Photosynthesis

Question 1

What is an endergonic reaction?

Answer 1

A reaction requiring energy to be driven (eg. photosynthesis)

Question 2

What is an exergonic reaction?

Answer 2

A reaction that gives off energy in the process (eg. cellular resp.)

Question 3

How does ATP release energy?

Answer 3

The third phosphate of ATP is broken away which releases energy, resulting in Adenosine diphosphate plus a separate phosphate.

Question 4

What is the equation for photosynthesis?

Answer 4

Carbon dioxide + water −−−−> glucose + oxygen + water
light

Question 5

What is the chloroplast’s role in photosynthesis?

Answer 5

• Site for photosynthesis
• Rich in enzymes enclosed by the membrane

Question 6

What is the stroma?

Answer 6

The fluid surrounding the grana in the chloroplast

Question 7

What are the grana?

Answer 7

Stacks of membrane-bound discs called thylakoids.

Question 8

What is the light-dependent cycle?

Answer 8

• Occurs within thylakoid membranes
• Chlorophylls absorb red and blue light
• When light is absorbed electrons in the thylakoid become energised
• This energy is used to split water molecules into hydrogen ions (H+) and oxygen (O2)
• This also produces ATP
• H+ and ATP are then used in the independent light stage

Question 9

What is the light-independent cycle (eg. dark phase)?

Answer 9

• Occurs in the stroma
• Carbon dioxide + hydrogen ions + ATP −> glucose

Question 10

What factors affect photosynthesis?

Answer 10

• Light intensity
• CO2 concentration
• Temperature

Question 11

How does light intensity or CO2 affect photosynthesis?

Answer 11

Increase in light intensity or CO2 will increase photosynthesis to a certain point which it plateaus.