Variation & Inhertiance Topic 13

Question 1

What is meiosis?

Answer 1

A type of cell division that reduces the chromosome number by half, producing four genetically different haploid cells

Meiosis is essential for sexual reproduction, allowing for genetic diversity.

Question 2

What is a diploid cell?

Answer 2

A cell containing two sets of chromosomes (2n)

• meaning each cell contains two of each chromosome (a pair). One from mum and one from dad

Normal human body cells are diploid.

Question 3

What is a haploid cell?

Answer 3

A cell containing a single set of unpaired chromosomes (n)

Gametes (sperm and eggs) contain the haploid number of chromosome

Question 4

Define homologous chromosomes.

Answer 4

Chromosomes that are similar in size, shape, and genetic content, one from each parent

They form pairs during meiosis.

Question 5

What is the role of gametes in reproduction?

Answer 5

Gametes are the reproductive cells that combine during fertilization to form a zygote

They are produced through meiosis.

Question 6

What occurs during Meiosis I?

Answer 6

Homologous chromosomes pair up and are separated, halving the chromosome number

This results in two haploid cells.

Question 7

What happens in Meiosis II?

Answer 7

Sister chromatids are separated, resulting in four genetically different haploid cells

Each cell has half the original chromosome number.

Question 8

What is the significance of genetic variation?

Answer 8

Genetic variation contributes to diversity within a species, allowing for adaptation and evolution

It arises from processes such as meiosis and mutations.

Question 9

Define phenotype.

Answer 9

An individual’s observable traits, influenced by genotype and environment

Examples include height, eye color, and blood type.

Question 10

Define genotype.

Answer 10

The genetic constitution of an organism, specifically the alleles present

It determines potential phenotypes.

Question 11

What is complete dominance?

Answer 11

A genetic scenario where one allele completely masks the expression of another

Example: Huntington’s disease where H is dominant over h.

Question 12

What is codominance?

Answer 12

A genetic condition where neither allele masks the expression of the other

Example: ABO blood groups where IA and IB are codominant.

Question 13

What is the Hardy-Weinberg equation used for?

Answer 13

To calculate allele, genotype, and phenotype frequencies in a population

It is based on the principle of genetic equilibrium.

Question 14

What does the term ‘gene pool’ refer to?

Answer 14

The complete set of genetic information within a population

It includes all the alleles for every gene in that population.

Question 15

What is the significance of the Chi-squared test (X²)?

Answer 15

It assesses whether observed results differ significantly from expected results

Used in genetics to compare phenotypic ratios.

Question 16

Fill in the blank: During meiosis, homologous chromosomes come together and pair up in _______.

Answer 16

Meiosis I

Question 17

What is variation caused by?

Answer 17

Differences from genetic and/or environmental factors

It can be influenced by mutations and sexual reproduction.

Question 18

Define zygosity.

Answer 18

The degree of similarity of the alleles in an organism

Types include homozygous, heterozygous, and hemizygous.

Question 19

What is a monohybrid cross?

Answer 19

A genetic cross that examines the inheritance of a single trait

It typically involves two alleles, one dominant and one recessive.

Question 20

What is codominance in alleles?

Answer 20

Codominance occurs when both alleles contribute to the phenotype of the organism.

Question 21

What is zygote?

Answer 21

*It’s a cell that forms when a sperm and egg cell unite during fertilization.
*It contains the genetic information for a new organism

Question 22

What does “sexual reproduction means”?

Answer 22

*It’s the process of creating new organisms by combining genetic information from two different parents.
*This process involves the fusion of a male and female sex cell, also known as gametes

Question 23

What is “gene” ?

Answer 23

It’s a section of DNA on a chromosome that controls a feature by coding for formation of one or more specific polypeptides or a functional RNA (including rRNA and tRNA).

Question 24

What is an “Allele”?

Answer 24

It’s an alternative forms of a particular gene with different base sequences, and therefore different codes

Question 25

What happens in meiosis?

Answer 25

* the cell divides * reproductive organs occur * productions of gametes * 4 daughter cells are produced * diploid to haploid * genetically different to parent cell (variation)

Question 26

Define the steps in “Meiosis”?

Answer 26

1. DNA unravels and replicates so there are 2 copies of each chromosome called chromatids 2. DNA condenses to form double-armed chromosomes. These consist of 2 sister chromatids, joined in the middle by a centromere. 3. Chromosomes arrange themselves into homologous pairs 4. Homologous pairs are then separated, halving the chromosome number 5. The pairs of sister chromatids that make up each chromosome are separated (Centromere divides) 6. Four haploid cells genetically different from each other have been produced

Question 27

Define what is “dominant”?

Answer 27

It’s an allele that expresses itself in the phenotype in heterozygous organisms

Question 28

Define what is recessive?

Answer 28

It’s an allele that does not express itself in the phenotype in heterozygous organisms

Question 29

Define what is a “trait”?

Answer 29

a trait is a characteristic of an organism that is determined by its genes and environment

Question 30

Define what is “mutation”?

Answer 30

* it’s a change in the DNA sequence of an organism. *Mutations can be caused by errors in cell division, exposure to radiation or chemicals, or viral infections.

Question 31

What is an “autosomal”?

Answer 31

A chromosome which is not a sex chromosome

Question 32

Define what is “homozygous”?

Answer 32

It’s a situation or organism in which paired alleles are the same

Question 33

Define what is “heterozygous”?

Answer 33

It’s a situation of organism in which paired alleles are different

Question 34

What do we mean by “hemizygous”?

Answer 34

It means having one copy of a gene or chromosome, instead of the normal two copies. *This can occur due to a number of reasons, including genetic deficiencies, abnormalities, or the pairing of an X and Y chromosome

Question 35

What is “Co-dominant”?

Answer 35

Alleles which both contribute to the phenotype (i.e. produce a blended effect) in the heterozygous condition

Question 36

What doe mean by “Locus”?

Answer 36

The specific linear position of a particular gene on a certain chromosome

Question 37

Define what is the “Inheritance of sex”?

Answer 37

* the inheritance of the sex of a child is 50% chance girl, 50% boy * the mother’s egg can only contain an X chromosome

Question 38

Who choose the sex of the baby?

Answer 38

* it is the father’s sperm that controls the sex if the child (X or Y) * therefore, if the sperm gets to the egg first containing an X chromosome it will be a girl and if Y then it’s a boy