12th Class Biology Principle Of Inheritance And Variation Question Bank

done Case Based (MCQs) - Principles of Inheritance and Variation Total Questions - 50

• question_answer1)

  Directions : (1 - 5)

  Read the passage given below and answer the following questions.

  Mendel crossed tall and dwarf Pea plants to study the inheritance of one gene. He collected the seeds produced as a result of this cross and grew them to generate plants of the first hybrid generation \[\left( {{F}_{1}} \right)\]. This generation is also called the Filial progeny or the \[{{F}_{1}}\]. Mendel observed that all the progeny plants were tall, like one of its parents; none were dwarf. He made similar observations for the other pairs of traits - he found that the always resembled either one of the parents, and that the trait of the other parent was not seen in them. Mendel then self-pollinated or selfing the tall F1 plants and to his surprise found that in the \[{{F}_{2}}\] generation some of the offspring were 'dwarf '; the character that was not seen in the \[{{F}_{1}}\] generation was now expressed. The proportions of dwarf plants were 1/4th of the plants while 3/4th of the plants were tall. The tall and dwarf traits were identical to their parental type and did not show any blending or mixing that is all the offspring were either tall or dwarf, none were of in between height. Similar results were obtained with the other traits that he studied: only one of the parental traits was expressed in the \[{{F}_{1}}\] generation while at the \[{{F}_{1}}\] stage both the traits were expressed in the proportion 3 : 1. The contrasting traits did not show any blending at either \[{{F}_{1}}\] or \[{{F}_{2}}\] stage. Based on these observations, Mendel proposed that something was being stably passed down, unchanged, from parent to offspring through the gametes, over successive generations. He called these things as 'factors' (Carl Corren, 1902). Nowadays these are genes (Johannsen, 1909). Genes, therefore, are the units of inheritance. They contain the information that is required to express a particular trait, in an organism. Genes which code for a pair of contrasting traits are known as alleles (Bateson, 1905), i.e., they are slightly different forms of the same gene. If we use alphabetical symbols for each gene, then the capital letter is used for the trait expressed i.e., dominant at the \[{{F}_{1}}\] stage and the small alphabet for the other trait i.e., recessive. For example, in case of the character of height, T is used for the Tall trait and t for the 'dwarf ', and T and t are alleles of each other. Hence, in plants the pair of alleles for height would be TT, Tt or tt.

  One character has how many traits
  A)
  One done clear
  B)
  Two done clear
  C)
  Three done clear
  D)
  Four done clear
  View Solution play_arrow

• question_answer2)
  F1 generation of tall and dwarf Pea plants is
  A)
  25 % tall Pea plants done clear
  B)
  50 % dwarf Pea plants done clear
  C)
  75 % hybrid Pea plants done clear
  D)
  100% hybrid Pea plants done clear
  View Solution play_arrow

• question_answer3)
  Gene term is coined by which of the following scientist
  A)
  Carl Corren, 1902 done clear
  B)
  Johannsen, 1909 done clear
  C)
  Bateson, 1905 done clear
  D)
  G. J. Mendel, 1859 done clear
  View Solution play_arrow

• question_answer4)
  Selfing of F1 hybrid tall is resulted into what percentage of pure tall Pea plant
  A)
  25% done clear
  B)
  50% done clear
  C)
  75% done clear
  D)
  100% done clear
  View Solution play_arrow

• question_answer5)
  Hybrid tall Pea plant is depicted by which of the following symbol
  A)
  Tt done clear
  B)
  ft done clear
  C)
  TT done clear
  D)
  Any of the above done clear
  View Solution play_arrow

• question_answer6)

  Directions : (6 - 10)

  Read the passage given below and answer the following questions.

