Genetic Cross Diagrams OALH

Define variation

Name two things that our characteristics can be affected by...

Define fertilisation

Define control variable

Calculate the mean 1.24 1.27 1.29

There are two genetically identical plants but one has grown taller than the other. Explain why

What is a gene?

What is an allele?

What does dominant mean?

What does recessive mean?

What does homozygous mean?

What does heterozygous mean?

What is a genotype?

What is a phenotype?

This allele will always be expressed, even if there is only one. It is represented by an upper case letter...

Having the same alleles e.g. blue eyes and blue eyes.

The pair of alleles found in your chromosomes e.g. Bb

A section of DNA found on a chromosomes which codes for a characteristic.

This allele will only be expressed if both alleles are recessive. It is represented by a lower case letter.

Blue eyes is caused by a recessive allele (b), whereas brown eyes is caused by a dominant allele (B). One parent has brown eyes and is homozygous, and the other parent has blue eyes. What is the probability that their offspring will have brown eyes. Use a genetic diagram to explain your answer.

Parent phenotype:

Parent genotype:

Punnett square:

Probability:

Blue eyes is caused by a recessive allele (b), whereas brown eyes is caused by a dominant allele (B). Both parents have brown eyes and are heterozygous What is the probability that their offspring will have brown eyes. Use a genetic diagram to explain your answer.

The inheritance of fur colour in mice is controlled by a single gene. White fur is recessive - a. Grey fur is dominant - A. Two mice that are heterozygous for the fur colour gene mate. Determine the probability that the offspring will have grey fur.

The allele for green peas (G) is dominant over the allele for white peas (g). Draw a Punnett square to show the possible offspring when a heterozygous green pea mates with a white pea.

1.Which of these alleles is heterozygous?

a.BB

b.Bb

c.bb

2. Which of these alleles is homozygous?

a.BB

b.Bb

c.Bb

3. Which of these would be the phenotype

a.Blue eyes

b.bb

c.Bb

4. Which of these is the genotype?

a.Blue eyes

b.bb

c.Brown eyes