Mendel (1822-1884) conducted breeding experiments on garden peas (Pisum sativum) in garden of his monastery from 1856 to 1865 i.e., for 8 years. He formulated laws of inheritance and published his paper “Experiments of plant hybridization” in the fourth volume of “Annual Proceedings of Natural History Society of Brunn” in 1886. Answer : (b)

Mirabilis jalapa shows incomplete dominance. Answer : (a)

Blood type (phenotype)	Genotype	Antigen	Antibodies
A	IAIA or IAIO	B	a
B	IBIB or IBIO	B	a
AB	IAIB	Both A and B	Neither a nor b
O	IOIO	Neither A nor B	Both a and b

Inheritance of ABO blood group is an example of dominance, codominance and multiple allele. Co-dominance because In ABO both allele expresses themselves in the organism. Multiple alleles because blood group is determined by combination of three alleles IA, IB and IO or i. Dominance because blood group is determined by antigen types. And IA and IB is codominant over recessive i. Answer : (c)

At the formation of gametes, pair of allele separate, otherwise the recessive type will not appear in F2 generation. The gametes which are always pure for a particular character. Answer : (b)

Mendel’s principles are based on transfer of character from one generation to another. It is related to heredity. Answer : (d)

Gametes	R	r
r	Rr (red flower)	Rr (white flower)

Rr (heterozygous red flower) × rr (white flower) Rr (red flower) : rr (white flower) 1 : 1 Answer : (a)

The ability of a gene to have multiple phenotypic effect because it influences a number of characters simultaneously is known as pleiotropy. The gene having a multiple phenotypic effect because of its ability to control expression of a number of characters is called pleiotropic gene. Since same gene is affecting eye colour as well as depigmentation of body parts, it is an example of pleiotropic gene. Answer : (b)

Gametes	B	b
b	Bb (brown eyes)	Bb (blue eyes)

Man has mother whose eye colour is blue. This means that man is heterozygous brown eyes. Brown eyed man marries blue eyed woman. Bb(brown eyes ) × bb (blue eyes) Brown eyes : blue eyes 1 : 1 Answer : (a)

Dihybrid cross is a cross between two individuals who differ in two observed traits that are controlled by two distinct genes Answer : (c)

Heterozygous allele means having two different allele i.e., one is dominant and one is recessive. Two gene alleles will be RrYy. Answer : (c)

Gametes	T	t
t	Tt (tall)	Tt (dwarf)

Tt × tt Answer : (c)

In dihybrid cross, two factors of each trait assort at random and independent of the factors of other traits at the time of meiosis and get randomly as well as independently rearranged in the offspring. Example:- Round : Wrinkled = 3 : 1 and yellow : green = 3 : 1 Round,yellow : Round, green : Wrinkled,yellow : wrinkled,green = (3 : 1) × (3 : 1) = 9 : 3 : 3 : 1 Answer : (b)

This is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous). The disease is controlled by a single pair of allele, HbA and HbS. Out of the three possible genotypes only homozygous individuals for HbS (HbSHbS ) show the diseased phenotype. Heterozygous (HbAHbS ) individuals appear apparently unaffected but they are carrier of the disease Answer : (b)

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

Mendel was born in 1822, 19th century. 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	R	r
r	Rr (normal)	rr (albino)

Albinism is an autosomal recessive metabolic disorder. Woman has albino father i.e., this means she is heterozygous (Rr). She marries an albino man. Man is allele is rr Rr × rr Normal progeny : albino progeny 1 : 1 Answer : (d)

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:(d)

Gametes	X	Y
Xc	XcX (carrier girl)	XcY (diseased boy)
X	XX (normal girl)	XY (normal boy)

Colour blindness is an sex linked recessive disorder. This defect is due to mutation in certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per cent of females. Mostly women are carrier of gene. They are colour blind only when her mother is carrier and father is colour blind. In the above case, man has colour blind father. Thus man is normal with genotype XY. Woman has colour blind mother and normal father. This means she is carrier of gene with genotype XcX XY × XcX Diseased boy : Normal boy 1 : 1 Answer:(a)

Turner’s Syndrome: Such a disorder is caused due to the absence of one of the X chromosomes, i.e., 45 with X0. Such females are sterile as ovaries are rudimentary besides other features including lack of other secondary sexual characters. Answer:(c)

