TundeThese are likely JAMB Biology questions and answers 2026 based on the official syllabus and past UTME trends.
The most likely JAMB Biology topics for 2026 are Cell Structure and Organisation, Photosynthesis and Respiration, Classification of Organisms, Genetics and Heredity, Ecology and Food Chains, and Evolution. These topics have appeared consistently in past JAMB papers and carry the highest number of questions.
Before you proceed, understand that these are not leaked questions. They are carefully compiled from:
- The official JAMB Biology syllabus
- Analysis of past UTME questions
- Frequently repeated and high-scoring topics
The Joint Admissions and Matriculation Board (JAMB) is the only body responsible for setting UTME questions, and no one has access to the exact exam questions before the exam. However, studying patterns and commonly tested areas gives you a strong advantage.
Many candidates search for “likely questions” because they want to focus on what truly matters, avoid wasting time on irrelevant topics, and improve their chances of scoring high. This guide is designed to help you do exactly that.
If used properly, these questions will help you:
- Understand how JAMB sets Biology questions
- Improve your speed and accuracy
- Identify your weak areas early
Practice every question carefully and treat it like a real exam.
ALSO READ: JAMB Biology Syllabus 2026
How to Use These Questions
Follow these steps to get the best results from this practice material:
- Attempt each question first before checking the answer.
- Read the explanation for every question, including ones you get right, it deepens understanding.
- Note your weak areas and revisit the relevant topics in your textbook.
- Repeat the quiz after 3–5 days to test retention.
- Time yourself, JAMB gives you about 2.5 minutes per Biology question.
Likely JAMB Biology Questions and Answers 2026
Section A: Variety of Organisms
Topic 1: Living Organisms – Characteristics, Cell Structure & Organisation
1. Which of the following is NOT a characteristic of living organisms?
A. Reproduction
B. Growth
C. Rusting
D. Excretion
Answer: C — Rusting
Explanation: Rusting is a chemical process that occurs in non-living metals. All living organisms must show nutrition, respiration, excretion, growth, reproduction, sensitivity and movement.
2. The organelle responsible for energy production in a cell is the
A. Ribosome
B. Mitochondrion
C. Golgi apparatus
D. Lysosome
Answer: B — Mitochondrion
Explanation: The mitochondrion is the ‘powerhouse of the cell’ where ATP is produced through aerobic respiration via the Krebs cycle and oxidative phosphorylation.
3. Which structure is found in plant cells but NOT in animal cells?
A. Mitochondria
B. Cell membrane
C. Cell wall
D. Nucleus
Answer: C — Cell wall
Explanation: Plant cells have a rigid cell wall made of cellulose that gives them shape and support. Animal cells lack a cell wall; they only have a flexible cell membrane.
4. Euglena is used as an example of organisation at the _______ level.
A. Tissue
B. Organ
C. Cell
D. System
Answer: C — Cell
Explanation: Euglena is a unicellular organism, representing the cell level of organisation. It performs all life functions within a single cell.
5. The correct sequence of levels of organisation from simplest to most complex is:
A. Cell → Organ → Tissue → System → Organism
B. Cell → Tissue → Organ → System → Organism
C. Tissue → Cell → Organ → System → Organism
D. Organ → Cell → Tissue → System → Organism
Answer: B — Cell → Tissue → Organ → System → Organism
Explanation: The five levels of biological organisation follow this strict hierarchy: Cell is the basic unit, cells form Tissues, tissues form Organs, organs form Systems, and systems form the whole Organism.
6. The function of the chloroplast in a plant cell is to
A. Control cell activities
B. Manufacture food by photosynthesis
C. Provide structural support
D. Digest worn-out cell parts
Answer: B — Manufacture food by photosynthesis
Explanation: Chloroplasts contain chlorophyll which traps sunlight energy used to convert carbon dioxide and water into glucose during photosynthesis.
7. Which of the following best describes the cell membrane?
A. Fully permeable to all substances
B. Impermeable to all substances
C. Selectively permeable
D. Permeable only to water
Answer: C — Selectively permeable
Explanation: The cell membrane is selectively (differentially) permeable — it allows certain substances to pass through while restricting others, helping maintain the cell’s internal environment.
8. Hydra is an example of organisation at the _______ level.
A. Cell
B. Tissue
C. Organ
D. System
Answer: B — Tissue
Explanation: Hydra is a multicellular organism whose body is organised at the tissue level — cells with similar structure are grouped to perform a common function.
Topic 2: Classification & Structural Complexity of Organisms
9. Which of the following organisms belongs to the kingdom Monera?
A. Mushroom
B. Amoeba
C. Blue-green algae
D. Spirogyra
Answer: C — Blue-green algae
Explanation: Monera (prokaryotes) includes bacteria and blue-green algae (cyanobacteria). They lack a membrane-bound nucleus and other membrane-bound organelles.
10. The correct classification of Rhizopus is
A. Monera
B. Protista
C. Fungi
D. Plantae
Answer: C — Fungi
Explanation: Rhizopus (bread mould) is a fungus. Fungi are heterotrophic organisms that feed by absorption (saprophytic nutrition) and reproduce by spores.
11. Which plant division produces seeds enclosed in a fruit?
A. Bryophyta
B. Pteridophyta
C. Gymnospermae
D. Angiospermae
Answer: D — Angiospermae
Explanation: Angiosperms (flowering plants) produce seeds enclosed within a fruit (the mature ovary). Gymnosperms produce naked (unenclosed) seeds.
12. The life cycle of a moss best demonstrates transition from
A. Water to land
B. Land to water
C. Air to soil
D. Soil to rock
Answer: A — Water to land
Explanation: Bryophytes (mosses and liverworts) represent the transition from aquatic to terrestrial life. They still require water for fertilisation but live on land.
13. Which of the following is an arthropod?
A. Earthworm
B. Snail
C. Mosquito
D. Tapeworm
Answer: C — Mosquito
Explanation: Arthropods are invertebrates with jointed legs and an exoskeleton. Mosquito, cockroach, housefly, bee and butterfly are all arthropods studied under the JAMB syllabus.
14. Taenia (tapeworm) belongs to the phylum
A. Nematoda
B. Platyhelminthes
C. Annelida
D. Arthropoda
Answer: B — Platyhelminthes
Explanation: Taenia is a flatworm belonging to phylum Platyhelminthes. It is an endoparasite found in the intestines of vertebrate hosts.
15. A plant that completes its life cycle in two years is called a
A. Annual
B. Perennial
C. Biennial
D. Seasonal
Answer: C — Biennial
Explanation: Biennials complete their life cycle in two years (e.g., carrot, onion). Annuals complete it in one year, and perennials live for more than two years.
16. Which of the following is a cartilaginous fish?
A. Tilapia
B. Catfish
C. Shark
D. Mackerel
Answer: C — Shark
Explanation: Sharks and rays are cartilaginous fish (class Chondrichthyes) — their skeleton is made of cartilage, not bone. Tilapia, catfish and mackerel are bony fish (Osteichthyes).
Topic 3: Structural, Functional & Behavioural Adaptations
17. Counter-shading as an adaptive colouration is best described as
A. Bright colours to warn predators of danger
B. Dark upper surface and light lower surface to reduce visibility
C. Mimicking the colour of a toxic organism
D. Changing colour to match the environment
Answer: B — Dark upper surface and light lower surface to reduce visibility
Explanation: Countershading is found in fish, toads and snakes. The dark dorsal (upper) surface blends with the dark water/ground when viewed from above; the light ventral (lower) surface blends with the bright sky when viewed from below.