  Though the genotypic ratios can be calculated using mathematical probability, but simply looking at the phenotype of a dominant trait, it is not possible to know the genotypic composition. That is, for example, whether a tall plant from \[{{F}_{1}}\] or \[{{F}_{2}}\] has TT or Tt composition, cannot be predicted. Therefore, to determine the genotype of a tall plant at \[{{F}_{2}}\], Mendel crossed the tall plant from \[{{F}_{1}}\], with a dwarf plant i.e., recessive parent. This he called a test cross. In a typical test cross an organism like Pea plants showing a dominant phenotype and whose genotype is to be determined is crossed with the recessive parent instead of self-crossing or selfing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism.

  What ratio did you get during test cross of a Pea plant?
  A)
  1 : 2 : 1 done clear
  B)
  1 : 1 done clear
  C)
  3 : 1 done clear
  D)
  2 : 1 done clear
  View Solution play_arrow

• question_answer7)
  With the help of Punnett square, try to find out the nature of offsprings of a test cross?
  A)
  25 % hybrid tall and 25 % dwarf done clear
  B)
  75 % hybrid tall and 25 % dwarf done clear
  C)
  50 % hybrid tall and 50 % dwarf done clear
  D)
  15 % hybrid tall and 85 % dwarf done clear
  View Solution play_arrow

• question_answer8)
  Using the genotypes of test cross, can you give a general definition for a test cross?
  A)
  \[~TT~\,\,\times \,\,\,tt\] done clear
  B)
  \[Tt~\,\,\,\times \,\,\,\,tt\] done clear
  C)
  \[Tt~\,\,\times \,\,\,Tt\] done clear
  D)
  \[tt~\,\,\times \,\,\,\,tt\] done clear
  View Solution play_arrow

• question_answer9)
  Test cross is a cross between
  A)
  \[{{F}_{1}}\] tall plant and \[{{F}_{1}}\] dwarf plant done clear
  B)
  \[{{F}_{1}}\] tall plant and \[{{F}_{1}}\] recessive parent done clear
  C)
  \[{{F}_{1}}\] tall plant and \[{{F}_{1}}\]dominant parent done clear
  D)
  \[{{F}_{1}}\] dwarf plant and \[{{F}_{1}}\]dominant parent done clear
  View Solution play_arrow

• question_answer10)
  Significance of the test cross in the genetics is to determine
  A)
  Genotype of a hybrid Pea plant done clear
  B)
  Genotype of a tall Pea plant done clear
  C)
  Genotype of a dwarf Pea plant done clear
  D)
  Phenotype of a hybrid Pea plant done clear
  View Solution play_arrow

• question_answer11)

  Directions : (11 - 15)

  Read the passage given below and answer the following questions.

  In co-dominance the \[{{F}_{1}}\] generation resembles both parents. A good example is different types of red blood cells that determine ABO blood grouping in human beings. ABO blood groups are controlled by the gene I. Tie plasma membrane of the red blood cells has sugar polymers that protrude from its surface and the kind of sugar is controlled by the gene. The gene (I) has three alleles \[{{I}^{A}}\], \[{{I}^{B}}\] and i. The alleles \[{{I}^{A}}\] and \[{{I}^{B}}\] produce a slightly different form of the sugar while allele i doesn't produce any sugar. Because humans are diploid organisms, each person possesses any two of the three I gene alleles.  \[{{I}^{A}}\]and \[{{I}^{B}}\] are completely dominant over in other words when \[{{I}^{A}}\] and \[{{I}^{B}}\] are present only \[{{I}^{A}}\] expresses because i does not produce any sugar and when \[{{I}^{B}}\] and i are present \[{{I}^{B}}\] expresses. But when \[{{I}^{A}}\]and \[{{I}^{B}}\] are present together they both express their own types of sugars: this is because of co-dominance. Hence red blood cells have both A and B types of sugars. Since there are three different alleles, there are six different combinations of these three alleles that are possible a total of six different genotypes of the human ABO blood types.

