Which of the following best describes the difference between saturated and unsaturated fatty acids?

Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

Saturated fatty acids have one or more double bonds between carbon atoms, while unsaturated fatty acids have only single bonds.

Saturated fatty acids are typically found in plants, while unsaturated fatty acids are found in animals.

Saturated fatty acids are liquid at room temperature, while unsaturated fatty acids are solid.

What is the role of bile in digestion?

It emulsifies fats, breaking them down into smaller droplets.

It breaks down proteins in the stomach.

It helps to digest carbohydrates in the small intestine.

It neutralizes the acid from the stomach to make the food alkaline.

Gobezoch › Past exams › Biology

Grade 12 Biology national exam, 2018 E.C. (2026 G.C.)

98 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.

Sit this paper (timed)Practice mode

1.Which of the following is a major carbohydrate found in plants that humans cannot digest?
- A. Glycogen
- B. Fructose
- C. Cellulose
- D. Maltose
Answer: C. Plants store energy as starch and build their cell walls from cellulose. Both are chains of glucose, but the glucose units in cellulose are joined by beta 1,4 links, and the human gut makes no enzyme that can cut that link. So cellulose passes through us as dietary fibre. Glycogen tempts because it is also a glucose polymer, but it is the animal storage carbohydrate and our amylase and maltase break it down without trouble. Textbook: Grade 10, unit 3 · section 3.1.3.
2.Which of the following best describes the difference between saturated and unsaturated fatty acids?
- A. Saturated fatty acids have one or more double bonds between carbon atoms, while unsaturated fatty acids have only single bonds.
- B. Saturated fatty acids are typically found in plants, while unsaturated fatty acids are found in animals.
- C. Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.
- D. Saturated fatty acids are liquid at room temperature, while unsaturated fatty acids are solid.
Answer: C. The key idea is that fatty acids differ in whether their carbon chain has double bonds. Saturated fatty acids have no carbon–carbon double bonds, while unsaturated fatty acids have one or more. A reverses these definitions; B gives an incorrect plant-and-animal distinction; D reverses the usual pattern, since saturated fats are often solid and unsaturated fats often liquid at room temperature. Textbook: Grade 10, unit 3 · section 3.1.3.
3.What is the role of bile in digestion?
- A. It breaks down proteins in the stomach.
- B. It emulsifies fats, breaking them down into smaller droplets.
- C. It helps to digest carbohydrates in the small intestine.
- D. It neutralizes the acid from the stomach to make the food alkaline.
Answer: B. Bile is made in the liver and stored in the gall bladder, and it contains no enzymes at all. Its bile salts break large fat drops into many tiny droplets, which multiplies the surface area that lipase can work on. Faster fat digestion is the result. Option D is not invented, because bile is alkaline and does help raise the pH of the food leaving the stomach, but the role the question is asking about is emulsification. Textbook: Grade 10, unit 5 · section 5.1.
4.Which part of the digestive system is responsible for producing enzymes that digest carbohydrates, proteins, and fats?
- A. Stomach
- B. Small intestine
- C. Pancreas
- D. Liver
Answer: C. The key idea is that the pancreas produces enzymes that digest carbohydrates, proteins, and fats. Its digestive enzymes include amylase, proteases, and lipase. A is wrong because the stomach mainly produces enzymes for protein digestion; B is wrong because the small intestine does not produce the full set described; D is wrong because the liver makes bile, not these digestive enzymes. Textbook: Grade 10, unit 5 · section 5.6.
5.Which structure separates the thoracic cavity from the abdominal cavity and plays a key role in breathing?
- A. Larynx
- B. Diaphragm
- C. Trachea
- D. Bronchi
Answer: B. The question tests the structure that separates the chest and abdominal cavities and helps with breathing. The diaphragm is a muscle below the lungs that moves to help draw air into and out of them. A is wrong because the larynx is part of the airway in the throat; C is wrong because the trachea carries air to the lungs; D is wrong because the bronchi carry air into the lungs. Textbook: Grade 10, unit 5 · section 5.2.2.