18. The primary function of warning colouration found in some mushrooms is to
A. Attract insects for pollination
B. Signal to predators that they are toxic or unpalatable
C. Attract mates during reproduction
D. Camouflage from herbivores
Answer: B — Signal to predators that they are toxic or unpalatable
Explanation: Warning (aposematic) colouration in poisonous mushrooms serves as a signal to potential predators that consumption will be harmful, thus protecting the organism.
19. Hibernation in animals is an adaptation for surviving
A. Drought and high temperatures
B. Cold winter conditions
C. Food abundance
D. Reproduction
Answer: B — Cold winter conditions
Explanation: Hibernation is a period of inactivity and reduced metabolism in winter to conserve energy when food is scarce. Aestivation is the equivalent adaptation for surviving hot, dry conditions.
20. The proboscis of a butterfly is an adaptation for
A. Piercing skin to suck blood
B. Chewing solid food
C. Sucking nectar from flowers
D. Tearing flesh
Answer: C — Sucking nectar from flowers
Explanation: The butterfly has siphoning mouthparts — a long coiled proboscis used to suck liquid nectar. The mosquito has piercing-and-sucking mouthparts for blood feeding.
21. The spines of a cactus plant are adaptations for
A. Reproduction
B. Conserving water
C. Photosynthesis
D. Support and climbing
Answer: B — Conserving water
Explanation: Cactus spines are modified leaves that reduce the surface area available for transpiration, minimising water loss in arid environments. The fleshy stem stores water.
22. The display of colourful feathers by male peacocks is an adaptation for
A. Camouflage
B. Warning predators
C. Securing mates
D. Regulating body temperature
Answer: C — Securing mates
Explanation: Elaborate plumage displays in male birds are sexual selection adaptations designed to attract and impress females during courtship, thereby securing a mate for reproduction.
Section B: Form and Functions
Topic 4: Internal Structure of Flowering Plants & Mammals
23. The vascular tissue responsible for transporting water and mineral salts from roots to leaves is the
A. Phloem
B. Xylem
C. Cortex
D. Epidermis
Answer: B — Xylem
Explanation: Xylem transports water and dissolved mineral salts from the roots upward to the rest of the plant. Phloem transports manufactured food (sucrose) from the leaves to other parts.
24. Which supporting tissue is found in the cortex of young plant stems?
A. Sclerenchyma
B. Collenchyma
C. Parenchyma
D. Phloem fibres
Answer: B — Collenchyma
Explanation: Collenchyma cells have unevenly thickened cell walls and provide flexible support in young, growing parts of the plant such as the petiole and outer cortex of stems.
25. The hepatic portal vein transports
A. Oxygenated blood from the lungs to the heart
B. Digested food from the small intestine to the liver
C. Deoxygenated blood from the kidneys
D. Hormones from the pancreas to the gonads
Answer: B — Digested food from the small intestine to the liver
Explanation: The hepatic portal vein carries nutrient-rich blood from the small intestine (after absorption of digested food) directly to the liver for processing and storage.
Topic 5: Nutrition
26. Which of the following is an autotrophic mode of nutrition?
A. Saprophytic feeding
B. Holozoic feeding
C. Photosynthesis
D. Parasitic feeding
Answer: C — Photosynthesis
Explanation: Autotrophic organisms (plants) manufacture their own food using light energy (photosynthesis) or chemical energy (chemosynthesis). Saprophytic, holozoic and parasitic nutrition are all heterotrophic.
27. The test for the presence of starch in a leaf involves
A. Benedict’s solution turning brick-red
B. Iodine solution turning blue-black
C. Biuret reagent turning purple
D. Ethanol turning milky white
Answer: B — Iodine solution turning blue-black
Explanation: Iodine solution (potassium iodide solution) turns blue-black in the presence of starch. This is the standard test used to detect starch as evidence of photosynthesis in a leaf.
28. Kwashiorkor is a deficiency disease caused by inadequate intake of
A. Carbohydrates
B. Fats
C. Proteins
D. Vitamin C
Answer: C — Proteins
Explanation: Kwashiorkor results from severe protein deficiency in the diet. Symptoms include oedema (swollen belly), muscle wasting, hair discolouration and retarded growth.
29. The light reaction of photosynthesis takes place in the
A. Stroma of chloroplast
B. Grana (thylakoid membranes)
C. Cytoplasm
D. Mitochondria
Answer: B — Grana (thylakoid membranes)
Explanation: The light-dependent reactions occur on the thylakoid membranes (grana) where chlorophyll absorbs light to split water (photolysis) and produce ATP and NADPH. The dark (Calvin cycle) reactions occur in the stroma.
30. Which of the following is a micro-nutrient required by plants?
A. Nitrogen
B. Phosphorus
C. Iron
D. Calcium
Answer: C — Iron
Explanation: Micro-nutrients (trace elements) are required in very small amounts. Iron is a micro-nutrient needed for chlorophyll synthesis. Nitrogen, phosphorus, and calcium are macro-nutrients required in larger quantities.
31. The enzyme that acts on proteins in the stomach is
A. Amylase
B. Lipase
C. Pepsin
D. Maltase
Answer: C — Pepsin
Explanation: Pepsin is a protease secreted by the stomach in inactive form (pepsinogen), activated by hydrochloric acid. It breaks proteins into shorter polypeptide chains.
32. Rickets is caused by deficiency of vitamin
A. A
B. B
C. C
D. D
Answer: D — Vitamin D
Explanation: Vitamin D is essential for calcium and phosphorus absorption needed for bone mineralisation. Its deficiency causes rickets in children (soft, deformed bones) and osteomalacia in adults.
33. Scurvy results from deficiency of
A. Vitamin A
B. Vitamin C
C. Vitamin K
D. Vitamin B12
Answer: B — Vitamin C
Explanation: Vitamin C (ascorbic acid) is essential for collagen synthesis. Deficiency causes scurvy — characterised by bleeding gums, skin haemorrhages and poor wound healing.
34. The dental formula of an adult human being is
A. I 2/2, C 1/1, PM 2/2, M 3/3
B. I 2/2, C 1/1, PM 3/3, M 2/2
C. I 3/3, C 1/1, PM 2/2, M 3/3
D. I 2/2, C 0/0, PM 2/2, M 3/3
Answer: A — I 2/2, C 1/1, PM 2/2, M 3/3
Explanation: The human dental formula (for one side of the jaw) is: Incisors 2/2, Canine 1/1, Premolars 2/2, Molars 3/3 = total 32 teeth.
35. Bladderwort is an example of which type of heterotrophic nutrition?
A. Saprophytic
B. Parasitic
C. Carnivorous (insectivorous)
D. Holozoic
Answer: C — Carnivorous (insectivorous)
Explanation: Bladderwort (Utricularia) and sundew are carnivorous plants that trap and digest insects to supplement their nitrogen intake in nutrient-poor habitats.
