3:1 ratio in F2 generation of a monohybrid cross suggested that segregation of alleles does take place and it can be confirmed by test cross. Answer : (c)

Number of gametes = 2n where n = no. of heterozygous allele pair. Female has two heterozygous allele pair. Thus number of gamete = 22 = 4. Gametes are AB, Ab, aB and ab. Male has no heterozygous allele pair. Thus number of gamete = 2. Gamete is Ab. Answer : (c)

Gametes	RY	Ry	rY	ry
RY	RRYY (round, yellow)	RRYy (round,yellow)	RrYY (round, yellow)	RrYy (round, yellow)
Ry	RRYy (round, yellow)	RRyy (round, green)	RrYy (round, yellow)	Rryy (round, green)
rY	RrYY (round, yellow)	RrYy (round, yellow)	rrYY ( wrinkled, yellow)	rrYy (wrinkled, yellow)
ry	RrYy (round, yellow)	Rryy ( round, green)	rrYy ( wrinkled, yellow)	Rryy (wrinkled, green)

Recombinant offspring are children that have a different allele combination to their parents i.e., have different phenotype. Example RRYY × rryy → F1 generation RrYy In a dihybrid cross, during F2 generation 16 progeny are formed, in this, 10 progeny shows parental phenotypes, remaining 6 progeny shows new phenotypes. These are called recombinants. So, in the F2 generation 1280 progeny are formed, in this 800 progeny shows parental phenotypes and 480 progenies are recombinants. Answer : (c)

Law of Mendel is not completely applicable for co-dominance. Answer : (c)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
1	Monohybrid cross	2	4	2	3	3:1	1:2:1

Answer : (b)

Gametes produced by individuals = 2n where n = no. of heterozygous allele pair. No. of gametes having produced from one heterozygous pair = 21 = 2 Answer : (a)

Law of independent assortment is demonstrated by dihybrid cross. Law of segregation or purity of gamete and law of dominance is demonstrated by monohybrid cross Answer : (b)

Brown eye colour is dominant and blue eye colour is recessive. The progeny has brown eyes. This implies that progeny has character of dominant individual. Since mother has blue eyes, phenotype of father should be brown eyes in order for progeny to have brown eyes. Answer : (d)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
2	Dihybrid cross	4	16	4	9	9:3:3:1	2:4:2:1:2:1:1:2:1

Answer : (b)

Mendelian principles are the rules of inheritance first discovered by Mendel. Law of dominance and law of segregation also called law of purity are based on monohybrid cross. Law of independent assortment are based on dihybrid cross. Answer : (c)

Gametes	AB	aB
aB	AaBB	aaBB
aB	AaBB	aaBB

AaBB × aaBB AaBB : aaBB 1 : 1 Answer : (a)

Answer : (d)

Complementary gene may be defined as two or more dominant genes present on separate gene loci which interact to produce a particular phenotypic trait, but neither of them produces phenotypic trait in absence of other. Supplementary gene are two independent genes (nonallelic pair) present on different gene loci, each producing its own trait. These genes interact when present in dominant state to produce a new trait. Answer : (a)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
2	Dihybrid cross	4	16	4	9	9:3:3:1	2:4:2:1:2:1:1:2:1

Answer : (c)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
3	Trihybrid cross	8	64	8	27	(3:1)3	(1:2:1)3

Answer : (b)

Gametes	R	r
R	RR (red)	Rr (pink)
r	Rr (pink)	Rr (white)

Blending inheritance is the phenomenon where none of two contrasting alleles or factors is dominant . Example: In a cross between true-breeding red-flowered (RR) and truebreeding white-flowered plants (rr), the F1 (Rr) was pink . When the F1 was self-pollinated the F2 resulted in the following ratio 1 (RR) Red: 2 (Rr) Pink: 1 (rr) White. The genotype ratios is exactly as monohybrid cross. Red flower (RR) × White flower (rr) → Pink flower (Rr) Pink flower (Rr) × Pink flower (Rr) → Genotypic ratio RR : Rr : rr = 1 : 2 : 1 Phenotypic ratio Red : pink : white = 1 : 2 : 1 Answer : (a)

