CBSE Questions for Class 12 Medical Biology Principles Of Inheritance And Variation Quiz 12 - MCQExams.com


In sickle-cell anaemia, shape of RBC's under oxygen tension becomes ____________________.
  • biconcave disc like
  • elongated and curved
  • circular
  • spherical
Failure of segregation of chromatids during cell division results in the gain or loss of chromosomes, this is called as 
  • Euploidy
  • Monoploidy
  • Aneuploidy
  • Polyploidy
An individual affected by phenylketonuria lacks an enzyme that converts the amino acid ______ into ______
  • tyrosine, phenylalanine
  • phenylalanine, tyrosine
  • homogentisic acid, phenylalanine
  • homogentisic acid, tyrosine
Given pedigree chart depicts the inheritance of attached ear lobes, an autosomal recessive trait.
Which of the following conclusions drawn is correct?

932070_7789c409bba341deb13747690c7f8b2a.png
  • Parents are heterozygous
  • Parents are homozygous dominant
  • Parents are homozygous recessive
  • None of these
Failure of cytokinesis after telophase stage of cell division results in an increase in a whole Set of chromosomes in an organism. The phenomenon is called as 
  • polyploidy
  • aneuploidy
  • haploidy
  • diploidy
Trisomy is represented by
  • (2n - 1)
  • (2n -2)
  • (2n + 2)
  • (2n + 1)
It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the
  • Results of $$F_3$$ generation of a cross
  • Observations that the offspring of a cross made between the plants having two contrasting characters shows only one character without any blending
  • Self pollination of $$F_1$$ offsprings
  • Cross pollination of $$F_1$$ generation with recessive parent
In human beings sex is determined
  • At the time of fertilization of ovum
  • During 6th week of foetal life when androgens are produced
  • Before fertilization of ovum
  • During 7th and 8th weeks of foetal Life when gonads differentiate into testis and ovaries
Due to the nondisjunction of chromosomes during spermatogenesis, some sperms carry both sex chromosomes (22A + XV) and some sperms do not carry any sex chromosomes (22A  + 0). If these sperms fertilise normal eggs (22A + X), what types of genetic disorders respectively appear among the offsprings?
  • Klinefelters syndrome and Turners syndrome
  • Turners syndrome and Klinefelters syndrome
  • Downs syndrome and Turners syndrome
  • Downs syndrome and Cri-du-chat syndrome
In the $$F_2$$ generation of a Mendelian dihybrid cross the number of phenotypes and  genotypes are
  • Phenotypes-4; Genotypes-16
  • Phenotypes-9; Genotypes-4
  • Phenotypes-4; Genotypes-8
  • Phenotypes-4; Genotypes-9
A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents?
  • TT and Tt
  • Tt and Tt 
  • TT and TT
  • Tt and tt
A pedigree is shown below for a disease that is autosomal dominant. What would be the genetic make up of the first generation?
933143_f0d2de26af484176a0764df56b35dfe6.png
  • AA, Aa
  • Aa, aa
  • Aa, AA
  • Aa, Aa
In the following pedigree charts, the mutant trait is shaded black. The gene responsible for the trait is 
1047842_7fa03cd6bc714bd887a790116af51038.PNG
  • Dominant and X linked
  • Dominant and autosomal or dominant and X linked
  • Recessive and X - linked
  • Recessive and Y- Linked
Mr. Christopher is colourblind and carrier for Phenylketonuria (PKU). What percentage of sperms possesses defective allele for both?
  • 0% 
  • 25%
  • 50%
  • 100% 
A cell at telophase stage is observed by a student in a plant brought from the field. He tells his teacher that his cell is not like other cells at telophase stage. There is no formation of cell plate and thus the cell is containing more number of chromosomes as compared to other dividing cells. This would result in 
  • polyploidy
  • somaclonal variation
  • polyteny
  • aneuploidy.
Select the incorrect statement regarding chromosomal theory of inheritance.
  • It was proposed by Sutton and Boveri
  • Chromosomes as the carriers of genetic material
  • Chromosomes and genes occur in pairs in diploid and haploid cells
  • The paired condition of both chromosomes as well as Mendelian factors is restored during fertilisation.
Morgan used Drosophila as experimental material because
  • They could be grown on simple synthetic medium in the laboratory.
  • It has a short life span
  • There was a clear differentiation of the sexes, the male and female flies are easily distinguishable.
