithecus
- C. The genus homo
- D. The genus Zinjanthropus
Answer, explanation and textbook page: open in the app. - 12.In which of the following is there a MISMATCH between the type of innate behavior and the resulting action/response?
- A. Instinctive behavior- imprinting in birds
- B. Reflex action- blinking of the eyes in humans
- C. Instinctive behavior- Nest-building in birds
- D. Presentational movement-weaving a web in spiders
Answer, explanation and textbook page: open in the app. - 13.Cells were first seen using the microscope by:
- A. Schleiden
- B. Robert Hooke
- C. Schwann
- D. Leeuwenhoek
Answer, explanation and textbook page: open in the app. - 14.The ultimate source of genetic variation is:
- A. Mutation
- B. Migration
- C. Genetic drift
- D. Selection
Answer, explanation and textbook page: open in the app. - 15.Which of the following is the first step in starting a research process?
- A. Searching sources of information to locate problem.
- B. Survey of related literature
- C. Identification of problem
- D. Searching for solution to the problem
Answer, explanation and textbook page: open in the app. - 16.For which of the following purpose is GLOBAL positioning system (GPS) used?
- A. Map of an area
- B. Theodolite
- C. Microwave
- D. Satellite signal
Answer, explanation and textbook page: open in the app. - 17.In the energy pyramid, which group of organisms has least amount of energy?
- A. Primary producers
- B. Tertiary producers
- C. Herbivores
- D. Animals
Answer, explanation and textbook page: open in the app. - 18.Which of the following properties of water makes sweat a good body coolant?
- A. Its strong surface tension
- B. Its low density in the solid state
- C. Its strong adhesion to ᓼa surface
- D. Its high heat of vaporization
Answer, explanation and textbook page: open in the app. - 19.How many molecule of glycerol and fatty acids, respectively, are needed to from 100 molecules of triglyceride fat?
- A. 50 and 50
- B. 100 and 100
- C. 100 and 300
- D. 150 and 400
Answer, explanation and textbook page: open in the app. - 20.In a metabolic pathway(A-->B-->C-->D) where each step is catalyzed by a separate enzyme which substance in the pathway serves as an allosteric regulator?
- A. Substance A
- B. Substance B
- C. Substance C
- D. Substance D
Answer, explanation and textbook page: open in the app. - 21.Which of the following organelles settles out last when homogenized cells are centrifuged?
- A. Chloroplast
- B. Nucleus
- C. Mitochondria
- D. Ribosome
Answer, explanation and textbook page: open in the app. - 22.At which stage is most of the carbon dioxide released during aerobic respiration?
- A. Glycolysis
- B. Kreabs cycle
- C. Electron transport
- D. Chemiosmosis
Answer, explanation and textbook page: open in the app. - 23.One of the following groups of plants carry out light dependent and ligh independent reactions of photosynthesis in separate cells of the leaf .
- A. Plants adapted to temperature regions
- B. Carbon -3 plants
- C. Carbon -4 plants
- D. Cacti
Answer, explanation and textbook page: open in the app. - 24.What is the nutritional mode of those bacteria which decompose dead organic matter and thus recycle nutrients?
- A. Auto trophic
- B. Parasitic
- C. Saprobiotic
- D. Symbiotic
Answer, explanation and textbook page: open in the app. - 25.In what main way do retroviruses such as HIV differ from other types of RNA viruses ?
- A. They require a host cell to reproduce
- B. They reversely copy RNA to DNA
- C. Their genes are resistant to mutation
- D. They are free living viruses
Answer, explanation and textbook page: open in the app. - 26.Which of the following is NOT true about the flow of energy in the ecosystem?
- A. It is recycled by decomposer.
- B. It passes from one trophic level to the next.
- C. It enters the ecosystem in the form of light.
- D. It leaves the ecosystem in the form of heat.
Answer, explanation and textbook page: open in the app. - 27.Through which of the following processes do all living organisms contribute to carbon cycle?
- A. Photosynthesis
- B. Cellular respiration
- C. Decomposition
- D. Combustion
Answer, explanation and textbook page: open in the app. - 28.In the process of allopatric speciation, which of the following is the mechanism that prevents populations from exchanging genes?
- A. Polyploidy
- B. Geographic barrier
- C. Seasonal isolation
- D. Temporal isolation
Answer, explanation and textbook page: open in the app. - 29.How are organic molecules distinguished from inorganic molecules? Organic molecules always contain:
- A. Oxygen and hydrogen
- B. Carbon and oxygen
- C. Oxygen and nitrogen
- D. Carbon and hydrogen
Answer, explanation and textbook page: open in the app. - 30.In which industrial enzyme technology is lactase practical applied to produce lactose-free mile for used by lactose intolerant individuals?
