(a) Explain briefly the following ecological terms: (i) biosphere (ii) habitat (b) Describe the mode of nutrition in a named carnivorous plant. (c) State th...

(a) Ecological terms

• (i) Biosphere: the part of the earth (land, water and air) and its atmosphere in which living organisms exist and can survive.
• (ii) Habitat: the specific place or natural environment where an organism (or community) lives, feeds and reproduces.

(b) Mode of nutrition in a named carnivorous plant (Sundew, Drosera): the sundew is a green plant that photosynthesises but grows in nitrogen-poor soil, so it supplements its nitrogen by trapping insects. Its leaves bear tentacles tipped with a sticky, glistening fluid that attracts and traps insects. When an insect lands, the tentacles bend inwards and hold it fast. The leaf then secretes digestive enzymes that break down the insect's proteins into soluble nitrogenous compounds, which are absorbed by the leaf. (Pitcher plant or Venus fly-trap are equally acceptable.)

(c) Three reasons why dispersal of fruits and seeds is important

• To reduce overcrowding and competition for light, water, space and nutrients between parent and offspring.
• To spread the species to new areas and colonise fresh habitats.
• To reduce the spread of diseases and pests among plants of the same kind.

(d) Six methods of conserving soil

• Crop rotation.
• Terracing on slopes.
• Contour ploughing/ridging.
• Afforestation and planting cover crops (mulching).
• Strip cropping.
• Building of windbreaks/shelter belts and avoiding overgrazing/bush burning.