Photosynthesis

Question 1

What is the distribution of photosynthesis globally?

Answer 1

50% in oceans and 50% on land

Question 2

What was the great oxygenation even which occurred 200 billion years ago?

Answer 2

involved the evolution of cyanobacteria which produces O2 via photosynthesis

Question 3

Whats the difference between heterotrophs and autotrophs?

Answer 3

heterotrophs can’t produce their own food, can only consume whereas autotrophs cant produce their own food and consume

Question 4

Name some components of cyanobacteria

Answer 4

• thylakoid membrane
• rubisco as a carbon fixer
• membrane and DNA

Question 5

What is endosymbiosis?

Answer 5

when originally living bacteria engulfed by a new cell in a phagosome

Question 6

What is the result of endosymbiosis?

Answer 6

• chloroplasts as the outer and inner membrane form a double membrane

Question 7

What are photons?

Answer 7

small packages of energy

Question 8

what is the equation for photon energy?

Answer 8

E= hc/y

Question 9

What are pigments?

Answer 9

molecules that can absorb photons e.g chlorophyll

Question 10

What is the role of photosystem 1?

Answer 10

it harnesses light to obtain and excite electrons from water

Question 11

What is the chloroplast electron transport chain also known as?

Answer 11

non cyclic phosphorylation

Question 12

What occurs during phosphorylation?

Answer 12

• split water using light (hydrolysis)
• creates an excited electron
• produces NADPH

Question 13

What are the 2 different ways in which organisms harness energy?

Answer 13

• no cyclic route; protons pumped, NADPH

- cyclic route; more protons pumped

Question 14

Name the 3 stages of light independent reactions?

Answer 14

• fixation
• reduction
• regeneration

Question 15

role of teh stomata?

Answer 15

gas exchange

Question 16

what is the problem that stomata causes for plants?

Answer 16

need to be open to take in CO2 and to remove O2

need to be closed to preserve H2O

Question 17

What is the c4 pathway?

Answer 17

It is the first step in extracting carbon from carbon dioxide to be able to use it in sugar and other biomolecules

Question 18

What is the c4 molecule?

Answer 18

the 4 carbon molecule which is the first product of this type of fixation

Question 19

What is photorespiration like as a pathway?

Answer 19

it is a wasteful pathway that occurs when the calvin cycle enzyme rubisco acts on oxygen rather than CO2

Question 20

What does CAM stand for when referring to a type of plant?

Answer 20

Crassulacean Acid metabolism

Question 21

When does photorespiration occur?

Answer 21

when plants close their stomata (leaf pores) to reduce water loss.

Question 22

Why are C4 and CAM pathways more beneficial than photorespiration?

Answer 22

they work by ensuring RUBISCO always encounters high concentrations of CO2, making it unlikely to bind to O2

Question 23

How did the C4 and CAM pathways evolve?

Answer 23

natural selection

Question 24

What are C4 plants?

Answer 24

plants in which light dependent reactions and calvin cycle are physically separated

Question 25

Where does LDR occur in C4 plants?

Answer 25

mesophyll cells

Question 26

Where does teh Calvin cycle occur in C4 plants?

Answer 26

in bundle-sheath cells

Question 27

How do CAM plants separate LDR and CC?

Answer 27

between day and night

Question 28

What occurs at night in CAM plants?

Answer 28

open stomata, allowing CO2 to diffuse into leaves, fixing CO2 by PEPC and then converted to malate

Question 29

How do CAM plant photosynthesize in the daytime?

Answer 29

organic acids are transported out of the vacuole and broken down to release CO2 which enters the calvin cycle

Question 30

Name 3 ways in which you can measure photosynthesis?

Answer 30

• measure co2 consumption
• measure increase in mass
• measure O2 production

Question 31

What do photosynthetic rates depend on? (3)

Answer 31

light, temperature and CO2 levels

Question 32

Name the 3 ways in which chloroplasts recharge ATP?

Answer 32

• electron transfer chain
• electrochemical gradient
• ATP synthase