Topic 6: Transport
36. Which of the following correctly describes an artery?
A. Carries blood away from the heart; has thin walls; contains valves
B. Carries blood to the heart; has thick walls; lacks valves
C. Carries blood away from the heart; has thick elastic walls; lacks valves
D. Carries blood to the heart; has thin walls; contains valves
Answer: C — Carries blood away from the heart; has thick elastic walls; lacks valves
Explanation: Arteries carry oxygenated blood away from the heart (except the pulmonary artery). They have thick, elastic muscular walls to withstand high pressure and generally lack valves.
37. Transpiration pull as a mechanism of water transport in plants occurs because
A. Root pressure forces water up the xylem
B. Water evaporates from leaves creating a tension that pulls water up
C. Osmosis in the phloem pushes water upward
D. Active transport pumps water through the stomata
Answer: B — Water evaporates from leaves creating a tension that pulls water up
Explanation: As water evaporates from leaf cells through stomata (transpiration), it creates a negative pressure (tension) that pulls water upward through the continuous xylem column — this is the transpiration pull (cohesion-tension mechanism).
38. Lymph differs from blood in that lymph
A. Contains red blood cells
B. Contains no white blood cells
C. Lacks red blood cells and platelets
D. Contains haemoglobin
Answer: C — Lacks red blood cells and platelets
Explanation: Lymph is a pale fluid similar to blood plasma. It contains white blood cells (lymphocytes) but lacks red blood cells and platelets, giving it a yellowish-white colour.
39. Plasmolysis occurs when a plant cell is placed in a
A. Hypotonic solution
B. Isotonic solution
C. Hypertonic solution
D. Distilled water
Answer: C — Hypertonic solution
Explanation: In a hypertonic solution (more concentrated than the cell’s contents), water leaves the cell by osmosis, causing the cell contents to shrink away from the cell wall — this is plasmolysis.
Topic 7: Respiration
40. The net gain of ATP molecules in glycolysis is
A. 38
B. 4
C. 2
D. 36
Answer: C — 2
Explanation: Glycolysis produces 4 ATP molecules but uses 2 ATP molecules to start the process, giving a net gain of 2 ATP per glucose molecule. The process occurs in the cytoplasm.
41. The end products of anaerobic respiration in yeast are
A. Carbon dioxide and water
B. Lactic acid only
C. Ethanol and carbon dioxide
D. Ethanol and water
Answer: C — Ethanol and carbon dioxide
Explanation: In yeast (and plants under anaerobic conditions), glucose is broken down to ethanol (ethyl alcohol) and carbon dioxide without oxygen. This process is called fermentation.
42. Gaseous exchange in insects occurs through
A. Lungs
B. Gills
C. Tracheae
D. Skin
Answer: C — Tracheae
Explanation: Insects have a tracheal system — a network of air tubes (tracheae and tracheoles) that open to the outside through spiracles and deliver oxygen directly to body tissues.
43. The Krebs cycle takes place in the
A. Cytoplasm
B. Nucleus
C. Mitochondrial matrix
D. Cell membrane
Answer: C — Mitochondrial matrix
Explanation: The Krebs (citric acid) cycle occurs in the matrix of the mitochondrion. It oxidises acetyl CoA to produce CO2, ATP, NADH and FADH2 which feed into the electron transport chain.
44. Guard cells control gaseous exchange in plants by regulating the opening of
A. Lenticels
B. Stomata
C. Chloroplasts
D. Root hairs
Answer: B — Stomata
Explanation: Guard cells are kidney-shaped cells flanking each stoma. When turgid (full of water), they bow outward and open the stoma. When flaccid (water-deficient), they close it. This regulates CO2 uptake and water loss.
45. The economic importance of yeast in fermentation includes
A. Production of antibiotics
B. Bread making and alcohol production
C. Manufacture of vaccines
D. Biogas production from cellulose
Answer: B — Bread making and alcohol production
Explanation: Yeast (Saccharomyces cerevisiae) is economically important in baking (CO2 produced causes dough to rise) and in brewing/wine making (ethanol produced from fermentation of sugars).
Topic 8: Excretion
46. The functional unit of the kidney is the
A. Ureter
B. Nephron
C. Glomerulus
D. Bowman’s capsule
Answer: B — Nephron
Explanation: The nephron is the structural and functional unit of the kidney. Each human kidney contains about 1 million nephrons. The nephron filters blood and produces urine.
47. The main nitrogenous excretory product of mammals is
A. Uric acid
B. Ammonia
C. Urea
D. Creatine
Answer: C — Urea
Explanation: Mammals excrete urea (produced in the liver via the ornithine/urea cycle from breakdown of excess amino acids). Fish excrete ammonia; reptiles and birds excrete uric acid.
48. Malpighian tubules are excretory organs found in
A. Earthworms
B. Insects
C. Flatworms
D. Fish
Answer: B — Insects
Explanation: Malpighian tubules are excretory organs found in insects and other arthropods. They extract nitrogenous wastes from the haemolymph and empty them into the hindgut for elimination.
49. Tannins and resins secreted by plants are classified as
A. Hormones
B. Vitamins
C. Excretory products
D. Enzymes
Answer: C — Excretory products
Explanation: Plants excrete metabolic waste products including tannins, resins, gums, mucilage, alkaloids, carbon dioxide and oxygen. Tannins have economic value in tanning leather and in medicine.
Topic 9: Support and Movement
50. The growth movement of a plant in response to light is called
A. Geotropism
B. Hydrotropism
C. Phototropism
D. Thigmotropism
Answer: C — Phototropism
Explanation: Phototropism is the directional growth response of a plant to light. Shoots are positively phototropic (grow toward light); roots are negatively phototropic.
51. Auxins cause unequal growth in plants by
A. Stimulating cell division uniformly on all sides
B. Concentrating on the shaded side and promoting cell elongation there
C. Inhibiting all growth below the shoot tip
D. Increasing chlorophyll production
Answer: B — Concentrating on the shaded side and promoting cell elongation there
Explanation: When light comes from one side, auxins (IAA) migrate to the shaded side of the shoot. Higher auxin concentration causes greater cell elongation on that side, bending the shoot toward the light source.
52. Chitin is the material that makes up the exoskeleton of
A. Earthworms
B. Arthropods
C. Fish
D. Frogs
Answer: B — Arthropods
Explanation: Chitin is a tough, nitrogen-containing polysaccharide that forms the exoskeleton (outer skeleton) of arthropods such as insects, crustaceans and arachnids.
53. A ball-and-socket joint allows movement in
A. One plane only
B. Two planes only
C. All directions (360°)
D. No movement at all
Answer: C — All directions (360°)
Explanation: Ball-and-socket joints (e.g., hip and shoulder joints) allow the widest range of movement in all planes and directions. Hinge joints (e.g., elbow, knee) allow movement in only one plane.
54. Nastic movements in plants differ from tropic movements in that nastic movements
A. Are directional responses to stimuli
B. Are non-directional responses independent of the direction of the stimulus
C. Only occur in roots
D. Are caused by auxins concentrating on one side
Answer: B — Are non-directional responses independent of the direction of the stimulus
Explanation: Tropic movements are directional (toward or away from the stimulus). Nastic movements are non-directional — the response is the same regardless of which direction the stimulus comes from (e.g., opening and closing of flowers).
