(a) List four functions of soil water to crops.
(b) Enumerate five factors that could cause low soil pH.
(c) Briefly discuss the life cycle of Liver Fluke.
Explanation
(a) Functions of soil water to crops
- Cooling of plants through transpiration
- Needed for all metabolic reactions in plants
- Used in photosynthesis
- Needed for germination of seeds
- helps in transportation of manufactured food
(b) Factors that could cause low soil pH
- Acid rains in industrial areas
- Use of sulphur-based agro-chemicals/fertilisers
- Leaching
- Erosion
- Acid parent materials
- Absorption of basic cations from the soil/ Preferential nutrient uptake by plants
- Hydrolysis of aluminum
(c) Explanation of the cycle of Liver fluke
- Eggs pass from the uterus of the adult liver fluke into the bile duct of the host (livestock)
- The eggs move from the bile duck into the intestine
- They are passed out with the faeces of host on to pastures
- Eggs hatch into miracidiae
- The miracidiae penetrate the water snail (secondary host)
- The miracidiae develop into sporocysts in the snail
- By cell division, the sporocysts develop into rediae
- The rediae develop into carcariae
- The carcariae pass out of the water snail, remain in the pasture and become encysted (metacercaria)
- Encysted cercaria is eaten by livestock host along with the pasture
- Metacercaria develops into young liver fluke
- Young liver fluke swims through the intestine into the blood streams to the liver and finally locates at the bile duct