Photosynthesis

Question 1

where did photosynthesis originate from

Answer 1

ancestral cyanobacteria

Question 2

What is a pphotoautotroph

Answer 2

• convert light energy to synthesise organic compounds which chemoatorophs require for survival

Question 3

significance of Photoautotrophs

Answer 3

• produce energy for chemoautotrophs
• produce O2

Question 4

where does photosyntheisis occur

Answer 4

• chloroplast

Question 5

What are the two phases of photosynthesis

Answer 5

• 1. Energy transduction = light dependent - convert light energy to chemical energy
     
     2. Carbon assimilation p light independent
• synthesise sugars from CO2 and H2O (glucose)

Question 6

Overall equation of photosynthesis

*what is reduced and oxidised

Answer 6

6Co2 (reduced to glucose) + 12 H2O (oxidised to O2) -> C6H12O6 + 6H2O + 6O2

Question 7

Explain the structure of a chloroplast
label

Answer 7

• granum stack together into thykaloids
• stroma thykaloids join them stroma together
• stroma is the fluid surrounding the thykaloids
• two membrane (outer, intermembrane space, inner membrane)

Question 8

What are plastids

Answer 8

• organelles within plants and algae -> many different types including chloroplasts, chromosplasts (pigment), amyloplasts (store starch)

*contain their own DNA

Question 9

how did plastids originate - what is endosymbiont theory

Answer 9

• cyanobacterium enetered a cell,
  -formed symbiotic relationship
• genes trasnfered from bacterium to cell
• symbiont became organelle in cell

Question 10

what wavelength of light does chlorophyll absorb

Answer 10

650nm (remember green is reflected, not absorbed)

Question 11

Explain Energy Transduction

Answer 11

• chloroplasts capture light energy
• light energy absorbed by chlorophyll
• energy from photons is trapped and trasnferred to a form of high energy state (called photoexcitation)
• H2O is oxidised to O2
• captured e- are then transferred to compounds along ETC to form NADPH
• ATP is produced by ATP synthase enzyme complex forming ADP and Pi
• Products are NADPH and ATP (useable)

Question 12

Where does Energy transduction occur

Answer 12

• thykaloid membrane/in granum

Question 13

Explain Carbon Assimilation

Answer 13

• use NADPH and ATP to fix CO2 into CH2O sugars (glucose)
• enzyme rubisco used to incorporate carbon into organic molecules and produce sugars
• thiis occurs in calvin cycle in stroma of matrix
• products = sugars
• stroma has an enzyme called rubisco that will work with ATP and NADPH to fix carbon compounds into organic molecules and then sugars

Question 14

Where does carbon assimilation occur

Answer 14

stroma

Question 15

compare and contrast photosynthesis and aerobic respiration

Answer 15

similarities:
- use specialised organelles
- use a form of ETC
- Use chemiosmosis and ATP synthase
- generate ATP
Differences:
- reactants Glucose and O2, compared to CO2 and H20
- products CO2 and H20 vs Glucose and O2
- photo = anabolic
- resp = catabolic

Question 16

what are similarities between chloroplast and mitochondria

Answer 16

• ovoid in shape
• double membrane
• site of electron transport chains and ATP synthase

Question 17

what is chemiosmosis

Answer 17

• process where an electrochemical gradient (H+) used to generate ATP (across membranes)

Question 18

compare and contrast electron transport chain of photosynthesis and respiration

Answer 18

Photo: in chloroplast, H+ are pumped from thykaloid membrane to stroma. Final electron acceptor = NADP+ reduced to NADH
Resp: In mito, H+ pumped from matrix to intermemebrane space, final electron acceptor = O2 to H20

• both have similar electron carriers (resp = NAD+ and FAD), (photo = NADP+)

Question 19

is photosynthesis anabolic or catabolic

Answer 19

• anabolic