Genetics & Inheritance

Question 1

Define inheritance?

Answer 1

Is the passage of hereditary traits from one generation to another

Question 2

Define genetics?

Answer 2

Is the branch of biology that deals with inheritance

Question 3

Define genotype?

Answer 3

Is the genetic make up of an individual

Question 4

Define phenotype?

Answer 4

Is the physical characteristics determined by the genotype and the environment e.g blue eyes and brown hair

Question 5

Define mutation?

Answer 5

Permanent change in a gene

Question 6

Define Autosomes?

Answer 6

Any chromosome other than the sex chromosomes

Question 7

Explain what is meant by recessive and dominant alleles?

Answer 7

Dominant: The dominant allele is an allele that is always expressed in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp
Recessive alleles: The recessive allele is an allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present. E.g. pp (homozygous recessive)

Question 7

Explain what is meant by recessive and dominant alleles?

Answer 7

Dominant: The dominant allele is an allele that is always expressed in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp
Recessive alleles: The recessive allele is an allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present. E.g. pp (homozygous recessive)

Question 8

Explain Autosomal dominant?

Answer 8

Caused by mutation of a single gene chromosome (Pp) e.g Huntington’s Disease

Question 9

Define Autosomal recessive?

Answer 9

Caused by mutations of two gene pairs on a chromosome (pp) e.g cystic fibrosis

Question 10

Define X-linked recessive?

Answer 10

Caused by the mutation on the X chromosome, usually expressed in males as they only have X chromosomes e.g colour blindness and haemophilia

Question 11

Most inherited traits are not controlled by one gene but by: the combined effects of two or more genes OR combined effects of many genes and environmental factors. Give examples?

Answer 11

Example: Skin colour, hair colour, height, body build.
Environmental factors: Skin colour affected by sun exposure. Height affected by malnutrition or disease. Body build affected by malnutrition or obesity

Question 12

Describe the difference between autosomes & sex chromosomes?

Answer 12

Autosomes: Autosomes are any chromosomes other than a sex chromosomes.
Sex chromosome: Sex chromosomes are the 23rd pair. In females, the 23rd pair consists of XX. In males, the 23rd pair consists of XY

Question 13

Explain the term trisomy?

Answer 13

There are three chromosomes not two as normal. Downs syndrome.

Question 14

Explain the term monosomy?

Answer 14

There is a missing chromosome e.g 45 instead of 46 chromosomes. An example of this is Turner’s syndrome when a female is born with only one X chromosome

Question 15

Somatic cell division results in?

Answer 15

2 genetically identical cells

Question 16

An example of a sex linked disorder is?

Answer 16

Haemophilia

Question 17

An example of an autosomal dominant condition is?

Answer 17

Huntington’s Disease

Question 18

The end result of Meiosis is the production of cells that have?

Answer 18

23 chromosomes

Question 19

State two functions of a nucleus?

Answer 19

Control cellular structure

Control cellular activites

Question 20

Describe somatic division and the number of chromosomes involved?

Answer 20

Productions of two genetically identical cells to replace dead, injured cells or add new cells each with the same number of chromosomes as the original cells e.g 23 pairs or 46 total

Question 21

Describe reproductive division and the number of chromosomes involved?

Answer 21

Production of gametes for sexually reproducing organs. Number of chromosomes in half the nucleus in half meiosis e.g 23