  A good example of codominance is
  A)
  A - ve blood group in human being done clear
  B)
  B - ve blood group in human being done clear
  C)
  AB blood group in human being done clear
  D)
  O blood group in human being done clear
  View Solution play_arrow

• question_answer12)
  The plasma membrane of red blood cell has
  A)
  Amino acid polymer done clear
  B)
  Lipid polymer done clear
  C)
  Sugar polymer done clear
  D)
  DNA polymer done clear
  View Solution play_arrow

• question_answer13)
  Genotypic ratio of co-dominance is
  A)
  9 : 3 : 3 : 1 done clear
  B)
  3 : 1 done clear
  C)
  12 : 3 : 1 done clear
  D)
  1 : 2 : 1 done clear
  View Solution play_arrow

• question_answer14)
  How many phenotypes are possible in a blood groups?
  A)
  Two done clear
  B)
  Three done clear
  C)
  Four done clear
  D)
  Five done clear
  View Solution play_arrow

• question_answer15)
  How many genotypes are possible in the blood groups of an adult human beings?
  A)
  Three done clear
  B)
  Four done clear
  C)
  Five done clear
  D)
  Six done clear
  View Solution play_arrow

• question_answer16)

  Directions : (16 - 20)

  Read the passage given below and answer the following questions.

  Mendel's mainly described those traits that have distinct alternate forms such as flower colour which are either purple or white. But if you look around, you will find that there are many traits which are not so distinct in their occurrence and are spread across a gradient. For example, in humans we don't just have tall or short people as two distinct alternatives but a whole range of possible heights. Such traits are generally controlled by three or more genes and are thus called as polygenic traits. F. Galton in 1883 suggested that many instances of continuous variation are heritable. He was impressed by the fact that taller humans beings generally produce taller children. He suggested that characters such as height and mental capabilities in humans are heritable although these show a continuous range of variation in a population. Gallon's postulate gained experimental support when it was found that at least in, some instances the same character can be determined by more than one gene, each with the same but cumulative or additive phenotypic effect. Quantitative characters like plant height, yield of crops (size, shape and number of seeds and fruits per plant), intelligence in human beings and milk yield in animals have been found to be determined by many genes and their effects have been found to be cumulative. Each gene has a certain amount of effect, and the more the number of dominant genes, the greater expression of the character. Though polygenic traits can be easily influenced by environment, these are generally controlled by three or more genes with phenotype reflecting the contribution of each allele.

  Polygenic traits are controlled by how many gene(s)?
  A)
  One gene done clear
  B)
  Two genes done clear
  C)
  Three or more genes done clear
  D)
  Not controlled by gene done clear
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• question_answer17)
  Which of the following scientist is concerned with polygenic inheritance?
  A)
  G. J. Mendel, 1856 done clear
  B)
  Carl Corren, 1902 done clear
  C)
  F. Gallon, 1883 done clear
  D)
  Sturtevent, 1911 done clear
  View Solution play_arrow

• question_answer18)
  Many genes are controlling one trait is referred as -
  A)
  Monogenes done clear
  B)
  Polygenes done clear
  C)
  Pleiotrophy done clear
  D)
  Phenotypic done clear
  View Solution play_arrow

• question_answer19)
  Quantitative inheritance is due to
  A)
  Cumulative effect done clear
  B)
  Additive effect done clear
  C)
  Both of the above done clear
  D)
  None of the above done clear
  View Solution play_arrow

• question_answer20)

  Assertion: Intelligence in human being is due to polygenes.

  Reason: Milk yield in animal is also an example of polygenes.

  A)
  Assertion and reason both are correct statements and reason is correct explanation for assertion. done clear
  B)
  Assertion and reason both are correct statements but reason is not correct explanation for assertion. done clear
  C)
  Assertion is correct statement but reason is wrong statement. done clear
  D)
  Assertion is wrong statement but reason is correct statement. done clear
  View Solution play_arrow

• question_answer21)

  Directions : (21 - 25)

  Read the passage given below and answer the following questions.