- A. Chocolate manufacturing industry
- B. Human hormone manufacturing industry
- C. Dairy product manufacturing industry
- D. Cereal food manufacturing industry
Answer, explanation and textbook page: open in the app. - 31.Which kind of enzyme inhibitors bind to enzyme only weakly and the bond that hold them breaks easily releasing the inhibitor to allow the enzyme to become active again?
- A. Irreversible inhibitors
- B. Reversible inhibitor
- C. Inhibitors that bind strongly to enzymes
- D. Inhibitors that permanently alter enzyme structure
Answer, explanation and textbook page: open in the app. - 32.Of the following models describing the nature of the cell membrane, which one was proposed before all the others?
- A. The sandwich model
- B. Fluid mosaic model
- C. The unit membrane model
- D. Phospholipid bilayer model
Answer, explanation and textbook page: open in the app. - 33.Why is that longer races by athletes must be run slower than shorter than shorter races?
- A. To give time for lactic acid fermentation in muscle cells
- B. To avoid hunger as food is quickly converted to energy
- C. To allow aerobic respiration to produce the required ATP
- D. To adapt to the weather condition at the racing place
Answer, explanation and textbook page: open in the app. - 34.In which organ of the human body are more bacteria found?
- A. Lungs
- B. Stomach
- C. Small intestine
- D. Large intestine
Answer, explanation and textbook page: open in the app. - 35.From which group of micro-organisms was the first antibiotics produced ?
- A. Gram-negative bacteria
- B. Gram-positive bacteria
- C. Fungal organism
- D. Viral agents
Answer, explanation and textbook page: open in the app. - 36.If two heterozygous tall pea plants are crossed, how many of the offspring would be phenotypically tall plants?
- A. 0%
- B. 25%
- C. 50%
- D. 75%
Answer, explanation and textbook page: open in the app. - 37.How can biotechnology be applied to reduce the use of inorganic fertilizers in agriculture?
- A. By using the golden rice and producing organic fertilizers from betacarotenes
- B. By using thermostable enzyme of genetically engineered bacteria used in washing powders
- C. By selecting and propagating varieties with high growth rates and high productivity.
- D. By using enzyme produced by genetically engineered bacteria used in the food industry
Answer, explanation and textbook page: open in the app. - 38.Which of the following feature do analogous structures mostly share?
- A. Phylogenetic similarity
- B. Development
- C. Ancestral similarity
- D. Functional similarity
Answer, explanation and textbook page: open in the app. - 39.In which of the following ways dose learned behavior differ from innate behavior?
- A. Learned behavior is adaptive in nature .
- B. Learned behavior is genetically determined.
- C. Learned behavior is modified by new experiences .
- D. Learned behavior is functional at the first attempt.
Answer, explanation and textbook page: open in the app. - 40.Current human concerns such as famine, pestilence, and environmental degradation would be solved through the use of:
- A. Biological principles
- B. Irrigation
- C. Aquaculture
- D. Terracing
Answer, explanation and textbook page: open in the app. - 41.Which is the possible effect of the weak hydrogen bond among water molecules?
- A. It helps water to boild at low temperature
- B. It results in the crystal shape of ice
- C. Plays a significant role in the interaction of a water molecule with hydrophobic surfaces
- D. It speeds up photosyntheses is
Answer, explanation and textbook page: open in the app. - 42.Cell organelles that contain hydrolytic enzymes are called:
- A. Peroxisomes
- B. Lysosomes
- C. Mesosomes
- D. Ribosomes
Answer, explanation and textbook page: open in the app. - 43.Which part of the cell makes necessary changes packages and secretes proteins?
- A. Golgi apparatus
- B. Endoplasmic ᓼreticulum
- C. Mitochondria
- D. Cell wall
Answer, explanation and textbook page: open in the app. - 44.Which of the following takes place under normal conditions as electrons flow down the electron transport chain of the mitochondria?
- A. $\mathrm{NADH}$ and $\mathrm{FADH_2}$ are oxidized
- B. The ph of the matrix increases
- C. The electrons lose free energy
- D. An electrochemical gradients is formed
Answer, explanation and textbook page: open in the app. - 45.In the processes of photosyntheses light is necessary to:
- A. Split carbon dioxide
- B. Releases energy
- C. Combine $\mathrm{CO_2}$ and $\mathrm{H_2O}$
- D. Produce ATP and a reducing substance
Answer, explanation and textbook page: open in the app. - 46.Which of the following is not an industrial use of bacteria?
- A. Recycling of minerals through ecosystems
- B. Food processing
- C. Genetic engineering
- D. Waste water treatment
Answer, explanation and textbook page: open in the app. - 47.Carbon cycle is important in nature because:
- A. The amount of energy before and after a reaction must be the same
- B. It continuously reuse and recycles carbon in the ecosystem.
