Communication + Homeostasis q's

Question 1

explain one adv of using a confocal microscope

Answer 1

can be used w/ living cells

Question 2

Answer 2

conc valid:
- conc of Ca2+ is proportional to strength of stimulus
- Ca2+ chnage from low to high causes increase in membrane potential
- action potential in presynaptic neurone leads to opening of Ca2+ channels
- Ca2+ causes release of neurotransmitter
- neurotransmitter causes Na+ channels to open in neurone
- if threshold is exceeded this causes AP in neurone

conc not valid
- changes in Ca+ conc may not be the cuase of AP
- Ca2+ change from medium to high but no change in potential

Question 3

Answer 3

• scales+ hair helps to reduce heat loss
• generate heat from respiration

Question 4

it is more difficult for moths+ bumblebees to maintain their body temp than for mammals + birds to maintain their body temp. explain why.

Answer 4

• insects are smaller + have a large SA:vol ratio
• insects have greater rate of heat loss
• mammals + birds have more thicker insulation
• wont have mammalian methods of precise control of body temp such as vasodilation

Question 5

Answer 5

• naked mole rat have a lower body temp
• nake mole rats use more behavioural responses
• core body temp of naked mole rats is not maintained within narrower rage/ fur to trap layer of air
• no hair

Question 6

explain how +ve feedback could accelerate the process of hypothermia ( causes decr in body temp to continue)

Answer 6

• +ve feedback is when an initial change is increased further
• lower temp reduces kinetic energy of molecules
• enzyme activity slowed
• respiration rate/ metabolism slowed
  -less metabolic heat generated
• so that body temp drops further

Question 7

Answer 7

false
true
true
false

Question 8

state where the core body temp is monitored

Answer 8

hypothalamus

Question 9

name the type of sensory cell in the skin that detects changes in environmental temperature

Answer 9

thermoreceptors

Question 10

name the coreective homeostatic mechanism that works to restore any changes in body temp to the normal range

Answer 10

negative feedback

Question 11

Answer 11

i) M N P
ii) K O
iii) L
iv) N

Question 12

explain how the following adaptation help the animal to control its body temp:
elephants have large, thin ears that they move backwards + forwards when hot

Answer 12

• large SA to lose heat
• thin so blood flows close to the skin surface to lose heat
• movement increases air movement over surface to lose heat

Question 13

explain how the following adaptation help the animal to control its body temp:
penguins living in cold climates have ‘shunt’ blood vessels. these shunt vessels link arterioles carrying blood towards their feet w/ small veins that carry blood away from their feet

Answer 13

• blood loses less heat bc less blood flow to feet
• less blood flows to feet so core body temp maintained

Question 14

describe 2 examples of communication between cells that occur during the life cycle

Answer 14

• attraction of cells to foilic acid from bacteria
• attraction of cells to each other by CAMP
• coordination movement in grex
• differenciation of grex cells in response to DIF

Question 15

suggest how the plasma membrane for D. discoideum is adapted for cell communication

Answer 15

• plasma membrane has receptors
• contains receptors for cAMP

Question 16

explain what is meant by the term homeostasis

Answer 16

• maintaining stable internal environment
• within limits
• even though environment is changing

Question 17

describe how negative feedback is used to control blood glucose conc

Answer 17

• beta cells detect increased in BGC
• if higher glucose conc, beta cells release insulin
• incr uptake of glucose by liver cells
• enters through glucoe transport proteins inc ell surface membrane
• glucose converted to glycogen/glycogenesis
• incr use of glucose in respiration
• if lower glucose conc, alpha cells release glucagon
• increased conversion of glycogen to glucose/ glyconeogenesis
• glucose leaves cells by facilitated diffusion

Question 18

Answer 18

i) required to take daily hormone injections
not affected by dietary changes

ii) developed in an older person

Question 19

describe the role of ATP in the cell

Answer 19

• releases energy
• phosphate can be removed by hydrolysis to provide energy
• energy released for metabolism (muscle contraction)
• ADP can attach to a phosphate forming ATP during respiration
• energy released is suitable quantity to prevent cell damage
• it releases 30kj of energy when a phosphate is removed by hydrolysis

Question 20

describe the way in which an endothermic animal , normally prevents its body temp from decreasing when the external temp decreases

Answer 20

• thermoreceptors stimulated by decrease in external temp
• impulses sent to hypothalamus
• vasconstriction of arterioles to reduce heat loss
• prevents heat loss by radiation
• release of adrenaline
• shivering to generate heat
• hair raise to trap heat