(a) State five reasons why animals move from place to place. (b) State one function each of the following structures found in plants: (i) epidermis (ii) phl...

(a) Five reasons why animals move from place to place

• To search for food.
• To find water.
• To escape from predators and danger.
• To search for a mate for reproduction.
• To seek shelter or favourable conditions (suitable temperature, breeding sites).

(b) One function each of plant structures

• (i) Epidermis: protects the inner tissues and (in leaves) reduces water loss.
• (ii) Phloem: transports (translocates) manufactured food from the leaves to other parts of the plant.
• (iii) Sclerenchyma: provides mechanical support and strength to the plant.

(c) Two examples each

• (i) Parasitic plants: mistletoe and dodder (Cassytha).
• (ii) Saprophytes: Mucor and Rhizopus (mushrooms/toadstools also acceptable).

(d) Two adaptive features of salt-water-swamp (mangrove) plants: possession of breathing roots (pneumatophores) for gaseous exchange in waterlogged mud; and viviparous germination (seeds germinate while still attached to the parent) with prop/stilt roots for support.

(e) Population density

• (i) Increase: high birth rate (natality) and immigration (or abundant food).
• (ii) Decrease: high death rate (mortality) and emigration (or disease/predation).

(f) Four ways modern agriculture threatens species survival

• Clearing of forests (deforestation) destroys natural habitats.
• Use of pesticides and herbicides kills non-target organisms.
• Bush burning destroys organisms and their habitats.
• Monoculture and drainage of wetlands reduce biodiversity; overgrazing degrades land.

(g) Three reasons why mitosis is important

• It brings about growth by increasing the number of cells.
• It enables repair and replacement of worn-out or damaged cells.
• It maintains a constant chromosome number and enables asexual reproduction.

(h) Three causes of food spoilage: activity of microorganisms (bacteria and fungi); action of enzymes in the food (autolysis); and attack by pests/insects (also moisture, heat and improper storage).