Theory question 102
Photosynthesis and Plant Nutrition(a) State two differences between photosynthetic mode of nutrition and chemosynthetic mode of nutrition.
Table columns: Photosynthetic nutrition | Chemosynthetic nutrition
(b)(i) What are saprophytes? (ii) Give two examples of saprophytic organisms. (iii) Explain briefly the mode of feeding in saprophytes. (iv) State three ways by which saprophytes are of economic importance.
(c) State three characteristic features of carnivorous plants.
(d) State the feeding habit of (i) butterfly; (ii) mosquito larva; (iii) mucor; (iv) housefly.
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(a) Any two: photosynthesis uses light energy, chemosynthesis uses energy from chemical reactions (oxidation of substances); photosynthesis needs chlorophyll, chemosynthesis does not; photosynthesis is carried out by green plants and algae, chemosynthesis by some bacteria (e.g. Nitrosomonas, iron and sulphur bacteria); photosynthesis releases oxygen, chemosynthesis usually does not.
(b)(i) Saprophytes are organisms that feed on dead and decaying organic matter.
(ii) Any two: Mucor; Rhizopus; mushroom; yeast; bacteria of decay.
(iii) They release digestive enzymes onto the dead matter (extracellular digestion), and the soluble products are absorbed through their hyphae or cell surface.
(iv) Any three: decompose dead bodies and recycle nutrients; yeast is used in baking and brewing; some are eaten (mushrooms); some give antibiotics; they spoil food, timber and leather.
(c) Any three: have special structures (pitchers, sticky hairs, hinged leaves) to trap insects; secrete enzymes to digest the prey; absorb nitrogen compounds from the prey; are green and photosynthesise; usually grow in soils poor in nitrogen.
(d)(i) Butterfly - sucking (fluid feeder, nectar through the proboscis). (ii) Mosquito larva - filter feeding. (iii) Mucor - saprophytic. (iv) Housefly - sponging/sucking of liquid food.
Keep the differences in (a) as matching pairs.