6.What is the main product of anaerobic respiration in muscle cells during vigorous exercise?
- A. Lactic acid
- B. Ethanol
- C. Oxygen
- D. Carbon dioxide
Answer, explanation and textbook page: open in the app.
7.Which of the following best describes the process of fermentation in yeast cells?
- A. Yeast cells use oxygen to break down glucose and produce ATP, water, and carbon dioxide.
- B. Yeast cells break down glucose without oxygen, producing ethanol and carbon dioxide.
- C. Yeast cells produce ATP by converting lactic acid into energy.
- D. Yeast cells use lactic acid as the main energy source in the absence of oxygen.
Answer, explanation and textbook page: open in the app.
8.Which of the following statements about red blood cells is true?
- A. Red blood cells have a nucleus and live for about 10-20 days.
- B. Red blood cells are shaped as biconcave discs, which gives them a large surface area for oxygen exchange.
- C. Red blood cells are responsible for fighting infections in the body.
- D. Red blood cells are made in the liver and transport carbon dioxide around the body.
Answer, explanation and textbook page: open in the app.
9.In the ABO blood group system, which blood type can receive blood from any of the four ABO blood types?
- A. Type A
- B. Type B
- C. Type AB
- D. Type O
Answer, explanation and textbook page: open in the app.
10.Which of the following is NOT a characteristic of bacteria?
- A. Bacteria are single-celled organisms.
- B. Bacterial cells contain a nucleus to store genetic material.
- C. Bacteria can have structures like flagella to help them move.
- D. Some bacteria are useful for processes like fermentation and decay.
Answer, explanation and textbook page: open in the app.
11.What is the main purpose of using UHT (Ultra High Temperature) treatment for food?
- A. To make the food taste better
- B. To keep the food warm for longer
- C. To sterilize the food by killing all micro-organisms
- D. To preserve the food by freezing
Answer, explanation and textbook page: open in the app.
12.Which of the following is the most common way people get infected with tapeworms?
- A. By drinking contaminated water
- B. By eating undercooked or raw meat containing young tapeworms
- C. By coming into contact with contaminated soil
- D. Through insect bites
Answer, explanation and textbook page: open in the app.
13.Which of the following is the most effective way to prevent the spread of gonorrhea?
- A. Getting vaccinated for gonorrhea
- B. Using a male or female condom during sexual activity
- C. Avoiding alcohol consumption
- D. Avoiding all contact with infected individuals
Answer, explanation and textbook page: open in the app.
14.What is the primary reason why chancroid is particularly concerning in regions with high HIV/AIDS rates?
- A. It causes severe pain and tissue damage
- B. It can lead to permanent infertility
- C. The sores caused by chancroid increase the likelihood of contracting HIV
- D. It has no effective treatment
Answer, explanation and textbook page: open in the app.
15.What is the primary role of neurotransmitters at a synapse?
- A. To produce electrical impulses
- B. To cross the synapse and start an electrical impulse in the next neuron
- C. To insulate the axon for faster impulse transmission
- D. To repair damaged neurons
Answer, explanation and textbook page: open in the app.
16.What is a conditioned reflex action?
- A. A reflex action that is innate and present at birth
- B. A reflex action that is learned through experience
- C. A reflex action that occurs only in response to physical injury
- D. A reflex action that is triggered by emotional stimuli
Answer, explanation and textbook page: open in the app.
17.Which of the following conditions can be corrected using concave (diverging) lenses?
- A. Long sight
- B. Short sight
- C. Astigmatism
- D. Presbyopia
Answer, explanation and textbook page: open in the app.
18.Which of the following is a function of the epidermis layer of the skin?
- A. Temperature regulation
- B. Protection against UV light
- C. Containing blood vessels and sweat glands
- D. Storing fat for insulation
Answer, explanation and textbook page: open in the app.
