Coordination Flashcards

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1
Q

What is the control of flowering a result of?

A

The photoperiod - the relative length of days and nights

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2
Q

What type of plants are short day plants (SDP)?

A

Plants that flower when day is short and night length is longer

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3
Q

What type of plants are long day plants (LDP)?

A

Plants that flower when days are long and nights are short

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4
Q

What is phytochrome?

A

A chemical in charge of the control of flowering

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5
Q

What happens to P730 at night?

A

SLOWLY converts to P660

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6
Q

What is the physiologically active form of phytochrome?

A

P730

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7
Q

Is P730 inhibitory or stimulatory?

A

In LDPs P730 stimulates flowering, in SDPs it is inhibitory

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8
Q

What does there need to be for a SDP to flower?

A

A long period of uninterrupted darkness, this allows enough time for the P730 to be converted back into P660 removing the inhibitory effect of P730

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9
Q

What does there need to be for LDP to flower?

A

A short enough night length to prevent too much P730 being converted back into P660 - the concentration of P730 needs to be high enough to stimulate flowering

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10
Q

What happens to LDP in a short day and long night?

A

P660 is converted to P730 during the day but the night is long enough for sufficient P730 to be slowly converted back to P660 to prevent the P730 reaching crucial level for flowering - NO FLOWERING

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11
Q

What happens to LDP in long day and short night?

A

Long day length allows P660 to be converted to P730 in high concentration. The night is too short for enough P730 to be converted to P660. P730 builds up to critical length

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12
Q

What happens to SDP in short day and long night

A

P660 is converted to P730 during day. Dark period is long enough for a sufficient level of P730 to be converted to P660 to remove inhibitory effect of P730.

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13
Q

What happens to SDP in long day and short night?

A

P660 is converted to P730 during day but dark period is not long enough for sufficient level of P730 to be converted to P660 to remove inhibition of P730 - NO FLOWERING

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14
Q

How do we match the supply and demand of flowers?

A

By manipulating their photoperiod.

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15
Q

What is a hormone?

A

An organic compound produced in 1 part of an organism and transported to other parts to cause a response

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16
Q

What plant hormones are there?

A
  • Auxins
  • Gibberellins
  • Cytokinins
17
Q

What are auxins involved in?

A

Phototropism

18
Q

What direction does auxin travel in?

A

Away from the tip

19
Q

What do auxins do?

A

Cause cell elongation and are responsible for maintaining the structure of cell walls and if in high concentration can inhibit growth

20
Q

What do gibberellins do?

A

Elongate the internodal distance. This increases overall length of stem.

21
Q

What do cytokinins do?

A

Promote cell division in presence of auxin. They have also been shown to prevent the process of aging and breakdown of chlorophyll in older leaves

22
Q

What is a coleoptile

A

a baby plant <3

23
Q

How do auxins cause plants to grow towards light?

A
  • Auxins produced in cells of apical meristems
  • Diffuse down the shoot to zone of elongation
  • Auxin binds to receptors in the cell membranes of newly formed cells in zone of elongation
  • Cells pump H+ ions into the cellulose cell walls
  • This acidification loosens the cross links in the cellulose microfibrils making the cell wall more flexible
  • As the cells absorb water by osmosis the cell walls stretch more readily due to the hydrostatic pressure exerted
  • The greater the concentration of auxin, the more flexible walls become