CAMPUSNINJA / THE STUDY DESK

JAMB BiologyStudy notes & practice

Understand living systems through clear explanations, biological examples and original practice.

01 Learn02 Practise03 Come back stronger

Foundation revision notes and original practice. These lessons cover major biological ideas with worked examples. Diagram interpretation, specimens and experimental data need further practice.

What these revision notes cover
  • These lessons cover major biological ideas with worked examples. Diagram interpretation, specimens and experimental data need further practice.
  • Use them alongside the full syllabus and practical learning materials.

01 A: Variety of organisms

Living cells and levels of organisation

Read this lesson

What you should be able to do

  • Relate cell structures to their functions
  • Trace organisation from cells to organ systems

Understand it

Living things carry out linked processes such as nutrition, respiration, excretion, growth, reproduction and response. One isolated feature, such as movement, is not enough to establish that something is alive. Cells are the basic structural and functional units of organisms.

The cell membrane regulates exchange; the nucleus contains most genetic material in a eukaryotic cell; ribosomes make proteins; mitochondria support aerobic ATP production. Plant cells typically have cellulose walls and large vacuoles. Chloroplasts occur in photosynthetic cells, not every plant cell.

Similar specialised cells form tissues, tissues form organs, and organs cooperate in systems. A leaf is an organ containing several tissues. A unicellular organism performs its life functions within one cell, so a single cell can also be a complete organism.

Work through an example

Why is a leaf an organ rather than a tissue?

Explanation: It contains different tissues, including epidermis, mesophyll and vascular tissue, working together in photosynthesis and exchange.

Watch out: Respiration releases usable energy; it is not simply another word for breathing.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which structure makes proteins?

  1. Ribosome
  2. Vacuole
  3. Golgi apparatus
  4. Cell wall
Show answer and explanation

Answer A: Ribosome

Ribosomes assemble amino acids into proteins using instructions carried by messenger RNA. A vacuole mainly has storage and related roles, while a cell wall provides support. A chloroplast contains its own ribosomes, but its membrane alone is not the protein-making structure named here.

Question 2

Which sequence increases in organisational level?

  1. Tissue → cell → organism
  2. System → cell → tissue
  3. Organ → tissue → cell
  4. Cell → tissue → organ
Show answer and explanation

Answer D: Cell → tissue → organ

Cells combine into tissues, and different tissues work together in an organ: cell → tissue → organ. For example, a leaf contains epidermal, mesophyll and vascular tissues. Each other option reverses the order at least once.

Link to this topic

02 A: Variety of organisms

Bacteria, protists and fungi

Read this lesson

What you should be able to do

  • Compare major microbial groups
  • Connect structures and nutrition to ecological roles

Understand it

Bacteria are prokaryotes: their DNA is not enclosed in a membrane-bound nucleus. Some are photosynthetic, some obtain energy from inorganic reactions, and many feed on organic substances. The syllabus uses the historical group Monera for prokaryotes.

Protists are eukaryotic organisms grouped together in traditional school classifications. Amoeba forms pseudopodia, Paramecium uses cilia, and Euglena has a flagellum and can photosynthesise when conditions allow. These examples show different ways single cells move and obtain food.

Fungi lack chlorophyll and absorb nutrients after external digestion. Rhizopus has thread-like hyphae forming a mycelium; sporangia produce spores. Many fungi decompose dead matter, while others are parasites or mutualists. Spores are reproductive units, not seeds.

Work through an example

A microbe has DNA but no membrane-bound nucleus. Which broad cell type does it have?

Explanation: It is prokaryotic. Absence of a nucleus does not mean absence of genetic material.

Watch out: Fungi are not non-green plants in modern classification; they form a separate kingdom.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Paramecium mainly moves using

  1. Jointed legs
  2. Roots
  3. Hyphae
  4. Cilia
Show answer and explanation

Answer D: Cilia

Coordinated beating of cilia propels Paramecium.

Question 2

How does a saprotrophic fungus obtain nutrients?

  1. Absorbs all nutrients from a living host without external digestion
  2. Ingests solid food before digestion
  3. Absorbs products of external digestion
  4. Produces sugars by photosynthesis
Show answer and explanation

Answer C: Absorbs products of external digestion

It releases enzymes outside its body and absorbs soluble digestion products.

Link to this topic

03 A: Variety of organisms

Plant groups and life cycles

Read this lesson

What you should be able to do

  • Distinguish algae, bryophytes, ferns and seed plants
  • Compare monocots, dicots and life spans

Understand it

Spirogyra is a filamentous green alga. Mosses and liverworts lack the well-developed vascular system of ferns and seed plants. Ferns have true vascular tissues and reproduce using spores; they do not make flowers or seeds.

Gymnosperms produce seeds that are not enclosed in a fruit, while angiosperm seeds develop within an ovary that normally becomes a fruit. Monocots typically have one cotyledon and parallel leaf veins; dicots typically have two cotyledons and net-like veins. Use several features when identifying a specimen.

Annuals complete their life cycle within one growing season or year; biennials usually need two growing seasons; perennials live for more than two years. Alternation of generations involves haploid gamete-producing and diploid spore-producing phases, with different dominant phases across plant groups.

Work through an example

Why is a fern vascular but not a seed plant?

Explanation: It has xylem and phloem, but reproduces with spores rather than seeds.

Watch out: Spore production does not mean a plant has no sexual phase in its life cycle.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which plant group produces seeds enclosed in fruits?

  1. Mosses
  2. Angiosperms
  3. Ferns
  4. Green algae
Show answer and explanation

Answer B: Angiosperms

Angiosperm ovules develop into seeds inside ovaries that form fruits.

Question 2

A plant completes its life cycle in one year. It is

  1. Annual
  2. Biennial
  3. Perennial
  4. Woody perennial
Show answer and explanation

Answer A: Annual

Life span, not cotyledon number, determines this classification.

