Photosynthesis

Question 1

Photosynthesis Equation

Answer 1

6CO2+ 6H2O –> C6H12O6 + 6O2

Question 2

Carbon fixation

Answer 2

conversion of inorganic carbon to organic carbon
no light required
occurs in stroma of chloroplasts

Question 2

Photolysis

Answer 2

Water is split by light
2H2O + photons –> 4H+ +O2 +4e-
Apart of light dependent reactions- role of generating ATP from e- when H2O is split

Question 3

Paper Chromatography

Answer 3

technique used to separate mixtures of substances based on the movement of different substances on a piece of paper by capillary action

retention factor= distance travelled by sample/ distance travelled by solvent

Question 4

Action Spectrum

Answer 4

Used to determine which wavelengths are most efficient for photosynthesis

Highest rates of photosynthesis: blue and red wavelengths

Lowest rates of photosynthesis: green wavelengths

Question 4

Absorption of light by photosynthetic pigments

Answer 4

Energy from radiation at wavelengths drive photosynthesis- photons of light with the energy it carries excites the e- in chlorophyll to power light-dependent reactions

Question 5

Limiting factors to the rate of photosynthesis

Answer 5

Light intensity, Co2 concentration and temperature

Question 6

Photosystems

Answer 6

Array of pigments within protein complexes

Question 7

Advantages of many pigment molecules in a photosystem

Answer 7

Allows for absorption of a wider range of wave lengths

Allows for enough light energy to be absorbed to photoactivate central chlorophyll molecule

Question 8

Chemiosmosis

Answer 8

Light-dependent stage of photosynthesis –> produce ATP by chemiosmosis

occurs in thylakoid of plant chloroplast known as photophosphorylation

involves the pumping of protons into intermembrane space pf thylakoids and diffusion of protons to produce ATP

Question 9

Photophosphorylation (mainly driven by photons- particles of light)

Answer 9

1. Excited e- released from reaction center, chanelled into the ETC
2. Energy levels drop, energy released used to carry out chemiosmosis
3. Protons pumped from stroma to thylakoid intermembrane space
4. Protons accumulate, electrochemical gradient established
5. High proton concentration gradient helps drive the synthesis of ATP by phosphorylation of ADP

Question 10

Cyclic Photophotophorylation

Answer 10

Electrons lost from and return to same photosystem

only PS1 involved

Question 11

Non- Cyclic photophophorylation

Answer 11

Electrons lost from photosystem do not return to same photosystem

Generates reduced NADP (NADPH)

Question 12

Reduction of NADP by PS1

Answer 12

Essential stage for the light-independent stages of photosynthesis to occur

Question 12

Thylakoid

Answer 12

Allow light dependent stages of photosynthesis to occur effectively

Feature: flattened membrane bound sacs

Question 13

Calvin cycle

Answer 13

occurs in the stroma of the chloroplasts (high rubisco concentration)

Rubisco is efficient at low co2 concentrations

1. Carbon fixation: RUBP (5C) forms 2 glycerate 3-phosphates (3C), catatlysed by rubisco
2. Synthesis of triose phosphates: Glycerate 3-phosphate reduced into triose phosphates with 1 ATP and NADPH
3. Regeneration of RUBP- 10 triose phosphates to make 6 RUBP, each RUBP requires 1 ATP

Question 14

Interdependence of light-dependent and light-independent reactions

Answer 14

Light-independent reactions require ATP and NADPH from light- dependent reactions

Light-dependent reactions require ADP and NADP from light-independent reactions