  We have so far seen the effect of a gene on a single phenotype or trait. There are however instances where a single gene can exhibit multiple phenotypic expression. Such a gene is called a pleiotropic gene. The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contributes towards different phenotypes. An example of this is the disease phenylketonuria (PKU; Foiling, 1934) which occurs in humans. The disease is caused by mutation in the gene that codes for the enzyme phenyl alanine hydroxylase i.e., single gene mutation. Pleiotropism is defined as a phenomenon when single gene may produce more than one effect i.e., the multiple effect of a gene or control several phenotypes depending on its position. This results in a phenotypic expression characterized by mental retardation and a reduction in hair and skin pigmentation (albinism). In Drosophila white eye mutation leads to depigmentation in many other parts of the body, giving a pleiotropic effect. In transgenic organisms, the introduced gene can produce different effects depending on where the gene has introgressed.

  Single gene is controlling multiple phenotypic expression is referred as
  A)
  Monogene done clear
  B)
  Polygenes done clear
  C)
  Pleiotropic done clear
  D)
  Digenes done clear
  View Solution play_arrow

• question_answer22)
  In phenylketonuria (PKU) disease of human being, there is deficiency of enzyme -
  A)
  Phenyl alanine oxidase done clear
  B)
  Phenyl alanine hydroxylase done clear
  C)
  Phenyl alanine tyrosinase done clear
  D)
  Phenyl alanine reductase done clear
  View Solution play_arrow

• question_answer23)
  Symptoms of phenylketonuria (PKU) disease is
  A)
  Mental retardation done clear
  B)
  Albinism done clear
  C)
  Reduction in hair done clear
  D)
  All of the above done clear
  View Solution play_arrow

• question_answer24)
  Phenylketonuria disease is first recorded by
  A)
  F. Galton, 1883 done clear
  B)
  Follin, 1934 done clear
  C)
  Hugo de Vries, 1901 done clear
  D)
  John Otto, 1803 done clear
  View Solution play_arrow

• question_answer25)
  Phenylketonuria (PKU) disease is due to which chromosome
  A)
  Chromosome number 10 done clear
  B)
  Chromosome number 11 done clear
  C)
  Chromosome number 12 done clear
  D)
  Chromosome number 13 done clear
  View Solution play_arrow

• question_answer26)

  Directions : (26 - 30)

  Read the passage given below and answer the following questions.

  Haemophilia or Bleeder's Disease is sex-linked recessive disease, which shows its transmission from unaffected or normal 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. The heterozygous female or carrier for haemophilia may transmit the disease to sons. The possibility of a female becoming a haemophilic is extremely rare because mother of such a female has to be at least carrier and the father should be haemophilic i.e., unviable in the later stage of life. The family pedigree of Queen Victoria (1819-1901) shows a number of haemophilic descendants as she was a carrier of the disease.

  Haemophilia is caused by :
  A)
  X Chromosome in male done clear
  B)
  X Chromosome in female done clear
  C)
  X Chromosome in both male and female done clear
  D)
  Y Chromosome in male done clear
  View Solution play_arrow

• question_answer27)
  Haemophilia is more commonly seen in human males than in human females because :
  A)
  A greater proportion of girls die in infancy done clear
  B)
  This disease is due to an Y linked recessive mutation done clear
  C)
  This disease is due to an X linked recessive mutant done clear
  D)
  This disease is due to an X linked dominant mutation done clear
  View Solution play_arrow

• question_answer28)
  Haemophilia is a condition, where there is :
  A)
  No production of haemoglobin in the blood done clear
  B)
  No production of melanin in the skin done clear
  C)
  A failure of clotting mechanism of blood done clear
  D)
  A delay in clotting of blood done clear
  View Solution play_arrow

• question_answer29)
  A man and a woman, who don't show any apparent signs of certain inherited disease, have seven children (2 daughters and 5 sons). Three of the sons suffer from the given disease but none of the daughters are affected. Which of the following mode of inheritance, do you suggest for the disease?
  A)
  Autosomal dominant done clear
  B)
  Sex-linked dominant done clear
  C)
  Sex-limited recessive done clear
  D)
  Sex-linked recessive done clear
  View Solution play_arrow

• question_answer30)

  Assertion: Haemophilia is a sex-linked disease.

