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#	Question	Answer
1	Which areas enriched our understanding of the molecular basis of evolution?	Molecular genetics, structural biology, and bioinformatics.
2	Which proposal made by Watson and Crick in 1953 became historic?	The double-helical structure for DNA and the replication scheme.
3	Define variation.	Variation is the degree by which progeny differ from their parents.
4	During which century was major progress made in understanding inheritance?	Mid-nineteenth century.
5	Give examples of contrasting traits studied by Mendel.	Tall/dwarf plants and yellow/green seeds.
6	What kind of pollination experiments did Mendel perform?	Artificial pollination/cross-pollination experiments.
7	Which symbols are used for tall and dwarf traits in pea plants?	T for tall and t for dwarf.
8	What is genotype?	The allelic composition of an organism.
9	Which allele is recessive in pea plant height?	t (dwarfness).
10	What is a monohybrid?	An organism heterozygous for genes controlling one character.
11	What is the probability of a gamete containing either allele in a heterozygote?	50 percent.
12	What is a Punnett Square?	A graphical representation used to calculate possible genotypes in a genetic cross.
13	What proportion of fertilisations produce Tt genotype?	1/2.
14	Why can phenotype alone not determine genotype in dominant traits?	Because both TT and Tt show the same dominant phenotype.
15	State the first point of the Law of Dominance.	Characters are controlled by discrete units called factors.
16	What type of gametes does a heterozygous parent produce?	Two kinds of gametes in equal proportion.
17	What does every gene contain?	Information to express a particular trait.
18	What are the three possible effects of a modified allele?	1. Normal/less efficient enzyme, 2. Non-functional enzyme, 3. No enzyme at all
19	Which gene controls ABO blood groups in humans?	Gene I.
20	What is multiple allelism?	Presence of more than two alleles governing the same character.
21	What is the seed shape of BB seeds after maturation?	Round.
22	Which symbols are used for seed shape alleles in the dihybrid cross?	R for round and r for wrinkled.
23	Which alleles are considered for seed colour in the dihybrid cross?	Y and y.
24	Why is segregation of R/r independent of Y/y?	Because alleles assort independently during meiosis.
25	What structures were observed doubling and dividing before cell division?	Chromosomes.
26	What does independent alignment of chromosome pairs explain?	Independent assortment of genes.
27	Which organism did Morgan use for genetic experiments?	Drosophila melanogaster (fruit fly).
28	What advantage did hereditary variations in Drosophila provide?	Variations could be observed easily with low-power microscopes.
29	On which chromosome were the studied genes located?	X chromosome.
30	Which gene pair in Drosophila showed only 1.3% recombination?	White and yellow genes.
31	Which major project used genetic maps extensively?	Human Genome Sequencing Project.
32	Define recombination.	Generation of non-parental gene combinations.
33	Which gene pair showed 37.2% recombination in Drosophila?	White and miniature wing genes.
34	Which project extensively used genetic maps?	Human Genome Sequencing Project.
35	What key concept did Morgan establish through his experiments?	Genes located on the same chromosome show linkage and do not assort independently.
36	Which genes are assumed to control human skin colour in the text?	A, B, and C.
37	What type of skin colour results from three dominant and three recessive alleles together?	Intermediate skin colour.
38	Which enzyme gene is mutated in phenylketonuria?	Phenylalanine hydroxylase.
39	In XO sex determination, what do all eggs contain?	An X chromosome besides autosomes.
40	What are autosomes?	Chromosomes other than sex chromosomes.
41	Which chromosome is smaller in XY type sex determination?	Y chromosome.
42	What are the two types of gametes produced in male heterogamety?	Gametes with X chromosome and gametes with Y chromosome (or without X in XO type).
43	Which sex produces two types of gametes in birds?	Females.
44	What type of ova are produced in human females?	Only X-bearing ova.
45	How is a male honey bee (drone) produced?	From an unfertilised egg by parthenogenesis.
46	What is mutation?	Alteration in DNA sequence causing changes in genotype and phenotype.
47	Which disease is a classical example of point mutation?	Sickle-cell anaemia.
48	Why is pedigree analysis important in human genetics?	It helps trace inheritance of specific traits, abnormalities, or diseases.
49	What is a mutation?	An alteration or change in genetic material.
50	Name some common Mendelian disorders mentioned in the text.	Haemophilia, cystic fibrosis, sickle-cell anaemia, colour blindness, phenylketonuria, and thalassemia.
51	Which colours cannot be distinguished in red-green colour blindness?	Red and green.
52	Why is a carrier mother usually not colour blind?	Because the normal dominant allele masks the recessive allele.
53	Can a heterozygous female transmit haemophilia?	Yes, to her sons.
54	What is the condition of heterozygous individuals (HbAHbS)?	They are carriers but usually unaffected.
55	How does sickle-cell anaemia affect RBC shape?	RBCs change from biconcave discs to elongated sickle-shaped structures.
56	What effect does accumulation of phenylalanine derivatives have on the brain?	Mental retardation.
57	Which globin chains are affected in thalassemia?	Alpha (α) and beta (β) globin chains.
58	What causes α-thalassemia?	Mutation or deletion of one or more α-globin genes.
59	What causes β-thalassemia?	Mutation in one or both HBB genes.
60	In which organisms is polyploidy commonly observed?	Plants.
61	What is genetics?	A branch of biology dealing with principles of inheritance and its practices.
62	In which condition are recessive traits expressed?	Homozygous condition.
63	What is a Punnett Square?	A square tabular representation showing theoretical combinations of gametes.
64	What causes distantly located linked genes to assort independently?	Recombination.
65	What are the sex chromosomes in male birds?	ZZ.
66	What is pedigree analysis used for?	Studying inheritance of traits and disorders in families.
67	Which scientist proposed the Chromosomal Theory of Inheritance?	Walter Sutton and Theodore Boveri (though Sutton specifically united the knowledge and named it).