Biology Paper 21
May / June 2025·5090·8 questions
Mock exam: 75 min, official timing
Question paper
Question 1
Question 2
Question 3
Question 4
Question 5
Question 6
Question 7
Question 8
Mark scheme
Question 1
1(a)[3]
1(b)[2]
1(c)[3]
Question 2
2(a)(i)[1]
2(a)(ii)[2]
2(a)(iii)[2]
2(b)(i)[2]
2(b)(ii)[4]
some water shrews have more of the protein / a mutation occurred (producing the protein);
water shrews compete for food;
shrews with the protein can collect more food;
these shrews are more likely to survive;
these shrews are more likely to reproduce;
they pass on the alleles (for the protein) to the next generation (max 4)
Question 3
3(a)(i)[2]
3(a)(ii)[3]
3(b)(i)[3]
3(b)(ii)[3]
Question 4
4(a)[2]
4(b)(i)[3]
4(b)(ii)[2]
4(b)(iii)[4]
4(b)(iv)[3]
Question 5
5(a)[3]
5(b)(i)[2]
5(b)(ii)[2]
5(c)(i)[2]
5(c)(ii)[2]
Question 6
6(a)(i)[2]
6(a)(ii)[1]
6(b)[3]
6(c)[3]
Question 7
7(a)(i)[1]
7(a)(ii)[1]
7(b)(i)[2]
7(b)(ii)[1]
7(b)(iii)[1]
Question 8
8(a)[6]
8(b)[4]