Designed to test your grasp of biological sciences, the 2021 WAEC Biology question paper covers a diverse array of topics ranging from microscopic cellular structures to broad ecological interactions. Key recurring themes visible in this paper include plant anatomy and fungal reproduction, mammalian organ systems such as the kidney and circulatory pathways, and fundamental physiological processes like cellular respiration and genetics. A productive way to utilize this practice page is to analyze why incorrect answers are wrong alongside understanding the correct choices, rather than relying solely on rote memorization.
Topics in this paper
Which of the following organelles is common to plant and animal cells?
Distractors such as cellulose cell wall or large vacuole are often incorrectly selected because they are prominent cellular features often studied in plants. The correct option is right because the cell membrane, also known as the plasma membrane, is a semi-permeable barrier present in both plant and animal cells that regulates the movement of substances in and out of the cell. Unlike the cellulose cell wall (plants only), chlorophyll (plants only), and large vacuole (more prominent in plants), the cell membrane is universal. Common mistake: attributing plant-exclusive structures like cell walls to animal cells.
In plant anatomy, a longitudinal section cuts along the length of the organ while a transverse section cuts across it. Which pair correctly identifies these cuts?
Students might lean toward anatomical terms like sagittal and coronal, forgetting they apply to animals rather than plants. The correct option is right because a longitudinal section is a vertical cut along the length of the organ, while a transverse section is a horizontal cut across the width. Sagittal and coronal are terms used in animal anatomy, and axial/oblique refer to different cutting planes not specific to plant sections. Common mistake: applying animal directional planes to botanical cross-sections.
Which of the following is a type of simple dry fruit that splits at maturity to release seeds?
Options like achene or nut might be chosen by students who fail to distinguish between dehiscent and indehiscent dry fruits. The correct option is right because a legume is a simple dry dehiscent fruit that splits along two seams (sutures) at maturity to release seeds, as seen in pods of beans and peas. Achene, samara, and nut are indehiscent fruits that do not split open. Common mistake: assuming all dry fruits open up naturally to scatter their seeds.
In fungi, the structure involved in asexual reproduction through spores is the
Learners often select mycelium or hypha, mistakenly assuming vegetative structures handle spore dispersal. The correct option is right because the sporangium is a spore-producing sac in fungi where asexual spores (sporangiospores) are formed and released for reproduction. Mycelium and hyphae are vegetative structures, while rhizoids are anchoring/absorbing. Common mistake: confusing the fungal body network with its reproductive spore sacs.
The spore-producing structure in bread mould (Rhizopus) is known as
Students frequently guess columella or stolon, mixing up internal support parts or horizontal runners with spore bearers. The correct option is right because in Rhizopus (bread mold), the sporangiophore is an upright hypha that bears the sporangium at its tip, where spores are produced asexually. Stolon is a horizontal hypha, columella is an internal structure, and apophysis is a swelling below the sporangium. Common mistake: mixing up the supporting stalk with the internal pillar inside the spore case.
In fungi like Rhizopus, the rhizoids primarily function to
Students might mistakenly think rhizoids function primarily to produce spores or gametes due to their specialized structures. The correct option is right because rhizoids in Rhizopus are root-like hyphae that primarily anchor the mycelium to the substrate, providing stability. While they may also aid in absorption, their main role is anchorage, unlike sporangiophores for spores or structures for gametes. Common mistake: confusing anchoring root-like structures with reproductive organs.
The level of organization of the organism is
Learners might choose tissue or organ, assuming single-celled organisms possess multi-tiered structures. The correct option is right because the organism is a unicellular protozoan, representing the cellular level of organization where a single cell performs all life functions, unlike higher levels in multicellular organisms. Common mistake: assigning multicellular tissue complexity to single-celled protozoa.
The organism belongs to the Phylum
Options like Ciliophora or Euglenophyta might be incorrectly chosen by confusing flagellated or ciliated protozoans with amoeboid forms. The correct option is right because Amoeba belongs to Phylum Rhizopoda (Sarcodina), characterized by pseudopodia for locomotion and feeding. Ciliophora use cilia, Euglenophyta are algae-like, and Rhodophyta are red algae. Common mistake: mixing up pseudopod-based locomotion with hair-like cilia movement.
A plant cell placed in a solution with a higher water potential will
Students might mistakenly pick options involving bursting, failing to account for the protective nature of plant cells. The correct option is right because higher water potential outside means water enters the cell by osmosis, causing the vacuole to fill and the cell to become turgid (firm) due to the rigid cell wall preventing bursting, unlike animal cells. Common mistake: expecting plant cells to burst in hypotonic environments just like animal red blood cells.
