The US government granted a patent for Indian Basmati to the company “Rice tech”. The diversity of rice in India is one of the richest in the world, 27 documented varieties of Basmati are grown in India. The government of India challenged. Consequently United States Patent and Trademark Office sent a notice to rice tech for amendments in their claims and the patent was eventually cancelled. Answer:(d)

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. Answer:(a)

Induced mutations are considered as an alternative to naturally occurring variation. Assertion is true. Major causes of variation include mutations, gene flow, and sexual reproduction. Mutation is not the only reason. Reason is false. Answer:(c)

Ratio of tall: dwarf is almost 3:1. This occurs when the progeny is of three genotype: (i) Homozygous recessive (tt) (ii) Homozygous dominant (TT) [tall] (iii) Heterozygous (Tt) [tall]. Answer:(b)

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

Term recombination means the generation of non-parental gene combinations. Morgan and his group also found that even when genes were grouped on the same chromosome, some genes were very tightly linked and showed very low recombination, while others were loosely linked and showed higher recombination. Answer:(a)

Phenylketonuria: The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine. As a result of this phenylalanine is accumulated and converted into phenylpyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney. Answer:(b)

Two heterozygous plants when intercrossed produces dominant trait progeny and recessive trait progeny. Dominant : recessive = 3 : 1 Answer:(b)

Chromosome segregation occurs at two separate stages during meiosis called anaphase I and anaphase II. Different pairs of chromosomes segregate independently of each other, a process termed “independent assortment of non-homologous chromosomes” In the mitosis two daughter cell formed, they are alike to parent cell in the number and type of chromosome. So due to mitosis, the number of chromosomes in the cell remains the same therefore the division occurred in the parent cell. Answer:(c)

Morgan carried out several dihybrid crosses in Drosophila to study genes that were sex-linked. The crosses were similar to the dihybrid crosses carried out by Mendel in peas. For example Morgan hybridised yellow-bodied, white-eyed females to brown-bodied, red-eyed males and intercrossed their F1 progeny. He observed that the two genes did not segregate independently of each other and the F2 ratio deviated very significantly from the 9:3:3:1 ratio. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage Answer:(c)

Colour Blindness : It is a sex-linked recessive disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour. Sickle-cell anaemia : 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). Down’s Syndrome : The cause of this genetic disorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21) Answer:(c)

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

Crossing of F1 individual having dominant phenotype with its homozygous recessive parents is called test cross. The test cross is used to determine whether the individuals exhibiting dominant characters are homozygous or heterozygous. Tt × tt Answer:(d)

From 1856 to 1865, Mendel conducted breeding experiments on garden peas (Pisum sativum) in the garden of his monastery. His breeding materials consisted of pure lines. Unlike his predecessors who worked on large number of characters simultaneously, Mendel worked with one or few pairs of traits at one time. He kept record of every cross and subsequent generations produced through self breeding. Thus he maintained statistical records of all the experiments and analysed them carefully. Different varieties of pure breeding pea had contrasting expression of traits like height, color of flower, position of flower etc. Answer:(c)

When only one allelic pair (one trait/ character) is considered in cross breeding, it is called monohybrid cross. Answer:(b)

Mendel’s work was rediscovered in 1900 by three workers independently. They were Hugo de Vries of Holland, Carl Correns of Germany and Erich von Tschermak of Austria. Mendel’s law of dominance states that characters are controlled by discrete units called factors. Factors occur in pairs. Mendel could not provide physical proof of existence of factor. He kept statistical records of all the experiment and analysed them carefully to formulate clear cut principles or law of heredity. Answer:(b)

No. of gametes = (2)n where n = no. of heterozygous alleles.       = (2)3      = 8 Answer:(b)

Penetrance refers to the proportion of people with a particular genetic variant (or gene mutation) who exhibit signs and symptoms of a genetic disorder. If some people with the variant do not develop features of the disorder, the condition is said to have reduced (or incomplete) penetrance. Answer:(b)

