Cell Division and Inheritance

Question 1

What is the function of the nucleus

Answer 1

Controls and regulates the activities of the cell, produces ribosomes and contains DNA

Question 2

Define the term Alleles

Answer 2

Are alternative versions of genes

Question 3

Define homozygous alleles

Answer 3

Have identical information for a trait

Question 4

Define heterozygous alleles

Answer 4

Have different information for a trait

Question 5

Name the two different types of cell division

Answer 5

Somatic cell division & reproductive cell division

Question 6

Describe somatic cell division

Answer 6

Aims to replicate cells to replace dead or injured cells or add new cells. Occurs through mitosis & cytokinesis (you dont have sex with your toes, mytoesis)

Question 7

Describe reproductive cell division

Answer 7

Aim is to produce the gamete cells (sperma nd oocyte). Occurs through meiosis (me=my sis=sex)

Question 8

How many chromosomes are there in each somatic cell in somatic cell division? And where does cell division occur?

Answer 8

46 chromosomes and occurs through three main phases, Interphase, Mitosis and cytokinesis

Question 9

How many chromosomes are there in each reproductive cell in cell reproductive cell division? and where does cell division occur?

Answer 9

23 chromosomes and occurs in the testes and ovaries

Question 10

Explain how genetic variation occurs

Answer 10

When two homologous chromosomes partner up they exchange genetic material between non-sister chromatids

Question 11

Define cancer

Answer 11

Cancer is the group of diseases that results from uncontrolled or abnormal cell proliferation

Question 12

Define the term malignant tumour

Answer 12

Malignant tumours undergo metastases (the spread of cancerous cells to other parts of the body)

Question 13

Define the term benign tumour

Answer 13

Benign tumours do not metastasise (they do not spread)

Question 14

Name the type of cancer cell that arises from epithelial tissue

Answer 14

Carcinoma arises from epithelial tissue

Question 15

Name the type of cancer cell that arises from melanocytes

Answer 15

Melanoma arises from melanocytes

Question 16

Name the type of cancer cell that arises from lymphatic tissue

Answer 16

Lymphoma arises from lymphatic tissue

Question 17

Name the type of cancer cell that arises from leukocytes

Answer 17

Leukemia arises from leukocytes

Question 18

State three causes of cancer

Answer 18

Environmental agents like cigarette tar or UV light.
Viruses like HPV stimulate abnormal cell proliferation
Genes - abnormalities of genes that control and regulate cell division

Question 19

Define inheritance

Answer 19

Inheritance is the passage of hereditary traits from one generation to another

Question 20

Define genetics

Answer 20

Genetics is the branch of biology that deals with inheritance.

Question 21

Define genotype

Answer 21

Genotype is the genetic makeup of an individual

E.g. Pp

Question 22

Define phenotype

Answer 22

Phenotype is the physical characteristics determined by the genotype & the environment
E.g. brown hair, blue eyes

Question 23

Define mutation

Answer 23

Mutation is a permanent, heritable change in a gene that causes it to have a different effect than it had previously.

Question 24

Define autosomes

Answer 24

Autosomes are any chromosomes other than a sex chromosomes.

Question 25

Define x-linked (sex) chromosomes

Answer 25

Sex chromosomes are the 23rd pair
In females, the 23rd pair consists of XX
In males, the 23rd pair consists of XY

Question 26

Explain what a dominant allele is. (include how the genotype would be written)

Answer 26

A dominant allele is an allele that is always expressed, or evident, in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome. E.g. Pp

Question 27

Explain what a recessive allele is. (include how the genotype would be written)

Answer 27

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 28

Explain the genetic condition autosomal dominant and give an example

Answer 28

Caused by a mutation of a single gene on a chromosome. One heterozygous parent will have a 50% chance of having a child with a disease. Pp Huntington’s disease is an example of an autosomal dominant genetic condition.

Question 29

Explain the genetic condition autosomal recessive and give an example

Answer 29

Caused by mutations of two gene pairs on a chromosome. pp Cystic fibrosis is an example of an autosomal recessive genetic condition

Question 30

Explain the genetic condition x-linked recessive and give and example

Answer 30

Caused by mutation on the X chromosome and is more common in men as they only have one X chromosome. Colour blindness is an example of a x-linked recessive genetic condition.

Question 31

Define multiple allele inheritance and give one example of a genetic trait carried by this type of inheritance

Answer 31

Some genes have more than two alternate forms. eg coding for blood type.

Question 32

Define complex inheritance and give one example of a genetic trait carried by this type of inheritance

Answer 32

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. eg skin or hair colour

Question 33

Describe the difference between autosomes & sex chromosomes

Answer 33

There are 23 pairs of chromosomes. 22 pairs of chromosomes are homologous and have the same appearance in both males and females and are called autosomes. Whereas sex chromosomes are the final pair which make up the 23 pairs and consist of XX (females) and XY (males)

Question 34

Explain why x-linked conditions primarily affect males

Answer 34

X-linked conditions primarily effect males because there are no counterbalancing dominant genes on the Y-chromosome

Question 35

Give two examples of x-linked conditions

Answer 35

Red-green colour blindness and hemophilia

Question 36

Explain the term trisomy and give an example

Answer 36

Trisomy has an extra chromosome with one of the pairs - down’s syndrome has 3 21st chromosomes

Question 37

Explain the term monosomy and give an example

Answer 37

Monosomy is missing a chromosome from one of the pairs for example turners syndrome