"Eugenics is the study of the agencies under social control that may improve or impair the racial qualities of future generations either physically or mentally." Eugenics, meaning "well born," was introduced in the 1880s by Sir Francis Galton, a cousin of Charles Darwin and the father of modern statistics. Answer : (c)

Mendel choose characters which shows complete independent assortment. He took only those traits for his studies which did not show linkage, interaction or incomplete interaction. Answer : (b)

The portion or region on chromosomes representing a single gene is called gene locus. Answer : (a)

Gregor Johann Mendel appropriately known as father of genetics, proposed the theory of inheritance. Answer : (b)

phenotype, all the observable characteristics of an organism that result from the interaction of its genotype (total genetic inheritance) with the environment. Answer : (b)

Mendel conducted breeding experiments on garden peas (Pisum sativum) in the garden of his monastery and was luckily the first to formulate clear cut principles or laws of heredity. Answer : (b)

Organisms have various traits and they have contrasting characters. Example height is trait which have contrast character like tall and dwarf. Option (a) is correct statement. Hybrids are fertilized and produces progeny. Option (b) is incorrect statement. Plants can undergo self fertilization. Example sunflowers. Option (c) is correct statement. Small herbaceous requires small area and thus can be easily cultivated. Option (d) is correct statement. Answer : (b)

While Mendel's work laid the foundation, it was German botanist Carl Correns (1864–1933) who is credited with the actual discovery of incomplete dominance. Answer : (b)

A genome is a complete set of chromosomes where every gene chromosome is represented singly as in gamete. Thus, genome represents total number of genes in haploid set of chromosomes. Answer : (c)

Mendel luckily studied only those characters which showed complete independent assortment. If one of the combination does not show independent assortment, that implies Mendel might not have studied all the combinations. Answer : (b)

Characters	Expected ratios	Example
Monohybrid cross	Phenotypic = 3 : 1 Genotypic = 1 :2 : 1	Pisum sativum
Dihybrid cross	Phenotypic = 9:3:3:1	Pisum sativum
Incomplete dominance	1 : 2 : 1	Mirabilis jalapa
Complementary genes	9 : 7	Lathyrus odoratus
Supplementary genes	9 : 3 : 4	Coat colour of mice
Collaborative supplementary genes	9 : 3 : 3 : 1	Poultry birds – comb pattern
Dominant epistasis	12 : 3 : 1	Fruit colour in Curcurbita
Recessive epistasis	9 : 3 : 4	Coat colour in mice/pigmentation in onion bulb
Duplicate genes	15 : 1	Fruit shape in Capsella bursapastoris
Polymeric gene	9 : 6 : 1	Cucurbita pepo
Suppresor gene	13:3	Leaf colour of rice

Answer : (c)

It was in 1900, three workers independently rediscovered the principles of heredity already worked out the mendel. They were Hugo de Vries of Holland, Carl Correns of Germany and Erich von Tschermak of Austria. Answer : (c)

Kolreuter, a German botanist obtained fertile interspecific hybrids in tobacco. The hybrid did not resemble either of the parents. Hybrids were self pollinated. Some offspring resembled the hybrids while remaining resembled one of the other grandparents in different characters. This proved that the traits have particulate nature and remain discrete. Answer : (c)

Answer : (b)

Gregor Johann Mendel was a meteorologist, mathematician, biologist, Augustinian friar and abbot of St. Thomas' Abbey in Brno, Margraviate of Moravia. He was an Austrian monk. Answer : (a)

Human eye colour, skin colour and height shows polygenic inheritance. ABO blood group is an example of co-dominance, multiple alleles and dominance. Mirabilis jalapa is an incomplete dominance. Sickle cell aneamia is an example of pleiotropy. Answer : (d)

Progeny has blood group O is IOIO. Each allele is obtained from each parent. That implies one IO is from mother and IO is from father. Thus genotype of father blood group should have IO. Since the father’s blood group is A, thus genotype will be IAIO Answer : (c)

Unlike his predecessors who worked on large number of characters simultaneously, Mendel worked with one or few pairs of trait at one trait. He kept record of every cross and subsequent generations produced through self-breeding. Thus he maintained the statistical records of all experiments and analyzed them carefully. Answer : (d)

The disease is controlled by a single pair of allele, HbA and HbS . HbS has ability to produce multiple phenotypic effect. In homozygous state, it is diseased phenotype. In heterozygous state, it is carrier phenotype. This ability is called pleiotropy. Answer : (c)

