Biology · Oct / Nov 2022 · Paper 41 · Question 4

any four from:

two strands ;

formed into (double) helix ;

ref. to four bases / A and T and C and G ;

pairing of, A with T / C with G ;

cross links between bases ;

any three from:

1

variation (in the bacteria) ;

2

ref. to mutations / described ;

3

mutations, give bacteria an advantage ;

4

non-resistant bacteria, killed / inhibited / AW (by antibiotic) ; 5

competition with non-resistant bacteria ;

6

resistant bacteria reproduce ;

7

pass on, gene / allele (for resistance) ;

8

natural selection ;

9

AVP ;

any one from:

1

no difference in appearance (of different strains of MRSA) / AW ;

2

no need to culture the bacteria ;

3

(gene sequencing is an) automated process / AW ; / easy to do / AW ;

4

only need small, number / quantity / amount (of bacteria) ; 5

more, accurate / precise (than traditional methods) / AW ; 6

explained in terms of comparing base sequences of different, strains / AW ;

7

AVP ;

any two from:

(resistant) bacteria will not be killed by antibiotics / AW ; idea that no antibiotic of last resort / AW ;

(bacterial diseases) cannot be treated / AW ;

infection / disease / (resistant) bacteria, will spread ;

AVP ;;

any two from:

antibiotics used only when essential ;

ensuring people, follow instructions / complete course of antibiotics ;

do not prescribe antibiotics for, viral / fungal, infections ; AVP ;;

placenta forms a barrier between mother and fetus / AW ;

any three from:

nitrogen fixation ;

decomposition / decay ;

nitrification ;

denitrification ;

deamination ;

fermentation ;

AVP ;;