Control of plant growth

Question 1

What is the communication pathway in plants?

Answer 1

Environment -> Sensory input -> Cell signalling -> Output

Question 2

Where is plant division limited to?

Answer 2

Meristems

Question 3

What is the main meristem?

Answer 3

The shoot apical meristem for primary growth

Question 4

What is the main meristem found?

Answer 4

The top of the stem

Question 5

What is the main growing root?

Answer 5

The root apical meristem for primary growth

Question 6

Where is the main growing root found?

Answer 6

The tip of the roots

Question 7

What is found in the meristem?

Answer 7

A zone of elongation and then division

Question 8

What is the lateral meristem?

Answer 8

Allows with of shoots and roots to increase (cambium) for secondary growth

Question 9

Where is the lateral meristem?

Answer 9

Outside of shoots and roots

Question 10

What is primary growth?

Answer 10

Getting longer

Question 11

What is secondary growth?

Answer 11

Getting wider

Question 12

What is the intercalary meristem?

Answer 12

Increases the distance between leaves

Question 13

Where is the intercalary meristem?

Answer 13

Between nodes

Question 14

What are the main meristem?

Answer 14

Shoot apical, root apical, lateral and intercalary

Question 15

What controls plant growth?

Answer 15

Tropism, apical dominance and stem elongation

Question 16

What coordinates plant growth?

Answer 16

Plant hormones

Question 17

How do plant hormones move?

Answer 17

By active transport, diffusion or phloem/xylem (mass flow)

Question 18

What is needed for plant hormone to move?

Answer 18

Incredibly low concentrations

Question 19

How are plant hormones produced?

Answer 19

By specific cells

Question 20

What is specific about plant hormones?

Answer 20

Their shape

Question 21

How do plant hormones act?

Answer 21

They bind to a receptor on/in the target cell which is complementary to the shape of the hormone

Question 22

What is the effect of plant hormone action?

Answer 22

Specific genes that promote growth are turned on

Question 23

What are tropisms?

Answer 23

A directional plant growth response to a directional stimuli

Question 24

What is the result of phototropism?

Answer 24

Shoot grows up towards light no rots grow down

Question 25

What is phototropism?

Answer 25

A growth response to light controlled by auxin

Question 26

What is geotropism?

Answer 26

A growth response to gravity controlled by auxin

Question 27

What is the result of geotropism?

Answer 27

Roots grow down into soil and shoots grow up

Question 28

What does etiolated mean?

Answer 28

Tall and thin

Question 29

Where are auxins found?

Answer 29

They are produced a very high concentrations in the shoot tip and are transported down the shoot

Question 30

How does auxin lead to growth?

Answer 30

1. Auxin is made at apex 2. Auxin diffuses or is actively transported to zone of elongation 3. Auxin binds to receptors on cells in zone of elongation 4. This triggers active transport of hydrogen ions into the cell wall. 5. Leads to high hydrogen ion concentration and low pH in cell wall 6. High hydrogen ion conc, breaks hydrogen bonds holding cellulose molecules together within fibres 7. Cell wall is less rigid 8. Drop in pressure potential 9. Water enters cell by osmosis and cell elongates

Question 31

What is the coleoptile?

Answer 31

A sheath that protects a young shoot tip found in grasses and cereals

Question 32

What did Darwin investigate?

Answer 32

The phototropic response when tip isn’t illuminated

Question 33

How does geotropsim work?

Answer 33

Auxin is produced at the tip and drops to the bottom due to gravity

Question 34

How do you investigate geotropism?

Answer 34

Using a clinostat which removed the effect of gravity as it rotates

Question 35

What is apical dominance?

Answer 35

The presence of a main growing shoot

Question 36

What is the result of apical dominance?

Answer 36

Less of the plant is shaded

Question 37

What is the effect of apical dominance?

Answer 37

The terminal bud contains auxin which inhibits growth of lateral buds

Question 38

What is apical bud decapitation?

Answer 38

Removal of the terminal bud via selective pruning

Question 39

What is the effect of apical bud decapitation?

Answer 39

The dormant lateral buds develop, producing bushier plants

Question 40

What happens to the auxin when the apical bud is cut off?

Answer 40

Auxin levels drop and new branches grow

Question 41

What happens if you put chemicals on the apical bud?

Answer 41

Transport can be inhibited and new branches will grow from the lateral and apical bud

Question 42

What does auxin do the abscisic acid?

Answer 42

Keep levels high

Question 43

What happens if you add cytokines to the lateral buds?

Answer 43

New branches will grow to override effect of auxin

Question 44

What is the effect of gibberellins?

Answer 44

Stem elongation at internodes and is structurally based on terpenes

Question 45

Where are gibberellins found?

Answer 45

Young and expanding shoots, buds, root tips and seeds

Question 46

How do gibberellins move?

Answer 46

Up and down plants through xylem and phloem

Question 47

What do gibberellins stimulate?

Answer 47

Mitosis in the intercalary meristem in the internodes so can convert dwarf plants to normal sizes and grow

Question 48

What happens when you apply giberellins?

Answer 48

Plants bold and produce flowers in the 1st season with larger internodes

Question 49

What happens when you increase concentration of gibberellins?

Answer 49

Increased growth

Question 50

What are uses of auxins?

Answer 50

Weed killers and rooting powder

Question 51

How does auxin work as a weed killer?

Answer 51

Weeds ar broad leaved plants that absorb a lot of hormone so they grow out of control, use up all nutrients and die

Question 52

How is auxin used as rooting powder?

Answer 52

It stimulates cell growth