Topic 2.9: Photosynthesis

Question 1

Define photosynthesis

Answer 1

Photosynthesis is the process by which cells synthesise organic compounds (e.g. glucose) from inorganic molecules (CO2 and H2O) in the presence of sunlight

Question 2

Define chlorophyll

Answer 2

Chlorophyll is a green pigment found in photosynthetic organisms that is responsible for light absorption

Question 3

Which portion of the em spectrum does chlorophyll absorb the most?

Answer 3

absorbs blue, then red

Question 4

Which portion of the em spectrum does chlorophyll absorb the least?

Answer 4

reflects green

Question 5

Define light dependent reaction

Answer 5

The light dependent reactions convert light energy from the Sun into chemical energy (ATP)

Question 6

Define light independent reaction

Answer 6

The light independent reactions use the chemical energy to synthesise organic compounds (e.g. carbohydrates)

Question 7

What is the first step of the light dependent reaction?

Answer 7

Light is absorbed by chlorophyll, which results in the production of ATP (chemical energy)

Question 8

After Light is absorbed by chlorophyll, which results in the production of ATP (chemical energy) what is the next step of the light dependent reaction?

Answer 8

Light is also absorbed by water, which is split (photolysis) to produce oxygen and hydrogen

Question 9

After Light is also absorbed by water, which is split (photolysis) to produce oxygen and hydrogen what is the last step of the light dependent reaction?

Answer 9

The hydrogen and ATP are used in the light independent reactions, the oxygen is released from stomata as a waste product

Question 10

What is the first step of the light independent reaction?

Answer 10

ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions

Question 11

After ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions what is the next step of the light independent reaction?

Answer 11

The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.)

Question 12

After The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.) what is the last step of the light independent reaction?

Answer 12

The ATP provides the required energy to power these anabolic reactions and fix the carbon molecules together

Question 13

Where do light dependent reactions take place?

Answer 13

in the thylakoids

Question 14

Where do light independent reactions take place?

Answer 14

stroma