<hr> <main> <hr> <h2 id="weight-47">title: Principale Of Inheritance And Variation weight: 47</h2> <h1 id="chapter-5">Chapter 5</h1> </main> <hr>

<hr> <main> <h3 id="principle-of-inheritance-and-variation">PrinCIPLe of INHeritanCe and Variation</h3> <p>MULTIPLE-CHOICE QUESTIONS</p> </main> <hr>

<hr> <main> <p><strong>1.</strong> All genes located on the same chromosome:</p> <div class="fragment"> <p>a. Form different groups depending upon their relative distance</p> <p>b. Form one linkage group</p> <p>c. Will not from any linkage groups</p> <p>d. Form interactive groups that affect the phenotype</p> </div> </main> <hr>

<hr> <main> <p><strong>2.</strong> Conditions of a karyotype $2 n+1,2 n-1$ and $2 n+2,2 n-2$ are called:</p> <div class="fragment"> <p>a. Aneuploidy</p> <p>b. Polyploidy</p> <p>c. Allopolyploidy</p> <p>d. Monosomy</p> </div> </main> <hr>

<hr> <main> <p><strong>3.</strong> Distance between the genes and percentage of recombination shows:</p> <div class="fragment"> <p>a. a direct relationship</p> <p>b. an inverse relationship</p> <p>c. a parallel relationship</p> <p>d. no relationship</p> </div> </main> <hr>

<hr> <main> <p><strong>4.</strong> If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:</p> <div class="fragment"> <p>a. Autosomal dominant</p> <p>b. Autosomal recessive</p> <p>c. Sex-linked dominant</p> <p>d. Sex-linked recessive</p> </div> </main> <hr>

<hr> <main> <p><strong>5.</strong> In sickle cell anaemia glutamic acid is replaced by valine. Which one of the following triplets codes for valine?</p> <div class="fragment"> <p>a. G G G</p> <p>b. AAG</p> <p>c. GA A</p> <p>d. GU G</p> </div> </main> <hr>

<hr> <main> <p><strong>6.</strong> Person having genotype $I^{A} I^{B}$ would show the blood group as AB. This is because of:</p> <div class="fragment"> <p>a. Pleiotropy</p> <p>b. Co-dominance</p> <p>c. Segregation</p> <p>d. Incomplete dominance</p> </div> </main> <hr>

<hr> <main> <p><strong>7.</strong> $ZZ / ZW$ type of sex determination is seen in:</p> <div class="fragment"> <p>a. Platypus</p> <p>b. Snails</p> <p>c. Cockroach</p> <p>d. Peacock</p> </div> </main> <hr>

<hr> <main> <p><strong>8.</strong> A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents?</p> <div class="fragment"> <p>a. $TT$ and $Tt$</p> <p>b. $Tt$ and $Tt$</p> <p>c. TT and TT</p> <p>d. $Tt$ and $tt$</p> </div> </main> <hr>

<hr> <main> <p><strong>9.</strong> In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:</p> <div class="fragment"> <p>a. The alleles of two genes are interacting with each other</p> <p>b. It is a multigenic inheritance</p> <p>c. It is a case of multiple allelism</p> <p>d. The alleles of two genes are segregating independently.</p> </div> </main> <hr>

<hr> <main> <p><strong>10.</strong> Which of the following will not result in variations among siblings?</p> <div class="fragment"> <p>a. Independent assortment of genes</p> <p>b. Crossing over</p> <p>c. Linkage</p> <p>d. Mutation</p> </div> </main> <hr>

<hr> <main> <p><strong>11.</strong> Mendel’s Law of independent assortment holds good for genes situated on the:</p> <div class="fragment"> <p>a. non-homologous chromosomes</p> <p>b. homologous chromosomes</p> <p>c. extra nuclear genetic element</p> <p>d. same chromosome</p> </div> </main> <hr>

<hr> <main> <p><strong>12.</strong> Occasionally, a single gene may express more than one effect. The phenomenon is called:</p> <div class="fragment"> <p>a. multiple allelism</p> <p>b. mosaicism</p> <p>c. pleiotropy</p> <p>d. polygeny</p> </div> </main> <hr>

<hr> <main> <p><strong>13.</strong> In a certain taxon of insects some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome-bearing organisms are:</p> <div class="fragment"> <p>a. males and females, respectively</p> <p>b. females and males, respectively</p> <p>c. all males</p> <p>d. all females</p> </div> </main> <hr>

<hr> <main> <p><strong>14.</strong> The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to:</p> <div class="fragment"> <p>a. quantitative trait</p> <p>b. Mendelian trait</p> <p>c. polygenic trait</p> <p>d. maternal trait</p> </div> </main> <hr>

<hr> <main> <p><strong>15.</strong> It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the</p> <div class="fragment"> <p>a. results of $F_3$ generation of a cross.</p> <p>b. observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending.</p> <p>c. self pollination of $F_1$ offsprings</p> <p>d. cross pollination of $F_1$ generation with recessive parent</p> </div> </main> <hr>

