Principles of Inheritance & Variation Test 11

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Principles of Inheritance & Variation Test 11

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Question 1
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Direction: Read the following text and answer the following questions on the basis of the same :
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens : physical and chemical mutagen.
Give one word for the following :

A
A. Point mutation

B
B. Somatic mutation

C
C. Deletion

D
D. Insertion

Solution

Point mutations refer to changes in the sequence of DNA bases, and include substitutions, insertions, and deletions of one or more bases.
Question 2
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Direction: Read the following text and answer the following questions on the basis of the same :
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens : physical and chemical mutagen.
Substitution of a purine with another purine is known as ............... :

A
A. Transversion

B
B. Inversion

C
C. Transition

D
D. Translocation

Solution

When a purine base is replaced by another purine and pyrimidine by another pyrimidine, it is transition.
Question 3
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Direction: Read the following text and answer the following questions on the basis of the same :
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens : physical and chemical mutagen.
Change in sequence of nucleotide in DNA is known as ...... .

A
A. Translation

B
B. Recombination

C
C. Mutation

D
D. Transcription.

Solution

Change in sequence of nucleotide in DNA is known as mutation. A mutation involves a change in the sequence of nucleotides in a nucleic acid molecule.
Question 4
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Direction: Read the following text and answer the following questions on the basis of the same :
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens : physical and chemical mutagen.
Aneuploidy which occurs due to loss of a complete homologous pair of chromosomes is:

A
A. Trisomy

B
B. Nullisomy

C
C. Tetrasomy

D
D. Euploidy

Solution

Nullisomy - the loss of both pairs of homologous chromosomes; individuals are called nullisomic and their chromosomal composition is 2N-2.
Question 5
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Direction: Read the following text and answer the following questions on the basis of the same :
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens : physical and chemical mutagen.
Which is the main category of mutation ?

A
A. Genetic mutation

B
B. Somatic mutation

C
C. Heterosis

D
D. None of these.

Solution

Mutation is a change of the nucleotide sequence of the genome of an organism. It is a sudden inheritable change. A genetic mutation is a permanent change in the DNA sequence that makes up a gene. It can occur in all type of cells even in virus and extrachromosomal plasmid.
Question 6
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Direction: Read the following and answer the questions given below:
During a study of inheritance of two genes, teacher asked students to perform an experiment. The students crossed white eyed, yellow bodied female Drosophila with a red eyed, brown bodied male Drosophila (i.e., wild). They observed that progenies in F₂ generation had 1.3 percent recombinants and 98.7 percent parental type combinations. The experimental cross with results is shown in the given figure. [Note: Dominant wild type alleles are represented with (+) sign in superscript.]
Assertion : When yellow bodied, white eyed Drosophila females were hybridised with brown-bodied, red eyed males; and F₁ progeny was intercrossed , F₂ ratio deviated from 9 : 3 : 3 : 1.
Reason : When two genes in a dihybrid are on the same chromosome, the proportion of parental gene combinations are much higher than the non-parental type.

A
A. Both assertion and reason are true and reason is the correct explanation of assertion.

B
B. Both assertion and reason are true but reason is not the correct explanation of assertion.

C
C. Assertion is true but reason is false.

D
D. Both assertion and reason are false.

Solution

In Drosophila, the genes for body and eye colour are located on X chromosome. When two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combination are higher than non-parental type. This occurs due to physical association or linkage of the two genes while non-parental gene combinations due to recombination between two genes. Thus, linkage and recombination deviates the ratio from Mendelian ratio of dihybrid cross ( 9 : 3 : 3 : 1 ) .
Question 7
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Direction: Read the following and answer the questions given below:
During a study of inheritance of two genes, teacher asked students to perform an experiment. The students crossed white eyed, yellow bodied female Drosophila with a red eyed, brown bodied male Drosophila (i.e., wild). They observed that progenies in F₂ generation had 1.3 percent recombinants and 98.7 percent parental type combinations. The experimental cross with results is shown in the given figure. [Note: Dominant wild type alleles are represented with (+) sign in superscript.]
Genes white eyed and yellow bodied located very close to one another on the same chromosome tend to be transmitted together are called

A
A. allelomorphs

B
B. identical genes

C
C. linked genes

D
D. recessive genes

Solution

Genes located very close to one another on the same chromosome tend to be transmitted together and are called linked genes.
Question 8
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Direction: Read the following and answer the questions given below:
During a study of inheritance of two genes, teacher asked students to perform an experiment. The students crossed white eyed, yellow bodied female Drosophila with a red eyed, brown bodied male Drosophila (i.e., wild). They observed that progenies in F₂ generation had 1.3 percent recombinants and 98.7 percent parental type combinations. The experimental cross with results is shown in the given figure. [Note: Dominant wild type alleles are represented with (+) sign in superscript.]
By conducting the given experiment, teacher can conclude that
A. Genes for eye colour and body colour are linked
B. Genes for eye colour and body colour show complete linkage
C. Linked gene remain together and are inherited

