Photosynthesis

Question 1

What is photosynthesis?

Answer 1

Photosynthesis is the process by which leaves absorb light and carbon dioxide to produce carbohydrate (food) for plants to grow.

Question 2

What is the equation for photosynthesis?

Answer 2

light

carbon dioxide + water —–> glucose + oxygen

Question 3

Why are plants green?

Answer 3

Plants are green because of the green pigments chlorophyll inside the chloroplasts in their cells.

Question 4

Why do leaves have a large surface area?

Answer 4

Leaves have a large surface area to absorb more light.

Question 5

Why are leaves thin?

Answer 5

Leaves are thin so there is a short distance for carbon dioxide to diffuse into leaf cells.

Question 6

Why do leaves have chlorophyll?

Answer 6

Leaves have chlorophyll to absorb sunlight to transfer energy into chemicals.

Question 7

Why is there a network of veins?

Answer 7

To support the leaf and transport water and carbohydrates.

Question 8

Why do leaves have stomata?

Answer 8

Leaves have stomata to allow carbon dioxide to diffuse into the leaf.

Question 9

Why in leaves is the epidermis is thin and transparent?

Answer 9

To allow more light to reach the palisade cells.

Question 10

Why in leaves is the thin cuticle made of wax?

Answer 10

To protect the leaf without blocking out light.

Question 11

Why in leaves is the palisade cell layer at top of leaf?

Answer 11

To absorb more light.

Question 12

Why is there a spongy layer in leaves?

Answer 12

Air spaces allow carbon dioxide to diffuse through the leaf, and increase the surface area.

Question 13

Why in leaves do palisade cells contain many chloroplasts?

Answer 13

To absorb all the available light.

Question 14

What are the possible factors that can affect photosynthesis?

Answer 14

• Temperature
• Light intensity
• Carbon dioxide
• Water

Question 15

What can farmers do to maximize growth?

Answer 15

Farmers can use their knowledge of these limiting factors to increase crop growth in greenhouses. They may use artificial light so that photosynthesis can continue beyond daylight hours, or in a higher-than-normal light intensity. The use of paraffin lamps inside a greenhouse increases the rate of photosynthesis because the burning paraffin produces carbon dioxide, and heat too.

Question 16

What is transpiration?

Answer 16

Water evaporates from the stomata in a process called transpiration.

Question 17

What happens to the rate of photosynthesis with a higher temperature used?

Answer 17

The higher the temperature, the faster the rate of photosynthesis and the faster the production of materials that enable plants to grow.

Question 18

What happens if the temperature continues to increase beyond an optimum?

Answer 18

If the temperature continues to increase beyond an optimum, photosynthesis slows down because the enzymes controlling the different reactions of photosynthesis have become denatured.

Question 19

What is xylem tissue?

Answer 19

Xylem tissue consists of columns of hollow, dead cells. It carries water and dissolved mineral salts from the roots, through the stem and out into every leaf and flower.

Question 20

What is phloem tissue?

Answer 20

Phloem tissue runs by the side of the xylem. Its tube-like cells carry dissolved glucose and other substances to all parts of the plant.

Question 21

What is the transpiration stream/

Answer 21

As more water is lost from the leaves, more is drawn up through the xylem tissue from the roots, which absorbs more water from the soil. This continuous movement of water is called the transpiration stream.

Question 22

What is osmosis?

Answer 22

Osmosis is the movement of water from high water concentration to a lower one across a partially permeable membrane.

Question 23

How do cells become flaccid (limp)?

Answer 23

Cells left in a concentrated salt or sugar solution will lose water by osmosis and become flaccid.

Question 24

What are root hair cells?

Answer 24

Root hair cells are fine, hair-like extensions of a root.

Question 25

What happens when water absorbs through a plant’s root system?

Answer 25

Water flows into root hair cells by osmosis. Their large surface area is an adaptation that enables plants to maximise their absorption of water from the soil.

Question 26

How do root hairs take up mineral salts in solution?

Answer 26

The solutions are much more concentrated in the cells of root tissue than in the soil. Therefore, mineral salts cannot pass into the roots by diffusion. Active transport is used, which requires energy from aerobic respiration.

Question 27

What is the job of the stomata?

Answer 27

The stomata allow carbon dioxide into the leaf.

Question 28

What is the job of the wax cuticle?

Answer 28

Prevent water loss.