B1 Genetic Diagrams

Question 1

What are gametes in sexual reproduction?

Answer 1

Reproductive cells from the mother and father (egg and sperm)

Question 2

What is contained in a each gamete?

Answer 2

One copy of each chromosome, so gametes only have one version of each gene, one allele.

Question 3

How are offspring produced? (We’re thinking about the gametes)

Answer 3

The chromosomes from a male gamete get mixed up with those from a female gamete.

Question 4

What does the offspring end up with?

Answer 4

Pairs of chromosomes and two alleles for each gene.

Question 5

What does it mean if the alleles are different?

Answer 5

The organism has instruction for two different versions of a characteristic but it only shows now version.

Question 6

What is the version of the characteristics displayed decided by?

Answer 6

The dominant allele

Question 7

What is the name for the allele that is not displayed when an organism has different alleles?

Answer 7

Recessive allele

Question 8

If a characteristic is caused by a recessive allele, when is it displayed?

Answer 8

When both alleles are recessive.

Question 9

How are dominant alleles shown in genetic diagram?

Answer 9

As a capital letter

Question 10

How are recessive alleles shown in a genetic diagram?

Answer 10

With a small letter

Question 11

What does it mean if you are homozygous for a trait?

Answer 11

You have alleles the same for that particular gene.

Question 12

What does it mean if you are heterozygous for a trait?

Answer 12

You have two different alleles

Question 13

What is it called if you have two alleles the same?

Answer 13

Homozygous

Question 14

What is it called if you have two alleles that are different?

Answer 14

Heterozygous

Question 15

What is a genotype?

Answer 15

The alleles an organism has.

Question 16

What is a phenotype?

Answer 16

The characteristics an organism displays.

Question 17

What is single gene inheritance?

Answer 17

A characteristics controlled by a single gene, e.g. Blood group

Question 18

What can genetic diagrams help predict?

Answer 18

The phenotype of the offspring, when you know the genotype of the parents.

Question 19

Look at genetic diagrams and practice drawing them

Answer 19

P7 in the revision guide.

Question 20

The height of garden pea plants is controlled by a single gen with two alleles. The allele for tall plants (T) is dominant over the allele for dwarf plants (t). Two heterozygous pea plants are crossed. Draw a genetic diagram to find what proportion of the offspring would be expected to be dwarf plants (3 marks)

Answer 20

I in 4, need to see a diagram