An allele is one of two, or more, forms of a given gene variant. Answer:(d)

Multiple alleles: They are multiple forms of a Mendelian factor or gene which occur on the same gene locus, distributed in different organisms in the gene pool with an organism carrying only two alleles and gametes only one allele. Answer:(d)

Genotype	IA	IO
IB	IAIB (AB blood group)	IBIO (B blood group)
IO	IAIO (A blood group)	IOIO (O blood group)

Answer:(d)

Mendel studied seven character of garden peas. These are plant height, flower position, pod colour, pod shape, flower colour, seed colour and seed shape. Out of these 2 are flower based i.e., Flower position and flower colour. Answer:(a)

A tall true breeding plant (TT) is crossed with a dwarf true breeding plant (tt). F1 generation has genotype is Tt. F1 generation is selfed. Tt (heterozygous tall plant) × Tt (heterozygous tall plant) → Genotypic ratio = TT (tall homozygous) : Tt (tall heterozygous) : tt (dwarf) 1 : 2 : 1 Answer:(a)

The ability of a gene to have multiple phenotypic effect because it influences a number of characters simultaneously is known as pleiotropy Polygenic inheritance - inheritance, involves the transfer of a character by the involvement of a more than one gene. It produces multiple phenotypes. Codominance: It is the phenomenon of two alleles lacking dominant recessive relationship and both expressing themselves in the organism. Answer:(b)

When a cross is conducted between F1 dihybrid flies with homozygous recessive parent fly, more parental type offspring were produced than recombinant type offspring. This indicates, that the two genes are linked and present on the same chromosome. Answer:(c)

A frequency of recombination of 50% indicates that the genes are independently assorting. Independent assortment signifies that genes are different chromosomes. This implies that genes are at distance and chance of crossing over increases The tightly linked genes show 100% parental types and 0% recombinants. Answer:(b)

Codominance: It is the phenomenon of two alleles lacking dominant recessive relationship and both expressing themselves in the organism. Answer:(a)

Codominance: It is the phenomenon of two alleles lacking dominant recessive relationship and both expressing themselves in the organism. Co-dominance Answer:(d)

Gametes	A	a
A	AA (normal)	Aa (carrier)
a	Aa (carrier)	aa (diseased)

Thalassemia–autosomal-linked recessive AA-Normal Aa-Carrier aa-Disease Aa × Aa → diseased = ¼ = 25% Answer:(c)

Gametes	X	X
Xc	XcX (carrier, girl)	XcX (carrier girl)
Y	XY (normal boy)	XY (normal boy)

Colour blindness is sex linked recessive disease. This defect is due to mutation in certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per cent of females. Man is colour blind, thus its genotype is XcY. Woman is homozygous for normal vision. Her genotype will be XX. XX × XcY Girls will be carrier of colour blindness and boys will be having normal vision. Answer:(c)

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)

During his experiments Mendel studied seven characters. Nature of trichomes i.e., glandular or non-glandular was not considered by Mendel Answer:(b)

Mendel conducted hybridization experiments on Pea plant for 7 years between 1856 to 1863 and his data was published in 1865 (according to NCERT) Answer:(a)

Thalassemia differs from sickle-cell anaemia in that the former is a quantitative problem of synthesizing too few globin molecules while the latter is a qualitative problem of synthesising an incorrectly functioning globin. Answer:(c)

Codominance: It is the phenomenon of two alleles lacking dominant recessive relationship and both expressing themselves in the organism. This is possible in the heterozygous allele. Answer:(a)

The gene controlling starch synthesis in pea exhibits pleiotropy. The gene regulates the starch synthesis and the shape of the seed. It has two alleles, B and b. Starch is synthesized by BB homozygotes and large starch granules are produced. Answer : (a)

Blood type (phenotype)	Genotype	Antigen	Antibodies
A	IAIA or IAIO	A	b
B	IBIB or IBIO	B	a
AB	IAIB	Both A and B	Neither a nor b
O	IOIO	Neither A nor B	Both a and b

Inheritance of ABO blood group is an example of dominance, codominance and multiple allele. Co-dominance because In ABO both allele expresses themselves in the organism. Multiple alleles because blood group is determined by combination of three alleles IA, IB and IO or i. Dominance because blood group is determined by antigen types. And IA and IB is codominant over recessive i. Answer : (b)

Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect for the following groups of genotype to have same phenotype, number of dominant genes should be equal in number. In first option, groups having dominant genes are 6, 3 and zero respectively. In second option, all the groups have equal dominant genes. In third option, Groups having dominant genes are 2, 4 and 1 respectively. Thus second option's genotypes have same phenotype. Answer : (b)

Experimental verification of the chromosomal theory of inheritance by Thomas Hunt Morgan and his colleagues, led to discovering the basis for the variation that sexual reproduction produced. Morgan worked with the tiny fruit flies, Drosophila melanogaster Answer : (d)

Genes for flower colour in snapdragon shows incomplete dominance which is an exception of Mendel's first principle i.e. Law of dominance. Whereas Law of segregation is universally applicable. When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly. This is known as the law of segregation. Answer : (b)

Genotypic and phenotypic ratio of incomplete dominance is 1 : 2 : 1. Phenotypic ratio of monohybrid cross is 3 : 1. Phenotypic ratio of dihybrid cross is 9 : 3 : 3 : 1. Dihybrid test cross ratio is 1 : 1 : 1 : 1. Answer:(a)

Whole genome sequencing (WGS), also known as full genome sequencing, complete genome sequencing, or entire genome sequencing, is the process of determining the entirety, or nearly the entirety, of the DNA sequence of an organism's genome at a single time. The genetic maps are used as a starting point in the sequencing of whole genomes Answer:(b)

Epistasis occurs when one gene is able to mask the phenotype of another gene. Dominant epistasis is when only one allele of the gene that shows epistasis can mask alleles of the other gene. Recessive epistasis is where two alleles have to be inherited in order for the phenotype of the second gene to be masked. a dominant allele at one locus may mask the phenotype of a second locus. This is called dominant epistasis, which produces a segregation ratio such as 12:3:1, which can be viewed as a modification of the 9:3:3:1 ratio in which the A_B_ class is combined with one of the other genotypic classes that contains a dominant allele. One of the best known examples of a 12:3:1 segregation ratio is fruit color in some types of squash . Alleles of a locus that we will call B produce either yellow (B_) or green (bb) fruit. However, in the presence of a dominant allele at a second locus that we call A, no pigment is produced at all, and fruit are white. The dominant A allele is therefore epistatic to both B and bb combinations as shown in figure. One possible biological interpretation of this segregation pattern is that the function of the A allele somehow blocks an early stage of pigment synthesis, before neither yellow or green pigments are produced. Ration 9:3:4 is for Recessive epistasis Answer : (d)

T.H. Morgan discovered linkage. Cross of parent and pure recessive plant is called test cross. It is done to determine whether the individual exhibiting dominant character is homozygous or herterozygous. G. Mendel is regarded as father of genetics and his three laws is well known. A ribozyme is a ribonucleic acid (RNA) enzyme that catalyzes a chemical reaction. They are RNA molecules able to break and form covalent bonds within a nucleic acid molecule. Answer : (b)

Answer : (a)

Please note given is "RrTy" Now there are three genes R, T, y Now R is in pair, But T and y are not T and y has to appear in all combinations thus Gamete type 1. RTy 2.rTy Answer : (b)

For example, in the snapdragon, Antirrhinum majus, a cross between a homozygous white-flowered plant (CWCW) and a homozygous red-flowered plant (CR CR) will produce offspring with pink flowers (CRCW) This type of relationship between alleles, with a heterozygote phenotype intermediate between the two homozygote phenotypes, is called incomplete dominance. self-fertilization of a pink plant would produce a genotype ratio of 1:2:1 and phenotype ratio of 1:2:1 red:pink:white Answer : (a)

Recessive trait are expressed when recessive allele are in homozygous. First seedn is colourless expressed as cc, smooth (SS) and waxy (WW). Genotype will be ccSSWW. Similarly second is coloured (CC), wrinkled (ss) and starchy (ww). Genotype will be CCssww. Answer:(b)

The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, The sex of birds is determined by the inheritance of sex chromosomes (ZZ male and ZW female). Genes carried on one or both of these sex chromosomes control sexual differentiation during embryonic life, producing testes in males (ZZ) and ovaries in females (ZW) Answer:(c)