Photosynthesis

Question 1

.Draw the structure of a chloroplast?

Question 2

What are the photosynthetic pigments?

Answer 2

chlorophyll a, chlorophyll b and carotene

Question 3

What is the role of a photosynthetic pigment?

Answer 3

They absorb the light energy needed for photosynthesis.

Question 4

What is a photosystem?

Answer 4

This is a protein attached to a pigment.

Question 5

What are the two photosystems in the thylakoid membrane? What are the wavelengths they absorb?

Answer 5

1. PSI- 700nm
2. PSII- 680nm

Question 6

What is reduction in terms of electrons, hydrogen and oxygen?

Answer 6

Reduction is the gain of electrons and hydrogen. It is also the loss of oxygen.

Question 7

What is oxidation in terms of electrons, hydrogen and oxygen?

Answer 7

Oxidation is the loss of electrons and hydrogen. It is also the gain of oxygen.

Question 8

What are coenzymes?

Answer 8

Substances that aid the function of an enzyme.

Question 9

What is the coenzyme involved in photosynthesis?

Answer 9

NADP.

Question 10

Where does the light dependent reaction take place?

Answer 10

thylakoid membranes

Question 11

What is an electron transport chain?

Answer 11

A chain of proteins that allows electrons to flow through it.

Question 12

Describe the stages of the light dependent reaction?

Question 13

What does cyclic photophosphorylation stand for?

Answer 13

ATP is only made in the PSI and the electrons from the chlorophyll aren’t passed onto the NADP, but are brought back to the PSI via the electron transport chain.

Question 14

Where does the Calvin cycle take place?

Answer 14

the stroma of the chloroplasts

Question 15

Describe the stages of the light-independent reaction.

Question 16

What are carbohydrates made up of?

Answer 16

Hexose sugars are made up of two TP molecules joined together. Larger carbohydrates are made up of many hexose sugars joined together.

Question 17

What are proteins made up of?

Answer 17

The amino acids are made from GP.

Question 18

What are lipids made up of?

Answer 18

The glycerol is made up of TP. The fatty acids are made up of GP.

Question 19

What are the optimum conditions needed for photosynthesis?

Answer 19

1. High light intensity of a certain wavelength.
2. Temperatures around 25 degrees
3. High carbon dioxide concentration.
4. Constant supply of water.

Question 20

Why do plants need high light intensity at certain wavelengths?

Answer 20

The higher the light intensity the more energy it provides for photosynthesis. It needs to be at certain wavelengths because the photosynthetic pigments only absorb red and blue light.

Question 21

Why do plants need temperatures of around 25 degrees for photosynthesis?

Answer 21

If the temperature becomes too low the enzymes, ATP synthase and rubisco, become inactive. If the temperature is too high the enzymes denature and the stomata close meaning carbon dioxide no longer enters the plant and photosynthesis slows down.

Question 22

Why do plants need high carbon dioxide concentrations for photosynthesis?

Answer 22

The higher the concentration of carbon dioxide the higher the rate of photosynthesis.

Question 23

Why do plants need a constant supply of water?

Answer 23

The higher the amount of water they have the higher the rate of photosynthesis. However, if there is too much the soil becomes waterlogged and that stops the roots from taking up important mineral ions.

Question 24

What are the limiting factors for photosynthesis?

Answer 24

1. Light intensity
2. Temperature
3. Carbon dioxide concentration
4. Water availability