<hr> <main> <p><strong>16.</strong> Two genes ‘A’ and ’ $B$ ’ are linked. In a dihybrid cross involving these two genes, the $F_1$ heterozygote is crossed with homozygous recessive parental type (aa bb). What would be the ratio of offspring in the next generation?</p> <div class="fragment"> <p>a. $1: 1: 1: 1$</p> <p>b. $9: 3: 3: 1$</p> <p>c. $3: 1$</p> <p>d. $1: 1$</p> </div> </main> <hr>

<hr> <main> <p><strong>17.</strong> In the $F_2$ generation of a Mendelian dihybrid cross the number of phenotypes and genotypes are:</p> <div class="fragment"> <p>a. phenotypes - 4; genotypes - 16</p> <p>b. phenotypes - 9; genotypes - 4</p> <p>c. phenotypes - 4 ; genotypes - 8</p> <p>d. phenotypes - 4; genotypes - 9</p> </div> </main> <hr>

<hr> <main> <p><strong>18.</strong> Mother and father of a person with ’ $O$ ’ blood group have ‘A’ and ’ $B$ ’ blood group, respectively. What would be the genotype of both mother and father?</p> <div class="fragment"> <p>a. Mother is homozygous for ’ $A$ ’ blood group and father is heterozygous for ’ $B$ '</p> <p>b. Mother is heterozygous for ‘A’ blood group and father is homozygous for ’ $B$ '</p> <p>c. Both mother and father are heterozygous for ’ $A$ ’ and ‘B’ blood group, respectively</p> <p>d. Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively</p> </div> </main> <hr>

<hr> <main> <h3 id="very-short-answer-type-questions">VERY SHORT ANSWER TYPE QUESTIONS</h3> </main> <hr>

<hr> <main> <p><strong>1.</strong> What is the cross between the progeny of $F_1$ and the homozygous recessive parent called? How is it useful?</p> </main> <hr>

<hr> <main> <p><strong>2.</strong> Do you think Mendel’s laws of inheritance would have been different if the characters that he chose were located on the same chromosome.</p> </main> <hr>

<hr> <main> <p><strong>3.</strong> Enlist the steps of controlled cross pollination. Would emasculation be needed in a cucurbit plant? Give reasons for your answer.</p> </main> <hr>

<hr> <main> <p><strong>4.</strong> A person has to perform crosses for the purpose of studying inheritance of a few traits / characters. What should be the criteria for selecting the organisms?</p> </main> <hr>

<hr> <main> <p><strong>5.</strong> The pedigree chart given below shows a particular trait which is absent in parents but present in the next generatoin irrespective of sexes. Draw your conclusion on the basis of the pedigree.</p> <p><img src="https://cdn.mathpix.com/cropped/2024_01_30_21108c308f4c7978476cg-033.jpg?height=170&width=635&top_left_y=561&top_left_x=573"></p> </main> <hr>

<hr> <main> <p><strong>6.</strong> In order to obtain the $F_1$ generation Mendel pollinated a pure-breeding tall plant with a pure breeding dwarf plant. But for getting the $F_2$ generation, he simply self-pollinated the tall $F_1$ plants. Why?</p> </main> <hr>

<hr> <main> <p><strong>7.</strong> “Genes contain the information that is required to express a particular trait.” Explain.</p> </main> <hr>

<hr> <main> <p><strong>8.</strong> How are alleles of particular gene differ from each other? Explain its significance.</p> </main> <hr>

<hr> <main> <p><strong>9.</strong> In a monohybrid cross of plants with red and white flowered plants, Mendel got only red flowered plants. On self-pollinating these $F_1$ plants got both red and white flowered plants in $3: 1$ ratio. Explain the basis of using RR and $rr$ symbols to represent the genotype of plants of parental generation.</p> </main> <hr>

<hr> <main> <p><strong>10.</strong> For the expression of traits genes provide only the potentiality and the environment provides the opportunity. Comment on the veracity of the statement.</p> </main> <hr>

<hr> <main> <p><strong>11.</strong> A, B, D are three independently assorting genes with their recessive alleles a, b, d, respectively. A cross was made between individuals of Aa bb DD genotype with aa bb dd. Find out the type of genotypes of the offspring produced.</p> </main> <hr>

<hr> <main> <p><strong>12.</strong> In our society a woman is often blamed for not bearing male child. Do you think it is right? Justify.</p> </main> <hr>

<hr> <main> <p><strong>13.</strong> Discuss the genetic basis of wrinkled phenotype of pea seed.</p> </main> <hr>

<hr> <main> <p><strong>14.</strong> Even if a character shows multiple allelism, an individual will only have two alleles for that character. Why?</p> </main> <hr>

<hr> <main> <p><strong>15.</strong> How does a mutagen induce mutation? Explain with example.</p> </main> <hr>

<hr> <main> <h3 id="short-answer-type-questions">SHORT ANSWER TYPE QUESTIONS</h3> </main> <hr>

<hr> <main> <p><strong>1.</strong> In a Mendelian monohybrid cross, the $F_2$ generation shows identical genotypic and phenotypic ratios. What does it tell us about the nature of alleles involved? Justify your answer.</p> </main> <hr>

