Genetics

Question 1

Define gene

Answer 1

A particular length of DNA at a particular location on the chromosome that influences a particular characteristic

Question 2

Define allele

Answer 2

Alternative forms of a gene found at the same locus, and providing different expressions of characteristics.

Question 3

Define phenotype

Answer 3

The external appearance of an organism

Question 4

Define genotype

Answer 4

The genetic composition of an individual

Question 5

Define homozygous

Answer 5

When an individual has 2 copies of the same allele for a particular characteristic

Question 6

Define heterozygous

Answer 6

When an individual has 2 contrasting or different alleles for a characteristic

Question 7

What is complete dominance?

Answer 7

one allele is dominant and the other is recessive, such that the effect of the recessive allele is masked by the dominant allele in the heterozygous condition

Question 8

What is incomplete dominance?

Answer 8

None of the 2 alleles of a gene is dominant over the other, resulting in an intermediate phenotype in the heterozygous condition

Question 9

What is co-dominance?

Answer 9

Both alleles of a gene are equally dominant whereby both alleles express themselves in the phenotype in the heterozygous condition

Question 10

What’s the function of a pedigree?

Answer 10

Traces the inheritance of characteristics over many generations

Question 11

What are the genotypes of AB, A, B, O?

Answer 11

• AB- IaIa
• A- (IaIa), (Iai)
• B- (IbIb), (Ibi)
• O- (ii)

Question 12

Define genetics

Answer 12

Sudden, random changes in a genetic organism which can be inherited

Question 13

Explain the effects of harmful and harmless mutations

Answer 13

Harmful (lethal): the mutated organism dies and the harmful characteristics are not passed down to the next generation

Harmless:
• Neutral mutation- it has no effect on the structure or the functioning of the organism which possesses them
• Advantageous mutation- it leads to new characteristics that are beneficial to the organism

Question 14

Define gene mutation

Answer 14

Sudden change to the structure of a gene leading to the altered characteristics

Question 15

Define chromosomal aberration

Answer 15

A change in the normal number and structure of chromosomes in an individual

Question 16

Name 3 genetic disorders

Answer 16

• Haemophilia- absence of blood clotting factors
• Colour-blindness- due to the absence of the proteins that comprise red or green photoreceptors in the eye
• Down syndrome- due to an extra copy of chromosome 21 as a result of non-disjunction in meiosis

Question 17

Gives the sources and uses of stem cells

Answer 17

Uses:
• replace diseased or damaged cells

Sources:
• cord blood
• embryo
• bone marrow

Question 18

Give the benefits of genetic modification

Answer 18

• biological and medical research
• production of pharmaceutical drugs
• experimental medicine
• agriculture

Question 19

What are the benefits of cloning?

Answer 19

• Farmers will be able to produce animals identical to the ones that they already have and prefer
• In embryo cloning, embryos are cloned to harvest stem cells from them

Question 20

What is the role of blood grouping & DNA profiles in paternity testing?

Answer 20

• Blood grouping: by testing the blood type of a person we can tell if the person is definitely not the father of the child or might be the father of a child
• DNA profiles: we can determine whether 2 individuals have a biological parent-child relationship