Repeated uses of the pesticide lead to increased population of less-susceptible individuals. Thus, the random mutation in less proportion of pest population is favoured and pesticide resistance is developed. Answer : (c)

According to Moody, mutation is a shotgun. It is an inheritable change in germplasm. Answer : (d)

The number of chromosomes found in a single complete set of chromosomes is called the monoploid number Answer : (d)

It's generally recognized that chromosomes were first discovered by Walther Flemming in 1882. Answer : (c)

Cytoplasmic inheritance is defined as the inheritance of organelle DNA from the parents. Several research experiments reports that almost all of the organelle DNA in certain groups of plants is inherited from the mother. Thus, cytoplasmic inheritance is also called maternal inheritance. Answer : (a)

Sex chromosomes of a female bird has been designated to be the Z and W chromosomes. In these organisms the females have one Z and one W chromosome, whereas males have a pair of Z-chromosomes besides the autosomes. Answer : (a)

he X-linked diseases are passed from father to daughters only, never to the sons because sons never receive the X-chromosome from father. Answer : (b)

Distance between two genes is measured in map unit. One map unit is equal to 1% recombination frequency. Recombination frequency is always less than map distance and never exceeds than 50%. Answer : (c)

Morgan carried out several dihybrid crosses in Drosophila to study genes that were sex-linked. Morgan and his group knew that the genes were located on the X chromosome and saw quickly that when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations Answer : (d)

he pathogenesis of Alzheimer's disease (AD) has been linked to a deficiency in the brain neurotransmitter acetylcholine. Answer : (d)

The Barr, or sex chromatin, body is an inactive X chromosome. It appears as a dense, dark-staining spot at the periphery of the nucleus of each somatic cell in the human female. XX females have one Barr body per cell, XXX females have 2 Barr bodies per cell. Answer : (a)

Triticale is a man-made cereal. Triticale is a hybrid cross of wheat and rye. The first cross was reported in 1875 and the first fertile cross in 1888. Answer : (c)

Y linkage, also known as holandric inheritance describes traits that are produced by genes located on the Y chromosome. It is a form of sex linkage. For a trait to be considered Y linkage, it must exhibit these characteristics: (i) occurs only in males (ii) appears in all sons of males who exhibit that trait (iii) is absent from daughters of trait carriers; instead the daughters that are phenotypically normal and do not have affected offspring. Answer : (b)

The inheritance of characters controlled by genes present in the cell cytoplasm rather than by genes on the chromosomes in the cell nucleus. Cytoplasmic male sterility is total or partial male sterility in plants as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure of plants to produce functional anthers, pollen, or male gametes. Answer : (d)

Somatic cells are the cells in the body other than sperm and egg cells (which are called germ cells). In humans, somatic cells are diploid, meaning they contain two sets of chromosomes, one inherited from each parent. Answer : (b)

Many chemical and physical factors that induce mutations. These are referred to as mutagens. UV radiations can cause mutations in organisms – it is a mutagen. Answer : (b)

Haemophilia : This sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny has been widely studied. In this disease, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected. Due to this, in an affected individual a simple cut will result in non-stop bleeding. Since it sex linked recessive, it means there is mutation in X chromosome. Answer : (c)

The number of Barr bodies is always one less than the total number of X chromosomes. A human male with XY sex chromosomes lacks Barr body. A normal human female with XX sex chromosome has 1 Barr body. Answer : (c)

The Y chromosome is one of the two sex chromosomes in humans. The other being X chromosome. Answer : (d)

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. This defect is due to mutation in certain genes present in the X chromosome. A daughter will not normally be colour blind, unless her mother is a carrier and her father is colour blind. For mother to be carrier, girl's maternal grandfather should be colour blind. Answer : (b)

Linkage is an exception to Mendel's law of independent assortment. The law states that inherited genes are independent of each other. Linkage is an exception to this law as two genes are situated on the same chromosome, however, this is usually diminished when there is a crossing over of chromosomes. Answer : (b)

A deletion, as related to genomics, is a type of mutation that involves the loss of one or more nucleotides from a segment of DNA. A deletion can involve the loss of any number of nucleotides, from a single nucleotide to an entire piece of a chromosome. Answer : (a)

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. Curly hair is considered a “dominant” gene trait. Answer : (a)

cross over frequency is directly proportional to recombination frequency. The more distantly located are the gene, the more are the chances of cross over between them and the more are the percent of recombinant genotypes in offspring. Answer : (b)

A telomere is a region of repetitive DNA sequences at the end of a chromosome. Telomeres protect the ends of chromosomes from becoming frayed or tangled. Answer : (b)

a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. Answer : (a)

Genetic disorders may be grouped into two categories – Mendelian disorders and Chromosomal disorders. Mendelian disorders are mainly determined by alteration or mutation in the single gene. Most common and prevalent Mendelian disorders are Haemophilia, Cystic fibrosis, Sickle cell anaemia, Colour blindness, Phenylketonuria, Thalassemia. Answer : (b)

Extranuclear inheritance or cytoplasmic inheritance is the inheritance of the characters of only one parent (generally the female parent). This occurs in killer paramecium. Answer : (b)

Mendelian disorders are mainly determined by alteration or mutation in the single gene. These disorders are transmitted to the offspring. Most common and prevalent Mendelian disorders are Haemophilia, Cystic fibrosis, Sickle cell anaemia, Colour blindness, Phenylketonuria, Thalassemia, etc Answer : (b)

Sickle cell anaemia is a mendelian disorder. Mendelian disorders are mainly determined by alteration or mutation in the single gene. 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). Answer : (c)

form all the kinds of gametes you can get with this,,, abXh ABXh abY AbY aBX aBY ABY AbXh but they are asking for portion of abXh.. therfore ans is 1/8 Answer : (a)

Linkage was discovered by Bateson and Punnett in sweet pea (Lathyrus odoratus). Answer : (d)

Some characters are controlled by cytoplasmic genes present in mitochondria and chloroplast because in zygote cytoplasm is derived from egg (female parent) Answer : (b)

Rcombinant type = 1000 - parental type. = 1000-650 = 350 The distance between a and b = no. of recombinants/total no. of offsprings * 100 = 350/1000 *100 = 35 map units. Answer : (a)

Jacobs syndrome, also known as 47,XYY syndrome, is a rare genetic condition that occurs in about 1 out of 1000 male children. It belongs to a group of conditions known as "sex chromosome trisomies", with Klinefelter's syndrome being the more common type. This condition was initially discovered in the 1960s. Answer : (c)

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A chimera is essentially a single organism that's made up of cells from two or more "individuals"—that is, it contains two sets of DNA, with the code to make two separate organisms. Mutations acquired by these cells during the course of their lifetimes, are called somatic mutations. The occurrence of a somatic mutation in the early stages of embryonic development or during the fusion of two zygotes, leads to an organism possessing more than one distinct set of DNA, and is called a chimera. OTHER OPTIONS Lethal mutation: A gene mutation whose expression results in the premature death of the organism carrying it. Dominant lethals kill heterozygotes, whereas recessive lethals kill homozygotes only. Reverse mutations: are defined as mutations that fully or partially restore the activity of a mutant gene. pleiotropic mutation: A mutation that affects expression of several characteristics. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function. Answer : (c)

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