Chapter 3.6 Response To Change In Conditions Flashcards

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1
Q

Why do plants need to respond to the environment?

A
  • prevent water loss
  • reproduce
  • increase chance of survival
  • maximise photosynthesis
    -reduce damage
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2
Q

Types of stimuli that a plant can respond to

A

Plants respond to; light, gravity and water to avoid abiotic stress
Also respond to predication by producing chemical toxins

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3
Q

How do plants respond to change in stimulus?

A

Plants change orientation of roots/leaves/stems to favourable conditions
By producing growth factors called tropism from growing regions to other tissues, where they regulate growth in response to stimuli

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4
Q

How do plants respond to light
+ what is it called

A

Stems respond to light by moving towards it = positive phototropism
Roots respond to light by moving away from= negative phototropism

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5
Q

How do plants respond to gravity
+what is it called

A

Stems respond by moving upwards = negative geotropism
Roots respond by moving downwards = positive geotropism

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6
Q

What is the growth factor produced by plant in response

A

Auxin (IAA) is the plant hormone which acts as growth factor

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7
Q

Describe the process of IAA synthesis and movement into shoot in plant response

A

1) IAA is synthesised in cells in shot tip (as stimuli detected by specific receptor proteins)
2) IAA diffuses down shoot equally on all sides

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8
Q

Describe the effect of different concentrations of IAA on cells in plants in response to light stimuli

A

3) light on 1 side causes IAA to be transported to shaded side
4) concentration of IAA increases on shaded side causing elongation of cells
5) IAA activates proteins in plasma membrane H+ ion breaks H bond between cellulose microfibrils = easier for cell wall to expand. Elastin enzymes in cell wall break bonds between cellulose microfibrils allowing cell walls to stretch
6) on shaded side, there is greater elongation of cells, causing the shoot to bend towards light

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9
Q

What type of response are taxes and kineses?

A

Simple innate responses that can maintain a Mobile organism in a favourable environment

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10
Q

Def of taxis response

A

Movement of whole organism in response to direction of a stimulus
E.g
Some move directly towards (positive taxis) or away (negative taxis) to stimulus

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11
Q

Def of kinesis response

A

Non-directional response in which rate of movement is related to the intensity of stimulus, not directional

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12
Q

What are the 2 types of kinesis response

A

Orthokinesis - change in rate of movement
Klinokinesis - change in the rate of turning

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