PP 11

Question 1

What is the meaning of hereditary?

Answer 1

Heredity: The transmission of traits from one generation to the next.

Question 2

What is the idea of blended inheritance?

Answer 2

it suggested that offspring inherit any characteristic as the average of the parents’ values of that characteristic.
The idea that genetic material contributed by the two parents mixes in a manner analogous to the way blue and yellow paint blend to make green. Blended would mean that the less desirable trait (let’s say blue) would be swamped out by constantly mating with the desired trait (yellow). So this would mean after many matings, the blue trait will be lost, which is why you never see a blue rabbit.

Question 3

What did Gregor Mendel 1822-1884 do?

Answer 3

He was credited with developing formal explanation of how characteristics were passes from one generation to the next.

• Mainly worked on pea plants, which reproduced quickly and produced lots of seeds.
• Chose easy to observe characteristics like flower colour, etc.
• Careful mathematical analysis of the results gave rise to Mendel’s Principles (Mendel’s Model).

Question 4

What is the meaning of:

character, trait and true breeding

Answer 4

Character = detectable inheritable feature of an organism (e.g., flower colour)
Trait = variant of an inheritable feature (e.g. purple or white flowers)
True breeding = always producing offspring identical to self-fertilizing parents

Question 5

What is the meaning of:

phenotype, genotype, allele, dominants allele, recessive allele

Answer 5

Phenotype = an organism’s expressed trait (i.e., what you can see, like white flowers
Genotype = an organism’s genetic makeup (i.e., the DNA sequence that produces white flowers
Alleles = alternate forms of the same gene (i.e., in peas, there is one gene for flower colour but one allele codes for white flowers and the other allele codes for purple flowers.
Dominant allele = the allele whose appearance will be apparent even though the alternate allele is present, e.g., the purple allele is dominant to the white allele in peas
Recessive allele = the allele whose appearance will not be seen if the dominant allele is present, but will be if both recessive alleles are present in the organism

Question 6

What is the meaning of:

linked genes, homozygous, heterozygous, monohybrid cross, dihybrid cross?

Answer 6

Linked genes = two different genes that are present on the same chromosome
Homozygous = having two identical alleles
Heterozygous = having two different alleles
Monohybrid cross = a mating of two parents that are heterozygous for one characteristic (1 gene, 2 different alleles)
Dihybrid cross = a mating of two parents that are heterozygous for two characteristics (2 genes, each with 2 different alleles)