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Biology- Ms Kad/Miss Patel > survival + response > Flashcards

survival + response Flashcards

1
Q

describe pathway by which organism responds to environment

A
  • stimulus
  • receptor
  • coordinator
  • effector
  • muscle
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2
Q

define stimulus

A

detectable change in environment

causing response

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3
Q

explain importance of reflex arc

A

rapid - only 3 neurones + few synapses
autonomic - doesntt involve passage to brain
protects from harm

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4
Q

define taxis

A

directional movement

organism moves towards/away stimulus

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5
Q

explain example of how woodlice show tactic response to light

A

-move away from light
keeps concealed from predators in daylight

-moves towards damp conditions
reduces water loss
improves chance of survival

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6
Q

define kinesis

A

non-directional movement
by organsims
who change speed of movement/rate of direction change
in response to non-directional stimulus

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7
Q

example of how woodlice show kinetic response to humidity

A

move faster/change direction more often when drier
increases chance of moving to area with higher humidity
less water loss
improves chance for survival

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8
Q

define tropism

A

growth of a part of plant in response to stimulus

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9
Q

2 types of tropisms?

A

positive - growth towards stimulus

negative - growth away from stimulus

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10
Q

what are growth factors in plants

A

plant responses to external stimuli involve growth factors

growth factors move from growing regions to other tissues

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11
Q

in roots IAA…

A

inhibits cell elongation

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12
Q

in shoots IAA…

A

promotes cell elongation

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13
Q

how does IAA cause phototropism in shoots

A
  • cells in tip produce IAA
  • IAA transported down shoot
  • IAA conc increases on shaded side
  • promotes cell elongation
  • shoot bends towards light
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14
Q

how does IAA cause gravitropism in roots

A
  • cells in tip produce IAA
  • IAA transported down shoot
  • IAA conc increases on lower side of root
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15
Q

how does the pacinican corpuscle produce a generator effect

A
  • mechanical stimulus -pressure deforms lamellae+ deform stretch-mediated sodium ion channel
  • sodium ion channels open + sodium ions diffuse into sensory neurone
  • greater pressure causes more channels to open + more sodium ions to enter
  • causes depolarisation, leading to generator potential
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16
Q

where are rods found

A

more at periphery of retina

absent in fovea

17
Q

how many pigments- rod

A

one type of rod

containing one pigment

18
Q

how are rod cells connected to bipolar

A

multiple connect to one bipolar neurone

19
Q

what is the photoreceptor in rod cells called

A

rhodopsin

20
Q

how sensitive are rod cells to light

A

very sensitive

21
Q

do rod cells have high or low visual acuity

A

low

22
Q

rod cells dected

A

black and white

23
Q

cone cells are found at

A

concentrated at fovea

fewer at periohery of retina

24
Q

how many pigments - cone

A

3 pgiment
blue
red
green

25
Q

photoreceptor in cone cells

A

iodopsin

26
Q

how are cone cells connected to bipolar

A

each cone cell

attached to its own bipolar neurone

27
Q

how sensitve are cone cells to light

A

less sensitve

require bright light

28
Q

do cone cells have high or low visual acuity

A

high

29
Q

cone cells detect

A

colour

30
Q

why is a single impulse generated in rod cells

A

many rod cells joined to the same bipolar

source of light cannot be distinguished between rod cells

31
Q

why is an impulse more liekly to be generated for rod cells

A

each rod cell simulation = sub-threshold
cells conncected - spatial summation
so threshold more likely met

32
Q

why is generator potential often not exceeded for cones

A

each cone cell has own bipolar sensory neurone

high light intensity needed to produce greater impulse

33
Q

why do cones have higher visual acutiy

A

one cone cell to one neurone

so source of light can be distinguished

34
Q

why do rods have lower visual acuiity

A

many rods connected to bipolar
many neurones generate one impulse
so source of light cannot be distunished

Biology- Ms Kad/Miss Patel (13 decks)

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