Consanguineous matings (marriages, if humans are under discussion) are those between related individuals, defined simply as those that share a common ancestor. Male is represented by square. Female is represented by circle. In pedigree charts, consanguineous matings are indicated by double lines between symbols. Answer:(c)

Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. For example, Down’s syndrome results in the gain of extra copy of chromosome 21. Answer:(d)

Ratio of the above progenies is almost 9 : 3 : 3 : 1. This ratio is seen in F2 generation of dihybrid cross. F2 generation is obtained by selfing of F1 generation i.e. heterozygous allele. Probable genotype of parent for the above mentioned progenies is AaLl. Answer:(a)

Haemophilia : This sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny. Colour Blidness : It is a sex-linked recessive disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour. This defect is due to mutation in certain genes present in the X chromosome. Answer:(c)

Haploid plants, are always pure because they possess only one set of chromosomes. So, the mutations are expressed very easily in haploid plants as compared to diploid plants. Answer:(b)

Lethal alleles 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. Assertin is true. Mutations can be harmful as well as beneficial. Subvital reduces the chances of survival. Supravital mutations result in the improvement of biological fitness under certain conditions. Reason is false. Answer:(c)

From the information, we can derive the conclusion that there is mutation on X chromosomes. This mutation is lethal and recessive. Female has pair of XX chromosomes that why they are carrier of mutation, but male has XY chromosomes and thus mutation on X chromosome does not allow zygote of XY to survive. Answer:(b)

Grasshopper is an example of XO type of sex determination in which the males have only one X-chromosome besides the autosomes, whereas females have a pair of X-chromosomes. AA (female) × AO (male) Gametes A A A AA (female) AA (female) O AO (male) AO (male) 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)

In DNA, mutations or accidental changes in its code can occur. Mutations can lead to missing or malformed proteins, and that can lead to disease. Most inherited genetic diseases are recessive, which means that a person must inherit two copies of the mutated gene to inherit a disorder. However, in heterozygotes, these recessive mutated alleles do not express themselves in presence of the dominant allele. Thus, harmful mutations are not expressed in presence of dominant gene. Answer:(b)

83% parental combinations 17% Recombinations Answer:(a)

Blood type (phenotype)	Genotype	Antigen	Antibodies
A	IAIA or IAIO	A	b
B	IBIB or IBI0	B	a
AB	IAIB	Both A and B	Neither a nor b
O	IOIO	Neither A nor B	Both a and b

Answer:(d)

Answer:(a)

Sickle-cell anaemia : 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)

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

A cross of F1 hybrid with either of the two parents is known as back cross. Crossing of F1 individual having dominant phenotype with its homozygous recessive parents is called test cross. The test cross is used to determine whether the individuals exhibiting dominant characters are homozygous or heterozygous Tt × tt Answer:(c)

Albinism is a lethal trait of corn because all the albino plants lack chlorophyll and cannot make their own food by photosynthesis. Therefore, they die as seedlings after their food supply in the seed is exhausted. Under cultivation, the lethal allele for albino has been maintained in a population of corn for decades. Answer:(a)

For the formation of 4 pollen grain= 1 meiotic division is required. So for formation 102 pollen grains will required 25.5 meiotic division. Since half meiosis doesn't occur, 26 meiotic divisions are required. Answer:(c)

Linked genes are genes that are likely to be inherited together because they are physically close to one another on the same chromosome. Linked genes are exceptions to the law of independent assortment because two genes are located on the same chromosome, but this is generally mitigated when chromosomes cross over. Answer:(d)

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:(d)

The cytoplasmic inheritance is the phenomena of inheritance of maternal characters present in the genetic material in the cytoplasm. It is mainly caused due to the expression of genes present in the extra-chromosomal segments. Mitochondria and chloroplast are the only organelles which are semi-autonomous which have their own DNA. Mitochondrial DNA is known as mt-DNA and the chloroplast is known as ct-DNA. The functional genes of the mitochondria and chloroplast express themselves and allow inheritance of maternal characters. Answer:(b)