Link to this topic

04 A: Variety of organisms

Animal diversity and insect development

Read this lesson

What you should be able to do

  • Identify major invertebrate and vertebrate features
  • Distinguish complete and incomplete metamorphosis

Understand it

Invertebrates include cnidarians such as Hydra, flatworms, roundworms, segmented annelids, arthropods and molluscs. Jointed appendages and an exoskeleton distinguish arthropods; a soft body and muscular foot are common molluscan features.

Vertebrates have a vertebral column. Fish are adapted mainly to aquatic life; amphibians commonly have aquatic larvae and moist skin; reptiles have keratinised scales; birds have feathers; mammals have hair and mammary glands. Classification uses shared features, not size.

Complete metamorphosis passes through egg, larva, pupa and adult, as in butterflies and mosquitoes. Incomplete metamorphosis passes through egg, nymph and adult, as in cockroaches. Insects may pollinate crops, recycle matter, damage stored food or transmit disease, depending on the species.

Work through an example

Compare a mosquito larva and a cockroach nymph.

Explanation: The larva is part of complete metamorphosis and is followed by a pupal stage. The nymph belongs to incomplete metamorphosis and develops without a pupa.

Watch out: Not every invertebrate is an insect; insects are one class within arthropods.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which animal has a segmented body without jointed legs?

  1. Hydra
  2. Earthworm
  3. Cockroach
  4. Snail
Show answer and explanation

Answer B: Earthworm

Earthworms are annelids with repeated body segments.

Question 2

Which feature is characteristic of birds?

  1. Moist glandular skin without feathers
  2. Feathers
  3. Jointed exoskeleton
  4. Mammary glands
Show answer and explanation

Answer B: Feathers

Feathers distinguish birds from the other listed groups.

Link to this topic

05 A: Variety of organisms

Adaptations and animal behaviour

Read this lesson

What you should be able to do

  • Link adaptive features to survival
  • Compare camouflage, warning colours and social roles

Understand it

An adaptation is an inherited feature that contributes to survival or reproduction in a particular environment. Structural adaptations include bird beaks suited to feeding; physiological adaptations concern internal processes; behavioural adaptations concern actions such as migration.

Camouflage reduces detection by matching surroundings. Warning colours advertise a defence, while mimicry involves resemblance to another organism or object. Countershading can reduce the visual contrast of a body when seen from above or below.

Social insects divide tasks among castes. Workers maintain the colony, soldiers defend where present, and reproductive individuals produce offspring. Basking helps an ectotherm raise its body temperature; dormancy can reduce activity during unfavourable conditions.

Work through an example

Why can a thick waxy leaf surface help a plant in a dry habitat?

Explanation: The waxy cuticle reduces water loss through the leaf surface, conserving water when supply is limited.

Watch out: An individual does not deliberately evolve a feature because it needs one.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A stick insect resembles a twig. The main advantage is

  1. More body segments
  2. Faster photosynthesis
  3. Reduced detection by predators
  4. More chlorophyll
Show answer and explanation

Answer C: Reduced detection by predators

Resemblance to its surroundings helps conceal it.

Question 2

A lizard warming itself in sunlight shows

  1. Nitrification
  2. Plasmolysis
  3. Internal fertilisation
  4. Basking behaviour
Show answer and explanation

Answer D: Basking behaviour

Basking uses external heat to raise body temperature.

Link to this topic

06 B: Form and functions

Internal structure of plants and mammals

Read this lesson

What you should be able to do

  • Identify major tissues in plant organs
  • Locate mammalian organ systems

Understand it

Roots anchor plants and absorb water and ions. Root hairs increase contact with soil. Stems support leaves and connect transport tissues, while leaves have broad surfaces, mesophyll and stomata suited to light capture and gas exchange.

Xylem vessels have lignified walls and transport water and mineral ions; phloem transports organic solutes. Collenchyma supports growing regions with flexible walls; sclerenchyma supplies stronger support through thick, usually lignified walls. Tissue arrangement differs between roots, stems and plant groups.

In mammals, the lungs and heart lie in the thorax, separated from the abdomen by the diaphragm. The stomach, intestines, liver and pancreas contribute to digestion. Kidneys filter blood, and reproductive organs produce gametes and support reproduction.

Work through an example

Why can xylem provide both transport and support?

Explanation: Its hollow connected cells conduct water, while their lignified walls resist collapse and strengthen the plant.

Watch out: Phloem is not simply a tube that carries only water downwards.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which structure increases the absorbing surface of a root?

  1. Root hair
  2. Anther
  3. Petal
  4. Cuticle
Show answer and explanation

Answer A: Root hair

Root hairs extend into soil spaces and increase surface area.

Question 2

Which muscle separates the thorax from the abdomen?

  1. Biceps
  2. Triceps
  3. Masseter
  4. Diaphragm
Show answer and explanation

Answer D: Diaphragm

The diaphragm forms the floor of the thoracic cavity and helps ventilation.

Link to this topic

07 B: Form and functions

Plant nutrition and photosynthesis

Read this lesson

What you should be able to do

  • Explain photosynthesis and limiting factors
  • Recognise mineral needs and nutrition types

Understand it

Autotrophs manufacture organic substances from inorganic materials. Photosynthesis uses light energy to convert carbon dioxide and water into organic compounds, releasing oxygen. Chemosynthetic organisms instead obtain energy from chemical reactions involving inorganic substances.

Light-dependent reactions capture light energy; carbon-fixation reactions use the resulting chemical energy to build organic molecules. Light, carbon dioxide, temperature and water availability can limit the overall rate. A starch test on a properly controlled leaf can provide evidence of photosynthetic activity.

Plants need mineral ions as well as light and water. Nitrogen supports amino acid and chlorophyll production; magnesium is part of chlorophyll; phosphorus contributes to nucleic acids and ATP. Parasitic plants obtain resources from hosts; insectivorous plants capture animals mainly to supplement mineral nutrition.