  • All of the above
XXX refer to__________.
  • Noraml female
  • Super female
  • Metal female
  • Normal (triploid) female
Which Genetic Disorder is this Pedigree Chart Depicting?
1028027_784fc702de0342fa81ec8afa4d25c1fc.png
  • Autosomal Dominant
  • Autosomal Recessive
  • X - Linked Dominant
  • Maternal Inheritance
Which condition describes the sex correctly
  • XO condition as in Turner's syndrome determines the female sex
  • XX sex chromosomes produce male in Drosophila
  • ZZ sex chromosomes determine female sex in birds
  • XO sex chromosomes determine male sex in Grasshopper.
Gender of child is determined by the male partner of couple. Explain with reasons whether this statement is true or false?
  • True
  • False
If the husband is PTC taster and wife is PTC non-taster. Their daughters are non-tasters but their son is a taster. This is not related to a sex-linked trait. Out of four a, b, c, d which pedigree is correct?
Match the following with respect to pedigree analysis
Column - IColumn II
aSolid symboliCarrier of sex-linked trait
bThe horizontal line between symbolsiiOffspring 
c.Horizontal line above the symbolsiiiTrait to be studied
d.Dot in centerivParents
  • a (iv), b (iii), c (ii), d (i)
  • a (ii), b (iii), c (iv), d (i)
  • a (iii), b (iv), c (ii), d (i)
  • a (i), b (ii), c (iv), d (iii)
Trace the trait in this pedigree-
1083310_ab8609334c56461e8a3a461bc1e937d7.PNG
  • X-linked dominant
  • X linked recessive
  • Autosomnal dominant
  • Autosomal recessive
Heterogametic sex determination based on the number of sex chromosomes among the following are which of the following?
  • XX-XO and XX-XY method
  • ZO-ZZ and ZW-ZZ method
  • XX-XY and ZW-ZZ method
  • XX-XO and ZO-ZZ method
What is the phenotypic ratio of a monohybrid cross?
  • 1:3
  • 3:1
  • 1:2:2:1
  • 9:3:3:1
The  grain colour of wheat is determine by the additive effects of two pairs of genes Accordingly the $$F_2$$ inhertance appears in the ratio of $$15$$ red ,$$1$$ white  the fifteen red appear in different shades in the ratio of 
  • $$9:3:3$$
  • $$6:6:3$$
  • $$1:4:7:3$$
  • $$1:4:6:4$$
Predict from the following chart
1068007_59ed58b2be724c5397f8be17bab7b8fc.png
  • Character is dominant and carried by X chromosome
  • Character is carried by Y chromosome
  • Character is sex linked recessive
  • Character is recessive autosomal
The trait traced in this pedigree is 
1083328_f66cae9c14594276af47f45c06212d3e.PNG
  • X linked recessive
  • X linked dominant
  • Autosomal recessive
  • Autosomnal dominant
Which of the following is not an aneuploid?
  • Monoploid
  • $$2n -1 $$
  • Trisomic
  • $$2n +1 $$
When a pure bred, red flower -producing plant of genotype RR is crossed with  pure bred , white flowers-producing plant of genotype rr,all the $${ F }_{ 1 }$$ plants produced pink flowers If all the plant in each generation from $${ F }_{ 1 }$$ to$${ F }_{ 6 }$$ are selfed, what will be the percentage of plants with red and white flowers in the final population of plants with red and white flowers in the final population consisting of a large number of individuals? (Consider that flowers colour has no effect on reproduction and survival.)
  • $$3-4$$
  • $$12-13$$
  • $$49-51$$
  • $$97-100$$
A couple has $$8$$ children, all boys. What is the chance that their ninth child will be another boy?
  • $$1/2$$
  • $$1/4$$
  • $$1/8$$
  • $$1/16$$
25:46:26 is the genotypic ratio in $${ F }_{ 2 }$$ generation is expected from which parental cross?
  • $$Aa \times Aa$$
  • $$AA \times Aa$$
  • $$Aa \times aa$$
  • $$AA \times AA$$
An individual homozygous to genes cd is crossed with wild type $$++$$ and $$F_1$$ crossed back with the double recessive. The appearance of the offsprings is as follows.
$$++ \rightarrow 903$$
$$cd \rightarrow 897$$
$$+d \rightarrow 98$$
$$c+ \rightarrow 102$$
The distance between the genes $$c$$ and $$d$$ is 
  • $$20$$ map units
  • $$9.8$$ map units
  • $$10.2$$ map units
  • $$10$$ map units
In our society, women are blamed for producing female children. Choose the correct option for sex determination in humans.