19.Which of the following is a primary function of insulin in the body?
- A. To increase blood sugar levels
- B. To regulate the heart rate
- C. To lower blood sugar levels by helping glucose enter cells
- D. To speed up the breathing rate
Answer, explanation and textbook page: open in the app.
20.Which of the following contraceptive methods is considered to be 99% effective at preventing pregnancy and does not require daily action from the user?
- A. The combined oral contraceptive pill
- B. Male condoms
- C. Hormonal implants
- D. Diaphragm
Answer, explanation and textbook page: open in the app.
21.What is the primary function of sweating in homoiotherms?
- A. To increase body temperature
- B. To release excess carbon dioxide
- C. To cool the body down by evaporation
- D. To conserve water and ions
Answer, explanation and textbook page: open in the app.
22.Which physiological response helps conserve heat when the core body temperature drops?
- A. Sweating
- B. Vasodilation
- C. Vasoconstriction
- D. Panting
Answer, explanation and textbook page: open in the app.
23.Which of the following structures in a leaf is primarily responsible for controlling gas exchange and water loss?
- A. Palisade mesophyll
- B. Stomata
- C. Xylem
- D. Phloem
Answer, explanation and textbook page: open in the app.
24.Which of the following is NOT a requirement for photosynthesis?
- A. Water
- B. Carbon dioxide
- C. Chlorophyll
- D. Nitrogen
Answer, explanation and textbook page: open in the app.
25.What is the main purpose of boiling a leaf in water during the starch test for photosynthesis?
- A. To remove the starch
- B. To soften the leaf
- C. To kill the leaf and stop biochemical processes
- D. To add iodine solution to the leaf
Answer, explanation and textbook page: open in the app.
26.Which of the following is responsible for the movement of water from the roots to the leaves in plants?
- A. Active transport
- B. Transpiration
- C. Photosynthesis
- D. Respiration
Answer, explanation and textbook page: open in the app.
27.What is the role of guard cells in the process of transpiration?
- A. They absorb water from the soil.
- B. They open and close the stomata to regulate water loss.
- C. They transport sugars through the plant.
- D. They produce chloroplasts for photosynthesis.
Answer, explanation and textbook page: open in the app.
28.What is the primary function of auxins (IAA) in plants?
- A. Inhibit cell division
- B. Stimulate root growth
- C. Stimulate cell elongation and shoot growth
- D. Promote fruit ripening
Answer, explanation and textbook page: open in the app.
29.In which response do roots grow towards water?
- A. Geotropism
- B. Hydrotropism
- C. Phototropism
- D. Thermotropism
Answer, explanation and textbook page: open in the app.
30.How does auxin (IAA) affect the growth of shoots and roots in response to gravity?
- A. Auxin promotes growth in both shoots and roots
- B. Auxin promotes growth in shoots and inhibits growth in roots
- C. Auxin inhibits growth in both shoots and roots
- D. Auxin inhibits growth in shoots and promotes growth in roots
Answer, explanation and textbook page: open in the app.
31.What is the primary role of enzymes in biochemical reactions?
- A. To increase the temperature of reactions
- B. To create products from substrates
- C. To lower the activation energy and speed up reaction
- D. To increase the activation energy needed for reaction
Answer, explanation and textbook page: open in the app.
32.Which of the following statements about enzyme specificity is true?
- A. Enzymes are specific only for a single bond type and not for a substrate.
- B. Enzyme specificity refers to the ability of an enzyme to act only on a particular substrate.
- C. Enzymes can act on any type of substrate without preference.
- D. Enzyme specificity refers to the size of the enzyme, not its function.
Answer, explanation and textbook page: open in the app.
33.What causes the denaturation of an enzyme?
- A. Low temperature and acidic pH
- B. High heat, extreme pH, heavy metals, or solvents
- C. Low concentration of substrate
- D. An increase in enzyme concentration
Answer, explanation and textbook page: open in the app.
34.Which of the following is a characteristic of an enzyme's active site?
- A. It is where the enzyme binds to its cofactor.