Topic 10: Reproduction
55. Which of the following is an example of natural vegetative propagation?
A. Grafting
B. Budding in horticulture
C. Formation of bulbs in onions
D. Layering
Answer: C — Formation of bulbs in onions
Explanation: Natural vegetative propagation occurs without human intervention. Examples include bulbs (onions), corms (cocoyam), rhizomes (ginger), stolons (strawberry), and tubers (yam). Grafting, budding and layering are artificial methods.
56. Cross-pollination is advantageous over self-pollination because it
A. Requires no pollinators
B. Produces genetically identical offspring
C. Promotes genetic variation leading to better-adapted offspring
D. Is faster and more efficient
Answer: C — Promotes genetic variation leading to better-adapted offspring
Explanation: Cross-pollination involves transfer of pollen between different plants, promoting genetic recombination. This increases genetic diversity, allowing populations to adapt better to environmental changes.
57. The acrosome of the sperm is important because it
A. Provides energy for swimming
B. Contains enzymes to penetrate the egg
C. Carries the genetic material
D. Stores nutrients for fertilisation
Answer: B — Contains enzymes to penetrate the egg
Explanation: The acrosome (at the tip of the sperm head) contains hydrolytic enzymes (hyaluronidase, acrosin) that digest the zona pellucida and outer layers of the egg, enabling fertilisation.
58. In vitro fertilisation (IVF) involves
A. Fertilisation of the egg inside the oviduct with the aid of drugs
B. Fertilisation of eggs outside the body in a laboratory, then implanting the embryo
C. Injecting sperm directly into the uterus
D. Using surrogate mothers exclusively
Answer: B — Fertilisation of eggs outside the body in a laboratory, then implanting the embryo
Explanation: IVF is a modern reproductive technology where eggs are retrieved from the ovaries and fertilised with sperm in a laboratory dish. The resulting embryo is then transferred into the uterus.
59. The part of a flower that receives pollen during pollination is the
A. Style
B. Stigma
C. Ovary
D. Anther
Answer: B — Stigma
Explanation: The stigma is the sticky, receptive tip of the carpel (pistil) that receives pollen grains. After landing on the stigma, pollen germinates and a pollen tube grows down the style to the ovule.
60. Fission as a method of asexual reproduction is demonstrated by
A. Yeast
B. Paramecium
C. Hydra
D. Spirogyra
Answer: B — Paramecium
Explanation: Paramecium reproduces asexually by binary fission — the organism divides into two equal daughter cells. Yeast reproduces by budding; Hydra by budding; Spirogyra by fragmentation.
Topic 11: Growth & Co-ordination
61. Epigeal germination differs from hypogeal germination in that
A. The cotyledons remain below the soil
B. The cotyledons are brought above the soil surface
C. Only monocots show epigeal germination
D. The radicle does not emerge first
Answer: B — The cotyledons are brought above the soil surface
Explanation: In epigeal germination (e.g., beans, pawpaw), the hypocotyl elongates and pushes cotyledons above soil. In hypogeal germination (e.g., maize, groundnut), cotyledons remain below ground while the plumule pushes up.
62. The part of the brain responsible for balance and coordination of movement is the
A. Cerebrum
B. Medulla oblongata
C. Hypothalamus
D. Cerebellum
Answer: D — Cerebellum
Explanation: The cerebellum (hindbrain) coordinates voluntary muscle movements, maintains posture and balance. The cerebrum handles conscious thought and voluntary actions; the medulla controls involuntary functions.
63. A reflex action differs from a voluntary action in that
A. Reflex actions are slower and deliberate
B. Reflex actions are fast, automatic and do not involve the brain’s conscious control
C. Voluntary actions bypass the spinal cord
D. Reflex actions always involve the cerebrum
Answer: B — Reflex actions are fast, automatic and do not involve the brain’s conscious control
Explanation: Reflex actions are rapid, involuntary responses to stimuli mediated through the spinal cord (reflex arc) without conscious brain involvement. Examples: knee jerk, blinking.
64. The hormone secreted by the adrenal gland in response to stress is
A. Insulin
B. Thyroxine
C. Adrenaline
D. Oestrogen
Answer: C — Adrenaline
Explanation: Adrenaline (epinephrine) is secreted by the adrenal medulla in response to stress, fear or excitement. It increases heart rate, dilates airways and raises blood glucose for the ‘fight or flight’ response.
65. Gibberellins as plant hormones primarily promote
A. Root growth and development
B. Stem elongation and breaking of seed dormancy
C. Leaf abscission
D. Fruit ripening
Answer: B — Stem elongation and breaking of seed dormancy
Explanation: Gibberellins promote cell elongation in stems (causing bolting), break seed dormancy to stimulate germination, and also promote flowering in some plants.
66. The maintenance of a constant internal body environment is called
A. Osmoregulation
B. Thermoregulation
C. Homeostasis
D. Excretion
Answer: C — Homeostasis
Explanation: Homeostasis refers to the ability of an organism to maintain a stable internal environment despite external changes. It includes regulation of body temperature, blood glucose, salt-water balance and pH.
67. The region of the eye responsible for sharp, detailed vision is the
A. Cornea
B. Fovea (yellow spot)
C. Blind spot
D. Iris
Answer: B — Fovea (yellow spot)
Explanation: The fovea centralis (yellow spot) contains the highest concentration of cone cells and is the point of sharpest vision and clearest colour perception on the retina.
Section C: Ecology
Topic 12: Factors Affecting Distribution of Organisms
68. Which of the following is a biotic factor affecting distribution of organisms?
A. Temperature
B. Rainfall
C. Predation
D. Salinity
Answer: C — Predation
Explanation: Biotic factors are living components of the environment including predation, competition, disease, parasitism and the presence of food. Abiotic factors are non-living (temperature, rainfall, pH, light).
69. The Secchi disc is used in ecology to measure
A. Wind speed
B. Soil pH
C. Water turbidity
D. Rainfall
Answer: C — Water turbidity
Explanation: A Secchi disc is a circular disc lowered into water to measure turbidity (water clarity). The depth at which it disappears from view indicates the transparency of the water body.
70. Edaphic factors refer to factors related to
A. Climate
B. Soil
C. Water
D. Altitude
Answer: B — Soil
Explanation: Edaphic factors are soil-related abiotic factors including soil pH, texture, mineral content, moisture, aeration and humus content — all of which influence the type of organisms in an area.
Topic 13: Symbiotic Interactions, Energy Flow & Nutrient Cycling
71. In a food chain, the organisms that feed on primary consumers are called
A. Producers
B. Primary consumers
C. Secondary consumers
D. Decomposers
Answer: C — Secondary consumers
Explanation: In a food chain: Producers → Primary consumers (herbivores) → Secondary consumers (carnivores) → Tertiary consumers. Secondary consumers eat primary consumers (herbivores).
72. The relationship between Loranthus (mistletoe) and its host tree is an example of
A. Mutualism
B. Commensalism
C. Parasitism
D. Saprophytism
Answer: C — Parasitism
Explanation: Loranthus is a parasitic plant that attaches to the branches of trees, obtaining water and mineral salts from the host (haustoria penetrate the host tissue). The host is harmed while Loranthus benefits.
73. Global warming is primarily linked to increased atmospheric concentration of
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen
Answer: C — Carbon dioxide
Explanation: Increased CO2 from burning fossil fuels and deforestation enhances the greenhouse effect, trapping more heat in the atmosphere and causing global temperature rise (global warming).
