AQA Biology A-Level - Inheritance and Hardy-Weinberg Principle MS PhysicsAndMathsTutor.com
Mark schemes
Q1.
(a) 1. Males have one allele;
Accept males only need one allele.
2. Females need two recessive alleles
OR
Females must be homozygous recessive
OR
Females could have dominant and recessive alleles
OR
Females could be heterozygous/carriers;
Ignore references to X and Y chromosomes.
Accept r as recessive allele and R as dominant
allele.
If no reference to allele, accept for one mark male
needs one recessive gene whereas females need
two recessive genes.
2
(b) 1. Box 2.
All females red-eyed, all males white-eyed.
Reject if more than one box with tick. Ignore
crossed-out ticks.
1
(c) 1. The (two) genes are linked
OR
Autosomal linkage;
Accept that the genes are on the same
chromosome.
Accept ‘Alleles are linked’ (accept symbols for
alleles) but reject if context suggests alleles of the
‘same gene’.
2. No crossing over (occurs)
OR
(Linked) genes are close together;
Accept crossing over less likely to occur.
, AQA Biology A-Level - Inheritance and Hardy-Weinberg Principle MS PhysicsAndMathsTutor.com
3. No Gl and no gL (gametes produced)
OR
No Ggll and no ggLl (offspring produced)
OR
Only GL and gl (gametes produced);
Ignore reference to independent assortment.
3
(d) 1. Correct answer of 8 × 1010 = 3 marks;;;
2. Correct answer not in standard form = 2 marks
OR
1.6 × 1013 = 2 mark
OR
1.6 × 1011 = 2 mark
OR
6.4 × 1011 = 2 mark
OR
Shows 8 × 1010 in the working = 2 marks;;
3. 1.28 × 1012 = 1mark
OR
3.2 × 1011 = 1 mark
OR
8 × 1011 = 1 mark
OR
8 × 109 = 1 mark
OR
Shows 1.6 × 1011 in the working = 1 mark
OR
Shows 2004 in the working = 1 mark;
If no other mark is credited accept for one mark
working which shows multiplication by 200 for 4
generations. This could be shown in a variety of
Mark schemes
Q1.
(a) 1. Males have one allele;
Accept males only need one allele.
2. Females need two recessive alleles
OR
Females must be homozygous recessive
OR
Females could have dominant and recessive alleles
OR
Females could be heterozygous/carriers;
Ignore references to X and Y chromosomes.
Accept r as recessive allele and R as dominant
allele.
If no reference to allele, accept for one mark male
needs one recessive gene whereas females need
two recessive genes.
2
(b) 1. Box 2.
All females red-eyed, all males white-eyed.
Reject if more than one box with tick. Ignore
crossed-out ticks.
1
(c) 1. The (two) genes are linked
OR
Autosomal linkage;
Accept that the genes are on the same
chromosome.
Accept ‘Alleles are linked’ (accept symbols for
alleles) but reject if context suggests alleles of the
‘same gene’.
2. No crossing over (occurs)
OR
(Linked) genes are close together;
Accept crossing over less likely to occur.
, AQA Biology A-Level - Inheritance and Hardy-Weinberg Principle MS PhysicsAndMathsTutor.com
3. No Gl and no gL (gametes produced)
OR
No Ggll and no ggLl (offspring produced)
OR
Only GL and gl (gametes produced);
Ignore reference to independent assortment.
3
(d) 1. Correct answer of 8 × 1010 = 3 marks;;;
2. Correct answer not in standard form = 2 marks
OR
1.6 × 1013 = 2 mark
OR
1.6 × 1011 = 2 mark
OR
6.4 × 1011 = 2 mark
OR
Shows 8 × 1010 in the working = 2 marks;;
3. 1.28 × 1012 = 1mark
OR
3.2 × 1011 = 1 mark
OR
8 × 1011 = 1 mark
OR
8 × 109 = 1 mark
OR
Shows 1.6 × 1011 in the working = 1 mark
OR
Shows 2004 in the working = 1 mark;
If no other mark is credited accept for one mark
working which shows multiplication by 200 for 4
generations. This could be shown in a variety of
