L.9 Photosynthesis I

Question 1

LO

Answer 1

• Differentiate between anabolism and catabolism, and oxidation and reduction
• Explain how ATP can power cellular processes
• Describe, in overview, the conversion of radiant energy into chemical energy
• Explain the overall organisation of the light reactions in photosystems I and II
• Describe ATP synthesis during photosynthesis

Question 2

Anabolism Vs Catabolism

Metabolism

Answer 2

Anabolism:
- Building, requires energy

Catabolism:
- Destroying, Releases energy

(AB, CD)

Question 3

Reduction Vs Oxidation

Metabolism

Answer 3

Reduction = gain e-
Oxidation = lose e-

OIL RIG

Question 4

Electron carriers

Answer 4

NAD+, accepts e- = NADH
FAD, acceps e- = FADH2
NADP+, accepts e- = NADPH

Question 5

2 Main ways organisms acquire energy

Answer 5

Heterotrophy:
1. Eat food
2. Undergo cellular respiration
3. Energy produced

Autotrophy:
1. Sun, CO2, H2O
2. Photosynthesis (light rctn. & calvin cycle)
3. Sugars created
4. Undergo cellular respiration
5. Energy produced

Question 6

Stage 1 of photosynthesis

Answer 6

Light Reactions:
- Light dependant
- Trap sunlight and convert into chemical energy

Question 7

Stage 2 of photosynthesis

Answer 7

Calvin Cycle:
- Light independant
- Convert CO2 into sugars using the chemical energy from stage 1 products.

Question 8

Chlorophylls

Answer 8

• The molecules that capsure the energy from sunlight
• Are inside the chloroplasts
• Work together in an antenna complex

Question 9

Antenna complex of chloroplast

Answer 9

• Made up of chlorophyll pigment molecules
• Capsures energy and passes it to the reaction centre through resonance energy transfer of each chlorophyll.

[heft]

Question 10

Light Reaction process (non-cyclic phosphorylation)

Answer 10

• uses sunlight to make ATP & NADPH
  Photosystem 2:
  1. Chlorophyll receives energy from the sun to split H2O, and increases in Redox potential
  2. Splitting the H2O releases e-, the e- is at excited state. O2 is waste product.
  3. e- moves down the transport chain, pumping H+ ions from the stoma into the lumen of the thylakoid
  4. H+ is used to synthesise ATP
  Photosystem 1:
  5. e- reaches the reaction centre and receives more energy, creating a higher redox potential.
  6. The very excited e- is then used to convert NADP+ into NADPH.
  7. NADPH can then be used to reduce molecules.

Question 11

ATP Synthesis

Answer 11

• H+ ions diffuse through ATP synthase from a high to low gradient, for every H+ ion diffused, energy is used to convert ADP +Pi into ATP.
• Occurs in the mitochondria

Question 12

Explain how ATP can power cellular processes

Answer 12

• Hydrolysis of ATP releases energy for other molecular processes such as anabolism.