Topic 6 - Plant Structured And Their Functions

Question 1

What are Auxins?

Answer 1

Auxins are plant hormones that control the rate of growth at the tips of shoots and roots.

Question 2

What does it mean when something is positively phototropic mean?

Answer 2

It will mean towards light when it is exposed to it.

Question 3

Are the shoots of plants negatively or positively phototropic?

Answer 3

Positively

Question 4

What does it mean when something is positively gravitropic?

Answer 4

It will move with gravity

Question 5

Where in the plant is auxin produced?

Answer 5

The tips of plants

Question 6

What does auxin cause plant cells to do?

Answer 6

Take in water, causing them to increase in size.

Question 7

If a plant shoot is being hit with light from one side, where will the auxin move to? Why?

Answer 7

The auxin will move towards the shaded side of the plant. This causes that side of the plant to grow and the plant bend upwards, towards the light.

Question 8

If a shoot is growing sideways, where will the auxin be? Why?

Answer 8

The auxin will move towards the bottom side of the plant. This causes that side of the plant to grow and the plant bend upwards.

Question 9

How are auxins used as weedkillers?

Answer 9

Auxins can be developed to only work on certain types of plants. They totally disrupt the growth pattern of the plant, which kills them.

Question 10

How are plant hormones used to produce seedless fruit?

Answer 10

Fruit normally only grows on flowering plants that have been pollinated by insects. Plant hormones such as gibberellins are applied to unpollinated flowers, the fruit will geow but the seeds won’t.

Question 11

How are plant hormones used to control the ripening of fruits?

Answer 11

The fruit is picked unripe. A ripening hormone, ethene, is added as the fruit is being transported to the supermarket.

Question 12

How are plant hormones used to control seed germination?

Answer 12

Lots of seeds only germinate in certain conditions. Seeds can be treated with gibberellins to make them germinate all at the same time.

Question 13

What is the word equation for photosynthesis?

Answer 13

Carbon dioxide + water –> glucose + oxygen

Question 14

What is the symbol equation for photosynthesis?

Answer 14

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 15

What is transpiration?

Answer 15

When water is taken in by the roots, up through the stem and into the leaves. There it evaporates and diffuses out of the leaf.

Question 16

What are the three factors that affect rate of transpiration?

Answer 16

Light intensity
Temperature
Air flow

Question 17

How does light intensify affect rate of transpiration?

Answer 17

Stomata begin to close as it gets darker, as photosynthesis can’t happen in the dark. When the stomata are closed the water can not diffuse out of the leaf.

Question 18

How does air flow affect the rate of transpiration?

Answer 18

The greater the air flow, the quicker the water vapour around the leaf moves away. This causes there to be a high concentration gradient, causing more water to diffuse out of the leaf.

Question 19

How do stomata open and close?

Answer 19

Stomata are surrounded by guard cells. The guard cells take in water which makes swell up, this causes the stomata to open. The guard cells release the water to decrease in size, causing the stomata to close.

Question 20

How do small leaves or spines help trees in very dry climates?

Answer 20

They reduce the surface area, so there is less stomata and so less places for water to escape.

Question 21

How do curled leaves or hairs help plants in very dry climates?

Answer 21

They reduce air flow close to the leaf, trapping water vapour near the surface of the leaf and reducing diffusion from the leaf to the air.

Question 22

How do stomata in sunken pits help plants in very hot climates?

Answer 22

This makes the stomata lower then the surface of the leaf, which reduces air flow close to the stomata. Trapping water vapour bear the stomata, which reduces diffusion from the leaf to the air.

Question 23

How are the tissues of leaves adapted to gas exchange?

Answer 23

The underside of leaves have lots of stomata, this lets carbon dioxide diffuse directly into the leaf. There are also air spaces behind the stomata, which increase the rate of diffusion into and out of the cell.

Question 24

How are leaves adapted for photosynthesis?

Answer 24

The top layer of the leaf is transparent, so light can pass through it to the chloroplasts.
The top of the leaf has lots of chloroplasts.
The xylem and phloem form a network of vascular bundles, which provide water for the leaf and take away the produced glucose.