- C. It consumes oxygen and nitrogen in the atmosphere.
- D. It is used in energy capture and recapture.
Answer, explanation and textbook page: open in the app. - 48.Which of the following is essential in order for a virus to replicate?
- A. The capsid must enter the host cell cytoplasm
- B. The host cell must be undergoing mitosis
- C. The host cell must lack cell membrane.
- D. The genome must be released in to the cytoplasm
Answer, explanation and textbook page: open in the app. - 49.Which one of the following NOT in situ conservation of Biodiversity?
- A. Botanical garden
- B. Sanctuary
- C. Biosphere reserves
- D. National parks
Answer, explanation and textbook page: open in the app. - 50.One goat is heterozygous, long hair(Rr), and its mate carries homozygous short (rr). What is the probability of the offspring having short hair?
- A. 25%
- B. 100%
- C. 75%
- D. 50%
Answer, explanation and textbook page: open in the app. - 51.The type of enzyme used in recombinant DNA technology to spilt a specific sugar phosphate bond in each strand of a DNA double helix is called:
- A. Esterase
- B. Restriction enzyme
- C. Lipase
- D. Ligase
Answer, explanation and textbook page: open in the app. - 52.Lamarck's theory of evolution is know as:
- A. Natural selection
- B. Survival of the fittest
- C. Mutation theory
- D. Inheritance of acquired characters
Answer, explanation and textbook page: open in the app. - 53.The evolution of species which is based upon the sum total adaptation changes could be preserved by:
- A. Natural selection
- B. Speciation
- C. Human conservation
- D. Isolation
Answer, explanation and textbook page: open in the app. - 54.Based on differences in DNA which of the following animals is closer to human beings?
- A. Frog
- B. Domestic pig
- C. Zebra fish
- D. Domestic chicken
Answer, explanation and textbook page: open in the app. - 55.To which group of sugar can the molecule dihydroxyacetone be classified ?
- A. Hexose sugars
- B. Pentose sugars
- C. Triose sugars
- D. Oligosugars
Answer, explanation and textbook page: open in the app. - 56.Choose the one in which the human digestive enzyme is INCORRECT matched with the substance that it normally catalyzes.
- A. Lipase-fat
- B. Pepsin-protein
- C. Trypsin-starch
- D. Pancreatic amylase-starch
Answer, explanation and textbook page: open in the app. - 57.The organelle of the cell which is concerned with the synthesis of lipids in addition to being associated with carbohydrate metabolism and detoxification is:
- A. Golgi body/apparatus
- B. Thylakoid membrane
- C. Rough endoplasmic reticulum
- D. Smooth endoplasmic reticulum
Answer, explanation and textbook page: open in the app. - 58.Where is convergence point for the metabolism of the building blocks of carbohydrates lipids and proteins
- A. Cytoplasm
- B. Krebs cycle
- C. Calvin cycle
- D. Electron transsport
Answer, explanation and textbook page: open in the app. - 59.Among the following crops, which one uses a non- photosynthetic pathways?
- A. Maize
- B. Sorghum
- C. Pineapple
- D. Sugarcane
Answer, explanation and textbook page: open in the app. - 60.Which of the following is responsible for rapid evolution in RNA viruses?
- A. High stability of its RNA
- B. High mutation rate of its RNA
- C. Reverse transcription of its RNA
- D. Accurate replication of its RNA
Answer, explanation and textbook page: open in the app. - 61.What major consequence dose primary ecological succession involve normally?
- A. Complexity of food webs increases
- B. Number of species present decreases
- C. A biotic factor become less favorable
- D. Habitats become harsher and deteriorate
Answer, explanation and textbook page: open in the app. - 62.How quickly a population would increase or decrease in size is probably least influenced by the presence of:
- A. Adequate supply of oxygen
- B. Disproportionate human races
- C. Severe inter-specific competition
- D. Carnivores and herbivores
Answer, explanation and textbook page: open in the app. - 63.Among the theories about the origin of life which one better agrees with the concept of change in organisms and their genetic composed over generation being caused by meiosis, hybridization, natural selection or mutation?
- A. Cosmozoan theory
- B. Biochemical origin theory
- C. Special creationism's theory
- D. Spontaneous generation
Answer, explanation and textbook page: open in the app. - 64.Which of the following is the most accepted theory about the origin of life on earth?
- A. Theory of spontaneous evolution
- B. ᓸTheory of chemical evolution
- C. The cosmic theory
- D. Theory of special creation
Answer, explanation and textbook page: open in the app. - 65.What is the possible cause or isolating mechanism for the formation of allopatric species?