Work through an example

Why destarch a plant before testing the effect of light on starch formation?

Explanation: Keeping it in darkness allows stored starch to be used, so new starch detected after illumination is more clearly linked to the experiment.

Watch out: The carbon-fixation reactions are not restricted to nighttime merely because they are sometimes called dark reactions.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

The carbon in glucose made during photosynthesis mainly comes from

  1. Carbon dioxide
  2. Oxygen gas
  3. Water
  4. Soil nitrogen
Show answer and explanation

Answer A: Carbon dioxide

Carbon dioxide supplies the carbon atoms used to build carbohydrates.

Question 2

Which ion is directly associated with chlorophyll structure?

  1. Lead
  2. Sodium
  3. Magnesium
  4. Chloride
Show answer and explanation

Answer C: Magnesium

Magnesium occupies a central position in the chlorophyll molecule.

Link to this topic

08 B: Form and functions

Animal nutrition, teeth and digestion

Read this lesson

What you should be able to do

  • Connect foods, tests and digestion products
  • Relate alimentary structures to their functions

Understand it

Carbohydrates and fats provide energy, proteins supply amino acids, and vitamins and minerals support specific functions. Water is needed for transport and reactions; fibre helps normal movement of gut contents. A balanced diet supplies these in suitable proportions.

Iodine turns blue-black with starch; heated Benedict’s reagent detects reducing sugars; Biuret reagent gives a violet result with proteins. Teeth mechanically break food: incisors cut, canines tear and premolars and molars crush or grind.

Digestion makes large food molecules small enough for absorption. Amylases act on starch, proteases on proteins and lipases on lipids. Bile emulsifies fats but is not an enzyme. Villi increase small-intestinal surface area; absorbed nutrients are then used or stored through assimilation.

Work through an example

Why does chewing help chemical digestion?

Explanation: It breaks food into smaller pieces, increasing the surface area exposed to digestive enzymes.

Watch out: Egestion of undigested food is different from excretion of metabolic waste.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which test detects starch?

  1. Biuret test
  2. Iodine test
  3. Glowing splint test
  4. Limewater test
Show answer and explanation

Answer B: Iodine test

Iodine forms a blue-black colour in the presence of starch.

Question 2

The main site of absorption of digested nutrients is the

  1. Small intestine
  2. Trachea
  3. Oesophagus
  4. Rectum
Show answer and explanation

Answer A: Small intestine

Its villi and microvilli provide a large absorbing surface.

Link to this topic

09 B: Form and functions

Transport, diffusion and osmosis

Read this lesson

What you should be able to do

  • Explain membrane transport and plant transport
  • Trace mammalian circulation

Understand it

Diffusion is net movement down a concentration gradient. Osmosis is net water movement through a selectively permeable membrane from higher to lower water potential. Active transport uses energy to move substances against a gradient. A plant cell becomes turgid after water entry; severe water loss can cause plasmolysis.

Transpiration from leaves helps pull water through xylem, supported by cohesion and adhesion. Root pressure can also contribute. Phloem translocation moves organic solutes from sources such as mature leaves to sinks such as growing roots or fruits.

The mammalian heart drives double circulation through the lungs and body. Arteries carry blood away from the heart and veins return it; oxygen content is not their defining feature. Red cells transport oxygen, white cells support defence, platelets assist clotting and plasma carries dissolved materials.

Work through an example

Why is the pulmonary artery still an artery although its blood is relatively low in oxygen?

Explanation: It carries blood away from the heart towards the lungs. Direction of flow defines an artery.

Watch out: Osmosis describes water movement, not the movement of every dissolved substance.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A plant cell placed in a concentrated salt solution may

  1. Lose water and plasmolyse
  2. Become more turgid
  3. Gain chloroplasts
  4. Divide immediately
Show answer and explanation

Answer A: Lose water and plasmolyse

Its water potential is initially higher than that of the solution, so water leaves.

Question 2

Which tissue transports sugars from leaves to growing fruits?

  1. Phloem
  2. Epidermis
  3. Xylem
  4. Cork
Show answer and explanation

Answer A: Phloem

Fruits act as sinks receiving organic solutes through phloem.

Link to this topic

10 B: Form and functions

Respiration and gas exchange

Read this lesson

What you should be able to do

  • Distinguish respiration from ventilation
  • Compare aerobic and anaerobic energy release

Understand it

Cellular respiration transfers energy from food molecules into usable forms such as ATP. Aerobic respiration uses oxygen and produces carbon dioxide and water overall. Glycolysis occurs in the cytoplasm; later aerobic stages in eukaryotes occur mainly in mitochondria.

Yeast can ferment sugars to ethanol and carbon dioxide without oxygen, releasing less ATP per glucose than aerobic respiration. Human muscle cells can regenerate NAD⁺ through lactate formation when aerobic supply cannot meet demand. Fermentation supports industries such as bread making.

Gas-exchange surfaces are thin, moist and have a large area. Fish use gills, insects use tracheal systems, and mammals use lungs. Stomata and lenticels allow exchange in plants; guard-cell changes regulate stomatal opening.

Work through an example

Why does bread dough expand when yeast ferments sugar?

Explanation: Carbon dioxide produced during fermentation becomes trapped in the dough and makes it rise.

Watch out: Breathing moves air; respiration is the chemical process that releases usable energy.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Glycolysis occurs in the

  1. Inner mitochondrial membrane
  2. Cytoplasm
  3. Nucleus
  4. Mitochondrial matrix
Show answer and explanation

Answer B: Cytoplasm

Glycolysis is a cytoplasmic pathway.

Question 2

Which feature improves gas exchange?

  1. Thin moist surface
  2. No concentration gradient
  3. Thick dry walls
  4. Small surface area
Show answer and explanation

Answer A: Thin moist surface

A thin moist surface reduces diffusion distance and allows gases to dissolve.