A
A. A and B only

B
B. B only

C
C. A and C only

D
D. A, Band C

Solution

By conducting the given cross teacher can conclude that the genes for eye colour and body colour are linked. Thus these genes were very tightly linked and showed very low recombination.
Question 9
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Direction: Read the following and answer the questions given below:
During a study of inheritance of two genes, teacher asked students to perform an experiment. The students crossed white eyed, yellow bodied female Drosophila with a red eyed, brown bodied male Drosophila (i.e., wild). They observed that progenies in F₂ generation had 1.3 percent recombinants and 98.7 percent parental type combinations. The experimental cross with results is shown in the given figure. [Note: Dominant wild type alleles are represented with (+) sign in superscript.]
Select the correct statement regarding the given experiment.

A
The physical distance between two genes determines strength of linkage.

B
The physical distance between two genes determines frequency of crossing over.

C
The two linked genes always segregate independently of each other.

D
Both (a) and (b)

Solution

The physical distance between two genes determines both the strength of the linkage and the frequency of the crossing over between two genes. The strength of the linkage increases with the closeness of the two genes. On the other hand the frequency of crossing over increases with the increase in the physical distance between the two genes.
Question 10
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Direction: Read the following text and answer the following questions on the basis of the same :
Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome hence its other name, trisomy 21. The affected individual mental retarded, short statured with small round, head, furrowed tongue and partially open mouth, Physical, psychomotor and mental development is retarded.
Down syndrome is caused due to

A
A. Assertion and Reason

B
B. a chromosomal abnormality lack of oxygen supply to the brain during birth

C
C. Viral infection

D
D. a chromosomal abnormality

Solution

Down syndrome is due to autosomal chromosome abnormality.
Question 11
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Direction: Read the following text and answer the following questions on the basis of the same :
Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome hence its other name, trisomy 21. The affected individual mental retarded, short statured with small round, head, furrowed tongue and partially open mouth, Physical, psychomotor and mental development is retarded.
Down syndrome is

A
A. Sex-linked

B
B. Chromoso mal

C
C. Dominant

D
D. Recessive

Solution

Down syndrome is an autosomal recessive disorder which can be inherited through normal parents in the child.
Question 12
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Direction: Read the following text and answer the following questions on the basis of the same :
Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome hence its other name, trisomy 21. The affected individual mental retarded, short statured with small round, head, furrowed tongue and partially open mouth, Physical, psychomotor and mental development is retarded.
Down Syndrome is an extra copy which chromosome

A
A. 22nd chromosome

B
B. 21st chromosome

C
C. 45th chromosome

D
D. 47th chromosome

Solution

Down Syndrome is due to extra copy of 21st chromosome forming trisomy condition.
Question 13
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Direction: Read the following text and answer the following questions on the basis of the same :
Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome hence its other name, trisomy 21. The affected individual mental retarded, short statured with small round, head, furrowed tongue and partially open mouth, Physical, psychomotor and mental development is retarded.
The number of chromosomes a child with Down syndrome has is

A
A. 45

B
B. 46

C
C. 47

D
D. 48

Solution

The affected person inherited with one extra copy of 21st chromosome that forms trisomy condition.
Question 14
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Direction: Read the following text and answer the following questions on the basis of the same :
Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome hence its other name, trisomy 21. The affected individual mental retarded, short statured with small round, head, furrowed tongue and partially open mouth, Physical, psychomotor and mental development is retarded.
One of this trait is seen in a person with Down syndrome

A
A. Upward slant eye

B
B. Baldness

C
C. Short stature

D
D. Long neck

Solution

The person affected with Down syndrome has symptoms like mental retarded, short statured with small round, head, furrowed tongue etc.
Question 15
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Directions: In the following questions, a statement of assertion is followed by a statement of reason.
Assertion: A good example of multiple alleles is ABO blood group system.
Reason: When IA and IB alleles are present together in ABO blood group system, they both express their own types.

A
A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

B
B. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

C
C. If Assertion is true but Reason is false.

D
D. If both Assertion and Reason are false.

Solution

In the ABO system, consists four blood groups A, B, AB and O. ABO blood groups are controlled by gene I. The gene has three alleles I^A, I^B and i. This phenomenon is known as multiple allelism. IA and IB are completely dominant over i. When I^A and I^B are present together, they both express themselves and produce AB blood group. This phenomenon is known as codominance.