Critical thinking questions 1. how do salty soils affect the matric potential and, in turn, affect root pressure and overall water uptake? 2. based on your knowledge of the relationship between volume and surface area, why do clay soils hold more water than sandy soils? 3. if you were breeding cotton plants to have increased water uptake in dry soils, you could breed plants that contain more amino acids and carbohydrates in the root cells. why would this be effective and why might crop yield be negatively affected? 4. how do cam plants solve the problem of obtaining co2 for photosynthesis while minimizing water loss? 5. how might the fitness cost of photorespiration in c3 plants favor the evolution of c4 plants? 6. how do leaf hairs that surround guard cells reduce water loss through the process of forming a boundary layer? 7. when animals hibernate, they lower their temperature. how would this reduce the rate of heat lost through conduction? 8. in addition to having highly efficient kidneys, what behaviors could you imagine desert animals using to reduce water loss? 9. if you designed an experiment to determine how temperature and the species composition of seeds affect the growth and reproduction of seed-eating birds, what would be the independent and dependent variables? 10. if you were to stand in a river with fast-moving water, which heat exchange processes might occur and why?