Link to this topic

11 B: Form and functions

Excretion and water balance

Read this lesson

What you should be able to do

  • Compare excretory structures
  • Explain filtration and selective reabsorption

Understand it

Excretion removes metabolic wastes such as carbon dioxide and nitrogenous compounds. It differs from egestion, which removes material that was not digested. Plants may release gases, store wastes in tissues or produce substances such as resins and gums.

Kidneys contain nephrons. Pressure filtration at the glomerulus forms filtrate containing small dissolved substances. Selective reabsorption returns useful substances and much water to the blood; secretion adds some substances to the tubule fluid.

Lungs remove carbon dioxide and water vapour, while skin loses water, salts and small quantities of nitrogenous waste in sweat. Other animals use structures such as flame cells, nephridia and Malpighian tubules. Contractile vacuoles mainly remove excess water in certain freshwater protists.

Work through an example

Why is glucose normally retained although it enters kidney filtrate?

Explanation: It is normally reabsorbed from the tubule into the blood rather than being lost in urine.

Watch out: The kidney filters blood, not food moving through the intestine.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which is an excretory product of aerobic metabolism?

  1. A swallowed stone
  2. Undigested cellulose
  3. Carbon dioxide
  4. Faecal fibre
Show answer and explanation

Answer C: Carbon dioxide

Carbon dioxide is produced by metabolic reactions.

Question 2

Earthworms possess which excretory structures?

  1. Nephridia
  2. Kidneys
  3. Malpighian tubules
  4. Flame cells
Show answer and explanation

Answer A: Nephridia

Segmental nephridia remove wastes in earthworms.

Link to this topic

12 B: Form and functions

Support and movement

Read this lesson

What you should be able to do

  • Compare skeleton types
  • Explain joints and antagonistic muscles

Understand it

A hydrostatic skeleton uses fluid pressure, an exoskeleton supports from outside, and an endoskeleton supports from within. Earthworms, arthropods and vertebrates illustrate these types. An exoskeleton restricts growth unless it is shed or enlarged through development.

The mammalian skeleton supports the body, protects organs and provides attachment points for muscles. Joints allow different movements: a hinge joint mainly moves in one plane, while a ball-and-socket joint allows movement in several directions.

Muscles pull when they contract; they do not actively push bones back. Antagonistic pairs act in opposite directions, such as biceps and triceps at the elbow. Tendons attach muscle to bone; ligaments join bone to bone. Turgor and strengthened tissues support plants.

Work through an example

How does the elbow bend and straighten?

Explanation: Biceps contraction with triceps relaxation bends it; triceps contraction with biceps relaxation straightens it.

Watch out: A tendon and a ligament have different attachment roles.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

The shoulder is mainly a

  1. Fixed joint
  2. Ball-and-socket joint
  3. Pivot joint
  4. Hinge joint
Show answer and explanation

Answer B: Ball-and-socket joint

Its shape allows movement in several directions.

Question 2

What joins muscle to bone?

  1. Ligament
  2. Articular cartilage
  3. Tendon
  4. Synovial fluid
Show answer and explanation

Answer C: Tendon

A tendon transmits muscular pull to bone.

Link to this topic

13 B: Form and functions

Reproduction in flowering plants

Read this lesson

What you should be able to do

  • Distinguish pollination and fertilisation
  • Explain seed formation and dispersal

Understand it

Pollination transfers pollen from an anther to a stigma. Self-pollination occurs within the same plant, while cross-pollination occurs between plants of the same species. Wind- and insect-pollinated flowers differ in pollen, stigma and floral features.

After compatible pollen germinates, a pollen tube grows towards an ovule. Fertilisation joins male and female gamete nuclei. In flowering plants, double fertilisation also forms the endosperm; ovules become seeds and the ovary normally develops into the fruit.

Vegetative reproduction uses parts such as runners, bulbs, tubers or cuttings and usually produces genetically similar offspring. Dispersal by wind, water, animals or explosive fruits can reduce competition near the parent. Germination generally requires water, oxygen and a suitable temperature.

Work through an example

Why do many wind-dispersed seeds have wings or hairs?

Explanation: They increase surface area relative to mass, helping air currents carry the seeds.

Watch out: Pollination occurs before fertilisation and is not the fusion of gametes.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

The ovule normally develops into the

  1. Pollen grain
  2. Stigma
  3. Seed
  4. Fruit wall
Show answer and explanation

Answer C: Seed

After fertilisation, the ovule becomes a seed.

Question 2

Which is a form of vegetative propagation?

  1. Runner production
  2. Fusion of gametes
  3. Pollination
  4. Meiosis only
Show answer and explanation

Answer A: Runner production

A runner grows into a new plant without gamete fusion.

Link to this topic

14 B: Form and functions

Animal reproduction and development

Read this lesson

What you should be able to do

  • Compare sexual and asexual reproduction
  • Explain gamete formation and mammalian development

Understand it

Asexual reproduction involves one parent without gamete fusion, as in binary fission or budding. Sexual reproduction combines gametes and introduces new genetic combinations. Internal and external fertilisation differ in where gametes meet.

Testes produce sperm and ovaries produce ova. Fertilisation in humans usually occurs in an oviduct, followed by cell divisions and implantation in the uterus. The placenta enables exchange between maternal and foetal circulations without their blood normally mixing directly.

Hormones coordinate reproductive cycles and development. Oviparous animals lay eggs; viviparous animals give birth to live young. Parental care can increase offspring survival, though it requires time and resources that vary among species.

Work through an example

Why does sexual reproduction usually create more variation than simple cloning?

Explanation: Meiosis and fertilisation combine alleles in new ways, whereas cloning largely copies an existing genetic combination.

Watch out: The placenta is an exchange organ, not an open connection that freely mixes both blood supplies.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Human sperm are produced in the

  1. Oviduct
  2. Prostate gland
  3. Uterus
  4. Testes
Show answer and explanation

Answer D: Testes

Sperm formation occurs in seminiferous tubules of the testes.

