Year 10 – Chapter 1.3

Question 1

Recall the term used to describe:

• alternative forms of gene
• an organism with different alleles for a particular gene
• the observable characteristics of an individual
• an individual with two copies of the same allele of a gene.

Answer 1

• Allele
• Heterozygous
• Phenotype
• Homozygous

Question 2

Predict the number of chromosomes that would be found in the following human cells:

• Ovum
• Muscle cell
• Skin cell
• Sperm cell

Answer 2

• 23
• 46
• 46
• 23

Question 3

Use an example to explain the relationship between genes and alleles.

Answer 3

Answer may vary, however, it MUST INCLUDE:

• Dominant and recessive alleles
• Genetic Code
• Genotype
• Phenotype

Question 4

Contrast:

• Homozygous and heterozygous
• Phenotype and genotype
• Autosome and sex chromosome

Answer 4

• Homozygous organisms have the same types of alleles, while heterozygous organisms have different types of alleles.
• A genotype is the written description of a trait and a phenotype is the observable description of a trait
• Autosomes are all the chromosomes in a cell except the sex chromosomes. Sex chromosomes determine the sex of an individual.

Question 5

State what is meant by a pure-breeding line of plants.

Answer 5

A pure-breeding line of plants would mean that all of the individuals have the same genetic information.