74. Leguminous plants are important in the nitrogen cycle because they
A. Release nitrogen gas into the atmosphere
B. Harbour nitrogen-fixing bacteria in their root nodules
C. Absorb nitrites from the soil
D. Convert ammonia to nitrates
Answer: B — Harbour nitrogen-fixing bacteria in their root nodules
Explanation: Rhizobium bacteria in the root nodules of legumes fix atmospheric nitrogen into ammonia (nitrogen fixation), which the plant converts to amino acids. This enriches the soil with nitrogen compounds.
75. Which of the following interactions benefits both organisms involved?
A. Parasitism
B. Predation
C. Amensalism
D. Mutualism
Answer: D — Mutualism
Explanation: Mutualism is a symbiotic relationship where both organisms benefit. Example: Rhizobium bacteria in legume root nodules (bacteria get food; plant gets fixed nitrogen). Parasitism and predation benefit only one organism.
76. The trophic level that fixes energy from the sun is occupied by
A. Herbivores
B. Carnivores
C. Green plants (producers)
D. Decomposers
Answer: C — Green plants (producers)
Explanation: Green plants (autotrophs/producers) are at the first trophic level. They convert solar energy into chemical energy (glucose) through photosynthesis, forming the base of all food chains.
Topic 14: Natural Habitats & Nigerian Biomes
77. The mangrove swamp habitat is characterised by
A. Freshwater fish and savanna grasses
B. Salt-tolerant trees with stilt roots growing in brackish water
C. Dense canopy of tropical forest trees with no undergrowth
D. Desert succulents and sand dunes
Answer: B — Salt-tolerant trees with stilt roots growing in brackish water
Explanation: Mangrove swamps are coastal wetland ecosystems dominated by halophytic (salt-tolerant) mangrove trees that have stilt/prop roots for anchorage in soft, waterlogged, saline mud.
78. Which of the following biomes is found on the Mambilla, Jos and Obudu plateaus in Nigeria?
A. Tropical rainforest
B. Sudan Savanna
C. Desert
D. Montane forest and highland grassland
Answer: D — Montane forest and highland grassland
Explanation: The Mambilla, Jos and Obudu plateaus are high-altitude regions in Nigeria characterised by montane (highland) forests and grasslands — a unique biome distinct from the surrounding lowland vegetation.
79. The tropical rainforest biome in Nigeria is characterised by
A. High rainfall, high temperature, and tall trees with wide canopy
B. Low rainfall, sparse vegetation and high temperatures
C. Seasonal flooding and grassland with scattered trees
D. Extreme cold with coniferous trees
Answer: A — High rainfall, high temperature, and tall trees with wide canopy
Explanation: Nigeria’s tropical rainforest (found in the south) receives over 2,000 mm of rainfall annually, has consistently high temperatures, multi-layered canopy and extremely high biodiversity.
Topic 15: Ecology of Populations & Soil
80. Population density is defined as
A. Total number of organisms in an ecosystem
B. Number of organisms per unit area or volume
C. Rate of growth of a population per year
D. Maximum population size possible in a habitat
Answer: B — Number of organisms per unit area or volume
Explanation: Population density = Number of individuals ÷ Area (or volume). It is a measure of how crowded a population is within its habitat.
81. Primary succession differs from secondary succession in that
A. Primary succession occurs on already colonised soil
B. Primary succession starts on bare, uninhabited substrate with no soil
C. Secondary succession is slower than primary succession
D. Primary succession begins with climax communities
Answer: B — Primary succession starts on bare, uninhabited substrate with no soil
Explanation: Primary succession begins on bare rock or new lava (no pre-existing soil or biota). Secondary succession occurs on areas where a community was previously present but was disturbed (e.g., abandoned farmland, burnt forest).
82. Loamy soil is considered the best for crop growth because it
A. Has the highest clay content and retains maximum water
B. Has the highest sand content allowing maximum drainage
C. Balances water retention, drainage, and aeration with high humus content
D. Has no organic matter
Answer: C — Balances water retention, drainage, and aeration with high humus content
Explanation: Loamy soil contains a balanced mixture of sand, silt and clay particles plus abundant humus. This gives it good drainage, good water retention, adequate aeration and rich nutrients — ideal for plant growth.
83. Contour ridging is a soil conservation practice that prevents
A. Soil compaction
B. Soil erosion on slopes
C. Loss of soil micro-organisms
D. Soil acidification
Answer: B — Soil erosion on slopes
Explanation: Contour ridging involves creating ridges along the contours of slopes perpendicular to the flow of water. This slows runoff, reduces erosion and encourages water infiltration into the soil.
Topic 16: Humans and the Environment – Disease, Pollution & Conservation
84. The vector of malaria is
A. Female Aedes mosquito
B. Female Anopheles mosquito
C. Housefly
D. Tsetse fly
Answer: B — Female Anopheles mosquito
Explanation: Malaria is caused by Plasmodium parasites transmitted through the bite of infected female Anopheles mosquitoes. Only females bite (requiring blood for egg development). Aedes transmits dengue and yellow fever.
85. AIDS is caused by
A. A bacterium called Mycobacterium
B. A protozoan called Plasmodium
C. Human Immunodeficiency Virus (HIV)
D. A fungus
Answer: C — Human Immunodeficiency Virus (HIV)
Explanation: AIDS (Acquired Immune Deficiency Syndrome) is caused by HIV (Human Immunodeficiency Virus), which attacks and destroys CD4+ T-lymphocytes, progressively weakening the immune system.
86. Which international organisation is primarily responsible for global health matters?
A. UNICEF
B. WHO
C. WWF
D. IUCN
Answer: B — WHO
Explanation: The World Health Organisation (WHO) is the United Nations agency responsible for international public health, coordinating responses to disease outbreaks, setting health standards and policies globally.
87. Onchocerciasis (river blindness) is transmitted by
A. Anopheles mosquito
B. Blackfly (Simulium species)
C. Tsetse fly
D. Sandfly
Answer: B — Blackfly (Simulium species)
Explanation: Onchocerciasis is caused by the nematode Onchocerca volvulus and transmitted by the bite of blackflies (Simulium species) that breed in fast-flowing rivers in West Africa.
88. Which of the following is a method of biological control of pollution?
A. Incineration of waste
B. Use of bacteria to degrade oil spills
C. Filtration of water
D. Dumping waste in designated landfill
Answer: B — Use of bacteria to degrade oil spills
Explanation: Bioremediation uses living organisms (bacteria, fungi or plants) to degrade pollutants. Using oil-degrading bacteria to clean up oil spills is a classic example of biological pollution control.
89. The Nigerian Conservation Foundation (NCF) is responsible for
A. Managing federal prisons
B. Administering JAMB examinations
C. Conservation of Nigeria’s biodiversity and natural resources
D. Regulating the oil and gas industry
Answer: C — Conservation of Nigeria’s biodiversity and natural resources
Explanation: The NCF is a non-governmental organisation dedicated to conserving Nigeria’s biodiversity. It manages conservation programmes, nature reserves, and public environmental education campaigns.
