Inheritance

Question 1

Dominant allele

Answer 1

Characteristic expressed in the phenotype even in the presence of another allele

Question 2

Recessive allele

Answer 2

Characteristic only expressed in the presence of another identical allele

Question 3

Genotype

Answer 3

The genetic makeup of an organism

Question 4

Phenotype

Answer 4

All the characteristics of an individual that are expressed, including physical, physiological and behavioural traits

Question 5

Why are dominant alleles expressed over recessive alleles (enzymes)

Answer 5

• The dominant allele codes for functioning enzyme and recessive codes for a dysfunctional enzyme.
• Hence in a heterozygous cell, at least some functional protein/enzyme is synthesized
• This is usually enought to express the dominant effect

Question 6

Mendel’s Law of Segregation

Answer 6

An organism’s characteristics are determined by internal factors occuring in pairs. Only one pair can be represented in a single genome

Question 7

Mendel’s Law of Independent Assortment

Answer 7

Any one pair of characteristics may combine with either one of another pair

Question 8

Heterozygous + Heterozygous

Answer 8

3:1

Question 9

Double Heterozygous + Double Heterozygous

Answer 9

9:3:3:1

Question 10

Heterozygous + Homozygous

Answer 10

1:1

Question 11

Double Heterozygous + Double Homozygous

Answer 11

1:1:1:1

Question 12

Codominance

Answer 12

Shows characteristics of both the alleles

Question 13

Incompete dominance

Answer 13

Shows an intermediate trait between the homozygous dominant and homozygous recessive phenotypes

Question 14

Sex linkage

Answer 14

Genes that are found on the sex chromosome and hence their expression will be affected by the sex/gender of the organism

Question 15

Autosomal linkage

Answer 15

2 separate genes found on the same chromosome; alleles of 2 genes that do not assort independently but are inherited together (w/o crossing over)

Question 16

Recombination frequency

Answer 16

Number of recombinants/ Total No. of offspring

Measures percentage of crossing over occurring

Question 17

Epistasis

Answer 17

Form of gene interaction where one epistatic gene masked or modifies the phenotypic expression of another hypostatic gene

Question 18

Double heterozygous + Double heterozygous
(epistasis)

Answer 18

12:3:1

Question 19

Duplicate genes

Answer 19

A gene at one locus may produce the same phenotype as another gene at another locus

Question 20

Double heterozygous + Double heterozygous
(duplicate genes)

Answer 20

15:1

Question 21

Variation

Answer 21

Differences in a characteristics observed in organisms of the same natural population or species

Question 22

Discontinuous variation

Answer 22

• Individuals show clear-cut differences
• Controlled by 1 or 2 genes

Question 23

Continuous Variation

Answer 23

• Individuals show a complete graduation from one extreme to another
• Additive effect of many genes