  • Due to some defect like aspermia in man
  • Due to genetic makeup of some particular sperm which fertilizes the egg
  • Due to genetic makeup of the eggs
  • Due to some defect in women
Which of the following is true for progenies of $$F_3$$ generation of monohybrid cross?
  • $$ 75 \% $$ pure and $$25 \%$$ impure
  • $$ 25 \% $$ pure and $$75 \% $$impure
  • $$ 50 \% $$ pure and $$50\%$$ impure
  • $$ 87.5 \% $$ pure and $$12.5 \%$$ impure
Haploid number is $$10.$$ What shall be the tetrasomic number?
  • $$22$$
  • $$18$$
  • $$20$$
  • $$19$$
Select the monohybrid ratio in Pea.
  • $$1039$$ tall $$:$$ $$178$$ dwarf
  • $$80$$ tall $$:$$ $$20$$ dwarf
  • $$401$$ tall $$:$$ $$133$$ dwarf
  • $$150$$ tall $$:$$ $$20$$ dwarf
If a mutation occurs in a gamete, it would influence 
  • only a single individual
  • sterility in the progeny
  • all successive generation of the parents
  • only the particular sex of the progeny, whose gamete had undergone mutation
Phenotype ratio in codominance
  • $$1:2:1$$
  • $$1:1$$
  • $$3:1$$
  • $$2:1:3$$
When a cross is made between round seed and yellow seeds (RrYy) and round seed and green seeds (Rryy), what proportion of phenotype in the offspring could be expected to be wrinkled and green
  • $$\dfrac{1}{8}$$
  • $$\dfrac{1}{4}$$
  • $$\dfrac{1}{2}$$
  • $$\dfrac{1}{16}$$
In a cross between individuals homozygous for (a, b) and wild type($$+ +$$). In this cross $$700$$ out of $$1000$$ individuals were of parental type. Then the distance between a and b is?
  • $$70$$ map unit
  • $$35$$ map unit
  • $$30$$ map unit
  • $$15$$ map unit
According to the concept of dominance the following statements are given. Read the statements carefully and choose the correct answer.
(a) Wild allele is a fully functional allele that forms RNA, proteins but no enzymes.
(b) The mutant allele may produce a faulty product or no product at all
(c) The modified functional wild type allele represents the original phenotype
(d) The modified or mutated non-functional allele behaves as recessive allele.
  • a, b & c are correct
  • b & d are correct
  • Only d is correct
  • b, c & d are correct
$$XYY \rightarrow$$ composition
  • Super female
  • Hermaphrodite
  • Male
  • Supermale
In sickle cell anaemia, an amino-acid substitution is?
  • Valine by glutamine in $$\alpha$$-chain
  • Valine by glutamine in $$\beta$$-chain
  • Glutamine by valine in $$\alpha$$-chain
  • Glutamine by valine in $$\beta$$-chain
_____ is the root of any plant breeding programme 
  • Mutation
  • micropropagation
  • Generic variability
  • Testing and commercialisation of new cultivars
What is common between Mendelian monohybrid cross and dihybrid cross?
  • Dominance
  • Segregation
  • Independent assortment
  • More than one options are correct
Mendelian monohybrid ratio is?
  • $$1:2:1$$
  • $$3:1$$
  • $$9:3:1$$
  • $$9:3$$
Fruit shape in shephered's purse(capseila bursa) is of two types- triangular and top-shaped. Triangular fruit shape(T) is dominant over top-shape(t). Following table summaries the results of several crosses.
CrossResult
Strain $$1\times$$ ttAll triangular
Strain $$2\times$$ tt$$1$$ triangular $$: 1$$ top-shaped
Strain $$3\times$$ ttAll top-shaped
Strain $$4\times$$ tt$$3$$ triangular $$: 1$$ top-shaped
Which pair of strains possess the genotype Tt?
  • Strains $$2$$ and $$3$$
  • Strains $$2$$ and $$4$$
  • Strains $$1$$ and $$3$$
  • Strains $$1$$ and $$4$$
In South-African populations, a gene mutation that does not allow the speed of malaria, actually causes?
  • Phenylketonuria
  • Sickle-cell anaemia
  • Alkaptonuria
  • Colour blindness
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