Question 2

Binary fission is a form of

  1. Cross-fertilisation
  2. Asexual reproduction
  3. Pollination
  4. Internal fertilisation
Show answer and explanation

Answer B: Asexual reproduction

One cell divides without fusion of gametes.

Link to this topic

15 B: Form and functions

Growth, mitosis and germination

Read this lesson

What you should be able to do

  • Distinguish growth from temporary size changes
  • Relate cell division and conditions to development

Understand it

Biological growth is a lasting increase in size or dry mass, often through cell division and enlargement. Development also involves changes in form and function. A temporary increase in water content alone does not prove growth.

Mitosis produces nuclei with the same chromosome number as the parent nucleus and supports growth and repair. Meiosis halves chromosome number for sexual reproduction. In plants, meristems are major regions of active cell division.

A germinating seed takes up water, activates metabolism and uses stored food. The radicle develops into the primary root. Growth curves commonly show slow early growth, faster growth and a later slowing as resources or developmental limits take effect.

Work through an example

Why is dry mass often more informative than fresh mass in a plant-growth experiment?

Explanation: Fresh mass changes with water content; dry mass better reflects accumulation of organic and mineral material.

Watch out: Mitosis does not halve chromosome number.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which region is especially active in plant cell division?

  1. Mature cork
  2. Mature xylem vessel
  3. Mature sieve tube
  4. Meristem
Show answer and explanation

Answer D: Meristem

Meristematic cells divide to produce new cells.

Question 2

The radicle develops into the

  1. Pollen tube
  2. Fruit wall
  3. First flower
  4. Primary root
Show answer and explanation

Answer D: Primary root

It is the embryonic root.

Link to this topic

16 B: Form and functions

Coordination, sense organs and hormones

Read this lesson

What you should be able to do

  • Trace a reflex pathway
  • Compare nervous and hormonal coordination

Understand it

The nervous system detects information and coordinates rapid responses. The central nervous system is the brain and spinal cord; peripheral nerves connect them with the body. A reflex pathway links receptor, sensory neurone, coordination centre, motor neurone and effector.

Sense organs convert particular stimuli into nerve signals: the retina responds to light, the cochlea supports hearing and skin contains receptors for several sensations. A reflex is automatic; a voluntary movement involves conscious control, although both use nervous pathways.

Endocrine glands release hormones into blood. Insulin and glucagon help regulate blood glucose, while other hormones influence metabolism, growth and reproduction. In plants, auxins influence elongation and tropisms, gibberellins promote several growth processes, cytokinins support cell division and ethylene promotes ripening in many fruits.

Work through an example

What is the effector when a hand withdraws from a hot surface?

Explanation: The contracting muscle is the effector. Skin receptors detect the stimulus, but muscles carry out the response.

Watch out: A hormone is a chemical messenger; a gland is the structure that secretes it.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which structure belongs to the central nervous system?

  1. Biceps
  2. Sciatic nerve
  3. Adrenal gland
  4. Spinal cord
Show answer and explanation

Answer D: Spinal cord

The brain and spinal cord form the CNS.

Question 2

Which plant hormone is associated with fruit ripening?

  1. Insulin
  2. Ethylene
  3. Thyroxine
  4. Adrenaline
Show answer and explanation

Answer B: Ethylene

Ethylene promotes ripening in many fruits.

Link to this topic

17 B: Form and functions

Homeostasis

Read this lesson

What you should be able to do

  • Explain negative feedback
  • Relate temperature and water regulation to effectors

Understand it

Homeostasis maintains internal conditions within workable ranges despite changes outside or inside the body. Negative feedback opposes a detected change rather than increasing it. A control system needs detection, coordination and an appropriate response.

When body temperature rises, increased skin blood flow and sweating can increase heat loss. When it falls, reduced skin blood flow and shivering can reduce loss or increase heat production. Evaporation, rather than the mere presence of sweat, produces cooling.

Water balance is regulated partly by adjusting kidney water reabsorption. Antidiuretic hormone increases collecting-duct water permeability, helping conserve water. Blood glucose regulation also uses opposing hormonal actions, with storage and release adjusted to the body’s needs.

Work through an example

Why can very humid air reduce cooling by sweating?

Explanation: High humidity reduces the water-vapour gradient, so sweat evaporates less readily.

Watch out: Homeostasis maintains a range, not a perfectly unchanging value.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Negative feedback generally

  1. Maintains a response after its stimulus disappears in every case
  2. Opposes a deviation from a normal range
  3. Amplifies the initial deviation
  4. Prevents the receptor from detecting change
Show answer and explanation

Answer B: Opposes a deviation from a normal range

Its response counteracts the original change.

Question 2

Increased ADH usually causes

  1. Less water reabsorption
  2. More water reabsorption
  3. No change in collecting ducts
  4. Complete loss of glucose
Show answer and explanation

Answer B: More water reabsorption

ADH increases water permeability, supporting water conservation.

Link to this topic

18 C: Ecology

Ecological factors and field measurements

Read this lesson

What you should be able to do

  • Distinguish biotic and abiotic factors
  • Choose suitable sampling and measurement methods

Understand it

An ecosystem includes organisms and their physical environment. Abiotic factors include light, temperature, salinity, pH, rainfall and soil properties. Biotic factors include competition, predation, food supply and the activities of other organisms.

A habitat is where an organism lives; its niche describes its ecological role and resource use. Tolerance limits help explain distribution: a species may be absent where one essential factor is unsuitable even if other conditions are favourable.

Thermometers measure temperature, rain gauges measure rainfall and Secchi discs estimate water transparency. Quadrats can estimate abundance of stationary organisms; transects investigate changes along a gradient. Random or systematic sampling reduces selective counting of unusually crowded areas.

