Module 5.1 - Communication and Homeostasis

Question 1

(MA) What are the advantages of being an ectotherm?

Answer 1

• less food used in respiration
• need less food
• more energy used for growth

Question 2

(MA) What are the disadvantages to being an ectotherm?

Answer 2

• less active in cold

- winter months

Question 3

(MA) What are the advantages of being endothermic?

Answer 3

• can maintain body temperature despite external conditions

- can be active in colder conditions

Question 4

(MA) What are the disadvantages of being an endotherm?

Answer 4

• a large portion of energy intake is needed to maintain body temperature in cold
• more food required
• less energy from food used for growth

Question 5

(MA) Describe what endotherms do when they get too hot.

Answer 5

• peripheral thermoreceotirs in skin stimulated by change in external temperature
• impulses sent to hypothalamus
• vasodilation of arterioles to increase heat loss
• by conduction/radiation
• decreased metabolic rate/respiration in liver
• to generate less heat
• sweating/panting - evaporation to remove heat from skin
• hair muscles cause hairs to lie flat, no insulating air trapped, heat can radiate more easily to the surroundings
• example of negative feedback
• behavioural responses: go to shade, larger SA for heat loss, less active

Question 6

(MA) Describe what endotherms do when they get too cold.

Answer 6

• peripheral thermoreceptors in skin stimulated by change in external temperature
• impulses sent to hypothalamus
• vasoconstriction of arterioles to reduce heat loss
• by radiation/conduction
• increased metabolic rate/respiration in liver
• to generate heat
• release of adrenaline
• rapid contraction and relaxation of skeletal muscles to shiver to generate heat
• hair muscles cause hairs to cause hairs to stand up, trap a layer of insulating air to prevent heat loss by conduction
• example of negative feedback