<hr> <main> <p><strong>2.</strong> Can a child have blood group O if his parents have blood group ‘A’ and ‘B’. Explain.</p> </main> <hr>

<hr> <main> <p><strong>3.</strong> What is Down’s syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down’s syndrome increases if the age of the mother exceeds forty years?</p> </main> <hr>

<hr> <main> <p><strong>4.</strong> How was it concluded that genes are located on chromosomes?</p> </main> <hr>

<hr> <main> <p><strong>5.</strong> A plant with red flowers was crossed with another plant with yellow flowers. If $F_1$ showed all flowers orange in colour, explain the inheritance.</p> </main> <hr>

<hr> <main> <p><strong>6.</strong> What are the characteristic features of a true-breeding line?</p> </main> <hr>

<hr> <main> <p><strong>7.</strong> In peas, tallness is dominant over dwarfness, and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated with a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny in numbers mentioned against them:</p> <table> <thead> <tr> <th style="text-align:left">Tall, Red</th> <th style="text-align:left">$=138$</th> </tr> </thead> <tbody> <tr> <td style="text-align:left">Tall, White</td> <td style="text-align:left">$=132$</td> </tr> <tr> <td style="text-align:left">Dwarf, Red</td> <td style="text-align:left">$=136$</td> </tr> <tr> <td style="text-align:left">Dwarf, White</td> <td style="text-align:left">$=128$</td> </tr> </tbody> </table> <p>Mention the genotypes of the two parents and of the four offspring types.</p> </main> <hr>

<hr> <main> <p><strong>8.</strong> Why is the frequency of red-green colour blindness is many times higher in males than that in the females?</p> </main> <hr>

<hr> <main> <p><strong>9.</strong> If a father and son are both defective in red-green colour vision, is it likely that the son inherited the trait from his father? Comment.</p> </main> <hr>

<hr> <main> <p><strong>10.</strong> Discuss why Drosophila has been used extensively for genetical studies.</p> </main> <hr>

<hr> <main> <p><strong>11.</strong> How do genes and chromosomes share similarity from the point of view of genetical studies?</p> </main> <hr>

<hr> <main> <p><strong>12.</strong> What is recombination? Discuss the applications of recombination from the point of view of genetic engineering.</p> </main> <hr>

<hr> <main> <p><strong>13.</strong> What is artificial selection? Do you think it affects the process of natural selection? How?</p> </main> <hr>

<hr> <main> <p><strong>14.</strong> With the help of an example differentiate between incomplete dominance and co-dominance.</p> </main> <hr>

<hr> <main> <p><strong>15.</strong> It is said, that the harmful alleles get eliminated from population over a period of time, yet sickle cell anaemia is persisting in human population. Why?</p> </main> <hr>

<hr> <main> <h3 id="long-answer-type-questions">LONG ANSWER TYPE QUESTIONS</h3> </main> <hr>

<hr> <main> <p><strong>1.</strong> In a plant tallness is dominant over dwarfness and red flower is dominant over white. Starting with the parents work out a dihybrid cross. What is standard dihybrid ratio? Do you think the values would deviate if the two genes in question are interacting with each other?</p> </main> <hr>

<hr> <main> <p><strong>2.</strong> a. In humans, males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?</p> <p>b. Also describe as to, who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.</p> </main> <hr>

<hr> <main> <p><strong>3.</strong> A normal visioned woman, whose father is colour blind, marries a normal visioned man. What would be probability of her sons and daughters to be colour blind? Explain with the help of a pedigree chart.</p> </main> <hr>

<hr> <main> <p><strong>4.</strong> Discuss in detail the contributions of Morgan and Sturvant in the area of genetics.</p> </main> <hr>

<hr> <main> <p><strong>5.</strong> Define aneuploidy. How is it different from polyploidy? Describe the individuals having following chromosomal abnormalities.</p> <div class="fragment"> <p>a. Trisomy of $21^{\text{st }}$ Chromosome</p> <p>b. XXY</p> <p>c. $XO$</p> </main> <hr>

<hr> <main> <h3 id="solution">Solution</h3> <table> <thead> <tr> <th style="text-align:left">$1-b$</th> <th style="text-align:left">$2-a$</th> <th style="text-align:left">$3-a$</th> <th style="text-align:left">$4-d$</th> <th style="text-align:left">$5-d$</th> <th style="text-align:left">$6-b$</th> </tr> </thead> <tbody> <tr> <td style="text-align:left">$7-d$</td> <td style="text-align:left">$8-b$</td> <td style="text-align:left">$9-d$</td> <td style="text-align:left">$10-c$</td> <td style="text-align:left">$11-a$</td> <td style="text-align:left">$12-c$</td> </tr> <tr> <td style="text-align:left">$13-a$</td> <td style="text-align:left">$14-b$</td> <td style="text-align:left">$15-b$</td> <td style="text-align:left">$16-d$</td> <td style="text-align:left">$17-d$</td> <td style="text-align:left">$18-c$</td> </tr> </tbody> </table> </main> <hr>