SB3g Alleles

Question 1

Allele

Answer 1

Most genes come in different versions, called alleles. So a gene for eye colour may have a version (allele) that can cause dark eyes and an allele that can cause pale eyes.

Question 2

Dominant

Answer 2

Allele that will always affect the phenotype (as opposed to a recessive allele, whose effect will not be seen if a dominant allele is present).

Question 3

Genetic diagram

Answer 3

Diagram showing how the alleles in two parents may form different combinations in the offspring when the parents reproduce.

Question 4

Genentic variation

Answer 4

Also called inherited variation. Differences between organisms passed on to offspring by their parents in reproduction.

Question 5

Genotype

Answer 5

The alleles for a certain characteristic that are found in an organism. Written in a shorthand using letters to represent the alleles (with the dominant allele having a capital and being written first).

Question 6

Heterozygous

Answer 6

When both the alleles for a gene are different in an organism.

Question 7

Homozygous

Answer 7

When both the alleles for a gene are the same in an organism.

Question 8

Monohybrid inheritance

Answer 8

The study of how the alleles of just one gene are passed from parents to offspring.

Question 9

Phenotype

Answer 9

The characteristics that a certain set of alleles produce.

Question 10

Ratio

Answer 10

A relationship between two quantities, usually showing the number of times one value is bigger than the other. For example, if there are six red buttons and two blue buttons, the ratio of red to blue is 3 to 1, also written 3:1.

Question 11

Recessive

Answer 11

Allele that will only affect the phenotype if the other allele is also recessive. It has no effect if the other allele is dominant.

Question 12

Zygote

Answer 12

Another term for ‘fertilised egg cell’.