- A. Seasonal isolation
- B. Temporal isolation
- C. Behavioral isolation
- D. Geographic isolation
Answer, explanation and textbook page: open in the app. - 66.Which of the following statement about instinctive actions is NOT true?
- A. Are innate.
- B. Are adaptive
- C. Require learning
- D. Have fixed pattern
Answer, explanation and textbook page: open in the app. - 67.What dose a low value for Simpson's index of diversity normally indicate to the researcher?
- A. An area with high number of endemic species
- B. An area dominated by one or just a few species
- C. A biodiversity hotspot wit abundant species
- D. An area with plants but no species of animals
Answer, explanation and textbook page: open in the app. - 68.A country with a high youth population but a low old age population and low infant population shows
- A. A population pyramid with bulge in the middle
- B. A population with wide base and narrow apex
- C. A inverted pyramid
- D. A pyramid assuming a rectangular shape
Answer, explanation and textbook page: open in the app. - 69.Which one of the following is the primary contribution of Darwin to biological theory?
- A. An important mechanism of biological evolution is natural selection
- B. New alleles arise through mutation
- C. Evolution is the change in gene frequencies over time.
- D. Genes are the units of inheritance.
Answer, explanation and textbook page: open in the app. - 70.Which of the following nucleotide sequences contains four pyrimidine bases?
- A. GATCAATGC
- B. UAGCGGUAA
- C. GCUAGACAA
- D. Both B and C
Answer, explanation and textbook page: open in the app. - 71.Significant change in Ph that can affect an enzyme molecule include
- A. Building strong ionic bonds leading to stabilization of enzymes
- B. Altering the charges on some substrates making it difficult to bind to enzyme
- C. Changing the color and palatability of food items
- D. Increasing the boiling temperature of the substrate
Answer, explanation and textbook page: open in the app. - 72.Which of the following two elements are found in all organic molecules?
- A. Carbon and oxygen
- B. Carbon and nitrogen
- C. Carbon and hydrogen
- D. Carbon and PHOSPHORUS
Answer, explanation and textbook page: open in the app. - 73.If two molecule of a six carbon sugar are condensed to form a disaccharide, which of the following is the correct molecular formula of the disaccharide?
- A. $\mathrm{C_{12}H_{24}O_{12}}$
- B. $\mathrm{C_6H_{12}O_6}$
- C. $\mathrm{C_{12}H_{24}O_{12}}$
- D. $\mathrm{C_{12}H_{22}O_{11}}$
Answer, explanation and textbook page: open in the app. - 74.Which of the following is NOT a requirement for a molecule to directly diffuse across the cell membrane?
- A. Small size
- B. Non-polarity
- C. Large size and polarity
- D. Lipid solubility
Answer, explanation and textbook page: open in the app. - 75.Which of the following molecules can provide the cell the least amount of energy per molecule?
- A. Glucose
- B. Reduced NAD
- C. Reduced FAD
- D. ATP
Answer, explanation and textbook page: open in the app. - 76.During photosynthesis, which of the following is first step in the transduction of light energy to chemical Energy?
- A. ATP formation
- B. Carbon fixation
- C. Photolysiss of water
- D. Glucose formation
Answer, explanation and textbook page: open in the app. - 77.Which of the following terms specifically refers to an ecological succession that starts in an aquatic environment?
- A. Xerosere
- B. Hydrosere
- C. Primary succession
- D. Secondary succession
Answer, explanation and textbook page: open in the app. - 78.Suppose the age pyramid of population has a broad base with a narrow top, which of the following is NOT true about the population?
- A. It is fast growing
- B. It has high growing
- C. It is dominated by young people
- D. It has a high birth rate
Answer, explanation and textbook page: open in the app. - 79.What is the reason that Stanley Miller excluded free oxygen from the Mixture of the gases that he used for his simulation experiment?
- A. Early organic molecules did not contain oxygen
- B. Oxygen cannot react with the rest of the gases
- C. Primitive atmosphere was reducing
- D. The primitive atmosphere was full of oxygen
Answer, explanation and textbook page: open in the app. - 80.Which of the following organic molecules is least informative about the evolutionary relationships between species
- A. Carbohydrates
- B. Proteins
- C. DNA
- D. RNA
Answer, explanation and textbook page: open in the app. - 81.In which of the following ways dose mutation contribute most to evolution?
- A. It preserves adaptive genes
- B. It creates new alleles
- C. It forms a new gene poll
- D. It helps genes to recombine
Answer, explanation and textbook page: open in the app. - 82.A small girl who had observed her mother making a telephone call one day made a call on her own. Which learning behavior dose this exemplify?
- A. Insight ?learning
- B. Trial and error
- C. Latent learning
- D. Sensitization
Answer, explanation and textbook page: open in the app.