AS Biology Paper 1 June 2017 Mistakes

Suggest why high doses of AZT lead to muscle wastage (lines 10-11).

1. (Fewer mitochondria so) less (aerobic) respiration; 2. (Muscles receive) less ATP (so waste);

Explain the role of the heart in the formation of tissue fluid

1. Contraction of ventricle(s) produces high hydrostatic pressure; 2. Forces water out (of blood capillaries);

Explain the advantages of lipid droplet and micelle formation

1. Droplets increase surface areas 2. Faster hydrolysis / digestion 3. Micelles carry fatty acids and monoglycerides to (epithelial) cell;

Name structure Q in Figure 2 and suggest how it is involved in the absorption of lipids.

1. Golgi apparatus 2. Modifies triglycerides 3. Combines triglycerides with proteins 4. Packages for exocytosis

Explain how the chromosome number is halved during meiosis.

1. Homologous chromosomes (pair); 2. One of each (pair) goes to each (daughter) cell / to opposite poles;

Crossing over greatly increases genetic diversity in this species of moss. Describe the process of crossing over and explain how it increases genetic diversity

1. Homologous pairs of chromosomes associate / form a bivalent; 2. Chiasma(ta) form; 3. (Equal) lengths of (non-sister) chromatids / alleles are exchanged; 4. Producing new combinations of alleles;

68% of all the fish caught in this investigation came from sample A. A student thought this showed that sample A had a greater index of diversity than any of the other samples. It is not possible to draw this conclusion from the given data. Give reasons why

1. Number of individuals of each species not known; 2. Almost all (of sample A / the 68%) could be of the same species; 3. Other samples may have more individuals of each species;

Suggest and explain why AZT does not destroy HIV in the body but stops or slows the development of AIDS (lines 3-4).

1. Person has HIV DNA (in their DNA); 2. New HIV still made; 3. (AZT) inhibits reverse transcriptase; 4. Slows / stops replication of HIV;

1 0 . 2 Suggest and explain two advantages of using HAART (lines 7-9).

1. Slows/stops development of AIDS; 2. Because HIV resistant to AZT is destroyed OR 3. AZT continues to work as a drug; 4. Because HAART prevents the spread of AZT-resistant HIV to rest of the human population;

Explain the purpose of transferring the same volume of liquid culture onto each agar plate.

1. So no contamination/ other bacteria; 2. So same number of bacteria transferred to allow comparison;

Table 3 shows features of a mitochondrion and a chloroplast. Complete Table 3 with ticks where a feature is present.

1. Training made no difference to number (of mitochondria per μm 2 ); 2. Training led to an increase in the area (of inner mitochondrial membrane);

Use information from Figure 3 to complete Table 2. Place the number 1, 2, 3 or 4 in the appropriate box.

2, 3 4, 1

The liquid culture the student transferred was diluted by 1 in 10 000 (10-4 ). Use information in this question to calculate how many bacteria were present in 1 cm3 of undiluted liquid culture.

6,000,000 (300 x 10^4) x 2

Use Figure 3 to calculate the volume of blood pumped per minute by the left ventricle.

6315.79

Which letter, A, B, C or D, in Figure 5, shows where meiosis occurs in the life cycle of the moss? Write the appropriate letter in the box provided.

D

Table 3 shows features of a mitochondrion and a chloroplast. Complete Table 3 with ticks where a feature is present.

Double Outer Memb: both yes Starch Grains: mit no, chloroplast yes Diff Oxygen into Org: yes mit, no chloro