5.1.3 temperature control in ectotherms

Question 1

ectotherm

Answer 1

organism which relies on external sources of heat to maintain body temperature

Question 2

endotherm

Answer 2

organism which uses heat from metabolic reactions to maintain body temperature

Question 3

what happens to molecules inside the body when temperature rises

Answer 3

• more kinetic energy
• move about quicker & collidemore frequently
• essential chemical reactions occur quicker

Question 4

using enzymes as an example, describe how temperature changes can impact the structure of proteins

Answer 4

• many proteins have metabolic function
• enzymes = globular proteins & have specific tertiary structure giving them specific 3-dimensional shape
• shape of active site is complementary to shape of substrate
• any change in shape will affect their ability to function normally
• if temperature allowed to exceed too much = enzymes change shape & function is lost

Question 5

what is temperature regulation reliant upoon in ectotherms

Answer 5

behavioural responses which can alter amount of heat exchanged with environment

Question 6

examples of how ectotherms try absorb heat from environment (if too cold)

Answer 6

• move into sunny area
• lie on warm surface
• expose larger surface area to sun

Question 7

examples of how ectotherms may try to lose heat if they’re too hot

Answer 7

• move out of sun
• move underground
• reduce body surface exposed to sun

Question 8

snake: behavioural adaptation & benefit

Answer 8

adaptation
- basks in sun
- UK = adders often lying on exposed path beside vegetation

benefit
- absorbs heat directly from sun

Question 9

locust: behavioural adaptation & benefit

Answer 9

adaptation
- early morning: sit side-on to sun exposing large SA
- midday: face sun head-on exposing smaller SA
- also climb to top of plant to get away from soil surface
- hot = increase rate/depth of breathing

benefit
- cool morning: absorb more heat
- midday (sun hotter): absorb less
- soil surface gets hot & radiates heat so gains less heat from soil
- more water evaporates from tracheal system = cooling body

Question 10

lizard: behavioural adaptation & benefit

Answer 10

adaptation
- use burrows/crevices between rocks
- hide in burrow in hottest part of day & coolest part of night

benefit
- underground burrow = more stable temperature
- hottest part of day = cooler in burrow
- coldest part of night = warmer in burrow

Question 11

horned lizard: behavioural adaptation & benefit

Answer 11

adaptation
- change shape by expanding/contracting rib cage

benefit
- expanding rib cage = increased SA so more heat absorbed from sun

Question 12

advantages of ectothermy

Answer 12

• less food used in respiration
• more energy/nutrients from food converted to growth
• find less food
• survive longer periods without food

Question 13

disadvantages of ectothermy

Answer 13

• less active in cooler temperatures = risk from predators
• unable to escape
• can’t take advantage of food available whilst they’re cold