Humans knew from as early as 8000-1000 B.C. that one of the causes of variation was hidden in sexual reproduction. They exploited the variations that were naturally present in the wild populations of plants and animals to selectively breed and select for organisms that possessed desirable characters. Answer:(a)

Law of segregation is based on the fact that the alleles do not show any blending and that both the characters are recovered as such in the F2 generation though one of these is not seen at the F1 stage. Though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors. Answer:(c)

In a large number of insects the mechanism of sex determination is of the XO type. Grasshopper is an example of XO type of sex determination in which the males have only one X-chromosome besides the autosomes, whereas females have a pair of X-chromosomes. There is involvement of the X-chromosome in the determination of sex, it was designated to be the sex chromosome. In human, a pair of X-chromosomes are present in the female, whereas the presence of an X and Y chromosome are determinant of the male characteristic. Answer:(c)

Myotonic dystrophy (DM) is a form of muscular dystrophy that affects muscles and many other organs in the body. Myotonic dystrophy (DM) is inherited in an autosomal dominant pattern. This means that one copy of the altered gene in each cell of the body is enough to cause symptoms of the disease. We inherit one copy of each gene from our mother and the other from our father. Answer:(b)

The probability of offspring being tall is ½. This occurs in cross of heterozygous allele and recessive homozygous allele. Genotype of parents for height trait is Tt and tt. The probability of offspring being coloured is ¾. This occurs in cross of heterozygous allele parents. Genotype of parents for colour trait is Cc and Cc. Genotype of parents will be TtCc and ttCc. Answer:(c)

The ratio of tall : dwarf is almost 3:1. Out of 3 dominant trait, 1 is homozygous tall and 2 is heterozygous tall. The ratio of homozygous tall : heterozygous tall : homozygous dwarf is 1 : 2 : 1. Therefore out of 1064 progenies, number of heterozygous condition = 2/4× 1064 = 532 Answer:(d)

A Double trisomy: 2n+1+1 = 26 2n= 24 B Simple nullisomy: 2n-2 = 48 2n = 50 C Double tetrasomy: 2n+2+2 = 28 2n = 24 D Simple monosomy: 2n-1 = 23 2n = 24 Answer:(b)

Gametes	X	Y
X	XX (female)	XY (male)
X	XX (female)	XY (male)

In case the ovum fertilises with a sperm carrying X-chromosome the zygote develops into a female (XX) and the fertilisation of ovum with Y-chromosome carrying sperm results into a male offspring. XX × XY Answer:(d)

Quantitative inheritance: It is a type of inheritance controlled by more genes in which the dominant alleles have cumulative effect with each dominant allele expressing a part or unit of trait, the full trait being shown only when all the dominant alleles are present. The genes involved are called polygenes. Quantitative inheritance is therefore, also called polygenic inheritance. Qualitative inheritance: It is the type of inheritance in which a single dominant gene influences a complete trait Answer:(b)

The genes that are carried on the Y chromosome are called holandric genes. Holandric genes can only be passed by males onto their sons; they code for 'maleness' but sometimes cause rare conditions like hypertrichosis pinnae and color blindness. Answer:(d)

Freemartinism is recognized as one of the most severe forms of sexual abnormality among cattle. This condition causes infertility in the female cattle born twin to a male. When a heifer twin shares the uterus with a bull fetus, they also share the placental membranes connecting the fetuses with the dam. As in cattle, caprine freemartinism is caused by the fusion of fetal membranes in twin gestation and the subsequent vascular anastomosis that allows the passage of cells and hormones from a male fetus to the female fetus . Answer:(d)

Crossing of F1 individual having dominant phenotype with its homozygous recessive parents is called test cross. The test cross is used to determine whether the individuals exhibiting dominant characters are homozygous or heterozygous. Recessive genotype is aabb Answer:(c)

Blood type (phenotype)	Genotype	Antigen	Antibodies
A	IAIA or IAIO	A	b
B	IBIB or IBI0	B	a
AB	IAIB	Both A and B	Neither a nor b
O	IOIO	Neither A nor B	Both a and b

Answer:(c)