Unit 4 More Questions

Question 1

Red seaweed lives under water at a depth of 2m. Suggest an advantage to the red seaweed of having other pigments in addition to chlorophyll a. (2)

Answer 1

More wavelengths absorbed More efficient photosynthesis at low light intensities

Question 2

Give one dependent variable the you could measure in order to determine the rate of photosynthesis in an aquatic plant. (1)

Answer 2

Count the number of bubbles Measure the change in pH

Question 3

Two of the products of the light-dependent reaction of photosynthesis are used in the light-independent reaction. Describe how and what each product is used for in the light independent reaction (4)

Answer 3

NADPH - reduces GP into TP ATP - supplies extra energy for the reaction

Question 4

Lowering the temperature has very little effect on the light-dependent reaction, but it slows down the light-independent reaction. Explain why the light-independent reaction slows down at low temperatures. (2)

Answer 4

Enzymes involved in this So slow rate of enzyme reaction So less kinetic energy/fewer collisions

Question 5

In June young birds leave the nest and join the adults Using mark release recapture to estimate the size of a blue tit population in June would NOT give reliable results. Why. (2)

Answer 5

Population changes Young birds join the population

Question 6

In nitrogen fixation what is the product? (1)

Answer 6

Ammonia

Question 7

What does the hardy-weinburg principle predict? (3)

Answer 7

Frequency of alleles of a particular gene Will stay constant from one generation to the next Providing no mutation/selection/isolation

Question 8

Describe the part played by the inner membrane of a mitochondrial in producing ATP. (3)

Answer 8

Electrons transferred down ETC Provide energy to take protons into inter-membrane space Protons pass back through via ATPase Energy used to combine ADP and Pi to make ATP

Question 9

Describe the part played by chlorophyll in photosynthesis (3)

Answer 9

Light energy is absorbed Radishes energy level of electrons ATP is formed

Question 10

Explain what is meant by the ecological term population. (1)

Answer 10

totaly number of organisms of one species in a habitat at s given time

Question 11

Explain what is meany by a recessive allele (1)

Answer 11

Only expressed (in the phenotype) when homozygous / two (alleles) are present

Question 12

Explain what is meany by codominant alleles (1)

Answer 12

both alleles are shown in phenotype

Question 13

RFI is residual food intake - it is the difference between the amount of food an animal acutally eats and its expected food intake.

Scientists have developed a standard procedure for comparing RFI in cattle. They ontrol two factors. These are type of food and environmental temperature. Explain why each of these factors needs to be controled (4)

Answer 13

Type of food (not a mark)

1. May vary in protein/fat/carbohydrate/fibre/roughage/ vitamins/minerals;
2. May affect absorption / digestibility / energy value / tastiness / growth / overall food intake

Temperature (not a mark)

3. Will affect heat loss/gain/respiration/metabolism;
4. (Need) to maintain/regulate body temperature;
5. More food/energy can be used for growth

Question 14

Methane is produced by anaerobic microorganisms in the soil. The scientists found that rice that are not flooded do not produce large amounts of methane. Suggest why (2)

Answer 14

Not flooded = aerobic conditions

Not flooded = fewer active anaerobic microorganisms

Question 15

Succession ocurs in natural ecosystems. Describe and explain how succession occurs (5)

Answer 15

1. (Colonisation by) pioneer (species);
2. Change in environment / example of change caused by organisms present;
3. Enables other species to colonise/survive;
4. Change in diversity/biodiversity;
5. Stability increases / less hostile environment;
6. Climax community

Question 16

Describe the way in which ATP and reduced NADP are produced in the light-dependent reaction of photosynthesis (5)

Answer 16

light raises energy level of / excites electrons;

pass through carriers;

energy released;

ATP formed from ADP + P;

In context of producing reduced NADP protons / H+ ions;

from photolysis / water

Question 17

Explain how ATP and reduced NADP are used in the light-independent reaction of photosynthesis. (4)

Answer 17

GP converted to triose phosphate / GALP;

this involves reduction;

reduced NADP provides reducing power / hydrogens;

ATP supplies energy for this reaction;

phosphate from ATP;

for production of RuBP

Question 18

Describe the role of electron transport chains in the light-dependent reactions of photosynthesis. (6)

Answer 18

1. electron transport chain accepts excited electrons;
2. from chlorophyll / photosystem;
3. electrons lose energy along chain;
4. ATP produced;
5. from ADP and Pi;
6. reduced NADP formed;
7. when electrons (from transport chain) and H+ combine with NADP;
8. H+ from photolysis

Question 19

Photosynthesis generally takes place in a leaf. Describe how the leaf is adapted to allow this process to occur effectively. (3)

Answer 19

Large surface area to collect solar energy;

transparent nature of cuticle to allow light penetration;

position of chlorophyll to trap light;

stomata to allow exchange of gases;

thin / max. surface area to volume ratio for diffusion of gases;

spongy mesophyll / air spaces for carbon dioxide store;

xylem for input of water;

phloem for removal of end products

Question 20

Explain the roles of water, light and ribulose bisphosphate in the process of photosynthesis. (6)

Answer 20

water: provides hydrogen; to reduce NADP; provides electron; to stabilise / reduce chlorophyll

light : excites / oxidises / removes an electron from chlorophyll / photosystem; photophosphorylation / ATP produced; electron used in reduction of NADP

Ribulose bisphosphate: carbon dioxide acceptor; forms GP

Question 21

Explain why an increase in temperature will increase the rate of photosynthesis. (3)

Answer 21

Enzymes are involved; extra kinetic energy / molecules move faster; molecules collide more often / more enzyme - substrate complexes formed;