Section D: Heredity and Variations
Topic 17: Variation in Populations
90. Which of the following is an example of continuous variation?
A. Blood groups (A, B, AB, O)
B. Ability to roll the tongue
C. Height in human beings
D. Presence or absence of widow’s peak
Answer: C — Height in human beings
Explanation: Continuous variation shows a gradual range of values with no distinct categories (e.g., height, weight, skin colour in a spectrum). Discontinuous variation shows distinct categories with no intermediates (e.g., blood groups, tongue rolling).
91. ABO blood grouping is an example of
A. Continuous variation
B. Discontinuous variation
C. Sex-linked variation
D. Environmental variation
Answer: B — Discontinuous variation
Explanation: Blood groups (A, B, AB, O) are distinct categories with no intermediates — this is discontinuous variation. It is genetically determined and not influenced by environmental conditions.
92. Fingerprint patterns are used in forensic science because
A. They change with age and disease
B. Each person’s fingerprints are unique and do not change
C. They reveal blood group information
D. They show the person’s chromosomal composition
Answer: B — Each person’s fingerprints are unique and do not change
Explanation: Fingerprints are unique to each individual (even identical twins have slightly different prints) and remain unchanged throughout a person’s life. This makes them reliable for identity detection and crime investigation.
93. Blood transfusion incompatibility occurs because
A. Donor blood has more haemoglobin than recipient blood
B. Antibodies in the recipient’s blood react with antigens on donor red blood cells
C. The donor blood type is always different
D. The recipient lacks white blood cells
Answer: B — Antibodies in the recipient’s blood react with antigens on donor red blood cells
Explanation: If a recipient receives incompatible blood, antibodies (agglutinins) in their plasma react with foreign antigens (agglutinogens) on the donor’s red blood cells, causing agglutination (clumping) and potentially fatal haemolysis.
Topic 18: Heredity & Genetics
94. Mendel’s Law of Segregation states that
A. Two genes for different traits are inherited together
B. Alleles of a gene separate during gamete formation so each gamete carries only one allele
C. Dominant alleles always mask recessive alleles
D. All offspring of a cross between pure-breeding parents are identical
Answer: B — Alleles of a gene separate during gamete formation so each gamete carries only one allele
Explanation: The Law of Segregation states that during meiosis (gamete formation), the two alleles of each gene separate so that each gamete receives only one allele. They reunite randomly at fertilisation.
95. A cross between a tall plant (TT) and a short plant (tt) gives offspring that are all
A. Short (tt)
B. Tall (Tt)
C. 50% tall, 50% short
D. Short (TT)
Answer: B — Tall (Tt)
Explanation: TT × tt → all offspring are Tt (heterozygous tall). Since T (tall) is dominant over t (short), all F1 offspring appear tall phenotypically, though they are heterozygous genotypically.
96. In humans, sex is determined by chromosomes such that females have
A. XY chromosomes
B. YY chromosomes
C. XX chromosomes
D. XO chromosomes
Answer: C — XX chromosomes
Explanation: Human females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome carries the SRY gene that triggers male development.
97. Haemophilia is a sex-linked recessive disorder that mainly affects males because
A. Females have two X chromosomes, so a second normal X can mask the defective gene
B. The gene is located on the Y chromosome
C. Males produce more clotting factors
D. The condition is not inherited but acquired
Answer: A — Females have two X chromosomes, so a second normal X can mask the defective gene
Explanation: Haemophilia is X-linked recessive. Females (XX) need two copies of the defective allele to be affected. Males (XY) with just one defective X have no normal allele to mask it, so they are always affected.
98. Sickle-cell anaemia is caused by
A. A deletion of the entire haemoglobin gene
B. A point mutation causing abnormal haemoglobin (HbS) production
C. A chromosomal translocation
D. Environmental toxin exposure
Answer: B — A point mutation causing abnormal haemoglobin (HbS) production
Explanation: A single nucleotide substitution (point mutation) in the beta-globin gene replaces glutamic acid with valine, producing abnormal haemoglobin S (HbS) that causes red blood cells to sickle under low oxygen conditions.
99. An individual with genotype AS in sickle-cell terminology is described as
A. Normal (unaffected)
B. A carrier (sickle-cell trait)
C. Sickle-cell anaemia patient
D. Immune to all infections
Answer: B — A carrier (sickle-cell trait)
Explanation: AS individuals have one normal haemoglobin allele (A) and one sickle allele (S). They are carriers (have sickle-cell trait) — generally healthy but can pass the S allele to offspring. Only SS individuals have full sickle-cell disease.
100. The process of meiosis is significant in inheritance because it
A. Produces genetically identical cells
B. Halves the chromosome number and creates genetic variation through recombination
C. Doubles the chromosome number for reproduction
D. Occurs only in somatic (body) cells
Answer: B — Halves the chromosome number and creates genetic variation through recombination
Explanation: Meiosis produces four haploid gametes from one diploid cell. During crossing over in meiosis I, genetic material is exchanged between homologous chromosomes, generating new allele combinations (genetic variation).
101. Genetically Modified Organisms (GMOs) are produced by
A. Selective breeding over many generations
B. Inserting specific genes from one organism into another organism’s genome
C. Exposing organisms to radiation to cause mutations
D. Cross-breeding within the same species
Answer: B — Inserting specific genes from one organism into another organism’s genome
Explanation: GMOs are produced through recombinant DNA technology — genes are isolated, cloned and inserted into the genome of a target organism using vectors (e.g., plasmids). Examples include Bt cotton and Golden Rice.
102. Insulin used to treat diabetes is now produced commercially through
A. Extraction from pig pancreases only
B. Recombinant DNA technology using bacteria
C. Chemical synthesis from amino acids in a laboratory
D. Plant extraction from soya beans
Answer: B — Recombinant DNA technology using bacteria
Explanation: Human insulin is produced by inserting the human insulin gene into bacterial plasmids (recombinant DNA). The bacteria (E. coli) then produce large quantities of human insulin for medical use.
Topic 19: Biotechnology
103. Biotechnology is defined as
A. The study of living organisms and their environments
B. The use of living organisms or their products to develop useful applications
C. The science of manufacturing synthetic drugs
D. The study of fossils and prehistoric life
Answer: B — The use of living organisms or their products to develop useful applications
Explanation: Biotechnology uses living organisms, cells or biological molecules to develop products and processes for medicine, agriculture, food production and environmental management.
104. In food biotechnology, microorganisms are used in the production of
A. Petroleum and plastics
B. Cheese, yoghurt and bread
C. Cotton and synthetic fabrics
D. Steel and cement
Answer: B — Cheese, yoghurt and bread
Explanation: Bacteria (Lactobacillus for yoghurt and cheese) and yeast (Saccharomyces for bread and alcohol) are classic biotechnology organisms used in food fermentation and preservation.
Section E: Evolution
Topic 20: Theories of Evolution
105. Lamarck’s theory of evolution is based on the principle of
A. Natural selection acting on random mutations
B. Inheritance of acquired characteristics through use and disuse of organs
C. Genetic drift in small isolated populations
D. Survival of the fittest in a competitive environment
Answer: B — Inheritance of acquired characteristics through use and disuse of organs
Explanation: Lamarck proposed that organs developed through use become stronger and are inherited, while disused organs weaken and disappear. Modern genetics has disproved the inheritance of acquired characteristics.
