DNA and Genetics Outcome 3 and 4

What does phenotype mean?

• The genetic make up of an individual

• Observable characteristics

• Whether they are dominant or recessive

What type of selection is "natural selection that produces a gradual change in allele frequencies over several generations"

• Stabilising

• Directional

• Disruptive

Directional selection occurs when there is...

• a change in environmental conditions

• Extremes of phenotype are selected again to maintain an intermediate phenotype

• a selection against intermediate phenotypes or alleles

Give an example of directional selection

• Birth weight

• Beak size of birds in Galapagos

• Peppered moths

If a plant homozygous for the recessive trait is crossed with a plant homozygous for the dominant trait, what percentage of the F 1 generation will be heterozygous?

• 25%

• 50%

• 75%

• 100%

If two F1 plants heterozygous for two traits were crossed, what would be the ratio of the offsprings' phenotypes that you would see in the F2 generation?

• 9:3:3:1

• 3:1

• 10:6

• 3:3:1

If a homozygous green seed colour (g) plant is crossed with a yellow heterozygous plant, what is the genotype of the offspring?

• 100% Gg

• 100% gg

• 50% Gg

  50% gg

If a flower with red petals was crossed with a flower with white petals and the offspring were all pink petals, what type of inheritance is this?

• Co-dominance

• Dominant

• Incomplete dominance

• Recessive

What does the term polygenic mean?

• Phenotype is controlled by more than one gene

• Genotype is controlled by more than one gene

• More than one gene is mutated

PKU is a recessive inherited trait. Around 1:10 000 babies are born in the UK with PKU. What are the frequencies of the possible genotypes?