(a) Name one instrument used for collecting: (i) soil organism from a soil sample (ii) tiny insects from a leaf or a stem. (b) make a diagram 6 cm - 8 cm lo...

(a) Instruments for collecting organisms

• (i) Soil organisms from a soil sample: a Tullgren funnel (Baermann funnel is used for aquatic/moist soil organisms).
• (ii) Tiny insects from a leaf or stem: a pooter (aspirator).

(b) Diagram of the pooter

A labelled drawing (6 cm to 8 cm long) of a pooter should be made showing: a small glass or plastic collecting jar (bottle) closed with a rubber bung, through which pass two tubes; the inlet tube (mouth of which is placed over the insect), the suction (mouth) tube through which the collector sucks air, and a piece of fine gauze / muslin tied over the inner end of the suction tube to prevent the insect from being sucked into the mouth. When air is sucked, the insect is drawn through the inlet tube into the jar.

(c) Relationship between symbiotic organisms

Symbiosis is a close association between two different organisms living together. Three examples:

• Lichen (alga and fungus): the alga carries out photosynthesis and provides food for both partners, while the fungus absorbs and stores water and mineral salts and provides anchorage and protection for the alga. Both benefit (mutualism).
• Rhizobium bacteria in the root nodules of leguminous plants: the bacteria fix atmospheric nitrogen into nitrates for the plant, and the plant supplies the bacteria with food and shelter. Both benefit.
• Sea anemone and hermit crab: the sea anemone rides on the crab's shell; its stinging tentacles protect the crab from enemies, while the crab carries the anemone to new feeding grounds and shares scraps of food. Both benefit.

(Others: ruminants and cellulose-digesting bacteria in their gut; Paramecium and Zoochlorella.)