B6- Plant Structures and Their Functions

Question 1

Translocation

Answer 1

The movement of food substances (mainly sucrose)

Question 2

Which tissue does translocation take place in a plant?

Answer 2

Phloem tissue

Question 3

Which strengthening tissue is present in the walls of xylem tubes?

Answer 3

Lignin

Question 4

What type of transport vessel is made up of dead cells?

Answer 4

Xylem

Question 5

How are root hair cells adapted for the uptake of water and mineral ions?

Answer 5

Large surface area

Question 6

What is the role of xylem tubes in a plant?

Answer 6

Carry water and mineral ions from the roots to the stem and the leaves

Question 7

How does the structure of phloem allow food substances to move between phloem cells?

Answer 7

Pores in the end walls of phloem cells for the food substances to move through

Question 8

Describe the movement of food substances, via phloem cells, in plants

Answer 8

• food substances move through phloem tubes in both directions
• food substances move from the leaves (where they are made) to the rest of the plant

Question 9

Explain the constant transpiration stream of water through a plant

Answer 9

• evaporation and diffusion of water from the leaves creates a shortage in the plant
• more water is drawn up from the rest of the plant through the xylem vessels to replace it
• more water to be drawn up from the roots

Question 10

Suggest how you could vary the light intensity when investigating the rate of photosynthesis

Answer 10

By varying the distance of the lamp from the algae

Question 11

Explain why you would use a gas syringe when investigating the rate of photosynthesis

Answer 11

To measure the volume of oxygen produced by the algae over a period of time (he can use this to calculate the rate of oxygen production, which corresponds to the rate of photosynthesis

Question 12

How can you control the CO2 concentration when investigating the rate of photosynthesis

Answer 12

By adding a set amount of sodium hydrogencarbonate to a set volume of water in the flask

Question 13

Give one factor that you should control when investigating the rate of photosynthesis

Answer 13

Temperature (as it effects the rate of photosynthesis, so it could effect the results)

Question 14

Give the three environmental factors that can effect the rate of photosynthesis

Answer 14

• light intensity
• temperature
• co2 concentration

Question 15

What type of reaction is photosynthesis?

Answer 15

Endothermic- energy is transferred from the environment to the plant

Question 16

What is biomass?

Answer 16

The mass of living material

Question 17

Word equation for photosynthesis

Answer 17

(light)

carbon dioxide + water —> glucose + oxygen

Question 18

How does the glucose produced in photosynthesis contribute to a plants biomass?

Answer 18

Glucose is used to make larger, complex molecules that are needed for the plants growth. These molecules make up the biomass of the plant

Question 19

Explain why photosynthesis organisms are described as the main producers of food for nearly all life

Answer 19

-energy stored in the biomass of photosynthetic organisms is passed along the food chain as animals eat the photosynthetic organisms. These animals are food for other animals. So most of the life on Earth is supported by photosynthetic organisms

Question 20

Inverse square law:

Answer 20

light intensity ∝ 1/ distance (d)²

Question 21

What controls the opening and closing of the stomata?

Answer 21

Guard cells (they open stomata when turgid and close stomata when flaccid)

Question 22

Factors that can affect the rate of transpiration

Answer 22

• light intensity
• temperature
• air flow

Question 23

Why is the rate of transpiration very low at night time

Answer 23

Photosynthesis can’t happen in the dark, so stomata don’t need to be open to let carbon dioxide inside the leaf. This means stomata begin to close as it gets darker, which reduces the amount of water able to escape from leaves.

Question 24

How might increasing the temperature in the rooms affect the rate of water uptake in the two plants?

Answer 24

-increasing the temperature would increase the rate of transpiration because the water particles would have more energy to evaporate and diffuse out of the stomata

Question 25

Where is the palisade layer found in a leaf?

Answer 25

At the top so it gets plenty of light

Question 26

Where on a leaf are most of the stomata found?

Answer 26

Lower epidermis (the underside of the leaf)

Question 27

How are the epidermal tissues in leaves adapted to reduce water loss?

Answer 27

The epidermal tissues are covered with a waxy cuticle that reduces water loss

Question 28

How are cells in the palisade layer adapted for photosynthesis?

Answer 28

They have lots of chloroplasts so that they can carry out photosynthesis

Question 29

Why is beneficial to the plant that the leaf upper epidermis is transparent?

Answer 29

Transparent means that light can pass through it to the palisade layer therefore the plant is able to photosynthesise

Question 30

Explain why it is important that the leaves are supplied by a network of xylem and phloem tubes

Answer 30

• xylem tubes are needed to provide the leaf with water for photosynthesis
• phloem tubes are needed to transport the glucose produced to other parts of the plant

Question 31

Explain how the structure of a leaf allows gases to diffuse in and out of cells

Answer 31

The lower epidermis is covered in lots of stomata, through which carbon dioxide diffuses into the leaf, and oxygen and water vapour diffuse out. The spongy mesophyll tissue contains air spaces which increases the rate of diffusion of gases into and out of the leaf’ cells

Question 32

Would having more stomata increase or decrease water loss?

Answer 32

Increase, as there are more pores out of which water can evaporate

Question 33

How can the cuticle be adapted to reduce water loss?

Answer 33

-thick and waxy, helping to reduce water loss by evaporation

Question 34

Explain why having sunken stomata is an adaption to dry environments

Answer 34

• makes the stomata lower than the surface area of the leaf
• reduces the air flow close to the stomata, trapping water vapour near the surface and reducing diffusion from the leaf to the air
• plant therefore loses less water in conditions where water is scarce

Question 35

How does having hairs on leaves helps plants survive?

Answer 35

• hairs on the surface reduce air flow close to the leaves
• traps water vapour near the surface reducing diffusion from leaves to the air
• prevents water loss helping the plant to survive in desert conditions

Question 36

In the Arctic tundra, wind speeds are high and conditions are dry would you expect plants growing in the Arctic tundra to have small or large leaves? Why?

Answer 36

• small leaves
• dry and strong air flow caused by high winds mean that it is likely water loss is a problem for plants in the Arctic tundra. Therefore they are more likely to have small leaves as this reduces the surface area for water loss

Question 37

What is phototropism?

Answer 37

The growth of a plant in response to light

Question 38

What does the hormone auxin control?

Answer 38

Growth at the tips of shoots and roots of plants

Question 39

Which plant hormone is used in rooting powder to grow plant cuttings?

Answer 39

Auxin

Question 40

Why might someone want to control seed germination?

Answer 40

• to make seeds germinate at times of the year they wouldn’t normally
• to make sure all the seeds in a batch germinate at the same time

Question 41

Give two things that adding gibberellin might stimulate in a plant

Answer 41

• stimulate stem growth

- stimulate flowering

Question 42

Explain how a farmer could use a plant hormone to moll weeds in her crop fields without killing her crops

Answer 42

• use an auxin to kill weeds in her crop fields
• selective weed killers can be used which only affect the broad-lived plants (weeds)
• they disrupt the weeds normal growth pattern causing the weeds to die

Question 43

How can plant hormones be used to produce seedless fruit?

Answer 43

Plant hormones such as gibberellins can be applied to unpollinated flowers of some types of plant. This will make the fruit grow but because the flower hasn’t been pollinated the seeds won’t grow.

Question 44

How can you use plant hormones to grow ripe and large fruit and veg?

Answer 44

• ethene to speed up the ripening
• gibberellins to reduce flower formation, which would cause the plants to produce less fruit/veg allowing the fruit/veg to grow larger