- B. It is the region where the enzyme binds to its substrate.
- C. It binds to non-protein molecules like vitamins.
- D. It is only responsible for enzyme activation.
Answer, explanation and textbook page: open in the app.
35.What is the primary function of oxidoreductase enzymes?
- A. Catalyze the transfer of functional groups.
- B. Catalyze the breakdown of starch.
- C. Catalyze oxidation-reduction reactions by transferring electrons.
- D. Catalyze the joining of two molecules using ATP.
Answer, explanation and textbook page: open in the app.
36.Which factor does NOT affect enzyme activity?
- A. Temperature
- B. pH
- C. Enzyme concentration
- D. The color of the enzyme
Answer, explanation and textbook page: open in the app.
37.What happens when an enzyme is exposed to extreme pH or temperature?
- A. The enzyme becomes more efficient.
- B. The enzyme becomes denatured and loses its function.
- C. The enzyme speeds up the reaction rate.
- D. The enzyme increases its affinity for the substrate.
Answer, explanation and textbook page: open in the app.
38.Which of the following is an example of a cofactor required by some enzymes for activity?
- A. Substrate
- B. Vitamin B complex (Coenzyme)
- C. Product
- D. Inhibitor
Answer, explanation and textbook page: open in the app.
39.What is the main difference between the structure of DNA and RNA?
- A. DNA has a single strand, while RNA has a double strand
- B. DNA contains uracil, while RNA contains thymine
- C. DNA contains deoxyribose, while RNA contains ribose
- D. DNA contains ribose, while RNA contains deoxyribose
Answer, explanation and textbook page: open in the app.
40.What is the function of RNA in cells?
- A. RNA is responsible for storing genetic information
- B. RNA facilitates the translation of DNA into proteins
- C. RNA stores energy for the cell
- D. RNA is responsible for DNA replication
Answer, explanation and textbook page: open in the app.
41.What is the primary function of meiosis in organisms?
- A. To produce genetically identical daughter cells for growth and repair
- B. To produce gametes (sex cells) with half the number of chromosomes
- C. To replicate DNA for cellular repair
- D. To divide somatic cells for tissue regeneration
Answer, explanation and textbook page: open in the app.
42.What happens during the S phase of the cell cycle?
- A. The cell grows and accumulates nutrients
- B. DNA is replicated to form sister chromatids
- C. The nuclear envelope dissolves, and chromosomes condense
- D. The cytoplasm divides into two separate cells
Answer, explanation and textbook page: open in the app.
43.In a monohybrid cross, when two heterozygous individuals (Tt x Tt) are crossed, what is the expected phenotypic ratio of the offspring?
- A. 1:1
- B. 3:1
- C. 2:1
- D. 1:2:1
Answer, explanation and textbook page: open in the app.
44.Which of the following statements best describes Mendel's Law of Independent Assortment?
- A. Alleles for a single trait separate during meiosis
- B. Alleles for different traits separate independently of each other during meiosis
- C. Dominant traits will always be expressed in offspring
- D. Recessive traits will always be expressed when two recessive alleles are inherited
Answer, explanation and textbook page: open in the app.
45.What is the genetic composition that determines an individual to be male in humans?
- A. XX
- B. XY
- C. X
- D. YY
Answer, explanation and textbook page: open in the app.
46.Which of the following is an example of non-Mendelian inheritance?
- A. Complete dominance
- B. Incomplete dominance
- C. Gene segregation
- D. Independent assortment
Answer, explanation and textbook page: open in the app.
47.What is one of the main uses of biotechnology in food production?
- A. Genetic engineering of crops
- B. Creating synthetic chemicals
- C. Developing biological weapons
- D. Reducing biodiversity loss
Answer, explanation and textbook page: open in the app.
48.Which of the following is a key feature of forensic biotechnology?
- A. The use of genetic engineering to improve crops
- B. Analysis of DNA and other biological evidence at crime scenes
- C. The development of new biofuels
- D. Engineering microorganisms for industrial use
Answer, explanation and textbook page: open in the app.
49.What is the main role of biotechnology in medicine?
- A. Increasing the cost of drug production
