9.3

Question 1

Define indeterminate growth

Answer 1

Plant growth is generally indeterminate. This means that cells will continue to grow indefinitely. Many plant cells, even fully differentiated types can generate whole new plants containing cells that are totipotent

Question 2

Outline role of mitosis in the growth of stem and leaves while maintaining a meristem.

Answer 2

Cells in the meristems undergo mitosis repeatedly to produce new cells and growth in a plant.

• Root meristems are responsible for growth and extension of the root.
• Shoot meristems creates cells responsible for shoot growth, but also create cells that will develop into flowers and leaves.
• Apical meristems create additional meristems including protoderm (forms epidermis), procambium (forms vascular tissue) and ground meristem (forms pith).
• Leaf primordia forms leaves

Question 3

Meristems

Answer 3

are tissues in a plant consisting of undifferentiated cells capable of indeterminate growth

Question 4

PIN3 proteins

Answer 4

A group of glycoproteins in the plasma membrane of cells in the stem that transport auxin hormone from cell to cell

Question 5

Steps in micropropagation

Answer 5

1. Stock plant with desirable feature identified
2. Tissues from plant (especially from shoot apex) are sterilised, cut into explants
3. Least differentiated tissue is the source tissue (meristems)
4. Explant placed into sterilised growth media with plant hormones
5. Equal portions of auxin and cytokinin in media allows formation of a callus
6. After roots and shoots develop, the cloned plant is transferred to soil

Question 6

What are the 2 parts found in an auxin regulated gene?

Answer 6

• the promoter region

- the gene itself

Question 7

Why is the function of auxin described as a double negative mechanism?

Answer 7

• Auxin inhibits the inhibitor of there genes transcription factor
• 2 inhibitors of a gene is like a double negative & the result switched on the gene

Question 8

Risks of micropropagation

Answer 8

• the cost of lab micropropagation is very high
• tissue culture techniques require trained lab technicians
• genetically identically plants produced in this way will be susceptible to the same disease
• the seedling grown in a lab may not survive in the field

Question 9

Describe the location of meristems & relate it to how plants grow

Answer 9

meristems are produced at the apical meristems.

Question 10

Describe 1 piece of evidence that demonstrates that the transport of auxin is polar

Answer 10

It moves from the shoot tip down the plant.

Question 11

What happens to auxin under dark conditions?

Answer 11

auxin moves evenly down the stem

- it is transported cell to cell by diffusion & transport proteins

Question 12

What causes auxin to ionise?

Answer 12

the pH of the cytoplasm

Question 13

what is a callus?

Answer 13

A callus is mass of undifferentiated parenchymatous cells. When a living plant tissue is placed in an artificial growing medium with other conditions favorable, callus is formed

Question 14

Where does the oxidative phosphorylation occur?

Answer 14

across the inner membrane

Question 15

What is the mode of transport for proteins across ATP synthase?

Answer 15

facilitated transport