Unit 5

Question 1

Explain why converting pyruvate to lactate allowes the continues production of ATP during anaerobic respiration

Answer 1

1) Oxidised NAD is produced
2) which is used in glycolysis

Question 2

Why is most of the light falling on producers not used in photosynthesis?

Answer 2

1) Light in wrong wavelength for photosynthesis
2) Light may have missed chloroplast/chlorophyll

Question 3

Name two products of the light dependend reaction that are required for the light independent reaction

Answer 3

1) reduced NADP
2) ATP

Question 4

How does light intensity affect the rate of photosynthesis

Answer 4

• light intensity is a limiting factor
• fewer electrons released from chrolophyll
• less photolysis therefore less oxygen from water

Question 5

Why use pencil rather than ink?

Answer 5

Ink and chlorophyll pigment would mix

Question 6

Suggest and explain the advantage of having different coloured pigments in leaves

Answer 6

• more wavelengths for photosynthesis

Question 7

How will an inbihitor that binds to proteins in the electron chain transfer chain in chloroplasts of weeds (reducing the transfer of electrons down the chain) reduce the rate of photosynthesis?

Answer 7

• reduced transfer of electrons across thylakoid membrane
• so less ATP produced
• less NAPD produced
• so light independent reaction stops

Question 8

ATP is useful in many biological proceses. Explain why.

Answer 8

• Phosphorylates / adds phosphate makes (phosphorylated substances)
more reactive / lowers activation energy
• Broken down) in a one step
• Releases energy in small

Question 9

Describe how ATP is made in mitochondria

Answer 9

Substrate level phosphorylation / ATP produced in Krebs cycle;

2. Krebs cycle / link reaction produces reduced coenzyme / reduced NAD /
   reduced FAD;
   3.from reduced / coenzymes / NAD / FAD;
3. (Electrons) pass along carriers / through electron transport chain /
   through series of redox reactions;
4. Energy released;
5. ADP / ADP + Pi;
6. Protons move into intermembrane space;
7. ATP synthase;

Question 10

Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis

Answer 10

1) In the dark no ATP production in photosynthesis;

• Some tissues unable to photosynthesise / produce ATP;
• ATP cannot be moved from cell to cell / stored;
• Plant uses more ATP than produced in photosynthesis;
•ATP for active transport / synthesis (of named substance);

Question 11

Describe the effect of light energy in the light-dependent reaction of photosynthesis

Answer 11

• excites chlorophyll / electrons;
• release electron(s)

Question 12

Describe the role od saprobionts in the nitrogen cycle

Answer 12

• They use enzymes to decompose proteins/DNA/RNA/urea
• Producing/releasing ammonia

Question 13

Explain how the sequence of chemical reactions in photosynthesis can be determined using radioactive carbon dioxide

Answer 13

• Co2 is absorbed by ribulosebisphosphate
• identifying compounds at different times allows sequence to be worked out

Question 14

Suggest two advantages of using a suspension of chloroplasts, rather than a green plant in this investigation

Answer 14

• easier to stop reactions
• light is absorbed more rapidly

Question 15

Give one reason a plant can absorb a range of different wavelengths of light

Answer 15

• contain a mixture of pigments which absorb different wavelengths

Question 16

Containing many stacks of thylakoid is an adaptation of chloroplasts for efficient photosynthesis.Explain how

Answer 16

• large surface area of thylakoid so more chlorophyll
• so more light is absorbed during light dependent reaction

Question 17

What does it mean when the figure shows a negative value for the rate of photosynthesis?

Answer 17

The rate of respiration is greater than the rate of photosynthesis

Question 19

Describe how a student can use materials to separate the photosynthetic pigments by chromatography

Answer 19

• Draw origin line using a pencil
• Use a pipette to add chrolophyll solution to the origin line
• add solvent below the origin
• remove the paper before the solvent reaches the end

Question 20

There is a net gain of ATP in glycolysis. Define net gain.

Answer 20

• more ATP produced than used

Question 21

explain why most of the energy supply is from an aerobic respiration during short races

Answer 21

• Respiration rate is high
• oxygen cannot be supplied to muscle quickly enough for aerobic respiration

Question 22

Equation to summarise the net production

Answer 22

N = I - (F+R)

Question 23

how to calculate % energy transfer in a food chain?

Answer 23

energy after / energy before