Work through an example

A plant occurs mainly beside a stream. Give one testable abiotic explanation.

Explanation: It may require higher soil moisture. Compare soil moisture and plant abundance at measured distances from the stream.

Watch out: An association suggests a possible explanation; it does not by itself prove causation.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which is a biotic factor?

  1. Soil pH
  2. Rainfall
  3. Predation
  4. Salinity
Show answer and explanation

Answer C: Predation

Predation is an interaction between living organisms.

Question 2

A Secchi disc is used mainly to estimate

  1. Air temperature
  2. Water transparency
  3. Wind direction
  4. Soil acidity
Show answer and explanation

Answer B: Water transparency

Visibility depth gives a measure related to water clarity.

Link to this topic

19 C: Ecology

Interactions, food webs and nutrient cycles

Read this lesson

What you should be able to do

  • Explain interactions and trophic energy flow
  • Trace carbon, nitrogen and water cycles

Understand it

Mutualism benefits both partners; commensalism benefits one with no clear effect on the other; parasitism benefits a parasite at its host’s expense. Predation, competition and amensalism have different effects and should be distinguished by who benefits or is harmed.

A food-chain arrow points from food to consumer, showing the direction of energy transfer. Producers occupy the first trophic level. Energy is lost from each transfer through processes including respiration and waste, so energy flows rather than cycling endlessly.

Carbon cycles through photosynthesis, feeding, respiration, decomposition and combustion. Nitrogen fixation converts atmospheric nitrogen to biologically usable compounds; nitrification forms nitrites and nitrates; denitrification returns nitrogen to the atmosphere. Evaporation, condensation and precipitation move water between major reservoirs.

Work through an example

In grass → grasshopper → lizard, which organism is the secondary consumer?

Explanation: The lizard eats the primary consumer, so it is the secondary consumer.

Watch out: Matter cycles through ecosystems; energy transfer includes continuing loss as heat.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which process returns nitrate nitrogen to atmospheric nitrogen?

  1. Nitrification
  2. Transpiration
  3. Photosynthesis
  4. Denitrification
Show answer and explanation

Answer D: Denitrification

Denitrifying microorganisms reduce nitrogen compounds to gaseous forms including nitrogen.

Question 2

A relationship benefiting both organisms is

  1. Parasitism
  2. Predation
  3. Amensalism
  4. Mutualism
Show answer and explanation

Answer D: Mutualism

Both partners receive a benefit.

Link to this topic

20 C: Ecology

Habitats and Nigerian biomes

Read this lesson

What you should be able to do

  • Relate organisms to aquatic and terrestrial habitats
  • Compare rainforest, savanna and highland conditions

Understand it

Aquatic habitats include freshwater, marine and brackish systems. Salinity, light penetration, oxygen and water movement influence their organisms. Mangroves tolerate saline or brackish conditions and waterlogged soils through specialised structural and physiological features.

Terrestrial habitats include soil, grassland, forest and tree canopies. Rainforests generally have high rainfall and layered vegetation; savannas combine grasses with scattered woody plants and stronger seasonal water limits. Nigerian vegetation varies broadly with rainfall, seasonality, soils and human activity.

Guinea and Sudan savannas differ in moisture and vegetation structure. High-altitude areas such as the Jos, Mambilla and Obudu regions have cooler conditions than nearby lowlands. Desert adaptations conserve water, but a biome example should not be used to label every dry part of Nigeria as true desert.

Work through an example

Why may floating aquatic leaves have stomata mainly on their upper surface?

Explanation: The upper surface contacts air, allowing gas exchange while the lower surface is in water.

Watch out: A habitat is local living space; a biome is a much larger ecological region.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A mixture of river water and seawater is

  1. Brackish water
  2. Distilled water
  3. Hypersaline brine
  4. Freshwater
Show answer and explanation

Answer A: Brackish water

Brackish water has salinity between typical freshwater and seawater.

Question 2

Scattered trees with a dominant grass layer best describes

  1. Desert with sparse vegetation
  2. Savanna
  3. Tropical rainforest
  4. Mangrove swamp
Show answer and explanation

Answer B: Savanna

A grass layer with scattered woody plants is characteristic of savanna.

Link to this topic

21 C: Ecology

Populations, competition and succession

Read this lesson

What you should be able to do

  • Calculate population density
  • Explain population change and succession

Understand it

A population consists of members of one species in a defined area. Density is number of individuals divided by area or volume. Births and immigration add members; deaths and emigration remove them.

Limited food, water, space and mates can create competition. Intraspecific competition occurs within a species, while interspecific competition occurs between species. Carrying capacity depends on the resources and conditions of the environment and can change over time.

Succession is a change in community composition over time. Primary succession begins where developed soil is absent; secondary succession follows disturbance where soil remains. Early species alter conditions for later species, but disturbance can prevent a single stable endpoint.

Work through an example

A 50 m² plot contains 200 seedlings. Calculate density.

Explanation: Density=200/50=4 seedlings per m².

Watch out: A high count does not necessarily mean high density; area must be considered.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Competition between two maize plants is

  1. Commensalism
  2. Interspecific
  3. Intraspecific
  4. Parasitism
Show answer and explanation

Answer C: Intraspecific

Both plants belong to the same species.

Question 2

Vegetation returning after farmland is abandoned is usually

  1. Nutrient leaching
  2. Seasonal migration
  3. Secondary succession
  4. Primary succession on newly exposed bare rock
Show answer and explanation

Answer C: Secondary succession

Soil is already present, so it is secondary succession.

Link to this topic

22 C: Ecology

Soil properties and fertility

Read this lesson

What you should be able to do

  • Compare sandy, clayey and loamy soils
  • Link conservation practices to soil problems

Understand it

Soil contains mineral particles, organic matter, organisms, air and water. Sandy soils have relatively large particles and generally drain rapidly; clayey soils have very small particles and often hold water strongly. Loams combine particle sizes and can support a useful balance of drainage and retention.

