please help. 5. How might the fitness cost of photorespiration in C3 plants favo
ID: 153740 • Letter: P
Question
please help.
5. How might the fitness cost of photorespiration in C3 plants favor the evolution of Ca 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?Explanation / Answer
5. Photorespiration is a wasteful pathway that occurs mostly when the Calvin cycle enzyme (Rubisco) acts upon oxygen rather than carbon dioxide. In this process, the plants use light energy to consume oxygen and thereby release carbon dioxide and water. The majority of C3 plants have no special features to combat photorespiration. Thus this process favors the evolution of C4 plants because C4 plants minimize photorespiration by separating initial Carbon Dioxide fixation and the Calvin cycle in space, performing these steps in different cell types.
6. Leaf hairs increase the boundary layer thereby reducing water loss.
The guard cells regulate transpiration by opening and closing the stomata. The stomatas open and close depending on the turgor pressure in the surrounding leaf hairs of the guard cells. When the guard cells take in water, the turgor pressure in them increases and the cells swell causing them to bow outwards, thereby opening the stomata. Again when the guard cells lose water, the turgor pressure decreases and the guard cells become flaccid,thus causing the stomata to close. Cohesion and adhesion both help maintain the water column all the way up from the root hairs to the leaves.
7. Lowering of the temperature reduces the rate of heat lost through conduction because by lowering the temperature, the animal comes at a temperature that is lower than its surroundings. The body temperature of any organism depends on the balance between the heat generated by the organism and the heat exchanged with (lost to or gained from) its surroundings or the environment. As we know heat flows from a body of higher temperature to a body of lower temperature. Thus, heat will flow from the surroundings to the body of the animal thus preventing any heat loss from the animal's body.
8. In addition to highly efficient kidneys, desert animals have thick and tough skin that do not allow water to pass out, have fewer sweat glands and they store fat in unusual places.
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