Survival and Response (14) Flashcards

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1
Q

What are plant growth factors?

A

chemicals that regulate plant growth in response to directional stimuli

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2
Q

Where are plant growth factors produced?

A

in apical meristems

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3
Q

What happens to plant growth factors?

A

diffuse from cell to cell/phloem via mass transport

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4
Q

What are the 5 steps of positive phototropism in plants?

A

1) IAA is produced in tip and diffuses to shaded side of shoot
2) active transport of hydrogen ions into cell walls occurs as IAA diffuses
3) H-bonds between cellulose are disrupted and action of expansins causes cell to become more permeable to water
4) cells on shaded side elongate faster due to higher turgor pressure
5) shoot bends towards light

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5
Q

What are the 5 steps of positive gravitropism in plants?

A

1) IAA is produced in tip and initially transported to all sides of the root
2) gravity causes IAA to accumulate on lower side
3) IAA inhibits the elongation of root cells where concentration is high
4) cells on upper side elongate faster as there is a low IAA concentration
5) root bends downwards

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6
Q

What is meant by taxis?

A

directional movement in response to external stimulus

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7
Q

What are the 2 types of movement?

A

kinesis
taxis

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8
Q

What is meant by kinesis?

A

non-directional response to presence and intensity of external stimulus

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9
Q

What is an advantage of kinesis and taxis?

A

maintain mobile organism in optimum environment

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10
Q

What are the 5 differences between mammalian hormones and plant growth factors?

A

1) concentration
2) action
3) synthesis
4) transport
5) speed

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11
Q

How do mammalian hormones and plant growth factors differ in terms of concentration?

A

MH - response not always dependent on concentration
PGF - response proportional to concentration

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12
Q

How do mammalian hormones and plant growth factors differ in terms of action?

A

MH - bind to complementary proteins on target cells
PGF - can affect all cells

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13
Q

How do mammalian hormones and plant growth factors differ in terms of synthesis?

A

MH - specialised glands
PGF - various tissues in growing regions

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14
Q

How do mammalian hormones and plant growth factors differ in terms of transport?

A

MH - circulatory system
PGF - diffusion or phloem translocation

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15
Q

How do mammalian hormones and plant growth factors differ in terms of speed?

A

MH - faster-acting (homeostasis)
PGF - slow-acting (plant growth)

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16
Q

How do organisms respond to temperature and humidity and why?

A

via kinesis because there are less directional stimuli so often no clear gradient from one extreme to another

17
Q

How do you recognise kinesis in organisms movement?

A
  • organism crosses sharp division between favourable and unfavourable environment + turning increases
  • then organism moves considerable distance into unfavourable environment + turning slowly decreases, moves in long straight lines, sharper turns - leading to new environment
18
Q

What is a chi-squared test suitable for in terms of organisms movements?

A

suitable for determining if a factor has a significant effect on movement of an animal in a choice chamber