Bio lesson 1.8 key terms

Question 1

Exception to Mendel’s Work

Answer 1

However, there are exceptions that occur

These exceptions do not invalidate Mendel’s work, rather demonstrated the complexity of genetic analysis

Variation of Dominance

Question 2

Define Incomplete Dominance

Answer 2

The heterozygous condition results in an intermediate phenotype – a “blend”

Red flowers + white flower produce pink flowers (snapdragon flowers are an example of this)

Question 3

Define Co-Dominance

Answer 3

A slightly different form of inheritance is observed in horses and cattle where 2 alleles are expressed at the same time.

CO – DOMINANCE Neither allele is completely dominant a “blend” does not exist (Roan bulls are an example of this)

Question 4

Define complete dominance

Answer 4

Complete dominance is when one allele is fully dominant over the other.

Question 5

Define Multiple Allelism

Answer 5

Geneticists have identified that it is possible to have more than 2 forms of a gene

This results in a larger number of possible genotypic combinations and a greater variety of phenotypes

Question 6

What insect shows Multiple Allelism

Answer 6

Drosophila (fruit fly)

A fruit fly can have 2 alleles at one time, but there are more
than 2 alleles for eye colour:

Question 7

What is the hierarchy for eye colour in fruit flies

Answer 7

red (E1) > apricot (E2) > honey (E3) > white (E4)

Question 8

What is an example of Co-dominance and multiple alleles

Answer 8

Human Blood Groups

Question 9

Why are Human Blood Groups an example of co-dominance and multiple alleles

Answer 9

The human blood group alleles show multiple allelism.

Allele for type O is recessive

Allele for type A and B are codominant

There are 4 blood types (or phenotypes) in the ABO
system