- B. Providing effective diagnostics, prevention, and treatment
- C. Reducing the need for medical research
- D. Limiting the development of new disease
Answer, explanation and textbook page: open in the app.
50.Which of the following is an example of a biotechnological process used for wastewater treatment?
- A. PCR amplification
- B. Bio-trickling filters
- C. Genetic engineering of plants
- D. DNA sequencing
Answer, explanation and textbook page: open in the app.
51.According to the World Health Organization (WHO), health is defined as:
- A. The absence of disease
- B. A state of complete physical, mental and social well-being
- C. The ability to grow and reproduce
- D. The ability to exercise regularly
Answer, explanation and textbook page: open in the app.
52.What is the primary role of biology in nature conservation?
- A. To reduce pollution
- B. To manage renewable and non-renewable resources properly
- C. To increase the demand for natural resources
- D. To exploit natural resources for immediate use
Answer, explanation and textbook page: open in the app.
53.Which of the following is an example of a non-renewable resource?
- A. Cattle
- B. Trees
- C. Coal
- D. Water
Answer, explanation and textbook page: open in the app.
54.Which of the following activities does not contribute to the appreciation of nature?
- A. Planting a tree
- B. Reducing pollution
- C. Hugging a tree
- D. Urbanization and excessive development
Answer, explanation and textbook page: open in the app.
55.What does food security ensure?
- A. That food is produced only for wealthy individuals
- B. That everyone has physical, social, and economic access to nutritious food
- C. That food prices are high to prevent overconsumption
- D. That food production remains the same each year
Answer, explanation and textbook page: open in the app.
56.Which of the following is a renewable resource in Ethiopia?
- A. Gold
- B. Coal
- C. Coffee
- D. Oil
Answer, explanation and textbook page: open in the app.
57.Which of the following is NOT a main group of microorganisms?
- A. Bacteria
- B. Fungi
- C. Mammals
- D. Viruses
Answer, explanation and textbook page: open in the app.
58.What is the key difference between prokaryotic and eukaryotic cells?
- A. Eukaryotic cells have no nucleus, while prokaryotic cells have a nucleus.
- B. Eukaryotic cells are unicellular, while prokaryotic cells are multicellular.
- C. Prokaryotic cells have no membrane-enclosed nucleus, while eukaryotic cells do.
- D. Eukaryotic cells lack cell membranes, while prokaryotic cells have them.
Answer, explanation and textbook page: open in the app.
59.Which shape do cocci bacteria have?
- A. Spiral-shaped
- B. Rod-shaped
- C. Spherical
- D. Oval-shaped
Answer, explanation and textbook page: open in the app.
60.Which of the following best describes the habitat of Archaea?
- A. Archaea are only found in warm, tropical climates.
- B. Archaea inhabit extreme environments such as hot springs, saline lakes, and deep-sea vents.
- C. Archaea only live in the human gut.
- D. Archaea thrive in forested areas with abundant rainfall.
Answer, explanation and textbook page: open in the app.
61.What is the primary difference between fungi and plants?
- A. Fungi can photosynthesize, while plants cannot.
- B. Fungi do not have cell walls, while plants do.
- C. Fungi have chitin in their cell walls, while plants have cellulose.
- D. Fungi are always unicellular, while plants are always multicellular.
Answer, explanation and textbook page: open in the app.
62.Which of the following is an example of how fungi benefit humans?
- A. Fungi can cause diseases in humans.
- B. Fungi help in the fermentation process to produce traditional beverages like Tej and Tella.
- C. Fungi only serve as food for other organisms.
- D. Fungi are used to produce energy in power plants.
Answer, explanation and textbook page: open in the app.
63.Which of the following diseases is caused by the protozoan Plasmodium?
- A. Giardiasis
- B. Malaria
- C. Toxoplasmosis
- D. Amoebiasis
Answer, explanation and textbook page: open in the app.
64.What is the primary mode of transmission for Leishmania parasites?
- A. Contaminated water
- B. Mosquito bites
- C. Sand fly bites
- D. Direct human-to-human contact
Answer, explanation and textbook page: open in the app.
