Theory question 102
Soil Properties(a) State four functions of soil water to crops.
(b) Outline five factors that could cause low soil pH.
(c) Explain the life cycle of liver fluke.
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(a) Any four: dissolves nutrients and carries them into roots; needed for photosynthesis; keeps cells turgid; cools the plant through transpiration; needed for germination; helps weathering/microbial activity.
(b) Any five: leaching of bases (Ca, Mg) by heavy rain; continuous use of acid-forming fertilizers (e.g. sulphate of ammonia); acidic parent rock; decomposition of organic matter (organic acids); removal of bases by crops; waterlogging; acid rain.
(c) Adult fluke lives in the bile ducts of the liver of sheep/cattle and lays eggs; eggs pass out with faeces; in water they hatch into miracidia; miracidia enter a water snail (Limnaea), where they multiply (sporocyst → redia → cercaria); cercariae leave the snail and encyst on grass as metacercariae; the animal eats the grass; young flukes bore through the gut wall to the liver and grow into adults.
Mention the snail as intermediate host.