Though Mendel did not know about chromosomes, all the traits he studied were on different pairs of homologous chromosomes. That is why he concluded that gene pairs segregate independently of one another. Mendel’s gene pair did not show linkage. Answer : (c)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
1	Monohybrid cross	2	4	2	3	3:1	1:2:1
2	Dihybrid cross	4	16	4	9	9:3:3:1	2:4:2:1:2:1:1:2:1
3	Trihybrid cross	8	64	8	27	(3:1)3	(1:2:1)3

Answer : (b)

Gametes	AB	Ab	aB	ab
AB	AABB	AABb	AaBB	AaBb
Ab	AABb	AAbb	AaBb	Aabb
aB	AaBB	AaBb	aaBB	aaBb
ab	AaBb	Aabb	aaBb	aabb

AABB × aabb → F1 generation AaBb AaBb × AaBb AABB : AABb : AaBB : AaBb 1 : 2 : 2 : 4 Answer : (d)

Mirabilis jalapa expresses incomplete dominance. Answer : (b)

Mendel’s principle of segregation is based on segregation of allele during gamete formation. At the formation of gamete, allele separate and gametes carry either dominant or recessive of alleleic pair but not both. The gametes which are formed are always pure for a particular character. Answer : (a)

The ratio suggests that incomplete dominance occur. In this phenomenon there is no dominant-recessive relationship, and the hybrid i.e., F1 generation is intermediate. In this case, pink flower is intermediate and its genotype is herterozygous allelic pair. Genotype of F1 is Rr. Answer : (b)

Gametes	A	a
a	Aa (dominant)	aa (recessive)
a	Aa (dominant)	aa (recessive)

Given result is obtained when one parent is heterozygous dominant and another is recessive. Aa × aa Answer : (c)

Mendel’s principle of segregation is based on segregation of allele during gamete formation. At the formation of gamete, allele separate and gametes carry either dominant or recessive of alleleic pair but not both. The gametes which are formed are always pure for a particular character. Answer : (c)

Gamete	RT	Rt	rT	rt
rt	RrTt;	Rrtt	rrTt	rrtt
rt	RrTt	Rrtt	rrTt	rrtt

RrTt × rrtt → F2 generation Round, tall : Round, dwarf : wrinkled, tall : wrinkled, dwarf 1 : 1 : 1 : 1 Answer : (b)

Traits	Dominant	Recessive
Plant height	Tall (1.2 – 2.0m)(T)	Dwarf (0.25 – 0.5m) (t)
Flower position	Axillary (A)	Terminal (a)
Pod colour	Green (G) or (Y)	Yellow (g) or (y)
Pod shape	Full or inflated (I) or (C)	Constricted (i) or (c)
Flower colour	Violet (V) or (W)	White (v) or (w)
Seed shape	Round (R) or (W)	Wrinkled (r) or (w)
Seed colour	Yellow (Y) or (G)	Green (y) or (g)

Mendel studied the following Pod length was not studied by Mendel. Ans:(c)

Gametes	RT	Rt
rt	RrTt (red fruit, tall)	Rrtt (red fruit, dwarf)

RRTt × rrtt All the progeny is red fruit and 50% progeny is tall and 50% dwarf. Answer : (b)

Gametes	AB	Ab	aB	ab
ab	AaBb	Aabb	aaBb	aabb

Progeny of AAbb and aaBB will be AaBb. AaBb × aabb → AaBb : Aabb : aaBb : aabb 1 : 1 : 1 : 1 Answer : (c)

Lethal alleles (also referred to as lethal genes or lethals) are alleles that cause the death of the organism that carries them. They are usually a result of mutations in genes that are essential for growth or development. Lethal genes are those genes which cause the death of organisms but only when they are present in the homozygous state. Answer : (d)

Inheritance of skin color, eye colour and height is an example of polygenic inheritance Answer : (c)

No. of traits (n)	Experiment	Types of gametes (2n)	No. of offsprings (gametes)2	No. of phenotype (2n)	No. of genotype (3n)	Phenotypic ratio	Genotypic ratio
2	Dihybrid cross	4	16	4	9	9:3:3:1	2:4:2:1:2:1:1:2:1

Answer : (d)