Plant Structures and their functions

Question 1

Where does photosynthesis take place?

Answer 1

Chloroplast

Question 2

What is the function of the chlorophyll?

Answer 2

Absorbs light

Question 3

What type of reaction is photosynthesis?

Answer 3

Endothermic (takes in energy)

Question 4

What are the three limiting factors in photosynthesis?

Answer 4

Light intensity, the concentration of carbon dioxide and temperature

Question 5

Function of the waxy cuticle

Answer 5

• Top of the leaf

- Thin layer that prevents water loss

Question 6

Function of the upper epidermis

Answer 6

• Top of the leaf

- Transparent and allows light to pass through to the palisade layer

Question 7

Function of the palisade layer

Answer 7

• Packed with palisade leaf cells
• Filled with chloroplast
• Near the top of leaf to get as much light

Question 8

Function of the spongy mesophyll layer

Answer 8

• Middle of the leaf

- Contains air spaces to increase the rate of diffusion of gases in and out of the cell

Question 9

Function of the lower epidermis layer

Answer 9

• Bottom of the leaf

- contains alot of stomata

Question 10

Function of the stomata

Answer 10

• tiny pores on the surface of the leaf

- allows carbon dioxide and oxygen to diffuse directly in and out of the of leaf

Question 11

Function of the guard cells

Answer 11

• The change size to control the size of the stomata

Question 12

Function of the root hair cell

Answer 12

• Take in minerals by active transport and water by osmosis
• Gives the plant a large surface area for absorbing water and minerals from the soil
• Large mitochondria from respiration for active transport

Question 13

Function of the phloem

Answer 13

• Transport food (sugars). This called translocation

Question 14

Adaptations of the phloem

Answer 14

• Made of living cells in a columns with small pores in the end walls
• Move in both directions

Question 15

Function of xylem

Answer 15

• Transport water and minerals. This called transpiration

Question 16

Adaptations of the xylem

Answer 16

• Made of dead cells joined with no cell walls between them
• The walls around are strengthened with lignin
• The move in one direction from roots to leaves

Question 17

How does transpiration work?

Answer 17

• By evaporation and diffusion
• The water lost is drawn up from the rest of the plant through the xylem vessels
• This is known as the transpiration stream

Question 18

Light intensity formula

Answer 18

1/(dxd)

Question 19

Explain light intensity being a limiting factor

Answer 19

• At first light intensity is directly proportional to the rate of photosynthesis until a certain point
• When the line on the graph plateaus light is no longer the limiting factor

Question 20

Explain carbon dioxide being a limiting factor

Answer 20

• As the carbon dioxide increases the rate of photosynthesis also increases until a certain point
• When the line plateaus carbon dioxide is no longer the limiting factor

Question 21

Explain temperature being a limiting factor

Answer 21

• If the temperature is too low the enzymes for photosynthesis will work slower
• If it is too hot the enzymes will denature
• This happens around 45 degrees

Question 22

What are the factors affect transpiration?

Answer 22

• Light intensity
• Temperature
• Air Flow
• Humidity

Question 23

How can you estimate transpiration rate?

Answer 23

Potometer

Question 24

How can you investigate the effect of light intensity on the rate of photosynthesis?

Answer 24

• Add sodium hydrogen carbonate to pondweed in water to make sure the pondweed gets enough carbon dioxide
• Attach gas syringe
• Put light sources at a specific distance
• Leave for a certain amount of time
• Repeat with different distances.

Question 25

What are auxins?

Answer 25

Plant hormones which control growth at the tips of shoots and roots

Question 26

What do the auxins do?

Answer 26

They dissolve in the solutions of the cell. They then diffuse backwards along the shoots and the roots.

Question 27

What does auxins do at the roots?

Answer 27

Inhibit growth

Question 28

What does auxins do at the shoots?

Answer 28

Stimulate growth

Question 29

What is it called when a plant responds to light?

Answer 29

Phototropism

Question 30

What side will the auxins accumulate?

Answer 30

They will either go on the shaded side or the lower side.

Question 31

What are the shoots positively and negatively?

Answer 31

They positively phototropic and negatively gravitropic

Question 32

What does it mean to be positively phototropic?

Answer 32

Grow towards the light

Question 33

What does it mean to be positively gravitropic?

Answer 33

Grow towards the gravity

Question 34

What are the roots positively and negatively?

Answer 34

They are negatively phototropic and negatively gravitropic

Question 35

What causes plants to grow towards the light?

Answer 35

Auxins accumulate on the shaded side. Therefore the cells on the shaded sides grow faster which causes the plant to bend to the light.

Question 36

What causes the roots to curve downwards?

Answer 36

If exposed to light the auxins will accumulate on the lower shaded side and in the roots auxins inhibit growth which them causes the upper side to grow faster

Question 37

What are the 3 uses of auxins?

Answer 37

- To grow plant clones - To grow plant cuttings - To kill weeds

Question 38

How does auxins kill plants?

Answer 38

By adding a lot of auxins it can disrupt the plants growth patterns

Question 39

What are 3 uses of gibberellin?

Answer 39

- Controlling dormancy - Inducing Flowering - Grow larger fruits

Question 40

How does gibberellin control dormancy?

Answer 40

Induces germination at certain times of the year when plants dont have the right conditions to grow

Question 41

How does gibberellin induce flowering?

Answer 41

Flowers need certain conditions to grow but gibberellin allows flowers to grow on demand which can allow farmers to grow bigger and more flowers

Question 42

How does gibberellin help growing larger fruits?

Answer 42

It is useful for seedless fruits that naturally dont grow as seeded fruits. Gibberellin allows the fruits to grow well.

Question 43

What is the used of the hormone ethene for plants?

Answer 43

Stimulate the ripening of fruits by stimulating a hormone.