2016 JAMB BIOLOGY PAST QUESTIONS AND ANSWERS

The scaly skin of the Agama lizard provides protection from environmental factors, reducing water loss and preventing injury. Other features like the nuchal crest, claws, and gular fold serve various functions but are not primarily for protection against environmental challenges.

Insects have specialized mouthparts adapted to their feeding habits, such as chewing, sucking, or piercing. Paired antennae, segmented bodies, and jointed appendages play roles in sensory functions, movement, or structural support but are not directly involved in feeding.

A cross between Yy (heterozygous) parents produces offspring in a 1:2:1 ratio—YY, Yy, and yy, respectively. This outcome follows Mendelian genetics for a monohybrid cross.

Nitrate formation is part of the nitrogen cycle, not the carbon cycle. The carbon cycle includes processes like organic carbon formation, decomposition, and photosynthesis, which circulate carbon among the atmosphere, organisms, and soil.

The leaf is an organ, as it consists of various tissues working together for photosynthesis and transpiration. Cells and tissues are lower levels of organization, while systems represent a higher level involving multiple organs.

Energy produced during cellular respiration is stored as adenosine triphosphate (ATP). ATP serves as the energy currency of the cell, unlike ADP and AMP, which are lower-energy forms. Heat energy is a byproduct, not the storage form.

The green leaf is the primary organ for photosynthesis in autotrophic organisms, where chlorophyll absorbs light to produce food. Roots, root hairs, and fruits do not contribute significantly to food manufacture.

Goiter is caused by iodine deficiency, affecting the thyroid gland and leading to an enlarged neck. Beriberi, scurvy, and rickets are due to deficiencies in vitamin B1, vitamin C, and vitamin D, respectively.

Natural selection is the process through which organisms with advantageous traits survive and reproduce, establishing those traits in the population. Gene mutation, dispersal, and overcrowding do not inherently involve adaptation to the environment.

Tides are the regular rise and fall of sea levels caused by the gravitational pull of the moon and sun. Gravity, pull, and zone do not describe this specific oceanic movement.

Nymphaea (water lily) is a producer that performs photosynthesis in aquatic habitats. Dryopteris is a fern, while planarians and Simulium (black fly) are consumers, not producers.

Commensalism describes the relationship where Remora benefits by attaching to the shark for transport and food scraps without harming the shark. This is distinct from parasitism, saprophytism, and symbiosis.

The correct sequence is Cell → Tissue → Organ → System, reflecting increasing organizational complexity from a single cell to a system of organs.

Poliomyelitis is caused by a virus and is not inherited, while sickle-cell anemia, mental illness, and hemophilia have genetic components that can be passed down.

The loop pattern is the most common fingerprint type among humans. Double-loops, whorls, and arches are less common.

Vitamin B1 (thiamine) deficiency causes beriberi, affecting the nervous and cardiovascular systems. Vitamin A, E, and C deficiencies result in other health issues but are unrelated to beriberi.

Nitrogen-fixing bacteria convert atmospheric nitrogen into forms usable by plants. Putrefying, nitrifying, and denitrifying bacteria play different roles in nitrogen and decomposition processes.

The spines serve as a defensive mechanism against predators, deterring attacks. They are not used for courtship, water conservation, or food acquisition.

Carnivores generally have a dental formula designed for tearing meat, represented by I 3/3, C 1/1, pm 4/4, m 2/2. This arrangement includes incisors, canines, premolars, and molars suited for carnivorous diets.

A thermometer measures temperature. Hygrometers measure humidity, anemometers measure wind speed, and hydrometers measure liquid density.

Kidney malfunction can lead to fluid retention and puffiness, as the kidneys are responsible for filtering excess water and waste. Bladder malfunction, poor digestion, and obesity may have different symptoms.

Charles Darwin’s theory of evolution suggests that all life evolved from a common ancestor through natural selection. Lamarck and Mendel had different theories, while Linnaeus developed taxonomy but did not propose evolution.

Roughage, or fiber, aids digestion by helping move food through the digestive tract. It does not provide energy, prevent disease, or slow aging directly, though it contributes to digestive health.

Cross-fertilization results in genetic variation among offspring. Self-pollination, binary fission, and asexual reproduction do not introduce significant genetic variation.

Temperature and turbidity impact habitats, affecting light penetration and organism survival, especially in aquatic environments. Rainfall, salinity, and humidity are also important, but temperature and turbidity are crucial for plant and animal life.

Species is the most specific level in the taxonomic hierarchy, defining a group of organisms that can interbreed. Kingdom, class, and phylum are broader taxonomic categories.

Osmosis and diffusion are essential for the movement of water and nutrients in plants. Flaccidity, turgidity, and plasmolysis are related but are not primary transport mechanisms.

A food chain represents the flow of energy from one organism to another within an ecosystem. Food webs and pyramids of numbers also describe energy transfer but are broader in scope.

The mitochondrion is responsible for cellular respiration, producing ATP. Other organelles, like the nucleus, nucleolus, and endoplasmic reticulum, perform different cellular functions.

Mangrove swamps are found in the Niger Delta region, where saline coastal conditions support this unique vegetation. Other regions, like the Chad Basin, Benue Valley, and Mambilla Plateau, do not have mangrove ecosystems.

Inbreeding and cross-breeding are selective breeding techniques used to enhance specific traits in animals and plants. Self-breeding and hetero-breeding are less relevant in this context.

Diffusion suffices in small organisms due to a large surface area-to-volume ratio, enabling efficient transport of materials over short distances without specialized systems.

The spinal cord transmits impulses to and from the brain and is involved in reflex actions. It does not maintain body structure, regulate developmental changes, or directly control involuntary actions.

Amphibians were the first vertebrates to transition from water to land, adapting to both aquatic and terrestrial environments. Fish (Pisces) are exclusively aquatic, while reptiles and birds (Aves) evolved later.

Temperature and rainfall are primary factors in biome classification, influencing vegetation types and animal habitats globally. Pressure and wind speed have minimal effects on biome distribution.

Xerophytes are plants adapted to arid environments with high temperatures, strong winds, and dry soils. Hydrophytes grow in water, mesophytes in moderate conditions, and thallophytes are simple non-vascular plants.