Biology 9700/43 — October/November 2016
Cambridge A-Level · A Level Structured Questions · worked solutions for every part, with the mark scheme
Topics Inheritance · Selection and Evolution · Control and Coordination · Energy and Respiration · (outdated) Crop Plants · Photosynthesis · +4 more
The Labrador retriever is a modern breed of dog that can have yellow, black or brown fur and pale, black or brown noses. The inheritance of fur and nose colour is the result of the interaction between genes at two different loci, the B locus and the E locus.
Fig. 1.1 shows a Labrador retriever.
Table 1.1 shows how gene interaction results in different phenotypes.
Table 1.1
| alleles at B locus | alleles at E locus | phenotype |
|---|---|---|
| B_ | ee | yellow fur black nose |
| bb | ee | yellow fur pale nose |
| B_ | E_ | black fur black nose |
| bb | E_ | brown fur brown nose |
A male Labrador retriever, heterozygous at the B locus and homozygous recessive at the E locus, was mated with a female Labrador retriever heterozygous at both loci.
Explain the terms locus and homozygous.
locus = ______
homozygous = ______
Use a genetic diagram to show the possible genotypes and phenotypes of the offspring from the mating between the two Labrador retrievers.
parental phenotypes
parental genotypes
gametes
offspring genotypes and phenotypes
The rest of this paper
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- Q3Genetic Technology · Selection and Evolution13M
- Q4Selection and Evolution12M
- Q5Classification, Biodiversity and Conservation11M
- Q6(outdated) Aspects of Human Reproduction8M
- Q7Control and Coordination · Energy and Respiration10M
- Q8Energy and Respiration13M
- Q9Homeostasis15M
- Q10Control and Coordination · Inheritance15M