25. Why do elephants have big ears? a. The ancestors of elephants had sharp hearing. b. Elephants use their ears to fan and cool themselves. c. Big ears increase the surface-to-volume ratio of elephants. d. Big ears help to reduce overall metabolic rate of the body. e. None of the above.
32. In mammals, what is the evidence that the “thermostat” is located in the hypothalamus? a. Direct warming of the hypothalamus results in reduction of metabolic activity. b. Direct cooling of the hypothalamus results in reduction of metabolic activity. c. There is a direct relationship between body temperature and metabolic rate. d. The temperature of the hypothalamus is always 37°C. e. Changes in hypothalamic temperature always precedes changes in body temperature.
25) The elephant possesses big ears that has large number of blood vessels present near the skin.
The correct option is (b). The elephants use their ears to fan and cool themselves.
Explanation for the correct option:
The big and relatively thin ears help elephants to regulate their body temperature by diffusing the heat.
Explanation for the incorrect options.
Smaller animals possesses high surface area to volume ratio.
The metabolic rate is not affected by the size of ear.
26) The thermostat region is the area which is involved in regulating the body temperature.
The correct option is (e). The changes in hypothalamic temperature always precedes the changes in the body temperature.
The hypothalamus performs the function of integrating the information from the temperature sensors and modify the body temperature by the help of appropriate efferent control of thermoregulatory processes.
Explanation for the incorrect options.
The hypothalamus does not undergo direct cooling but they integrate the signal from various thermoreceptors.
When the body temperature increases the hypothalamus sends the signal to reduce the body temperature and metabolic rate of the body
25. Why do elephants have big ears? a. The ancestors of elephants had sharp hearing. b....