Nutrition and Transport in flowering plants

Question 1

What are the 3 functions of the upper epidermis?

Answer 1

Reduces evaporation of water from the leaves, prevents entry of disease causing microbes, allows light to penetrate into the inner layers

Question 2

What is the purpose of having numerous chloroplasts in the palisade mesophyll cells?

Answer 2

So that photosynthesis can mainly take place in this region

Question 3

What is the function of the intercellular air spaces in the spongy mesophyll cells?

Answer 3

Air spaces allow rapid diffusion of carbon dioxide and oxygen in and out of the cell

Question 4

What does the spongy mesophyll contain?

Answer 4

vascular bundle

Question 5

What do the guard cells that surround the stomata in the lower epidermis do?

Answer 5

It regulates the opening and closing of stomata for diffusion of carbon dioxide and oxygen in and out of the cell

Question 6

Why do stomates close on extremely hot days?

Answer 6

To reduce the amount of water vapour escaping the leaf

Question 7

Describe the xylem vessels

Answer 7

long, continuous and hollow tubes made of many dead cells

Question 8

What does lignified walls do?

Answer 8

provide mechanical support to the plant to prevent the xylem from collapsing

Question 9

What do xylem vessels transport?

Answer 9

water and dissolved mineral salts

Question 10

What does the phloem consist of?

Answer 10

sieve tubes and companion cells

Question 11

What are sieve tubes made up of?

Answer 11

living cells called sieve tube cells

Question 12

What is the characteristic of sieve tube cell?

Answer 12

elongated cell with a thin film of cytoplasm

Question 13

Why does the sieve tube not transport glucose?

Answer 13

Glucose lowers the water potential of the cell thus the sieve tube transports manufactured food like sucrose

Question 14

What does the companion cell do?

Answer 14

keep the sieve tube cell alive

Question 15

What is the characteristic of a companion cell? What does it contain? ( numerous )

Answer 15

narrow, thin walled cells that contain numerous mitochondria

Question 16

How does the companion cell support the sieve tube cell?

Answer 16

The companion cell carry out essential metabolic processes and provide nutrients for sieve tube cells

Question 17

What does the mitochondria in the companion cells do?

Answer 17

provide energy to transport the manufactured food from the mesophyll cells into the sieve tubes by active transport

Question 18

What is the vascular bundle made up of?

Answer 18

xylem, phloem and cambium

Question 19

Define photosynthesis

Answer 19

photosynthesis is the process by which green plants take in carbon dioxide and water in the presence of light to manufacture glucose.

Question 20

Write the equation for photosynthesis

Answer 20

carbon dioxide + water -( light and chlorophyll )—> glucose + oxygen

Question 21

Chemical equation for photosynthesis

Answer 21

6CO2 + 6H2O —> C6H12O6 + 6O2

Question 22

what are the three limiting factors of photosynthesis?

Answer 22

light intensity, temperature, carbon dioxide concentration

Question 23

Define limiting factor

Answer 23

A limiting factor is any factor that directly affects the rate of a chemical equation, when the quantity of the limiting factor is changed.

Question 24

What happen when light intensity is the limiting factor?

Answer 24

The rate of photosynthesis increases as more light is supplied to the plant and the amount of energy for photosynthesis increases.

Question 25

When is temperature no longer a limiting factor?

Answer 25

When it reaches the optimum temperature

Question 26

Why is glucose used immediately in the leaves

Answer 26

for cellular respiration to release energy for cellular activities and form cellulose cell walls

Question 27

State the conversion between glucose and starch

Answer 27

In daylight, excess glucose is converted to starch for storage. In darkness, starch is converted back to glucose

Question 28

What is translocation?

Answer 28

Translocation is the transport of manufactured food such as sugars and amino acids, in plants

Question 29

What are the studies that provide evidence of the transport of manufactured food substances in the phloem tissue of a plant?

Answer 29

ringing experiment, use of aphids in translocation studies and the use of isotopes in translocation studies

Question 30

What is the suction force that pulls water up the xylem?

Answer 30

transpiration pull

Question 31

Define transpiration

Answer 31

transpiration is the loss of water vapour from the aerial parts of a plant, mainly through the stomata of the leaves.

Question 32

What affects the rate of transpiration?

Answer 32

wind or air movement, temperature, light intensity, humidity of air

Question 33

experiment to investigate factors affecting the rate of transpiration

Answer 33

using a balance, using a potometer

Question 34

What happens to the rate of transpiration when the temperature of the surrounding air increases

Answer 34

Transpiration will take place more rapidly when the surrounding temperature is high as water from the leaves will evaporate more readily at higher temperatures.