65.Which of the following protozoan diseases affects the liver and causes diarrhea in humans?
- A. Malaria
- B. Toxoplasmosis
- C. Amoebiasis
- D. African trypanosomiasis
Answer, explanation and textbook page: open in the app.
66.What is the outer protein shell of a virus called?
- A. Envelope
- B. Genome
- C. Capsid
- D. Peplomer
Answer, explanation and textbook page: open in the app.
67.Which of the following types of viruses contain RNA as their genetic material?
- A. Papovavirus
- B. Parvovirus
- C. Retroviruses
- D. Herpesvirus
Answer, explanation and textbook page: open in the app.
68.In which of the following structures do DNA viruses primarily replicate?
- A. Cytoplasm
- B. Nucleus
- C. Ribosomes
- D. Mitochondria
Answer, explanation and textbook page: open in the app.
69.Which of the following is NOT a stage in the viral replication cycle?
- A. Attachment of the virus to a host cell
- B. Replication of the viral genome
- C. Fusion of the viral particle with a host's DNA
- D. Release of new virus particles
Answer, explanation and textbook page: open in the app.
70.What role do microorganisms play in agriculture?
- A. They help in the decomposition of organic matter and formation of humus
- B. They prevent the nitrogen cycle from occurring
- C. They convert phosphorus to a form that plants cannot use
- D. They eliminate all plant pests
Answer, explanation and textbook page: open in the app.
71.What is the main benefit of using anaerobic bacteria in sewage treatment?
- A. They produce oxygen for the process
- B. They reduce the volume of sludge and produce methane gas, which can be used as an energy source
- C. They increase the oxygen consumption of the water
- D. They prevent bacteria from spoiling the water
Answer, explanation and textbook page: open in the app.
72.Which of the following is an example of disease transmission via droplet infection?
- A. Cholera
- B. Malaria
- C. Pneumonia
- D. Salmonella
Answer, explanation and textbook page: open in the app.
73.Which of the following is an example of a disaccharide?
- A. Glucose
- B. Maltose
- C. Starch
- D. Cellulose
Answer, explanation and textbook page: open in the app.
74.What is the main difference between alpha-D-glucose and beta-D-glucose?
- A. The number of carbon atoms
- B. The position of the hydroxyl group on carbon 1
- C. The type of glycosidic bond formed
- D. The size of the glucose molecule
Answer, explanation and textbook page: open in the app.
75.Which of the following is a polysaccharide that is a storage form of glucose in animals?
- A. Starch
- B. Glycogen
- C. Cellulose
- D. Chitin
Answer, explanation and textbook page: open in the app.
76.What type of reaction results in the formation of disaccharides from monosaccharides?
- A. Hydrolysis
- B. Condensation
- C. Oxidation
- D. Reduction
Answer, explanation and textbook page: open in the app.
77.Which of the following lipids are made up of fatty acids, glycerol or other alcohol, and phosphoric acid?
- A. Triglycerides
- B. Waxes
- C. Phospholipids
- D. Sterol
Answer, explanation and textbook page: open in the app.
78.What is the main reason lipids are insoluble in water?
- A. They contain a large number of oxygen atoms.
- B. They are polar molecules.
- C. They are hydrophobic in nature.
- D. They have a high molecular weight.
Answer, explanation and textbook page: open in the app.
79.Which type of lipid is an ester of fatty acids and long-chain alcohols?
- A. Triglycerides
- B. Waxes
- C. Phospholipids
- D. Steroids
Answer, explanation and textbook page: open in the app.
80.What is the primary function of glycolipids in the cell membrane?
- A. To store energy
- B. To provide insulation
- C. To maintain the stability of the membrane and facilitate cellular recognition
- D. To act as an energy source
Answer, explanation and textbook page: open in the app.
81.What is the primary function of the Calvin cycle in photosynthesis?
- A. To split water molecules
- B. To convert light energy into chemical energy
- C. To fix carbon and produce glucose
- D. To generate oxygen gas
Answer, explanation and textbook page: open in the app.
82.Which pigment is most responsible for the absorption of light energy in photosynthesis?
- A. Carotenoids
- B. Phycobilins
- C. Chlorophyll a
- D. Chlorophyll b
Answer, explanation and textbook page: open in the app.
