6) Using the figure on the next page, answer the following questions A) On the f
ID: 180617 • Letter: 6
Question
6) Using the figure on the next page, answer the following questions A) On the figure, DRAw (with arrows in correct direction) and LABEL all heat gain and loss pathways that may affect the body temperature of MERRIAM's KANGARoo RAT. Be sure to make clear whether they are heat gains/losses. B) How would these pathways change if the kangaroo rat was active ATNIGHT (as it is usually nocturnal, where air temperatures are 20°C and substrates eventually match Ta)? Be specific relative to each pathway. c) What are the water loss pathways for this mammal? How does it reduce water loss?Explanation / Answer
a. Tsun------Tair---loss of heat; Air----rocks--gain of heat; Sun---rocks-lossof heat; sun----sand-loss of heat;
b. Kangaroo rat use both behavioural and physiological means to conserve wate and energy. At temperatures within their thermoneutral zone they minimize energy expenditute but there is imbalance in water as the ratio of water loss to water gain is high. At temperatures below thermoneutral zone water balance may be improved as kangaroos generate more oxidatve water and reduce loss of water by evaporation. They must also increase energy expenditure to maintain normal body temperature. During nights kangaroo rats choose temperatures near the bottom of their thermoneutral zone. During day time they choose temperatures top of theit thermoneutral zone. Kangaroo rats choose thermal environments that minimize energy requirements not water requirements.
C. They reduce water loss by several means. These include; These animals preferentially eats seeds gathered at night and stored in burrows. Stored sedes absorb water from the air originating from rats breath or from soil. underground in their cool humid burrows kangaroo rats retain as much water as possible by effectively recycling water which would otherwise be lost in their breath. Kidneys of these rats produce less amount of concentrated urine.The long loop of Henley provides greater oppurtunity to absorb more water.
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