Respiration and Photosynthesis

Question 1

what happens to sugar (glucose) in cellular respiration

Answer 1

oxidised

Question 2

where does respiration occur

Answer 2

mitochondria

Question 3

what are the 2 phases of glycolysis and what do they yield

Answer 3

energy investment phase
- 2 ATP (cleaves 6C sugar)
energy payoff phase
- 4 ATP, 2 Pyruvate, 2 NADH

Question 4

what is substrate level phosphorylation

Answer 4

production of ATP by an enzyme

substrate(+P) + ADP = product + ATP

Question 5

what are the 3 metabolic stages that make up respiration

Answer 5

1 - glycolysis
2 - citric acid cycle
3 - oxidative phosphorylation

Question 6

what do the 3 metabolic stages of respiration each do

Answer 6

1) glycolysis converts glucose -> 2 pyruvate
2) citric acid cycle completes glucose breakdown
3) oxidative phosphorylation uses e- transport chain to drive ATP generation

Question 7

how do the products of glycolysis move into the mitochondrial matrix (link glycolysis to citric acid cycle)

Answer 7

pyruvate -> acetyl CoA

• 2 carbon acetyl fragment removed from pyruvate
• move through transport protein
• added to Coenzyme A
• forms acetyl CoA

Question 8

What is the input and output of the citric acid cycle

Answer 8

input = acetyl CoA
output = 3 NADH, 1 GTP, 1 FADH2
(NADH and FADH2 store high energy electrons released)

Question 9

explain the process of the electron transport chain in respiration

Answer 9

• electrons from NADH, FADH2 lose energy through several steps
• energy drives H+ ions across membrane (matrix -> intermembrane space)
• transmembrane gradient created
• ATP synthase (protein) spins as protons move back down gradient
• turning motion generates ATP

Question 10

draw a summary diagram of the steps of respiration

Question 11

Where does photosynthesis take place

Answer 11

chloroplast

Question 12

what are chlorophyll, and what is their structure

Answer 12

light capturing pigments

head: light absorbed by electrons
tail: hydrophobic, holds chlorophyll in thylakoid membrane

Question 13

what are the 2 stages of photosynthesis

Answer 13

1) light reactions
2) dark reactions (carbon fixation)

Question 14

what are the 3 key components of the light reaction stage of photosynthesis

Answer 14

• pigments (chlorophyll)
• photosystems I & II
• e- transport chain

Question 15

what do photosystems I & II do in photosynthesis (light reactions)

Answer 15

-harvest light energy by antenna complex
- funnel to chlorophyll molecules in reaction centre
- high energy e then from reaction centre to e- transport chain in thylakoid membrane

Question 16

how is the H+ gradient created in e- transport chain in photosynthesis

Answer 16

• photosystem II splits H2O -> H+
• H+ taken up on other side, strengthening gradient

Question 17

Why is carbon fixation required in photosynthesis in chloroplasts

Answer 17

inner membranes of chloroplast impermeable to ATP and NADH, so must convert to sugar to export and provide energy to rest of the cell

Question 18

what is the central reaction in carbon fixation and what enzyme carries this out

Answer 18

inorganic (CO2) -> organic
done by Rubisco (slow)

Question 19

what is the net input and output of carbon fixation

Answer 19

input: 3 CO2
output: 1 G3P

Question 20

What are the 3 ways G3P can be used after being generated in carbon fixation

Answer 20

1) retained -> starch (in times of excess photosynthesis)
2) moved into cytosol and into glycolytic pathway (to be used)
3) exported and converted to other metabolites