Humus improves several soil properties, including water retention and nutrient supply. Soil organisms break down residues and mix materials. Fertility depends on nutrient availability, pH, structure, water and aeration, not only on how dark the soil looks.

Erosion removes topsoil; leaching carries soluble nutrients downwards; repeated harvesting removes nutrients in crops. Mulching, cover crops, contour cultivation, appropriate fertilisation and crop rotation address different problems. Adding nutrients alone does not repair severe compaction or erosion.

Work through an example

Why can mulch reduce soil erosion?

Explanation: It protects the surface from raindrop impact and slows runoff while helping retain moisture.

Watch out: High water retention does not always mean good drainage or good root aeration.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which soil generally has the largest mineral particles?

  1. Sand
  2. Humus
  3. Silt
  4. Clay
Show answer and explanation

Answer A: Sand

Sand particles are larger than silt and clay particles.

Question 2

Loss of dissolved nutrients in downward-moving water is

  1. Pollination
  2. Leaching
  3. Translocation
  4. Germination
Show answer and explanation

Answer B: Leaching

Leaching moves soluble substances below the main root zone.

Link to this topic

23 C: Ecology

Disease transmission, sanitation and substance misuse

Read this lesson

What you should be able to do

  • Distinguish pathogens, vectors and transmission routes
  • Relate prevention to how infections spread

Understand it

A pathogen causes disease; a vector carries a pathogen between hosts. Malaria is caused by Plasmodium parasites and is commonly transmitted by infected female Anopheles mosquitoes. The mosquito is the vector, not the organism that causes malaria.

Cholera is caused by Vibrio cholerae and spreads through contaminated food or water. Safe water, sanitation and hygiene interrupt this route. Other infections spread through different routes, so a control method must match the pathogen’s biology rather than treating all diseases alike.

Vaccination prepares immune responses to specific infections. Public-health agencies support prevention, surveillance and coordinated response. Substance misuse can impair judgement, damage health and lead to dependence; understanding these effects is part of health education, not a substitute for individual clinical care.

Work through an example

In malaria transmission, identify the pathogen and the vector.

Explanation: Plasmodium is the pathogen; an infected female Anopheles mosquito is the vector.

Watch out: A disease vector and its pathogen are not interchangeable names.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Cholera is most closely associated with

  1. Contaminated food or water
  2. Direct inheritance of a defective allele
  3. Bites from infected mosquitoes
  4. Airborne respiratory droplets
Show answer and explanation

Answer A: Contaminated food or water

The bacterium can be ingested in contaminated food or water.

Question 2

The main biological purpose of vaccination is to

  1. Provide food energy
  2. Replace all white blood cells
  3. Remove all microbes from the environment
  4. Prepare specific immune protection
Show answer and explanation

Answer D: Prepare specific immune protection

Vaccines stimulate protective immune responses to particular infections.

Link to this topic

24 C: Ecology

Pollution, conservation and protected habitats

Read this lesson

What you should be able to do

  • Explain effects of major pollutants
  • Compare conservation approaches

Understand it

Pollution introduces harmful substances or forms of energy into an environment. Sewage and fertiliser runoff can increase nutrient levels in water, encouraging algal growth; decomposition may then reduce dissolved oxygen available to animals.

Air pollution can include smoke, fine particles and harmful gases. Persistent chemicals may accumulate in organisms and become more concentrated through some food chains. Waste reduction, appropriate treatment and control at the source are more effective than simply moving pollution elsewhere.

Conservation protects species, habitats and resources for continued use and ecological function. In-situ conservation protects organisms in their habitats; ex-situ conservation uses facilities such as seed banks. Protected areas, sustainable harvesting and habitat restoration work best alongside local participation and effective management.

Work through an example

Why can excessive fertiliser entering a pond lead to fish deaths?

Explanation: Nutrient enrichment can cause algal growth; decomposition consumes dissolved oxygen, leaving too little for fish.

Watch out: Renewable resources can still be exhausted locally if used faster than they recover.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A seed bank is an example of

  1. Erosion
  2. Primary succession
  3. Ex-situ conservation
  4. Biomagnification
Show answer and explanation

Answer C: Ex-situ conservation

Seeds are preserved outside their normal habitat.

Question 2

Which action directly reduces soil erosion?

  1. Maintaining vegetation cover
  2. Dumping sewage
  3. Burning all crop residues
  4. Removing all ground cover
Show answer and explanation

Answer A: Maintaining vegetation cover

Roots bind soil and vegetation reduces runoff and raindrop impact.

Link to this topic

25 D: Heredity and variation

Variation and interpreting biological data

Read this lesson

What you should be able to do

  • Compare continuous and discontinuous variation
  • Separate genetic and environmental influences

Understand it

Variation means differences among members of a species. Continuous variation, such as height, spans a range and often reflects many genes plus environmental influences. Discontinuous variation has distinct categories, such as ABO blood groups.

Morphological variation concerns observable structure; physiological variation concerns function. To study variation, use consistent measurements and a sufficiently varied sample. Frequency plots can reveal distributions, but a pattern alone does not identify the genes or environmental causes involved.

Inherited DNA contributes to variation, while nutrition, disease and other conditions can also change traits. A scar is acquired rather than a DNA allele passed to offspring. Simple classroom traits should not automatically be treated as proven single-gene examples.

Work through an example

Why can identical twins have different body masses?

Explanation: They can experience different diets, activity levels and other environmental conditions despite sharing nearly the same inherited DNA.

Watch out: A visible difference is not necessarily entirely genetic.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which is a clear example of discontinuous variation?

  1. Leaf length
  2. Adult height
  3. ABO blood group
  4. Body mass
Show answer and explanation

Answer C: ABO blood group

ABO groups form named categories rather than a continuous numerical range.

Question 2

Which feature is acquired rather than inherited as an allele?

