Thermoregulation in Hot environments

Question 1

What are the 4 types of heat transfer?

Answer 1

1. Radiation.
2. Conduction.
3. Convection.
4. Evaporation.

Question 2

Describe radiation.

Answer 2

The transfer of heat from a hot object by infrared rays.

Question 3

Describe conduction.

Answer 3

The transfer of heat from a relatively hot object to a relatively cold object by direct contact.

Question 4

Describe convection.

Answer 4

The transfer of heat by means of rising currents of warm air or water.

Question 5

Describe evaporation.

Answer 5

The process in which liquid water changes to water vapour through heating.

Question 6

What is an ectothermic organism?

Answer 6

Gain heat from the external environment. Body temperature fluctuates with the external environment. May regulate temperature through behaviour.

Question 7

What are 4 examples of ectothermic organisms?

Answer 7

1. Invertebrates.
2. Reptiles.
3. Amphibians.
4. FIsh.

Question 8

What are 4 advantages of being ectothermic?

Answer 8

1. Little energy is required and so have a low metabolism.
2. Can feed less often.
3. Stay in the shelter longer.
4. Tolerate larger fluctuations in internal body temperature.

Question 9

What are 3 disadvantages of being ectothermic?

Answer 9

1. Inactive in cold and night.
2. More likely to get eaten.
3. Restricted geographic range.

Question 10

What is an endothermic organism?

Answer 10

Organims that gain body heat from metabolic activity. They have a high metabolism and contact temperature.

Question 11

What are 4 examples of endothermic organisms?

Answer 11

1. Birds.
2. Mammals.
3. Fast fish (tuna)
4. Insects (bumble bees)

Question 12

What are 4 advantages of being endothermic?

Answer 12

1. Body temperature remains constant.
2. Active at any temperature.
3. Able to avoid predators.
4. Makes them good predators.

Question 13

What are 2 disadvantages of being endothermic?

Answer 13

1. Large energy requirement (high metabolism)
2. Need insulation or cooling mechanisms.

Question 14

What are the 8 ways body heat is lost?

Answer 14

1. Urine.
2. Faeces.
3. Lungs.
4. Skin.
5. Convection.
6. Conduction.
7. Radiation.
8. Evaporation.

Question 15

What are the different categories of adaptations?

Answer 15

1. Physiological.
2. Behavioural.
3. Strucutral.

Question 16

List 5 physiological adaptations to hot environments.

Answer 16

1. Sweating.
2. Panting.
3. Coat thining.
4. Vasodilation.
5. Decreased metabolic rate.

Question 17

Describe sweating.

Answer 17

Sweat glands open up to release water and salt onto the skin which evaporates and cools the skin. Evaporated water carries away heat energy from the body and lowers the internal temperature. This is evaporative cooling.

Question 18

Describe panting.

Answer 18

Expels hot air and brings in cooler air, which then helps moisture in the mouth to evaporate quickly, reducing body temperature. Involved in the lungs, mouth and throat.

Question 19

Describe coat thining.

Answer 19

Also known as fur flattening, some animals shed a thick coat from winter during warm weather. Thick fur traps a layer of air close to the skin preventing heat loss via convection.

Question 20

Describe vasodilation.

Answer 20

Nerve impulses stimulate smooth muscles in the wall of blood vessels to relax causing them to widen. This leads to a greater blood flow close to the skin’s surface and heat to escape by radiation and convention.

Question 21

Describe decreased metabolic rate.

Answer 21

Reduced secretion of adrenaline and thyroxine, hormones that control metabolism. Heat is a by product of metabolism.

Question 22

List 2 structural adaptations to a hot environment.

Answer 22

1. Insulating fur.
2. SA:VOL ratio.

Question 23

Describe insulating fur.

Answer 23

Sheads the skin and prevents the skin surface absorbing heat by radiation.

Question 24

Describe SA:VOL ratio.

Answer 24

Large extremities aid in the loss. A sphere is a shape with the smallest SA:VOL ratio. A long and thin shape has the largest SA:VOL ratio. The larger the shape the smaller the SA:VOL ratio.

Question 25

List 4 behavioural adaptations to a hot environment.

Answer 25

1. Wallowing in water.
2. Burrowing/lying in the shade.
3. Decrease voluntary movement.
4. Increase SA:VOL ratio.

Question 26

Describe wallowing in water.

Answer 26

SOme organisms will roll in mud or water bodies to coll themselves down. As the water in mud evaporates from their skin it carries heat away in the same way sweat does in humans. Water has a 50x cooling effect.

Question 27

Describe burrowing/lying in shade.

Answer 27

Organisms may rest in burrows or ly in shade to stay out of direct sunlight to prevent heat gain by radiation or conduction.

Question 28

Describe a decrease in voluntary activity.

Answer 28

This will reduce the body’s metabolism and heat production.

Question 29

Describe an increase in SA:VOL ratio.

Answer 29

This leads to an increase in heat loss as organisms may spread out. Organisms may flap their ears as a way to create airflow and blood vessels to vasodilate. Organisms may stand on two legs not four to reduce heat gain by conduction and radiation.

Question 30

What percentage of heat is lost by radiation?

Answer 30

65%

Question 31

What percentage of heat is lost by conduction?

Answer 31

2%

Question 32

What percentage of heat is lost by convection?

Answer 32

15%

Question 33

What percentage of heat is lost by evaporation?

Answer 33

20%