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Waec 2024 Biology Answer



Organic evolution refers to the gradual and cumulative change in the heritable characteristics of biological populations over successive generations.

– Wind
– Animal

– Photosynthesis occurs in plants and some bacteria, while respiration occurs in all living organisms.
– Photosynthesis produces oxygen and glucose, while respiration uses oxygen to break down glucose and produce energy.

– It promotes cell elongation
– It controls tropic responses like phototropism and gravitropism.

Metamorphosis in houseflies involves four stages: egg, larva (maggot), pupa, and adult. The adult female housefly lays eggs on suitable organic material. These eggs hatch into larvae or maggots, which feed on the organic matter. The larva then transforms into a pupa, where it undergoes a complex series of changes. Finally, an adult housefly emerges from the pupa, completing the metamorphic cycle.

– Cellular level
– Tissue level
– Organ level
– Organ system level
– Organismal level

(i) Imbibition: The seed absorbs water from the soil, causing it to swell and activate biochemical processes within the seed.
(ii) Activation of Enzymes: The imbibed water activates enzymes within the seed, which initiate the metabolic processes necessary for germination.
(iii) Mobilization of Stored Energy: The stored energy reserves, such as starch and proteins, within the seed are broken down into simple sugars to provide energy for the growing embryo.
(iv) Growth of the Embryo: The embryo grows, and the radicle (primary root) emerges from the seed, followed by the emergence of the shoot, which develops into the stem and leaves.
(v) Photosynthesis: As the shoot emerges and develops leaves, the plant is able to carry out photosynthesis, which provides it with the energy to continue growing.

(i) Availability of Resources: The availability of food, water, shelter, and suitable habitat directly influences the population size.
(ii) Predation: The presence of predators can limit the population size of organisms as they prey on them, causing a decrease in the population.
(iii) Competition: Competition for limited resources, such as food and territory, can limit the population size of organisms as individuals have to compete for these resources.
(iv) Disease and Parasites: The presence of diseases and parasites can negatively impact the population size by causing morbidity and mortality.

-Bush Burning-
(i) Loss of vegetation: Bush burning destroys plants, resulting in a loss of habitat and decreased biodiversity.
(ii) Soil degradation: Intense heat from bush burning can lead to soil degradation, reducing its fertility and ability to support plant growth.

-Fertilizer Application-
(i) Eutrophication: Overuse or improper application of fertilizers can lead to eutrophication, where excessive nutrients enter water bodies, leading to algal blooms and oxygen depletion.
(ii) Soil pollution: Certain fertilizers can contain harmful chemicals that can pollute the soil, affecting soil quality and the health of organisms living in it.

-Use of Pesticides-
(i) Harm to non-target organisms: Pesticides can harm not only the targeted pests but also beneficial organisms such as pollinators, natural predators, and soil organisms, affecting biodiversity.
(ii) Bioaccumulation and biomagnification: Some pesticides can accumulate in the body tissues of organisms and can become more concentrated as they move up the food chain, posing a risk to higher-level consumers.

(i) Pulmonary Respiration
(ii) Cutaneous Respiration
(iii) Buccopharyngeal Respiration

– camera traps
– transect lines
– mark-recapture techniques.

(ii) The process of ionic transmission of a nerve impulse in a neuron starts with the generation of an action potential. When a nerve impulse reaches the end of one neuron, it triggers the release of neurotransmitters, which are chemical messengers.

These neurotransmitters cross the synapse, a small gap between neurons, and bind to receptors on the receiving neuron.

This binding causes a change in the electrical charge of the receiving neuron, allowing the nerve impulse to continue along the neural pathway.

– myopia (nearsightedness)
– hyperopia (farsightedness).

– petals
– sepals
– stamen
– pistil.

Grass—> Grasshopper—> Lizard–>Snake




(i) Water
(ii) Oxygen
(iii) Temperature
(iv) Light m
(v) Soil or substrate
(vi) Time

In Tabular form

-Hormonal Coordination-
(i) Hormones are chemical messengers secreted by endocrine glands and released into the bloodstream.
(ii) Hormonal responses are slower and more gradual compared to nervous responses.
(iii) Hormonal responses are often long-lasting.
(iv) Hormonal communication is based on the release and diffusion of hormones throughout the body.
(v) Hormones act on specific target cells or organs that have appropriate receptors.
(vi) Hormonal coordination controls processes such as growth, development, reproduction, and metabolism.

-Nervous Coordination-
(i) Nerves are specialized cells that transmit electrical impulses rapidly.
(ii) Nervous responses are rapid and immediate.
(iii) Nervous responses are often short-lived.
(iv) Nervous coordination is based on the transmission of electrical signals along nerve cells.
(v) Nerves directly connect specific cells, tissues, and organs.
(vi) Nervous coordination controls processes such as movement, sensation, and reflex actions.

(i) Inhalation: Before exhalation, there is an inhalation phase where the diaphragm contracts and moves downward. This causes the volume of the chest cavity to increase and the lungs to expand, allowing air to enter.
(ii) Oxygen exchange: During inhalation, oxygen from the inhaled air passes through the respiratory system’s airways and reaches the alveoli. In the alveoli, oxygen diffuses into the capillaries, where it binds to hemoglobin in red blood cells.
(iii) Carbon dioxide removal: Simultaneously, carbon dioxide, a waste product of cellular respiration, diffuses from the capillaries into the alveoli.
(iv) Exhalation: After oxygen and carbon dioxide exchange, the diaphragm relaxes and moves upward, reducing the volume of the chest cavity. This forces air out of the lungs.
(v) Exhaled air: The exhaled air contains mainly carbon dioxide, along with trace amounts of other gases.

(i) Succulence: Xerophytic plants have adapted to store water in their leaves, stems, or roots to survive in arid environments. They may have fleshy, water-storing tissues or specialized structures to reduce water loss.
(ii) Reduced leaf surface: Many xerophytic plants have smaller or modified leaves, such as spines or scales, to minimize water loss through transpiration.
(iii) Deep-rooted: Xerophytic plants often have deep and extensive root systems to reach underground water sources.
(iv) Waxy or hairy surfaces: Xerophytic plants may have a waxy cuticle or hairy surfaces on their leaves to reduce water loss through evaporation.
(v) CAM metabolism: Some xerophytic plants employ Crassulacean acid metabolism (CAM) photosynthesis, a specialized pathway that allows them to open their stomata at night, reducing water loss during the day.



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