  Reason: It is due to presence of a recessive gene on X chromosome.

  A)
  Both assertion and reason are true, and reason is the correct explanation of assertion. done clear
  B)
  Both assertion and reason are true, but reason is not the correct explanation of assertion. done clear
  C)
  Assertion is true but reason is false. done clear
  D)
  Both assertion and reason are false. done clear
  View Solution play_arrow

• question_answer31)

  Directions : (31 - 35)

  Read the passage given below and answer the following questions.

  Sickle cell anaemia is an autosome (chromosome 11) 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, \[H{{b}^{A}}\] and \[H{{b}^{S}}\]. Out of .the three possible genotypes only homozygous individuals i.e., \[H{{b}^{S}}H{{b}^{S}}\] show the diseased phenotype. Heterozygous \[\left( H{{b}^{A}}H{{b}^{S}} \right)\] individuals appear apparently unaffected or normal but they are carrier of the disease as there is 50 per cent probability of transmission of the mutant gene to the progeny, thus exhibiting sickle-cell trait. The defect is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule. The substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG. The mutant haemoglobin molecule undergoes polymerization under low oxygen tension causing the change in the shape of the RBC from biconcave disc to elongated sickle like structure.

  Sickle cell anaemia is :
  A)
  Autosomal dominant inheritance done clear
  B)
  X-linked recessive inheritance done clear
  C)
  Autosomal recessive inheritance done clear
  D)
  X-linked dominant inheritance done clear
  View Solution play_arrow

• question_answer32)
  Sickle cell anaemia is :
  A)
  An autosomal linked dominant trait. done clear
  B)
  Caused by substitution of valine by glutamic acid in the -globin chain of haemoglobin. done clear
  C)
  Caused by a change in base pair of DNA. done clear
  D)
  Characterized by elongated sickle like RBCs with a nucleus. done clear
  View Solution play_arrow

• question_answer33)
  Sickle cell anaemia is caused by the substitution of
  A)
  valine by glutamic acid at sixth position of alpha chain of haemoglobin. done clear
  B)
  valine by glutamic acid at sixth position of beta chain of haemoglobin. done clear
  C)
  glutamic acid by valine at sixth position of alpha chain of haemoglobin. done clear
  D)
  glutamic acid by valine at sixth position of beta chain of haemoglobin. done clear
  View Solution play_arrow

• question_answer34)
  In sickle cell anaemia, the sequence of amino acids from the first to the seventh position of the \[\beta \]-chain of haemoglobin \[S\left( H{{b}^{S}} \right)\]is
  A)
  His, Leu, Thr, Pro, Glu, Val, Val done clear
  B)
  Val, His, Leu, Thr, Pro, Glu, Glu done clear
  C)
  Thr, His, Pro, Val, Pro, Val, Glu done clear
  D)
  Val, His, Leu, Thr, Pro, Val, Glu done clear
  View Solution play_arrow

• question_answer35)
  Sickle cell anaemia is caused due to the substitution of
  A)
  valine at the 6th position of beta globin chain by glutamine done clear
  B)
  valine at the 6th position of alpha globin chain by glutamic acid done clear
  C)
  glycine at the 6th position of alpha globin chain by glutamic acid done clear
  D)
  glutamic acid at the 6th position of beta globin chain by valine done clear
  View Solution play_arrow

• question_answer36)

  Directions : (36 - 40)

  Read the passage given below and answer the following questions.