106. Darwin’s theory of natural selection proposes that
A. All organisms evolve at the same rate
B. Organisms with favourable variations survive and reproduce more successfully
C. Evolution is directed by the organism’s desire to improve
D. New species arise only through genetic mutation
Answer: B — Organisms with favourable variations survive and reproduce more successfully
Explanation: Darwin proposed that in a struggle for survival, individuals with beneficial variations (adaptations) are more likely to survive, reproduce and pass those traits to offspring — ‘survival of the fittest’ (natural selection).
107. Which of the following is evidence for organic evolution?
A. The existence of game reserves
B. Fossil records showing gradual changes in organisms over time
C. The presence of the same blood group in all humans
D. Seasonal variation in temperature
Answer: B — Fossil records showing gradual changes in organisms over time
Explanation: Fossil records show preserved remains of past organisms, documenting gradual morphological changes over geological time. Other evidence includes comparative anatomy (homologous/analogous structures), embryology and molecular genetics.
108. Homologous structures are defined as structures that
A. Look similar and perform the same function but have different origins
B. Have the same basic structural plan and origin but may serve different functions
C. Are vestigial and serve no function in modern organisms
D. Are found exclusively in vertebrates
Answer: B — Have the same basic structural plan and origin but may serve different functions
Explanation: Homologous structures share common ancestry (same embryological origin and basic structure) but may be modified for different functions. Example: the forelimbs of a human arm, whale flipper, horse leg and bat wing.
109. Mutation is significant in evolution because it
A. Always produces beneficial organisms
B. Creates new alleles that can be acted upon by natural selection
C. Prevents natural selection from occurring
D. Only occurs in plants
Answer: B — Creates new alleles that can be acted upon by natural selection
Explanation: Mutations (changes in DNA sequence) are the ultimate source of new genetic variation. While most mutations are neutral or harmful, some are beneficial. Natural selection acts on this variation, driving evolutionary change.
110. Analogous structures in organisms are evidence of
A. Common ancestry (divergent evolution)
B. Convergent evolution — similar environments selecting for similar forms
C. Genetic drift
D. Artificial selection
Answer: B — Convergent evolution — similar environments selecting for similar forms
Explanation: Analogous structures (e.g., wings of insects and birds) look similar and perform the same function but have different evolutionary origins. They arise because unrelated organisms evolved similar solutions to similar environmental challenges.
111. Vestigial structures in organisms provide evidence for evolution because they
A. Perform important functions that are not yet understood
B. Are remnants of structures that were functional in ancestral organisms
C. Appear only in organisms undergoing rapid evolution
D. Are examples of acquired characteristics
Answer: B — Are remnants of structures that were functional in ancestral organisms
Explanation: Vestigial organs (e.g., human appendix, coccyx, wisdom teeth; whale pelvic bones) are reduced or non-functional remnants of structures that served important functions in evolutionary ancestors, implying common descent.
Bonus: Mixed Practice — 20 Rapid-Fire Questions
Use this section to test your overall speed and retention. Attempt each question before reading the answer.
Tip: Press Ctrl+F (Windows) or Cmd+F (Mac) and type a question number (e.g., “Question 120”) to jump directly to any question on this page.
112. Which gas is released during the light reaction of photosynthesis?
A. CO2
B. N2
C. O2
D. H2
Answer: C — O2
Explanation: Water is split (photolysis) during the light reaction, releasing oxygen gas as a by-product: 2H2O → 4H+ + 4e- + O2.
113. The centre of osmoregulation and temperature regulation in the brain is the
A. Cerebellum
B. Medulla oblongata
C. Hypothalamus
D. Cerebrum
Answer: C — Hypothalamus
Explanation: The hypothalamus regulates body temperature (via shivering/sweating signals), water balance (via ADH production) and links the nervous and endocrine systems.
114. Which of the following is NOT a component of blood?
A. Platelets
B. Red blood cells
C. Bile
D. White blood cells
Answer: C — Bile
Explanation: Blood consists of plasma, red blood cells (erythrocytes), white blood cells (leucocytes) and platelets (thrombocytes). Bile is a digestive fluid produced by the liver, not a blood component.
115. The process by which roots absorb mineral salts against a concentration gradient is
A. Diffusion
B. Osmosis
C. Active transport
D. Transpiration
Answer: C — Active transport
Explanation: Active transport requires ATP energy to move mineral ions from the dilute soil solution into root hair cells against the concentration gradient. This is why waterlogged soil (which limits root respiration) reduces mineral uptake.
116. Which of the following diseases is caused by a bacterium?
A. Malaria
B. Cholera
C. AIDS
D. Onchocerciasis
Answer: B — Cholera
Explanation: Cholera is caused by the bacterium Vibrio cholerae. Malaria is caused by Plasmodium (protozoan); AIDS by HIV (virus); Onchocerciasis by Onchocerca volvulus (nematode).
117. The product of fertilisation in flowering plants is the
A. Seed
B. Zygote
C. Embryo sac
D. Pollen tube
Answer: B — Zygote
Explanation: Fertilisation is the fusion of the male gamete (from pollen) with the female egg cell. The product is a diploid zygote, which develops into an embryo within the seed.
118. Which level of ecological organisation encompasses all the abiotic factors and living organisms in an area?
A. Population
B. Community
C. Ecosystem
D. Biome
Answer: C — Ecosystem
Explanation: An ecosystem includes all the living organisms (biotic components) interacting with each other AND with the non-living (abiotic) environment. A community is biotic only; a population is one species; a biome is a large-scale ecosystem type.
119. The fluid that surrounds the cells and tissues of the body, carrying nutrients and waste, is called
A. Blood plasma
B. Lymph
C. Tissue fluid
D. Serum
Answer: C — Tissue fluid
Explanation: Tissue fluid (interstitial fluid) is filtered from blood capillaries and bathes the body’s cells. It carries nutrients and oxygen to cells and collects their waste. Excess tissue fluid drains into lymph capillaries.
120. Which of the following correctly pairs an endocrine gland with its hormone?
A. Pancreas — Thyroxine
B. Thyroid — Insulin
C. Adrenal gland — Adrenaline
D. Pituitary — Oestrogen
Answer: C — Adrenal gland — Adrenaline
Explanation: The adrenal medulla produces adrenaline. The pancreas produces insulin and glucagon; the thyroid produces thyroxine; oestrogen is produced by the ovaries (gonads).
121. Crossing over during meiosis results in
A. Reduced chromosome number
B. Recombination of genetic material
C. Duplication of chromosomes
D. Formation of two cells
Answer: B — Recombination of genetic material
Explanation: During prophase I of meiosis, homologous chromosomes pair up and exchange segments (crossing over at chiasmata). This creates new combinations of alleles (recombinant chromosomes), increasing genetic diversity.
122. The role of decomposers in an ecosystem is to
A. Synthesise food from sunlight
B. Feed on living animals
C. Break down dead organic matter and recycle nutrients
D. Fix atmospheric nitrogen
Answer: C — Break down dead organic matter and recycle nutrients
Explanation: Decomposers (bacteria and fungi) break down dead organisms and faeces, releasing inorganic minerals back into the soil and atmosphere for uptake by producers — completing nutrient cycles.
123. In which part of the alimentary canal is most digested food absorbed?
A. Stomach
B. Large intestine
C. Oesophagus
D. Small intestine
Answer: D — Small intestine
Explanation: The small intestine (especially the ileum) is the main site of absorption. Its large surface area (due to villi and microvilli) and rich blood supply ensure efficient absorption of digested food.
