2019 P2

Question 1

Describe and explain how succession occurs (4)

Answer 1

Colonisation by pioneer species
Pioneers change environment
Environment becomes less hostile for new species
Causes increase in biodiversity to climax community

Question 2

Calculate percentage of sunlight energy transferred into faeces and urine of a zebra (1)

Answer 2

0.155%

Question 3

Calculate the energy stored in new tissues of the zebra

Answer 3

178

Question 4

Explain how a single base substitution causes a change in the structure of this polypeptide (3)

Answer 4

Change in amino acid sequence
changes interaction between hydrogen bonds
which alters tertiary structure of polypeptide

Question 5

Give the full genotype of the fly numbered 6 in Figure 4 (1)

Answer 5

GgXRXr

Question 6

Give one piece of evidence from Figure 4 to show the allele for grey body colour is dominant (1)

Answer 6

If recessive, all 3 and 4 offspring would be grey but 9 is black

Question 7

Explain one piece of evidence from Figure 4 to show that the gene for body colour is no on the X chromosome (2)

Answer 7

Fly 3 and 4 produce 9 which is a black fly

Fly 3 would pass dominant ALLELE to 9

Question 8

Complete genetic diagram (3)

Answer 8

FLY

ratio = 1:1:1:1

Question 9

Use Hardy-Weinburg equation to calculate percentage of flies heterozygous for gene G. (2)

Answer 9

48%

Question 10

In photosynthesis, which chemicals are needed for the light-dependent reaction? (1)

Answer 10

3. Reduced NADP, ATP, water, carbon dioxide

Question 11

Describe what happens during photosynthesis in the light-dependent reaction? (2)

Answer 11

CHLOROPHYLL absorbs light

electrons lost

Question 12

Explain why the student marked the origin using a pencil rather than ink (1)

Answer 12

If ink was used the ink and leaf pigments would mix.

Question 13

Describe method student used to seperate the pigments after the solution of pigments had been applied to the origin (2)

Answer 13

Level of solution below the origin

Remove paper before solvent reaches top

Question 14

Rf value for pigment C (1)

Answer 14

0.6

Question 15

Suggest and explain the advantage of having different coloured pigments in leaves (1)

Answer 15

Absorb different wavelengths of light for photosynthesis

Question 16

Describe how you could estimate the size of a population of sundews in a small marsh (5)

Answer 16

Use a grid to divide area into sections
Use random number generator to select sections to count
Count number of sundews in each selected section
Ensure large sample size AND calculate mean
Multiply mean number per section by total number of sections to find estimate of population size

Question 17

Suggest and explain how digesting insects helps the sundew to grow in soil with very low conc of nutrients (2)

Answer 17

Digestion and breakdown of PROTEINS provides soil with AMINO ACIDS