  Colour blindness 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. It occurs in about 8 percent of males and only about 0.4 percent of females. This is because the genes that lead to red-green colour blindness are on the X-chromosome. Males have only one X-chromosome and females have two. The son of a woman who carries the gene has a 50 percent, chance of being colour blind. The mother is not herself colour blind because the gene is recessive. That means that is effect is suppressed by her matching dominant normal gene. A daughter will not normally be colour blind, unless her mother is a carrier and her father is colour blind. The gene for normal vision is dominant. The normal gene and its recessive allele are carried by X-chromosome. In female colour blindness appears only when both the sex chromosomes carry the recessive gene\[\left( {{X}^{c}}/{{X}^{c}} \right)\]. The females have normal vision but function as carrier if a single recessive gene for colour blindness is present \[\left( X{{X}^{c}} \right)\]. However, in human males the defect appears in the presence of a single recessive gene \[\left( {{X}^{c}}Y \right)\] because Y chromosomes of males do not carry any gene for colour vision. Colour blindness, like any other sex linked trait, shows criss-cross inheritance. Colour- blindness does not mean not seeing any colour at all, it means that those who are colourblind have trouble in seeing the differences between certain colours. Most colourblind people can't tell the difference between red or green. That does not mean that they cannot do their normal work - Infact they can also drive - they learn to respond to the way the traffic signal lights up, the red light is generally on the top and. green is on the bottom.

  A colour-blind daughter is born when :
  A)
  Father is colour-blind, mother is normal done clear
  B)
  Mother is colour-blind, father is normal done clear
  C)
  Mother is carrier, father is normal done clear
  D)
  Mother is carrier, father is colour-blind done clear
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• question_answer37)
  A woman with normal vision, but whose father was colour-blind, marries a colour-blind man. Suppose that the fourth child of this couple was a boy. This boy :
  A)
  Must have normal colour vision done clear
  B)
  Will be partially colour-blind since he is heterozygous for the colour-blind mutant allele done clear
  C)
  Must be colour-blind done clear
  D)
  May be colour-blind or may be of normal vision done clear
  View Solution play_arrow

• question_answer38)
  A marriage between normal visioned man and colour-blind woman will produce, which of the following type of offspring?
  A)
  Normal sons and carrier daughters    done clear
  B)
  Colour-blind sons and carrier daughters done clear
  C)
  Colour-blind sons and 50% carrier daughters done clear
  D)
  50% colour-blind sons and 50% carrier daughters done clear
  View Solution play_arrow

• question_answer39)
  A colour-blind man marries the daughter of another colour-blind man whose wife has a normal genotype for colour vision. In their progeny
  A)
  all the children would be colour blind done clear
  B)
  all their sons are colour blind done clear
  C)
  none of the daughters would be colour blind done clear
  D)
  half of their sons and half of their daughters would be colour blind. done clear
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• question_answer40)
  A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind?
  A)
  Nil done clear
  B)
  0.25 done clear
  C)
  0.5 done clear
  D)
  1 done clear
  View Solution play_arrow

• question_answer41)

  Directions : (41 - 45)

  Read the passage given below and answer the following questions.

  Thalassemia is also an autosome linked recessive i.e., chromosome 11 and 16, blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene or heterozygous. The defect could be due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globin chains that make up haemoglobin. This causes the formation of abnormal haemoglobin molecules resulting into anaemia which is characteristic of the disease. Thalassemia can be classified according to which chain of the haemoglobin molecule is affected. Thalassaemia is a genetic defect, originated in Mediterranean region by their mutation or deletion. In thalassaemia too few globin's are synthesised whereas in sickle cell anaemia there is a synthesis of incorrectly functioning globin. Thalassemia's are a group of disorders caused by defects in the synthesis of globin polypeptide. Absence or reduced synthesis of one of the globin chains results in an excess of the other. In this situation free globin chains, which are insoluble, accumulate inside the red cells and form precipitates which damage the cell, causing cell lysis and resulting in anemia. It is common in Mediterranean, Middle East, Indian subcontinent and in south east Africa.