  1. A chromosome variant
  2. An inherited haemoglobin variant
  3. ABO allele
  4. A scar after injury
Show answer and explanation

Answer D: A scar after injury

An injury scar is not a hereditary DNA variant.

Link to this topic

26 D: Heredity and variation

Inheritance, DNA and genetic crosses

Read this lesson

What you should be able to do

  • Use alleles and crosses to predict probabilities
  • Explain chromosome segregation and sex linkage

Understand it

DNA stores genetic information in a sequence of bases. Genes are regions of DNA, and alleles are alternative versions. Chromosomes carry many genes. During meiosis, homologous chromosomes separate, allowing gametes to receive one allele from a pair.

For a simple dominant-recessive trait, AA and Aa show the dominant phenotype while aa shows the recessive phenotype. A Punnett square lists possible combinations, not a guaranteed birth order. Independent assortment applies most directly to genes on different chromosomes or sufficiently far apart.

ABO inheritance involves multiple alleles, including codominant A and B forms. Some traits, such as certain forms of red-green colour-vision deficiency, can be X-linked. Biological sex determination in the common XX/XY model depends on whether the sperm contributes X or Y.

Work through an example

For Aa × Aa, what fraction of offspring is expected to be aa?

Explanation: The combinations are AA, Aa, Aa and aa; the probability is 1/4 for each offspring.

Watch out: A dominant allele is not necessarily more common or more beneficial.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

A heterozygous genotype is

  1. A only
  2. aa
  3. Aa
  4. AA
Show answer and explanation

Answer C: Aa

A heterozygote has two different alleles at the locus.

Question 2

If both parents have genotype Aa, the probability of AA is

  1. 0
  2. 1
  3. 1/4
  4. 1/2
Show answer and explanation

Answer C: 1/4

Each parent supplies A with probability 1/2, so the combined probability is 1/4.

Link to this topic

27 D: Heredity and variation

Biotechnology and applications of heredity

Read this lesson

What you should be able to do

  • Compare selective breeding and genetic modification
  • Explain useful applications and limitations

Understand it

Biotechnology uses organisms, cells or biological processes to make useful products. Fermentation is a traditional example; tissue culture, DNA analysis and recombinant protein production are modern examples. Not all biotechnology involves changing DNA directly.

Selective breeding chooses parents with desired characteristics. Inbreeding can make traits more uniform but can also increase expression of harmful recessive alleles. Crossbreeding can introduce useful variation; the outcome must still be assessed for the intended environment.

Genetic engineering changes DNA using laboratory methods. Microorganisms can produce proteins such as human insulin when given suitable genetic instructions. Evaluation includes effectiveness, possible environmental effects and biosafety; blood-group evidence alone cannot establish a person’s parentage conclusively.

Work through an example

How is selective breeding different from inserting a gene in a laboratory?

Explanation: Selective breeding chooses parents and recombines existing variation through reproduction. Genetic engineering directly alters genetic material using laboratory methods.

Watch out: Genetically modified does not mean that every product has the same benefits or risks.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which is a traditional biotechnology process?

  1. Separating cream by centrifugation
  2. Bread fermentation
  3. Pasteurising milk by heat alone
  4. Distilling an already-made ethanol solution
Show answer and explanation

Answer B: Bread fermentation

Yeast metabolism is used to produce a useful food product.

Question 2

Repeated inbreeding can increase the chance of

  1. All recessive alleles becoming dominant
  2. Heterozygosity increasing at every locus
  3. New beneficial alleles being created by selection alone
  4. Harmful recessive traits being expressed
Show answer and explanation

Answer D: Harmful recessive traits being expressed

It increases homozygosity, which can expose recessive alleles.

Link to this topic

28 E: Evolution

Evolution and evidence

Read this lesson

What you should be able to do

  • Explain natural selection
  • Compare evidence for evolutionary relationships

Understand it

Evolution is change in inherited characteristics of populations across generations. Mutation creates new genetic variants, while recombination reshuffles existing variants. Natural selection acts when inherited differences affect survival and reproduction.

Darwin emphasised selection among existing variations. Lamarck proposed inheritance of acquired characteristics as a general explanation, but ordinary acquired changes such as strengthened muscles are not generally transmitted as matching genetic changes to offspring. Modern explanations combine genetics with population processes.

Fossils provide records through time; homologous structures indicate shared ancestry; molecular similarities help test relationships. Analogous features can perform similar functions without having the same evolutionary origin. Evolution is branching, so living species should not be arranged as a simple ladder from inferior to superior.

Work through an example

How can antibiotic resistance become more common in a bacterial population?

Explanation: Resistant variants may survive exposure and leave more descendants, increasing the frequency of resistance in the population.

Watch out: Natural selection does not give every individual the feature it needs.

2 practice questions with answers

Try each question before opening its answer. These are original CampusNinja practice questions.

Question 1

Which process creates new alleles?

  1. Segregation of existing alleles
  2. Natural selection acting on existing variation
  3. Mutation
  4. Recombination of existing alleles
Show answer and explanation

Answer C: Mutation

A mutation changes DNA and can create a new allele.

Question 2

Similar underlying limb bones in different mammals mainly support

  1. Identical functions for every limb
  2. Inheritance of changes caused by exercise
  3. Independent origin from identical habitats alone
  4. Shared ancestry
Show answer and explanation

Answer D: Shared ancestry

Their common structural pattern is evidence of homology and shared ancestry.

Link to this topic

Syllabus source and learning material

Scope checked against JAMB’s IBASS source on 2026-10-16. Current IBASS file; not independently labelled 2027. Notes, examples and practice questions are original CampusNinja learning material, not authenticated JAMB past questions.

Check the syllabus source

CampusNinja Study · Built for the work behind your goals.

Your progress stays in this browser. Export a backup to keep it.

Original practice, not official JAMB questions or a score prediction.