Unit 6.2- Patterns of Inheritance

Question 1

Types of chromosome mutations:

Answer 1

• Deletion
• Inversion
• Translocation
• Duplication
• Non-disjunction

Question 2

Translocation chromosomal mutation definition:

Answer 2

A piece of a chromosome breaks off and then becomes attached to another chromosome

Question 3

Duplication chromosomal mutation definition:

Answer 3

Part of a chromosome may be duplicated

Question 4

Non-disjunction chromosomal mutation definition:

Answer 4

One pair of chromosomes or chromatids fails to separate, leaving one gamete with an extra chromosome. When fertilised with a normal haploid gamete, the resulting zygote has one extra chromosome

Question 5

Aneuplody defintion:

Answer 5

The chromosome number is not an exact multiple of the haploid number for that organism. Sometimes chromosomes or chromatids fail to separate during meiosis

Question 6

Polyploidy definition:

Answer 6

If a diploid gamete is fertilised by a haploid gamete, resulting in a zygote that will be triploid

Question 7

When does genetic variation occur in meiosis?

Answer 7

• Allele shuffling/ crossing over in prophase 1

- Independent assortment in anaphase 1 and 2

Question 8

Heterozygous definition:

Answer 8

Not true-breeding; having different alleles at a particular gene locus on a pair of homologous chromosomes

Question 9

Homozygrous definition:

Answer 9

True-breeding; having identical alleles at a particular gene locus on a pair of homologous chromosomes

Question 10

Monogenic definition:

Answer 10

Determined by a single gene

Question 11

Dyhybrid definition:

Answer 11

Involving two gene loci

Question 12

Codominance definition:

Answer 12

Where both alleles present in the genotype of a heterozygous individual contribute to the individual’s phenotype

Question 13

Sex-linked definition:

Answer 13

Gene present on one of the sex chromosomes

Question 14

Autosomal linkage definition:

Answer 14

Gene loci present on the same autosome (non- sex chromosome) that are often inherited together

Question 15

What genes form as a result of crossing over of autosomal genes?

Answer 15

Recombiant genes

Question 16

Epistasis definition:

Answer 16

Interaction of non-linked gene loci where one masks the expression of the other

Question 17

Recessive epistasis:

Answer 17

The homozygous presence of a recessive allele at the first locus prevents the expression of another allele at a second locus. The alleles at the first locus are epistatic to those at the second locus, which are hypostatic to those at the first

Question 18

Dominant epistasis:

Answer 18

The presence of one epistatic allele prevents the other being shown

Question 19

How can genes work in a complementary fashion (epistasis)?

Answer 19

They code for two enzymes that work in succession, catalysing sequential steps of a metabolic pathway

Question 20

Directional selection definition:

Answer 20

A type of natural selection that occurs when an environmental change favours a new phenotype and so results in a change in the population mean

Question 21

Founder effect definition:

Answer 21

When a small sample of an original population establishes in a new area; its gene poo; is not as diverse as that of the parent population

Question 22

Genetic bottleneck definition:

Answer 22

A sharp reduction in population size due to environmental catastrophes or human activities, which reduces genetic diversity. As the population expands, it is less diverse than it was before

Question 23

Stabilising selection definition:

Answer 23

Natural selection leading a constancy within a population. Intermediate phenotypes are favoured and extreme phenotypes selected against. Alleles for extreme phenotypes may be removed from the population. This reduces genetic diversity

Question 24

What are the two equations for the Hardy-Weinberg principle?

Answer 24

p+q=1

p^2 +2pq +q^2 =1

Question 25

Speciation definition:

Answer 25

The splitting of a genetically similar population into two or more populations that undergo genetic differentiation and eventually reproductive isolation, leading to the evolution of two or more new species

Question 26

Allopatric speciation:

Answer 26

Formation of two different species from one original species, due to geographical isolation

Question 27

Sympatric speciation definition:

Answer 27

Formation of two different species from one original species due to reproductive isolation, while the populations inhabit the same geographical location

Question 28

Examples of gene banks:

Answer 28

• Rare breed farms
• Wild populations of organisms
• Botanic gardens and zoos
• Seed banks
• Sperm banks
• Frozen embryos

Question 29

Ethical considerations of artificial selection:

Answer 29

• Domesticated animals may retain juvenile characteristics, making them less able to defend themselves
• Some inbred dogs have susceptibility to disease
• Some coat colours would fail to camouflage animals