  Thalassemia is due to:
  A)
  Chromosome number 11. done clear
  B)
  Chromosome number 12. done clear
  C)
  Chromosome number 13. done clear
  D)
  Chromosome number 11 and 16. done clear
  View Solution play_arrow

• question_answer42)
  Thalassemia develops in human being is due to:
  A)
  Mutation. done clear
  B)
  Deletion. done clear
  C)
  Crossing over. done clear
  D)
  a and b. done clear
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• question_answer43)
  Thalassemia and sickle cell anaemia are due to a problem in globin molecule synthesis. Select the correct statement.
  A)
  Sickle cell anaemia is due to a quantitative problem of globin molecules. done clear
  B)
  Both are due to a qualitative defect in globin chain synthesis. done clear
  C)
  Both are due to a quantitative defect in globin chain synthesis. done clear
  D)
  Thalassemia is due to less synthesis of globin molecules. done clear
  View Solution play_arrow

• question_answer44)
  Thalassemia is:
  A)
  Autosomal recessive disease. done clear
  B)
  Autosomal dominant disease. done clear
  C)
  Allosomal dominant disease. done clear
  D)
  Allosomal recessive disease. done clear
  View Solution play_arrow

• question_answer45)
  Carrier of Thalassemia is:
  A)
  Male only. done clear
  B)
  Female only. done clear
  C)
  Both of the above. done clear
  D)
  None of the above. done clear
  View Solution play_arrow

• question_answer46)

  Directions : (46 - 50)

  Read the passage given below and answer the following questions.

  The chromosomal disorders on the other hand are caused due to absence or excess or abnormal arrangement of one or more chromosomes. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy (hyper or hypo). For example. Down's syndrome results in the gain of extra copy of chromosome 21. Similarly, Turner's syndrome results due to loss of an X chromosome in human females. Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy. This condition is often seen in plants. The total number of chromosomes of a normal human being is 46 (23 pairs). Out of these 22 pairs are autosomes or body chromosome and one pair of chromosomes are sex chromosome allosome. Sometimes, though rarely, either an additional copy of a chromosome may be included in an individual or an individual may lack one of any one pair of chromosomes. These situations are known as trisomy \[\left( 2n+1 \right)\] or monosomy \[\left( 2n-1 \right)\]of a chromosome, respectively. Such a situation leads to very serious consequence in the individual.

  Trisomy is :
  A)
  One chromosome less than 2n done clear
  B)
  One chromosome more than 2n done clear
  C)
  A hybrid obtained by crossing diploid and tetraploid done clear
  D)
  Three chromosomes more than 2n done clear
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• question_answer47)
  When a diploid female plant is crossed with a tetraploid male plant, then ploidy of endosperm cells in the resulting seed is :
  A)
  Triploidy done clear
  B)
  Diploidy done clear
  C)
  Pentaploidy done clear
  D)
  Tetraploidy done clear
  View Solution play_arrow

• question_answer48)
  When a diploid female plant is crossed with a hexaploid male, the ploidy of endosperm cells in the resulting seed is
  A)
  Tetraploidy done clear
  B)
  Pentaploidy done clear
  C)
  Diploidy done clear
  D)
  Triploidy done clear
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• question_answer49)
  Polyploidy can be produced artificially by :
  A)
  Colchicine done clear
  B)
  Inbreeding done clear
  C)
  Line breeding done clear
  D)
  Self-pollination done clear
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• question_answer50)
  Choose the wrong statement.
  A)
  Failure of segregation of chromatids during cell division results in aneuploidy done clear
  B)
  Additional copy of 'X' chromosome in males results in Klinefelter's syndrome done clear
  C)
  Closely located genes in a chromosome always assort independently resulting in recombinants done clear
  D)
  According to Mendel, recessive character never blends in heterozygous condition done clear
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