A) What characteristic features do birds and mammals have in common? b) State the functions of i. Vagina ii. Breast iii. Testis in mammals c) How is the Tilapia fish adapted to life in water? d) Descr

SECTION A: ANSWER ALL 3 QUESTIONS

1. a) What characteristic features do birds and mammals have in common?

• Both are warm-blooded (endothermic), meaning they can maintain a constant internal body temperature.
• Both have a four-chambered heart for efficient circulation.
• Both breathe using lungs.
• Both have internal fertilization.

b) State the functions of

• i. Vagina: Receives the penis during sexual intercourse and serves as the birth canal during childbirth.
• ii. Breast: Produces milk to nourish offspring (lactation) and is a secondary sexual characteristic.
• iii. Testis in mammals: Produces sperm (male gametes) and male hormones, primarily testosterone.

c) How is the Tilapia fish adapted to life in water?

• Tilapia have gills for efficient oxygen extraction from water.
• Their streamlined body shape reduces drag, allowing for efficient movement through water.
• They possess fins for propulsion, steering, and balance.
• Their body is covered in scales for protection.

d) Describe the economic importance of insects.

• Insects are vital pollinators for many crops, contributing significantly to food production.
• They produce valuable products like honey and silk.
• Some insects are used in biological pest control, reducing the need for chemical pesticides.
• They serve as a food source for other animals and, in some cultures, for humans.

2. a) Define the following:

• i. Excretion: The process by which metabolic waste products, such as urea, carbon dioxide, and excess salts, are removed from an organism's body.
• ii. Homeostasis: The ability of an organism to maintain a stable internal environment despite changes in external conditions.

b) What are the adaptations of the mammalian skin in the protection of the body?

• The epidermis forms a physical barrier against pathogens and injury.
• Keratin in the skin and hair provides waterproofing and protection.
• Melanin pigment protects against harmful ultraviolet (UV) radiation.
• Hair provides insulation and sensory perception.
• Sebaceous glands produce oil (sebum) which lubricates the skin and has antimicrobial properties.

c) Describe the role of the kidney in the regulation of water content of the body.
The kidneys regulate water content through selective reabsorption in the renal tubules. When the body is dehydrated, more water is reabsorbed into the bloodstream under the influence of Antidiuretic Hormone (ADH), leading to concentrated urine. When the body has excess water, less water is reabsorbed, resulting in dilute urine.

d) Imagine that Insulin and Glucagon are like two players in a team that work together to keep blood sugar level just right. Which of these two players do you think is the most important? Explain your answer, saying what would happen if that player was not there.
Neither insulin nor glucagon is more important than the other; both are equally crucial for maintaining blood glucose homeostasis. They have opposing but complementary roles.

• Insulin lowers high blood glucose levels by promoting glucose uptake by cells and conversion to glycogen. If insulin were absent, blood glucose levels would remain dangerously high, leading to diabetes mellitus.
• Glucagon raises low blood glucose levels by stimulating the liver to release stored glucose. If glucagon were absent, blood glucose levels could drop too low, causing hypoglycemia, which can lead to unconsciousness and brain damage.

3. a) What do you understand by the following terms as used in ecology:

• i. Ecosystem: A community of living organisms (biotic components) interacting with each other and with their non-living physical and chemical environment (abiotic components).
• ii. Conservation: The protection, preservation, management, and restoration of natural environments, ecosystems, and wildlife to ensure their long-term sustainability and biodiversity.

b) Differentiate between a food chain and a food web.
A food chain illustrates a single, linear pathway of energy flow from one organism to another (e.g., grass → rabbit → fox). A food web consists of multiple interconnected food chains, showing the complex feeding relationships and energy flow among various organisms within an ecosystem.

c) How may the extinction of species of organisms in an ecosystem be reduced?

• Habitat preservation and restoration to protect natural environments.
• Reducing pollution (air, water, soil) that harms species and ecosystems.
• Implementing sustainable resource management practices (e.g., sustainable fishing, forestry).
• Controlling and eradicating invasive species that outcompete native organisms.
• Establishing protected areas like national parks and wildlife reserves.
• Engaging in captive breeding programs for critically endangered species.