Monohybrid Inheritance

Question 1

Monohybrid Inheritance

Answer 1

The expression of a trait controlled by a single gene with two or more alleles.

Question 2

Autosomes

Answer 2

Any chromosomes not considered a sex chromosomes

Question 3

Sex chromosomes

Answer 3

Determine the sex of an organism - two forms called X and Y chromosome

Question 4

Dominant allele

Answer 4

Masks the effect of a recessive allele and will always be expressed - complete dominance

Question 5

Punnett square

Answer 5

Possible genotypes that can occur in offspring when two parental gametes are fused during fertilisation. Cannot model an exact outcome but can predict proportion of offspring that may inherit each genotype.

Question 6

Pure breeders

Answer 6

Individuals that are homozygous for a particular trait, can only pass one form of allele to their offspring.

Question 7

Test cross

Answer 7

Individual with unknown genotype is crossed with an individual that is homozygous recessive for the same trait.

Question 8

Result of a test cross showing recessive form of a trait?

Answer 8

Individual must be heterozygous

Question 9

Result of a test cross has no offspring with recessive trait

Answer 9

Individual is homozygous dominant and therefore is a pure breeder

Question 10

What is an issue with only carrying out one test cross?

Answer 10

All offspring produced could possess the dominant trait but still have a heterozygous parent, therefore to increase the certainty of the unknown parental genotype we must carry out multiple test crosses.

Question 11

What animals are test crosses best suited for?

Answer 11

Animals that quickly reproduce in large numbers.

Question 12

Test Cross Purpose:

Answer 12

Determine an individual’s previously unknown genotype.

Question 13

Pedigree Chart

Answer 13

A diagram that allows us to track the presence or absence of certain traits through two or more generations of a particular family.

Question 14

What are females represented by in Pedigree charts?

Answer 14

Circle

Question 15

What are males represented by in pedigree charts?

Answer 15

Square

Question 16

How are phenotypes differentiated if they are different for a particular trait?

Answer 16

Different colours

Question 17

Breeding pair in pedigree charts

Answer 17

Individuals connected with a horizontal line

Question 18

What do two capital letters for each allele or superscript mean?

Answer 18

Neither allele is dominant or recessive

Question 19

Incomplete dominance

Answer 19

When there are two alleles for a trait but neither is dominant over the other. When these alleles are inherited together, they form a third intermediate phenotype. This phenotype will be a blend of the other two.

Question 20

Co dominance

Answer 20

When two alleles are equally dominant to each other. Both alleles will be equally and independently expressed in the phenotype. It creates a third phenotype but both original colours appear separately.

Question 21

Multiple allele

Answer 21

Occurs when there are more than two alleles for the gene within a population.

Each individual still inherited one allele from each parent but this creates more variation of the gene in the population that an individual can have.

Question 22

Blood Type Details

Answer 22

Ia and Ib are co dominant and i is recessive.

Question 23

Lethal Allele

Answer 23

Mutated alleles that can cause the death of individuals

Question 24

How to confirm if an allele is lethal:

Answer 24

If the phenotypic ratio is lower than you would expect, it is likely there is a lethal allele present and number of offspring is smaller because some died during embryonic development.