(a) (i) Define the term hydrosphere. (ii) Give three examples of hydrosphere. (b) (i) State the two laws of thermodynamics levels. (c) (i) Name two local bi...

Answer Details

(a)(i) Hydrosphere

The hydrosphere is the part of the earth that is made up of all the water bodies; that is, the total mass of water that covers the surface of the earth in liquid, solid or vapour form.

(a)(ii) Three examples of the hydrosphere

Oceans and seas, rivers and streams, and lakes (also ponds, springs, ground water, and ice caps/glaciers).

(b) The two laws of thermodynamics

• First law (law of conservation of energy): energy can neither be created nor destroyed but can only be transformed (changed) from one form to another. In a food chain, light energy is converted into chemical energy and then into other forms.
• Second law: whenever energy is transformed from one form to another, some of the energy is lost (usually as heat) to the surroundings, so no energy transfer is 100 per cent efficient. This is why the amount of usable energy decreases from one trophic level to the next.

(c)(i) Two local biotic communities in Nigeria (with a State)

• Mangrove swamp / rainforest community – Rivers or Delta State (Niger Delta area).
• Guinea/Sudan savanna (grassland) community – Kano or Sokoto State (northern Nigeria).

(Other acceptable pairs: freshwater swamp – Bayelsa; derived savanna – Oyo.)

(c)(ii) Three factors affecting organisms in the marine habitat

• Salinity (high salt concentration of the water).
• Light penetration (which decreases with depth).
• Temperature of the water.
• Water pressure and wave/tidal action (also acceptable).

(c)(iii) Three adaptive features of seaweeds

• They have holdfasts (root-like structures) for firm attachment to rocks against wave action.
• They have flexible, slippery (mucilage-covered) bodies that bend with the waves and resist drying.
• They possess air bladders that keep the fronds afloat near the surface for adequate light for photosynthesis.
• Their whole surface can absorb water and dissolved mineral salts.