Paper 2: Topic 5 Homeostasis & response - Plant hormones (LV) Flashcards Preview

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Flashcards in Paper 2: Topic 5 Homeostasis & response - Plant hormones (LV) Deck (42)
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1

State an example of a plant growth hormone

Auxin

2

Describe the role of growth hormones in plants

To co-ordinate and control plant growth in response to light, water and gravity

AND

to control responses such as flowering and fruit production

3

State where in a plant auxin is produced

Shoot tips

Root tips

 

Hint: do not just say shoot and root

4

Describe 3 roles of auxin in plants

It controls the direction of growth of plants in response to light, water and gravity

5

Define the term phototropism

The directional growth of plants in response to light

6

Define the term geotropism

The directional growth of plants in response to gravity

7

Define the term gravitropism

The directional growth of plants in response to gravity

8

Define the term hydrotropism

The directional growth of plants in response to water

9

Describe the how different parts of a plant respond to light

  • Shoot tips grow towards the light
  • Root tips grow away from the light

10

Describe the how different parts of a plant respond to gravity

  • Root tips grow in the same direction of gravity (positive geotropism)
  • Shoot tips grow away from the direction of gravity (negative geotropism)

11

Explain how a shoot tip grows towards the light

  • Auxin is produced in the shoot tip
  • The auxin diffuses to the shaded side of the shoot tip
  • This casues unequal distrbution of auxin in the shoot tip
  • The high concentration of auxin causes the cells just below the shoot tip on the shaded side to elongate faster
  • This causes the shoot tip to curve towards the light

12

Explain how a shoot tip grows away from gravity

  • Auxin is produced in the unequally in the shoot tip
  • The auxin collects on the lower side of the shoot tip
  • This causes unequal distribution of auxin in the root tip
  • The high concentration of auxin causes the plant cells on the underside of the shoot tip on the lower side to elongate faster
  • This causes the shoot tip to curve upwards away from gravity

13

Explain how a root tip grows away from gravity

  • Auxin is produced in the unequally in the shoot tip
  • The auxin collects on the lower side of the shoot tip
  • This causes unequal distribution of auxin in the root tip
  • The high concentration of auxin inhibits growth in roots
  • This causes the plant cells on the top of the root tip to elongate faster
  • This causes the root tip to curve downwards towards gravity

14

Describe how plant cells in the root and shoot tip respond differently to auxin

  • Auxin stimulates plant cells to elongate in shoot tips
  • Auxin inhibits elongation in plants cells found in root tips

15

State 5 variables that must be controlled during an investigation studying the effect of light on plant growth

  1. Type of seeds
  2. Number of seeds
  3. Volume of water added to the seeds
  4. Temperature
  5. Light intensity and duration

16

State independent variable in an investigation studying the effect of light on plant growth

Direction of the light

17

State dependent variable in an investigation studying the effect of light on plant growth

The angle of the seedling

18

Describe and explain what happens if a shoot tip is removed from a seedling

Description:

  • No directional growth occurs

Explanation:

  • If the shoot tip is removed no auxin is produced
  • Plant cells on both the lit and shaded side of the seedling elongate at the same rate
  • The seedling grows straight (with no curvature)

19

State the term used to describe plant growth towards a stimulus

Positive tropism

20

State the term used to describe plant growth away from a stimulus

Negative tropism

21

State the term used to describe plant growth towards the light

Positive phototropism

22

State the term used to describe plant growth away from the light

Negative phototropism

23

State the term used to describe plant growth towards gravity

Positive geotropism / positive gravitropism

24

State the term used to describe plant growth away from gravity

Negative geotropism / negative gravitropism

25

State the term used to describe plant growth towards water

Positive hydrotropism

26

State the term used to describe plant growth away from water

Negative hydrotropism

27

Name the plant hormone important in initiating seed germination

Gibberellins

28

Name the plant hormone important in controlling cell division and ripening of fruits

Ethene

29

Give 3 uses of auxins in agriculture and horticulture

  1. Weed killers
  2. Rooting powders (to promote root formation)
  3. Promoting growth in tissue cultures

30

State the use of ethane in the food industry

To control the ripening of fruit during storage and transportation

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