83.Where does the light-dependent reaction of photosynthesis take place?
- A. In the stroma of the chloroplast
- B. In the cytoplasm
- C. In the thylakoid membranes of the chloroplast
- D. In the mitochondria
Answer, explanation and textbook page: open in the app.
84.What is the role of NADPH in the light-dependent reactions of photosynthesis?
- A. To produce ATP
- B. To provide reducing power for the Calvin cycle
- C. To absorb light energy
- D. To split water molecules
Answer, explanation and textbook page: open in the app.
85.Which of the following occurs during the light-independent reactions (Calvin cycle)?
- A. Water is split to release oxygen
- B. Light energy is converted into chemical energy
- C. Carbon dioxide is fixed into an organic molecule
- D. ATP is converted into NADP+
Answer, explanation and textbook page: open in the app.
86.Which of the following plants uses the C4 pathway for carbon fixation?
- A. Peanuts
- B. Cacti
- C. Sugarcane
- D. Soybeans
Answer, explanation and textbook page: open in the app.
87.What is the primary reason that C4 and CAM plants are more efficient in hot, dry climates?
- A. They have larger stomata
- B. They reduce photorespiration by increasing CO2 concentration in their cells
- C. They do not require light for photosynthesis
- D. They only perform photosynthesis at night
Answer, explanation and textbook page: open in the app.
88.What does photorespiration involve in C3 plants?
- A. The enzyme rubisco adds O2 instead of CO2 to RuBP, wasting energy
- B. The plant fixes CO2 twice in one cycle
- C. The plant produces excess sugars that are stored for later use
- D. The plant converts light energy directly into ATP without CO2 fixation
Answer, explanation and textbook page: open in the app.
89.Which of the following is a direct consequence of photosynthesis for life on Earth?
- A. It contributes to the oxygen balance in the atmosphere
- B. It releases carbon dioxide into the atmosphere
- C. It consumes all atmospheric carbon
- D. It destroys fossil fuels
Answer, explanation and textbook page: open in the app.
90.Where does glycolysis occur in a eukaryotic cell?
- A. Mitochondria
- B. Cytosol
- C. Nucleus
- D. Ribosomes
Answer, explanation and textbook page: open in the app.
91.What is the main role of ATP in cellular metabolism?
- A. To store energy in chemical bonds
- B. To transport oxygen in the cell
- C. To store and transfer energy for biochemical reactions
- D. To break down glucose
Answer, explanation and textbook page: open in the app.
92.Which of the following is a product of the Krebs cycle?
- A. Oxygen
- B. NADH, FADH2, ATP, and CO2
- C. Pyruvate
- D. Glucose
Answer, explanation and textbook page: open in the app.
93.What occurs during the pyruvate oxidation (link reaction)?
- A. Glucose is broken into two pyruvate molecules
- B. Pyruvate is converted into acetyl CoA
- C. Oxygen is consumed to form water
- D. ATP is synthesized directly
Answer, explanation and textbook page: open in the app.
94.What is the final electron acceptor in the electron transport chain (ETC)?
- A. NADH
- B. Oxygen
- C. FADH2
- D. Glucose
Answer, explanation and textbook page: open in the app.
95.Which part of the mitochondria is involved in oxidative phosphorylation?
- A. Outer membrane
- B. Inner membrane
- C. Matrix
- D. Cristae
Answer, explanation and textbook page: open in the app.
96.What is the main purpose of a respirometer?
- A. To measure the volume of carbon dioxide produced during respiration
- B. To measure the temperature change during aerobic respiration
- C. To measure the volume of oxygen consumed during aerobic respiration
- D. To measure the amount of glucose used in the respiration process
Answer, explanation and textbook page: open in the app.
97.What happens during fermentation in the absence of oxygen?
- A. Oxygen is consumed to produce ATP
- B. Pyruvate is converted to lactate or ethanol to regenerate NAD+
- C. The electron transport chain produces ATP
- D. Glucose is completely oxidized to carbon dioxide and water
Answer, explanation and textbook page: open in the app.
98.Which type of fermentation occurs in muscle cells when oxygen is scarce?
- A. Alcohol fermentation
- B. Aerobic respiration
- C. Lactic acid fermentation
- D. Glycolysis
Answer, explanation and textbook page: open in the app.

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