Topic 6 - Plants

Question 1

What is the equation for photosynthesis?

Answer 1

Carbon dioxide + water —> glucose + oxygen

Question 2

What does photosynthesis require?

Answer 2

Sunlight

Question 3

Where does photosynthesis occur?

Answer 3

Chloroplasts

Question 4

What is glucose used for?

Answer 4

1) Stored as starch
2) Used for respiration
3) Converted into cellulose
4) Used to make protein

Question 5

What are photosynthetic organisms the main producers of?

Answer 5

Food and therefore biomass.

Question 6

What type of reaction is photosynthesis?

Answer 6

Endothermic
Requires energy for it to occur.

Question 7

What are limiting factors?
Definition

Answer 7

When a process depends on 2 or more factors, the rate of that process is limited by the factor which is in shortest supply.

Question 8

What limiting factors is photosynthesis affected by?

Answer 8

• Light intensity
• Temperature
• Availability of carbon dioxide
• Availability of chlorophyll
• Availability of water

Question 9

What are the interactions of limiting factors in limiting the rate of photosynthesis?

Answer 9

As a factor increases so will the rate of photosynthesis until it has no effect as the rate of photosynthesis is limited by availability of another factor.

Question 10

What is the distance from the lamp and light intensity known as?

Answer 10

They are inversely proportional to each other - this means as the distance increases, the light intensity decreases.

Question 11

What is the inverse square law?
Definition

Answer 11

Light intensity decreases in proportion to the square of the distance.

Question 12

What is the equation for inverse square law?

Answer 12

1/ distance squared
If you halve the distance, the light intensity will be 4 times greater. If you double the distance the light intensity will be 4 times smaller.

Question 13

What is the role of the root hair cell?

Answer 13

To absorb water and mineral ions.
Mineral ions are absorbed by active transport. Water is absorbed by osmosis.

Question 14

What are features of root hair cells?

Answer 14

• Long projections that increases the surface area that the plant can use to absorb water an minerals.
• No chloroplasts because they are located underground.

Question 15

What is transpiration?

Answer 15

The movement of water and mineral ions into the root, up the stem through the xylem vessels and evaporating out of the leaf. This is done by capillary action

Question 16

What is the function of the stomata?

Answer 16

Controls water lost by transpiration
Controls gas exchange in the leaf

Question 17

What is the structure of the stomata?

Answer 17

Surrounded by 2 guard cells. They control the opening and closing by filling with or loosing water.
Most stomata are underneath the leaf to limit evaporation.

Question 18

What does the phloem transport and what’s the method called?

Answer 18

Sucrose
Translocation = Sugars distributed to all cells in the body of the plant.

Question 19

What is the structure of the phloem?

Answer 19

Living
Not hollow
Sieve cells
Transports in both directions
Transports by active transport
Companion cells - filled with mitochondria to pump out sucrose.

Question 20

What does the xylem transport?

Answer 20

Water and minerals

Question 21

What is the structure of the xylem?

Answer 21

Dead
Hollow
Only one direction
Cell walls are strengthened with lignin
No end cells (continuous column)
Transports by osmosis
From roots to leaves
Moves the water by capillary action

Question 22

Why is transpiration important?

Answer 22

Cools the plant
Pumping water and minerals to the leaves for photosynthesis.

Question 23

What kind of factors will affect transpiration?

Answer 23

Any factor that reduces the number of water molecules outside the stomata to increase the gradient will affect the rate of transpiration.

Question 24

What are the 4 factors affecting rate of transpiration?

Answer 24

1) Light - increase
2) Temperature - increase
3) Humidity - decrease
4) Wind - increase

Question 25

How does light affect the rate of transpiration?

Answer 25

In bright light transpiration increases.
This is because the stomata is open wider to allow CO2 into the leaf for photosynthesis.

Question 26

How does temperature affect the rate of transpiration?

Answer 26

Transpiration is faster in higher temperatures.
Evaporation and diffusion take place at a faster rate because the molecules have more energy.

Question 27

How does humidity affect the rate of transpiration?

Answer 27

Transpiration is slower in humid conditions.
Diffusion slows down due to a lower concentration gradient. High humidity = air saturated with water.

Question 28

How does wind affect the rate of transpiration?

Answer 28

Transpiration is faster in windy conditions.
Water vapour is removed quickly by air movement, speeding up diffusion and increasing the concentration gradient.

Question 29

What is the equation for rate of transpiration?

Answer 29

Total distance moved / total time

Question 30

What is a potomoter used for?

Answer 30

A device used for measuring the rate of water uptake which is equal to the water lost through transpiration.