N5 Unit 2 KA4 HW

Which term describes the type of variation in which a characteristic is controlled by one gene?

• Continuous

• Discrete

• Polygenic

• Heterozygous

In humans the inheritance of wet or dry earwax is an example of discrete variation. The allele for wet earwax (E) is dominant to the allele for dry earwax (e). The diagram shows the inheritance of this characteristic.

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Variation in a characteristic can either be discrete or continuous. The range of heights and weights for a group of students were measured and recorded. Ear lobe types were also examined and categorised into groups. Which line identifies the type of variation shown by each of these human characteristics?

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The alleles shown on the chromosomes can be identified using the key in the picture. Which fly is homozygous for body pattern and heterozygous for antennae type?

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Distichiasis is a dominant characteristic in humans which causes the person to have two rows of eyelashes. A woman who is homozygous for the condition and a man who is unaffected have children. What proportion of their children would be expected to have Distichiasis?

• 0%

• 25%

• 50%

• 100%

Answer explanation

As the mother is Homozygous for a dominant trait that means she expresses it. The Father is unaffected so must have a recessive trait. This means 100% of their children would be affected.

Which line in the table describes correctly the possible chromosome content of human gametes?

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In dogs, uniform coat colour is dominant to spotted coat. From the family tree, in which generation(s) are all the dogs heterozygous for coat colour?

• P only

• F1 only

• F2 only

• P and F1

In humans, the allele for free earlobes (E) is dominant to the allele for fixed earlobes (e). The diagram below shows the inheritance of this characteristic. Which line identifies correctly the genotypes of persons P and Q?

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Feather colour in parrots is controlled by a single gene. Blue feather colour (B) is dominant to yellow feather colour (b). A homozygous blue parrot is crossed with a homozygous yellow parrot. State the genotypes of the P generation.

Feather colour in parrots is controlled by a single gene. Blue feather colour (B) is dominant to yellow feather colour (b). A homozygous blue parrot is crossed with a homozygous yellow parrot. State the genotype of the F1 parrots.