4. metabolism in conformers and regulators

Question 1

the ability of an organism to maintain its metabolic rate is affected by…

Answer 1

external abiotic factors (eg. temperature, pH, salinity)

The further away an abiotic factor gets from the optimum requirements of an organism, the greater physiological stress an organism is under which decreases its ability to grow and survive

Question 2

describe conformers

Answer 2

Conformers’ internal environment is dependent upon the external environment.

Behavioural responses by conformers allow them to tolerate variation in their external environment to maintain optimum metabolic rate. Conformers have low metabolic costs and a narrow range of ecological niches

Question 3

describe regulators

Answer 3

Regulators maintain their internal environment regardless of external environment.

Regulators use metabolism to control their internal environment, which increases the range of possible ecological niches. This regulation requires energy to achieve homeostasis. This increases their metabolic costs.

Question 4

describe thermoregulators

Answer 4

they are able to maintain a constant body temperature regardless of the environmental temperature.

they don’t absorb heat from the surroundings because they gain heat energy from their own metabolism

regulate their body temperature using homeostatic negative feedback mechanisms

Question 5

what is thermoregulation

Answer 5

refers to an organisms ability to control its own temperature

Question 6

what is the hypothalamus

Answer 6

the temperature monitoring centre in the brain. Information is communicated by electrical impulses through nerves to the effectors, which bring about corrective responses to return temperature to normal.

Question 7

mechanisms to aid thermoregulation - hair

Answer 7

When thermoreceptors in your hypothalamus detect the body temperature cooling below 37C, the hair erector muscles (in the skin) contract, (the hairs stand up), which traps a layer of insulating air.

Question 8

mechanisms to aid thermoregulation - sweating

Answer 8

When the body temperature increases sweat glands increase the secretion of sweat onto the surface of the skin.
Body heat used to evaporate water in the sweat, cooling the skin

Question 9

mechanisms to aid thermoregulation - shivering

Answer 9

body temperature decreases the hypothalamus can also send nerve impulses to the skeletal muscles which will make them contract and relax rapidly - the muscle contraction generates heat

Question 10

mechanisms to aid thermoregulation - blood capillieries (hot external environment)

Answer 10

vasodilation occurs. (blood vessels near the skin surface dialate (widen)) which results in increased flow of blood to the skin surface.

heat radiates out skin which increases heat loss

Question 11

mechanisms to aid thermoregulation - blood capillieries (cold external environment)

Answer 11

vasoconstriction occurs. (Blood vessels near the skin surface constrict (narrow)) which results in decreased blood flow to skin

less heat radiates out of skin which decreases heat loss

Question 12

how do both vasodilation and vasoconstriction occur

Answer 12

due to nerve impulses from the hypothalamus

Question 13

mechanisms to aid thermoregulation - metabolic rate

Answer 13

metabolic reactions generate heat energy

A too-high increase in body temperature results in a decreased metabolic rate - so that less heat produced

A too-high decrease in body temperature results in an increased metabolic rate - so that more heat is produced

Question 14

why is thermoregulation important for metabolism

Answer 14

it is important to regulate temperature (thermoregulation) for optimal enzyme activity and high diffusion rates to maintain metabolism

Question 15

describe the role of corrective responses to an increase in body temperature

Answer 15

sweating – body heat used to evaporate water in the sweat, cooling the skin.
vasodilation of blood vessels – increased blood flow to the skin increases heat loss.
decreased metabolic rate – less heat produced.

Question 16

describe the role of corrective responses to a decrease in body temperature

Answer 16

hair erector muscles contract - traps layer of insulating air.
vasoconstriction of blood vessels - decreased blood flow to the skin decreases heat loss.
shivering - muscle contraction generates heat.
increased metabolic rate - more heat produced.

Question 17

Explain why diffusion rates in cells would be higher at 37˚C compared with a slightly lower temperature

Answer 17

molecules move faster at warmer temperatures therefore the movement of molecules through a membrane (from higher to lower concentration, by diffusion) will also be higher at the higher temperature.

Question 18

explain why it is essential for humans to be able to maintain this constant body temperature of approximately 37˚C.

Answer 18

Enzymes involved in the metabolic reactions/pathways in our body cells have an optimum temperature of 37C therefore thermoregulation helps maintain this high metabolism.