photosynthesis year 2

Question 1

What is photosynthesis?

Answer 1

The production of organic compounds, such as carbohydrates and lipids, from the inorganic compounds carbon dioxide and water, using light energy.

Question 2

Photosynthesis equation

Answer 2

6CO2 + 6H20 —light energy, chlorophyll—– C6H12O6 + 6O2

Question 3

What are the conditions required for photosynthesis?

Answer 3

• carbon dioxide
• water
• light
• chlorophyll
• optimum temp for enzymes

Question 4

What is ATP made up of?

Answer 4

Adenine (a base)
Ribose (a pentose sugar)
3 phosphate groups

Question 5

What does ATP do?

Answer 5

provides small packages of energy quickly in a single step reaction.

Question 6

What enzyme is needed in the hydrolysis of ATP to ADP + P?

Answer 6

ATP hydrolase

Question 7

What enzyme is needed in the condensation reaction of ADP + P

Answer 7

ATP synthase

Question 8

Give 4 features of ATP

Answer 8

• releases small packets of energy when its hydrolyses
• hydrolyses quickly in a single step reaction
• re synthesised quickly
• makes other molecules more reactive by transferring one of its phosphate groups

Question 9

Function of the thylakoid

Answer 9

membranes contain chlorophyll pigments that absorb light, where the light dependent reaction takes place

Question 10

Function of granum(stack of thylakoids)

Answer 10

More membranes present so rate of photosynthesis is greater

Question 11

Function of stroma

Answer 11

fluid containing enzymes for the light reactions

Question 12

Function of the double membrane surrounding the chloroplast

Answer 12

two phospholipid bilayers- one o2 diffuses out of, the other CO2 diffuses into the chloroplast along their conc gradients

Question 13

What happens in the ribosomes?

Answer 13

enzyme synthesis takes place

Question 14

What 2 parts can photosynthesis be divided up into?

Answer 14

1. ) Light dependent reaction occurs in the thylakoid/ grana of the chloroplast
2. ) light independent reaction occurs in the stroma of the chloroplast

Question 15

Where does light dependent reactions occur?

Answer 15

thylakoid membranes

Question 16

what term describes- ‘The formation of ATP using energy from light’?

Answer 16

chemiosmosis

Question 17

What term describes- ‘the emission of an electron from a molecule due to the absorption of light’

Answer 17

photoionization

Question 18

What is photolysis?

Answer 18

The splitting of water in the presence of light

Question 19

What are limiting factors of photosynthesis?

Answer 19

light intensity, temp, co2 conc

Question 20

Explain the trend of light being a limiting factor of photosynthesis

Answer 20

As light intensity (LI) increases, rate of photosynthesis increases as light is the limiting factor;
As LI increases further, rate of photosynthesis stays constant as another factor is now the limiting factor.

Question 21

Why is light a limiting factor of photosynthesis?

Answer 21

Light excites electrons in chlorophyll, causing photoionisation;
Electrons move through the ETC, releasing energy for the pumping of protons into the thylakoid space;
These diffuse back through ATP synthase, causing photophosphorylation.

Question 22

Explain the trend of co2 being a limiting factor of photosynthesis

Answer 22

As CO2 increases, rate of photosynthesis increases as CO2 is the limiting factor;
As CO2 increases further, rate of photosynthesis stays constant as another factor is now the limiting factor.

Question 23

Explain the trend of temperature being a limiting factor of photosynthesis

Answer 23

As temperature increases, rate of photosynthesis increases until the optimum temperature; molecules gain kinetic energy so E-S complexes form more quickly.
Beyond this temperature, rate of photosynthesis decreases, as enzyme denaturation takes place so fewer E-S complexes form.

Question 24

Why should more CO2 increase growth rate?

Answer 24

More CO2 leads to more GP and more TP thus more glucose;

More glucose means rate of respiration is higher so more ATP for cell division and protein synthesis.

Question 25

Why should more light increase growth rate?

Answer 25

More light means more LDRs take place;
So more ATP and reduced NADP for reduction of more GP to form more TP, therefore more glucose is produced;
More glucose means rate of respiration is higher so more ATP for cell division and protein synthesis.

Question 26

Why should higher temperature increase growth rate?

Answer 26

Higher temperature means LIRs happen faster;
So GP reduced to TP faster, so glucose produced faster;
More glucose means rate of respiration is higher so more ATP for cell division and protein synthesis.