In mice, black fur is caused by dominant allele B B\,B and white fur by recessive allele bbb .
Two black mice produce a white offspring. One of the original black parents is then crossed with a white mouse. They produce six offspring, all black.
Which statement correctly gives the probability of this result and its implication for the black parent's genotype?
The probability is 164\frac{1}{64}641 ; the black parent must still be heterozygous.
The probability is 164\frac{1}{64}641 ; the black parent must now be homozygous.
The probability is 132\frac{1}{32}321 ; the black parent must still be heterozygous.
The probability is 132\frac{1}{32}321 ; the black parent must now be homozygous.
76 exam-style questions on AQA GCSE Biology 6.1 Reproduction, covering 6.1.1 Sexual and asexual reproduction, 6.1.2 Meiosis, 6.1.3 Advantages and disadvantages of sexual and asexual reproduction, 6.1.4 DNA and the genome, 6.1.5 DNA structure, 6.1.6 Genetic inheritance, 6.1.7 Inherited disorders, and 6.1.8 Sex determination. Each one has a worked solution and a mark scheme showing where the marks go.