Offspring formed by sexual reproduction exhibit more variation than those formed by asexual reproduction because
Students may select the option involving different species, confusing hybridization with normal sexual reproduction processes. The correct option is right because sexual reproduction involves fusion of genetically diverse gametes from two parents, leading to recombination and variation via meiosis. Asexual reproduction produces clones with identical genetics. Common mistake: attributing genetic variation to cross-species breeding instead of normal meiotic recombination.
Radius and ulna are bones of the
Options like pectoral girdle or upper arm are often incorrectly chosen by confusing the humerus with forearm bones. The correct option is right because the radius and ulna are the two long bones of the forearm (lower arm), articulating with the humerus at the elbow and carpals at the wrist, enabling rotation and flexion. Common mistake: mixing up upper arm and lower arm skeletal anatomy.
The blood vessel which carries blood from the alimentary canal to the liver is the
The hepatic artery or vein might be mistakenly selected by confusing oxygenated supply or general systemic drainage with intestinal transport. The correct option is right because the hepatic portal vein collects nutrient-rich, deoxygenated blood from the intestines (alimentary canal) and transports it directly to the liver for processing before entering the systemic circulation. Common mistake: confusing arterial blood supply with the portal system draining the digestive tract.
In the mammalian kidney, the cortex is
Learners often pick the innermost layer, confusing the outer cortical region with the inner medullary zone. The correct option is right because the renal cortex is the outer region of the kidney containing glomeruli and proximal/distal convoluted tubules for filtration and reabsorption, surrounding the inner medulla with loops of Henle. Common mistake: reversing the positions of the renal cortex and medulla.
The main function of the kidney in mammals is
Students might mistakenly choose digestion or respiration, confusing the urinary system's role with processing food or air. The correct option is right because the kidneys primarily excrete metabolic wastes (e.g., urea) via urine formation, while regulating water, electrolytes, and pH balance, distinct from other systems' functions. Common mistake: attributing digestive waste clearance entirely to renal functions.
Detoxification of urea takes place in the
Options like the pancreas or heart might be selected by students guessing general visceral organs. The correct option is right because the liver detoxifies ammonia (from protein metabolism) into urea via the ornithine cycle, which is then excreted by the kidneys, preventing toxic buildup. Common mistake: confusing the organ that produces urea with the organ that filters it out.
Which of the following hormones is suddenly secreted into the bloodstream of a frightened person?
Insulin or thyroxine might be chosen by learners confusing metabolic regulation or sugar storage with acute stress responses. The correct option is right because adrenaline (epinephrine) is released rapidly from the adrenal medulla during the fight-or-flight response to fear, increasing heart rate, blood glucose, and energy mobilization. Common mistake: attributing immediate panic responses to metabolic hormones like insulin.
Which of the following organisms contains chlorophyll in its cells?
Students might mistakenly pick Paramecium due to its microscopic nature, forgetting its lack of photosynthetic pigments. The correct option is right because Euglena is a photosynthetic protozoan containing chlorophyll for autotrophic nutrition in light, unlike heterotrophic animals like caterpillars and grasshoppers or non-photosynthetic Paramecium. Common mistake: assuming all microscopic single-celled organisms lack chlorophyll.
Species are groups of organisms that
Learners often pick options involving different niches or origins, misinterpreting environmental adaptation as speciation. The correct option is right because a species is defined as a group of organisms with similar morphological, physiological, and genetic traits that can interbreed to produce fertile offspring, sharing a common evolutionary origin. Common mistake: defining species purely by shared appearance rather than interbreeding capability.
A plant with short, vertical underground stem is a
Options like rhizome or tuber are commonly confused with corms due to underground stem similarities. The correct option is right because a corm is a short, vertical, swollen underground stem (e.g., gladiolus) that stores nutrients and produces new plants, differing from bulbs (leaf scales), rhizomes (horizontal), and tubers (swollen roots). Common mistake: confusing horizontal stems with short, vertical underground storage stems.
The bursting of a red blood cell placed in a hypotonic solution is called
Students frequently select plasmolysis or crenation, mixing up plant cellular responses with animal cell shrinkage or water loss. The correct option is right because haemolysis occurs when RBCs in hypotonic solution gain water by osmosis, swell, and burst due to lack of cell wall, releasing hemoglobin. Crenation is in hypertonic, plasmolysis in plants. Common mistake: applying plant terms like plasmolysis to animal red blood cells.
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