Topic 6 - Plant Structures And Their Functions

Question 1

What is the equation for photosynthesis?

Answer 1

Carbon dioxide + water –> glucose + oxygen

6CO2 + 6H2O –> C6H12O6 + 6O2

Question 2

Is photosynthesis an endothermic or exothermic reaction?

Answer 2

Endothermic - energy is taken in during the reaction

Question 3

Where does photosynthesis take place?

Answer 3

The chloroplasts

Question 4

What does chlorophyll do?

Answer 4

It absorbs light

Energy is taken transferred to the chloroplasts by light

Question 5

What are the three factors that affect photosynthesis?

Answer 5

Light intensity, the concentration of CO2 and the temperature

Question 6

What is a limiting factor in photosynthesis?

Answer 6

Something that is stopping photosynthesis from happening any faster

Question 7

What does not having enough light have to do with the rate of photosynthesis?

Answer 7

Not having enough light slows down the rate of photosynthesis

Question 8

What does not having enough carbon dioxide have to do with the rate of photosynthesis?

Answer 8

Too little carbon dioxide slows down the rate of photosynthesis

Question 9

How does temperature affect the rate of photosynthesis?

Answer 9

The temperature has to be around the optimum temperature for photosynthesis to happen quickly

The enzymes cannot work best if the outside temperature exceeds their optimum temperature

If this happens, the enzymes will denature and photosynthesis cannot take place

Question 10

What is the purpose of root hair cells?

Answer 10

To take in minerals and water

Question 11

What do phloem tubes transport?

Answer 11

Transport food - mainly sucrose - around the plant

Question 12

Give an adaptation of root hair cells

Answer 12

They have microscopic hairs on the surface of the plant roots which stick out into the soil

This gives the roots a larger surface area, and the plant is therefore more able to absorb minerals and water quicker

Question 13

How are minerals absorbed in root hair cells?

Answer 13

Active transport

Question 14

How is water absorbed in root hair cells?

Answer 14

Osmosis

Question 15

Give an adaptation of phloem tubes

Answer 15

They are made of elongated living cells with small pores to allow substances to flow through easily

Question 16

What is the purpose of xylem tubes?

Answer 16

They take water up the plant

Question 17

What is transpiration?

Answer 17

The loss of water from a plant

Question 18

What is transpiration caused by?

Answer 18

Evaporation and diffusion

Question 19

How does transpiration allow more water to be drawn up through the roots?

Answer 19

The loss of water creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through xylem vessels in order to replace it

This in turn means that more waterside drawn up from the roots and so there’s a constant transpiration stream of water through the plant

Question 20

How do you calculate light intensity?

Answer 20

1 (divided by) distance (d)^2

Question 21

What are stomata used for?

Answer 21

Gas exchange

Question 22

What are stomata? What gases diffuse out of them?

Answer 22

Tiny pores on the surface of a plant. They are mostly found on the lower surface of leaves.
Carbon dioxide and oxygen diffuse directly out of the leaf through the stomata, as well as water vapour during transpiration

Question 23

What surrounds stomata to open and close them?

Answer 23

Guard cells

Question 24

What three environmental factors affect the transpiration rate?

Answer 24

• Light intensity
• Temperature
• Air Flow

Question 25

How does light intensity affect transpiration?

Answer 25

Brighter the light, the greater the transpiration rate. Stomata close as it gets darker. Photosynthesis can't happen in the dark, and therefore they don't need to let CO2 out.

Question 26

How does temperature affect the transpiration rate?

Answer 26

The warmer it is, the faster transpiration happens. When it's warm the water particles have more energy to evaporate and diffuse out of the stomata

Question 27

How do you estimate the transpiration rate?

Answer 27

Using a potometer. It measures water intake in the plant, but it is assumed that water uptake is directly related to water loss from the leaves

Question 28

What are leaves adapted for?

Answer 28

Photosynthesis and gas exchange

Question 29

Leaves are broad. Why is this a good adaptation?

Answer 29

Because it means they have a larger surface area exposed to the light, making photosynthesis happen faster

Question 30

How is the palisade layer adapted for photosynthesis?

Answer 30

It is very close to the surface and they have lots of chloroplasts, so they can get the most light

Question 31

How is the upper epidermis adapted for photosynthesis?

Answer 31

it is a transparent layer so that light can pass through easier

Question 32

How has the waxy cuticle adapted?

Answer 32

it is a waxy layer which helps reduce water loss

Question 33

Why are air spaces good in photosynthesis?

Answer 33

it gives a larger surface area for gas exchange and diffusion

Question 34

Give 3 adaptations of plants living in warm climates

Answer 34

Small leaves - reduces surface area for water loss Curled leaves - reduces air flow which traps water vapour near the surface Thick waxy cuticles - reduces water loss Thick stem - stores water Fewer stomata which only open at night - reduce water loss by evaporation

Question 35

Name 3 plant hormones

Answer 35

Auxins Gibberellins Ethene gas

Question 36

What do auxins do?

Answer 36

Plant hormone that controls growth at the tip of shoots and roots. They move through the plant in a solution They change the direction of shoot and root growth

Question 37

What is positive and negative phototropism?

Answer 37

Where a shoot or root either grows towards or away from the light Positive - grows towards the light Negative - grows away from the light

Question 38

What is positive and negative geotropism?

Answer 38

Where a shoot or root either grows towards or away from gravity Positive - grows towards gravity Negative - grows away from gravity

Question 39

What are roots - phototropic / geotropic?

Answer 39

Positively geotropic | Negatively phototropic

Question 40

What are shoots - phototropic / geotropic?

Answer 40

Positively phototropic | Negatively geotropic

Question 41

How do auxins cause shoots and roots to move?

Answer 41

Auxins accumulate on the shaded side of the shoot or root, which makes the cell elongate faster on the shaded side so it bends towards the light

Question 42

What plant hormone is in selective weed killers?

Answer 42

Auxins

Question 43

What plant hormone is in rooting powder?

Answer 43

Auxins

Question 44

What plant hormone is in the control of fruit and flower formation?

Answer 44

Gibberelins

Question 45

What plant hormone is used in producing seedless fruits

Answer 45

Gibberellins

Question 46

What plant hormone is involved in the ripening of fruits?

Answer 46

Ethene gas

Question 47

What plant hormone is in controlling seed germination?

Answer 47

Gibberellins