Ecosystems rely on energy transfer T5/photosynthesis.

Question 1

Name the two elements needed to make proteins that are not present in glucose.
(2)

Answer 1

• Nitrogen

- Sulfur

Question 2

Name the two elements needed to make nucleic acids that are not present in glucose.
(2)

Answer 2

• Nitrogen

- Phosphorus

Question 3

Which molecule provides the source of hydrogen for photosynthesis?

Answer 3

-H20

Question 4

What is the source of energy for photosynthesis?

Answer 4

-Light

Question 5

Which molecule provides the hydrogen for the light independent reactions?

Answer 5

-Reduced NADP

Question 6

Which molecule provides the energy for the reduction of carbon dioxide to glucose in the light-I reactions?

Answer 6

-ATP

Question 7

Where does the light-dependant reaction take place?

Answer 7

The thylakoid membranes of chloroplasts.

Question 8

Where does the light-independent reaction take place?

Answer 8

The chloroplast stroma.

Question 9

Plant fibres and oil-based plastics have both been used to make ropes.
Describe one advantage and one disadvantage of using ropes made from plant fibres rather than ropes made from oil-based plastics.
(2)

Answer 9

• Advantage: is sustainable /biodegradable / can decompose.

- Disadvantage: less strong /can decompose/ is biodegradable.

Question 10

Plant cell walls contain cellulose. Name the monomer that makes up cellulose.
(1)

Answer 10

Beta-glucose

Question 11

How are the beta-glucose monomers held together in a cellulose molecule?
(1)

Answer 11

-By glycosidic bonds in an unbranched chain.

Question 12

Photosynthesis is a two-stage process by which plants fix carbon dioxide.
Describe the light-dependent reactions of photosynthesis.
(5)

Answer 12

• Use of light energy to excite electrons in chlorophyll/ photosystem 1 and 2/electrons promoted to higher energy level.
• Photolysis of water to produce oxygen, electrons and hydrogen ions.
• Electrons used in the electron transport chain/ to replace those lost by chlorophyll/ electrons used in redox reactions/ move along electron carrier proteins.
• Generation of ATP/ photo-phosphorylation.
• Reduction of NADP.

Question 13

Describe the structure of a cellulose cell wall.

3

Answer 13

• Cellulose molecule is a polymer/ chain of beta-glucose molecules.
• Cellulose molecules held together by hydrogen bonds as microfibrils.
• Microfibrils arranged in parallel/ criss cross.
• Ref. to hemicelluloses.

Question 14

Write an equation summarising:

• The splitting of water
• The reduction of NADP

Answer 14

a) H20=2H and 2e- and 1/2 O2

b) 2H+ and 2e- and NADP = reduced NADP

Question 15

Which enzyme catalyses the breakdown of ATP to ADP?

1

Answer 15

-ATPase

Question 16

Why can the Clavin cycle be described as using carbon fixation?

Answer 16

-In the Calvin cycle, the inorganic carbon in CO2 is incorporated into organic molecules. The Carbon is fixed in organic molecules making it available to other organisms. These compounds can store energy.

Question 17

Name a substance that has been phosphorylated in the light independent reaction.
-Name a substance formed by reduction.
(1)

Answer 17

• RuBP

- GALP

Question 18

Describe how a plant converts glucose into sucrose.

Answer 18

-A glucose molecule is converted into fructose, which joins with a glucose molecule in a condensation reaction to form the disaccharide sucrose.

Question 19

Describe how a plant produces cellulose using the glucose formed in photosynthesis.
(3)

Answer 19

• B-glucose molecules join together, 1,4 glycosidic bonds form between adjacent B glucose molecules.
• Straight chains of B-glucose form cellulose.
• Hydrogen bonds form between the cellulose molecules, forming microfibrils.

Question 20

What additional elements are involved in the formation of i) amino acids and ii) nucleic acids, explain how in each case the plants obtains these elements.

Answer 20

i) Amino acids - nitrogen and sulfur; obtained from nitrate and sulfate ions absorbed by the plant roots.
ii) Nucleic acids - nitrogen in nitrogenous bases and phosphorus in phosphate group; obtained from nitrate and phosphate ions absorbed by the plant roots.

Question 21

What’s the overall reaction of photosynthesis?

Answer 21

6CO2 + 6H2O > (energy from light in the presence of chlorophyll) > C6 H12 O6 + 6O2

Question 22

Plants produce ATP in their chloroplasts during photosynthesis. They also produce ATP during respiration. Explain why it is important for plants to produce ATP during respiration in addition to during photosynthesis.
(5)

Answer 22

• 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;
• ATP for synthesis (of named substance)

Question 23

Light energy is absorbed by the chlorophyll. After the absorbed energy excites the electrons, what state is the chlorophyll considered to be in?

Answer 23

Photo ionised

Question 24

Which photosystem is involved in cyclic phosphorylation?

Answer 24

PS1

Question 25

What is starch made up of.

Answer 25

Polysaccharides branched amylopectin and unbranched amylose.