124. Denitrification in the nitrogen cycle is carried out by
A. Rhizobium bacteria
B. Nitrosomonas bacteria
C. Denitrifying bacteria (e.g., Pseudomonas)
D. Azotobacter bacteria
Answer: C — Denitrifying bacteria (e.g., Pseudomonas)
Explanation: Denitrifying bacteria convert nitrates back to nitrogen gas (N2) in anaerobic (waterlogged) soil conditions, completing the nitrogen cycle by returning nitrogen to the atmosphere.
125. Which of the following is an example of secondary succession?
A. Colonisation of bare volcanic rock by lichens
B. Vegetation developing on newly formed sand dunes
C. Regrowth of vegetation on abandoned farmland
D. Gradual formation of soil on bare granite
Answer: C — Regrowth of vegetation on abandoned farmland
Explanation: Secondary succession occurs where soil and some biological legacy already exist after a disturbance. Abandoned farmland retains soil and seed banks, allowing faster recovery than primary succession on bare rock.
126. The role of the placenta during pregnancy includes
A. Producing sperm for fertilisation
B. Exchanging nutrients, gases and waste between mother and foetus
C. Storing excess food for the mother
D. Producing digestive enzymes for the foetus
Answer: B — Exchanging nutrients, gases and waste between mother and foetus
Explanation: The placenta is the organ of exchange between maternal and foetal blood. It allows oxygen, glucose and antibodies to pass to the foetus, and CO2 and urea to pass back to the mother, without direct mixing of blood.
127. Which of the following statements about enzymes is CORRECT?
A. Enzymes are consumed in the reactions they catalyse
B. Enzymes are denatured at high temperatures
C. Each enzyme can catalyse all types of reactions
D. Enzymes are only found in animals
Answer: B — Enzymes are denatured at high temperatures
Explanation: Enzymes are biological catalysts (mostly proteins) that are not consumed in reactions and are highly specific (one enzyme, one substrate). High temperatures disrupt their 3D shape (denaturation), destroying their activity.
128. The knee jerk reflex is an example of a
A. Voluntary action
B. Conditioned reflex
C. Unconditioned (innate) reflex
D. Learned behaviour
Answer: C — Unconditioned (innate) reflex
Explanation: The knee jerk (patellar reflex) is an innate, unconditioned reflex — it is automatic and inborn. Conditioned reflexes (e.g., Pavlov’s dogs salivating at a bell) are learned associations.
129. In an experiment to demonstrate osmosis, a potato chip placed in a concentrated salt solution will
A. Gain mass and become turgid
B. Lose mass and become flaccid (plasmolysed)
C. Remain unchanged
D. Absorb salt and increase in length only
Answer: B — Lose mass and become flaccid (plasmolysed)
Explanation: The concentrated salt solution is hypertonic to the potato cell contents. Water moves out of the potato cells by osmosis (down the water potential gradient), causing the cells to lose mass and become flaccid/plasmolysed.
130. Which of the following correctly represents the path of a nerve impulse in a reflex arc?
A. Effector → Motor neurone → Relay neurone → Sensory neurone → Receptor
B. Receptor → Sensory neurone → Relay neurone → Motor neurone → Effector
C. Receptor → Motor neurone → Brain → Sensory neurone → Effector
D. Effector → Relay neurone → Brain → Sensory neurone → Receptor
Answer: B — Receptor → Sensory neurone → Relay neurone → Motor neurone → Effector
Explanation: In a reflex arc: Stimulus → Receptor → Sensory neurone (afferent) → Relay/interneurone (in spinal cord) → Motor neurone (efferent) → Effector (muscle or gland) → Response.
131. The term ‘climax community’ in ecological succession refers to
A. The pioneer species that first colonise bare ground
B. The final, stable and self-sustaining community that replaces all seral stages
C. The maximum population density in an ecosystem
D. The most economically valuable ecosystem
Answer: B — The final, stable and self-sustaining community that replaces all seral stages
Explanation: A climax community is the stable, self-perpetuating endpoint of ecological succession. It represents a balance between the community and its environment. For example, tropical rainforest is the climax community in humid Nigeria.
Quick Answer Key
Use this table for quick revision. Full explanations are provided with each question above.
Tip: Press Ctrl+F and type any question number to jump directly to the detailed explanation.
| Q | Ans | Q | Ans | Q | Ans | Q | Ans | Q | Ans |
|---|---|---|---|---|---|---|---|---|---|
| 1 | C | 2 | B | 3 | C | 4 | C | 5 | B |
| 6 | B | 7 | C | 8 | B | 9 | C | 10 | C |
| 11 | D | 12 | A | 13 | C | 14 | B | 15 | C |
| 16 | C | 17 | B | 18 | B | 19 | B | 20 | C |
| 21 | B | 22 | C | 23 | B | 24 | B | 25 | B |
| 26 | C | 27 | B | 28 | C | 29 | B | 30 | C |
| 31 | C | 32 | D | 33 | B | 34 | A | 35 | C |
| 36 | C | 37 | B | 38 | C | 39 | C | 40 | C |
| 41 | C | 42 | C | 43 | C | 44 | B | 45 | B |
| 46 | B | 47 | C | 48 | B | 49 | C | 50 | C |
| 51 | B | 52 | B | 53 | C | 54 | B | 55 | C |
| 56 | C | 57 | B | 58 | B | 59 | B | 60 | B |
| 61 | B | 62 | D | 63 | B | 64 | C | 65 | B |
| 66 | C | 67 | B | 68 | C | 69 | C | 70 | B |
| 71 | C | 72 | C | 73 | C | 74 | B | 75 | D |
| 76 | C | 77 | B | 78 | D | 79 | A | 80 | B |
| 81 | B | 82 | C | 83 | B | 84 | B | 85 | C |
| 86 | B | 87 | B | 88 | B | 89 | C | 90 | C |
| 91 | B | 92 | B | 93 | B | 94 | B | 95 | B |
| 96 | C | 97 | A | 98 | B | 99 | B | 100 | B |
| 101 | B | 102 | B | 103 | B | 104 | B | 105 | B |
| 106 | B | 107 | B | 108 | B | 109 | B | 110 | B |
| 111 | B | 112 | C | 113 | C | 114 | C | 115 | C |
| 116 | B | 117 | B | 118 | C | 119 | C | 120 | C |
| 121 | B | 122 | C | 123 | D | 124 | C | 125 | C |
| 126 | B | 127 | B | 128 | C | 129 | B | 130 | B |
| 131 | B |
Conclusion
Success in JAMB Biology does not come from guesswork, it comes from a clear strategy and consistent practice.
The winning formula is simple: Syllabus + Past Questions + Regular Practice = High Score
By focusing on the official topics, practising likely questions, and testing yourself under exam conditions, you will build both confidence and speed, both of which are essential for the UTME.
Remember, JAMB sets Biology questions strictly from the syllabus, so staying within the approved content is your biggest advantage.
Focus on the high-frequency topics: Cell Biology, Genetics, Ecology, Photosynthesis, Respiration, Classification, and Evolution.
Save this page, practice daily, and prepare smartly for JAMB Biology 2026.
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