Nutrition(plant)

Question 1

Describe how you would test a leaf for starch and include the safety precautions you would take and the results you would expect to see.

Answer 1

Safety precaution - turn off flame

• Boil leaf in ethanol
• Add iodine solution
• leaf turns blue-black

Question 2

Explain what happens in a leaf when it is destarched.

Answer 2

• There is no starch
• All the starch is converted to glucose for respiration

Question 3

Describe how the green pigment in leaf cells is removed safely before testing a leaf for the presence of starch.

Answer 3

• Boil the leaf in ethanol
• Place it in a water bath

Question 4

What does the waxy cuticle do?

Answer 4

To prevent transpiration (loss of water vapor from the leaf)

Question 5

What does the upper epidermis do?

Answer 5

It is transparent to allow light to enter the leaf

Question 6

What does the palisade mesophyll do?

Answer 6

It contains lots of chloroplasts which absorb light in photosynthesis

Question 7

What does the spongy mesophyll contain?

Answer 7

• It contains air spaces to allow gases to diffuse
• contains veins - XYLEM and PHLOEM
• xylem: brings water to the leaves
• phloem: Phloem removes sugar

Question 8

What does the guard cell do?

Answer 8

Guard cells control the opening and closure of the stomata

Question 9

What does the stomata do?

Answer 9

It allows carbon dioxide into the leaf and oxygen out

Question 10

Word and chemical symbol equation for photosynthesis

Answer 10

Carbon dioxide + water —-> glucose + Oxygen

CO2 + H2O —-> C6H12O6 + O2

Question 11

How is the leaf adapted to carrying out photosynthesis?

Answer 11

• The palisade layer is packed with chloroplasts for photosynthesis.
• The leaf has a transparent upper epidermis to let light through to the palisade layer.
• The leaf has a broad shape to increase surface area to catch more light.
• The leaf is thin to allow rapid diffusion for gaseous exchange.
• The leaf has air spaces in the spongy layer to allow for gaseous
  exchange.
• The leaf has lots of stomata to allow for gaseous exchange.
• The leaf has guard cells to control if the stomata or open or closed.
• The waxy cuticle reduces water loss by evaporation.

Question 12

Explain how you would safely test a variegated leaf to show that chlorophyll is needed for photosynthesis.
(6 marks)

Answer 12

• Boil leaf in water
• Turn off the Bunsen burner
• Boil in ethanol
• Rinse
• Test with iodine
• The green part goes blue/black
• The white part stays brown/yellow

Question 13

What is the purpose of Nitrates? and what is the deficiency?

Answer 13

Nitrates: used to make amino acids which is used to make proteins

Deficiency: Stunted growth and yellow leaves

Question 14

What is the purpose of Magnesium? and what is the deficiency?

Answer 14

Magnesium: Used to make chlorophyll for the plant

Deficiency: Yellow leaves

Question 15

What effect does light intensity have on the rate of photosynthesis?

Answer 15

• The higher the light intensity, the faster the rate of photosynthesis – provided that there is lots of carbon dioxide and the temperature is warm enough.
• However, at a certain point it won’t matter
  how much more light you give to the
  plant the rate is at its maximum
  or one of the factors (temp or
  CO2) is in short supply.

Question 16

How does the amount of carbon dioxide affect the rate of photosynthesis?

Answer 16

• The higher the carbon dioxide level, the faster the rate of photosynthesis – again, provided there is plenty of light and a suitable temperature.
• However, at a certain point it won’t matter
  how much more CO2 you give to the
  plant the rate is at its maximum or one of the factors(light intensity or temperature) is in short supply.

Question 17

How does temperature have an effect on the rate of photosynthesis?

Answer 17

• As the temperature rises, the rate of photosynthesis increases – provided there is plenty of carbon dioxide and light. This is because the temperature affects the enzymes controlling photosynthesis.
• However, at a certain point (over 45 degrees Celsius) the higher temperature causes the enzymes to denature and photosynthesis slows down and stops.

Question 18

Suggest one advantage and one disadvantage of using the chicken manure pellets compared to the cow manure.

Answer 18

Advantage: More minerals

Disadvantage: Costly/not free

Question 19

What process do plants use to move these mineral ions into root cells?

Answer 19

Active Transport

Question 20

Describe how water moves from roots to the leaves.

Answer 20

by transpiration and water is pulled with the help of the xylem

Question 21

Describe how the leaf produces glucose.

Answer 21

Plants use light energy from the sun that is trapped during photosynthesis to convert water and carbon dioxide into glucose.

Question 22

The student concluded that the plants growing in the shade had longer leaves. Suggest why the student came to this conclusion.

Answer 22

The higher mean of leaves was longer.

Question 23

Describe how glucose is transported down to the root hair cells.

Answer 23

• Glucose is sucrose in a solution and is transported through the phloem.

Question 24

Explain how changes to the guard cells on a warm day help the plant to survive.

Answer 24

• Stomata closes on a warm day to reduce the water loss by evaporation from the leaf

Question 25

Describe the function of chlorophyll in plant cells.

Answer 25

• Chlorophyll absorbs light energy for the process of photosynthesis.
• Is the green pigment for the leaf

Question 26

Explain why the hydrogen carbonate indicator in the bottle nearest to the light source turned purple.

Answer 26

• Greater light intensity leads to more photosynthesis
• Lower concentration of carbon dioxide causing the solution to become more acidic and the pH to increase.