Chromosome Maps

Q. What map unit (centimorgan) is adopted in the construction of genetic maps?

1. A unit of distance between two expressed genes, representing 10% crossover
2. A unit of distance between two expressed genes, representing 1% crossover
3. A unit of distance between genes on chromosomes, representing 50% crossover
4. A unit of distance between two expressed genes, representing 100% crossover

Q.

The linkage map of the X-chromosome of fruit flies has 66 units, with yellow body gene (y) at one end and bobbed hair (b) gene at the other end. The recombination frequency between these two genes (y and b) should be :

1. $60\%$
2. $>50\%$
3. $\le 50\%$
4. $100\%$

Q. There are three genes a, b and c. The percentage of crossing over between a and b is $20\%$, b and c is $28\%$ and a and c is $8\%$. What is the sequence of genes on chromosomes?

1. None
2. b, a, c
3. a, b, c
4. a, c, b

Q.

The map distances between genes A and B is 3 units, between B anc C is 10 units and between C and A is 7 units. The order of the genes in a linkage map constructed on the above data would perhaps be:

1. A, B, C

2. A, C, B

3. B, C, A

4. B, A, C

Q.

A set of unpaired chromosomes is said to be ________ .

Q. Read the following five statements in the context of a plasmid.
(A) Its DNA is always double stranded.
(B) Its DNA is naked and without histone proteins.
(C) Its DNA can replicate independent of genomic DNA.
(D) Both exons and introns are present in plasmid DNA.
(E) Plasmid DNA can be either linear or circular.
Which of the above given statements are incorrect?

Q.

How many chromosomes are in a human oogonia?

Q. There are three genes a, b, c. Percentage of crossing over between a and b is 20%, b and c is 28% and a and c is 8%. What is the sequence of genes on chromosome?

1. b, a, c
2. a, c, b
3. a, b, c
4. None of the above

Q. In Drosophila, the yellow gene (y) and white gene (w) showed 1.3% recombination while white (w) and miniature wing gene (m) showed 37.2% recombinations. This indicates that:

1. w and m are on different chromosomes
2. w and m are closer than w and y
3. w and y are on the same chromosome while m is on a different chromosome
4. w and y are closer than w and m

Q. Alfred Sturtevant defined one map unit on a chromosome as the equivalent of a _______ recombination frequency.

1. 0%
2. 1%
3. 10%
4. 100%

Q. What is actually Morgan's unit?

Q.

Determination of percentage of crossing over between two linked genes is important in

1. Maintaining heterozygosity in population

2. Indicating relative position of genes in chromosomes

3. Fixation of heterosis in organisms

4. Explaining the phenomenon of coupling and repulsion.

Q.

Map distance of genes is calculated by ___.

1. Number of mutant genes

2. crossover percentage

3. Recombination frequency of each gene locus

4. Non crossover percentage

Q. Read the following five statements in the context of a plasmid.
(A) Its DNA is always double stranded.
(B) Its DNA is naked and without histone proteins.
(C) Its DNA can replicate independent of genomic DNA.
(D) Both exons and introns are present in plasmid DNA.
(E) Plasmid DNA can be either linear or circular.
Which of the above given statements are incorrect?

1. (A) and (E)
2. (A), (B) and (C)
3. (C) and (E)
4. (D) and (E)

Q. Distance between two linked genes is measured in map units which depicts the of crossing over.

1. frequency
2. strength
3. intensity
4. alleles

Q. In somatic cells, chromosomes are found in while in gametic cells, chromosomes are found in .

1. pairs
2. single sets
3. triplet
4. random numbers

Q. What map unit (centimorgan) is adopted in the construction of genetic maps?

1. A unit of distance between two expressed genes, representing 100% crossover
2. A unit of distance between genes on chromosomes, representing 50% crossover
3. A unit of distance between two expressed genes, representing 1% crossover
4. A unit of distance between two expressed genes, representing 10% crossover

Q. In somatic cells, chromosomes are found in while in gametic cells, chromosomes are found in .

1. pairs
2. single sets
3. triplet
4. random numbers

Q.

What map unit (Centimorgan) is adopted in the construction of genetic maps?

1. A unit of distance between genes on chromosomes, representing 50% crossover.

2. A unit of distance between two expressed genes representing 10% crossover.

3. A unit of distance between two expressed genes representing 100% crossover.

4. A unit of distance between genes on chromosomes, representing 1% crossover.

Q.

What do you mean by Recombinant DNA ?

Q. Number of gamete types formed by AaBbCc individual/heterozygous for three gene loci is

1. 2
2. 4
3. 8
4. 16

Q. The distance between the genes a, b, c and d in mapping units are a-d = 3.5; b-c = 1; a-b = 6; c-d = 1.5 and a-c = 5. Find out the sequence of arrangement of these genes.

1. abcd
2. acdb
3. acbd
4. abdc
5. adcb

Q. What is the distance between the genes A and B?
(a) 20 map unit
(b) 10 map unit

Q. What will be the recombination frequency between two gene (a and b), if the linkage map of X-chromosomes of Drosophila has 66 units, with yellow body gene (a) at one end and bobbed hair gene (b) at another end? (a)

1. $\le 50$%
2. Exact 66%
3. $>50$ %
4. Exact 100%

Q. Assertion :The maximum frequency of recombination, that can result from crossing over between linked genes, is 50 percent. Reason: Linked genes shown higher frequency of crossing over if distance between them is longer.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Gene mutation is caused

1. Due to reproduction
2. Due to change in sequence of nitrogenous base
3. Due to linkage
4. Due to change in sequence of genes in DNA

Q. There are three genes: a, b, and c. The percentage of crossing over between a and b is 20%, b and c is 28%, and a and c is 8%. What is the sequence of genes on chromosomes?

1. b, a, c
2. a, b, c
3. a, c, b
4. None of these

Q. There are three genes a, b and c. The percentage of crossing over between a and b is $20\%$, b and c is $28\%$ and a and c is $8\%$. What is the sequence of genes on chromosomes?

1. b, a, c
2. a, b, c
3. a, c, b
4. None

Q.

Determination of percentage of crossing over between two linked genes is important in

1. Maintaining heterozygosity in population

2. Indicating relative position of genes in chromosomes

3. Fixation of heterosis in organisms

4. Explaining the phenomenon of coupling and repulsion.

Q. Distance between two linked genes is measured in map units which depicts the of crossing over.

1. frequency
2. strength
3. intensity
4. alleles