Explanation

(a)Hormones- These are chemical substances secreted by endocrine/ductless glands, directly into the blood/ circulatory system, which on reaching a target organ, stimulate activity of that organ.

(c)(i) Effects of over-secretion: -

1. Over active/Hyperactive/Irritable/nervous.
2. Excessive growth/gigantism
3. Loss of weight
4. Enlarged thyroid gland/exothalmic goitre
5. Accelerated/increased heartbeat
6. Protrusion/bulging out of eyeball.

(ii) Effects of under-secretion: -

1. Cretinism/dwarfism in children.
2. Overweight/increase in subcutaneous fat/obesity.
3. Physical/mental sluggishness in adults.
4. Reduced heart rate.
5. Lowered/reduced metabolic rate/ myxceodema.
6. Goitre formation/hyperplastic goiter.

(d)Labels: Receptor organ, sensory neurone, intermediate/relay neurone; motor neurone, synapse, spinal cord, ventral root, dorsal root, effector organ, spinal nerve.

Explanation

(a)Adaptation: These are special features/characteristics that an organism possesses, which enable it to live/ survive successfully in an environment

(b)(i) Aloe: -

• The succulent leaves are adaptations for water storage.
• They are also adapted for surviving high temperatures and drought.

(ii)Cactus: Stems are thick and succulent for water storage, while leaves are reduced to conserve water, by reducing rate of transpiration.

(iii)Fowl: The beak is short/ strong/straight for picking insects/seeds, earthworms/small pieces of food, pecking of feathers.

(iv)Fish: The dorsal side is dark while the ventral side is silvery/counter shading. - This dual coloration protects the fish from predators, looking at them from above and below the water.

(v)Pines: The needle like leaves reduce water loss by transpiration. - Also conserves water for use in the long dry season.

(c)(i) Population: This is the total number of individuals of the same species, living together in a habitat, at a given time.

(ii) Effects of over population: -

• Competition for limited resources.
• Predation/cannibalism.
• Spread of diseases.
• Food shortage.
• build up toxic waste in the environment.
• Limited space for individual dwellings.
• High mortality/mortality rate.
• Increase of social vices/behaviour.

Correct Answer: A. I only

Correct Answer: D. The oxygenated blood enters the lungs through the pulmonary vein

Correct Answer: B. testis, prostrate gland, sperm duct and vas deferens

Correct Answer: A) platelets

Explanation

Blood clotting is a crucial process that helps to stop bleeding when we get injured. The particles found in the blood that play an important role in blood clotting are called platelets. These are tiny, disk-shaped cells that are formed in the bone marrow and circulate in the blood. When we get injured, platelets rush to the site of injury and start to clump together, forming a plug that seals the wound. They also release chemicals that trigger a complex cascade of reactions involving other blood clotting factors, which ultimately results in the formation of a blood clot. Red blood cells, on the other hand, are responsible for carrying oxygen from the lungs to the rest of the body. Monocytes and granulocytes are types of white blood cells that play important roles in the immune system, helping to fight off infections. Therefore, the correct answer to the question is Option A: platelets.

Correct Answer: C) Jean Lamarck

Explanation

The correct answer is Option C: Jean-Baptiste Lamarck. Jean-Baptiste Lamarck was a French biologist who proposed an early theory of evolution known as Lamarckism, which includes the concept of the inheritance of acquired characteristics. According to his theory, an organism can change during its lifetime in response to its environment, and those changes are then passed on to its offspring. This idea is often summarized with the phrase use it or lose it and is sometimes referred to as the inheritance of acquired traits or soft inheritance. Lamarck's theory was innovative for his time, but it has largely been discredited by modern genetics. The more widely accepted theory of evolution by natural selection was proposed by Charles Darwin and Alfred Russel Wallace. Gregor Mendel, on the other hand, is known for his work on genetics and heredity, particularly his laws of inheritance. Even though Lamarck's theory is not supported by modern science, it's important to note that his work was a significant step in the development of evolutionary thought and contributed to the eventual acceptance of the idea that life evolves.

Correct Answer: B. nerves and hormones

Correct Answer: B. no chlorophyll

Correct Answer: D. pumping action of the heart to move blood round the body.