Tag: botany

Questions Related to botany

The phenomenon of closely placed genes being inherited together is

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. Linkage

  2. Crossing over

  3. Gene interaction

  4. Qualitative inheritance

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Correct Option: A
Explanation:

  • Linkage refers to the presence of two different genes on the same chromosome. Two genes that occur on the same chromosome are said to be linked, and those that occur very close together are tightly linked.
  •  Crossing over is the exchange of chromosome segments between non-sister chromatids during the production of gametes.
  • When the expression of one gene depends on the presence or absence of another gene in an individual, it is known as gene interaction.
  • The pattern of inheritance for a qualitative trait is typically monogenetic, which means that the trait is only influenced by a single gene. Inherited diseases caused by single mutations are good examples of qualitative traits.

So, the correct answer is 'Linkage'.

Number of linkage groups in Pisum sativum is?

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. $4$

  2. $5$

  3. $7$

  4. $10$

Show answer
Correct Option: C
Explanation:
Number of linkage groups is equal to its haploid number.
Since haploid number of Pisum sativum is 7, it has 7 linkage groups.

So, the correct answer is '7'.

The cross-over percentage between linked genes is (a) J and M- $20\%$ (b) J and L - $35\%$ (c) J and N - $20\%$ (d) L and K - $15\%$ (e) M- N - $50\%$ (f) M and L - $15\%$. The sequence of genes on the chromosomes is?

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. J, N, M, L, K

  2. J, M, L, N, K

  3. J, M, L, K, N

  4. M, J, L, K, N

Show answer
Correct Option: C

Consider the following statements regarding linkage of genes.
a. Two genes are said to be linked when they fail to show independent assortment.
b. The strength of the linkage is determined by the distance between the two genes in question.
c. The strength of the linkage is directly proportional to the distance between the two genes.
Of these statements.

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. $1, 2$ and $3$ are correct

  2. $1$ and $2$ are correct

  3. $2$ and $3$ are correct

  4. $1$ and $3$ are correct

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Correct Option: A

If, in Macrospore, the progenies of the cross between an Orange colonial strain and Albino spreading strain segregated into $1:1:1:1$ ratio of Albino spreading: Orange colonial : Normal Albino colonial, then the inference is that the traits are controlled by.

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. Single gene

  2. Two genes

  3. Three genes

  4. Four genes

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Correct Option: A

Assuming that genes x and y are linked and exhibit 20% recombination. If ++/++ individuals are crossed with xy/xy, then types and percentage proportion of gametes in $F 1$ will be _____________.

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. ++80%: xy 20%

  2. ++40%: xy 40%: +x10%: y 10%

  3. +x40%: xy 40%: ++20%

  4. +x20%: ++ 40%: xy 20%

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Correct Option: A

Distance between 2 linked genes is measured in map units that depict:

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. ratio of crossing over between them

  2. cross-over value

  3. number of gene

  4. both b and c

Show answer
Correct Option: A
Explanation:

The methods used to identify the locus of a gene and the distances between genes is called gene mapping. It indicates the % of crossing over occurs between the linked genes. The essence of all genome mapping is to place a collection of molecular markers onto their respective positions on the genome. Recombination between linked genes can be used to map their distance apart on the chromosome. The distance between the two linked genes is measured by centimorgans or map units.

So, the correct option is ‘ratio of crossing over between them’.

How many linkage groups would be revealed by careful analysis of human genetics?

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. 23

  2. 4

  3. 3

  4. 1

Show answer
Correct Option: A
Explanation:
Linkage group, in genetics, all of the genes on the single chromosome, they are inherited in groups and move as a unit rather than independently. In human beings have 23 linkage groups.
So, the correct option is '23'.

The number of linkage groups is greater in Drosophila than in human beings.

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. True

  2. False

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Correct Option: B
Explanation:

The number of linkage groups is four in number which is less than humans. Fruit-fly Drosophila melanogaster has four linkage groups (4 pairs of chromosomes), human beings 23 linkage groups (23 pairs of chromosomes) So, the correct option is 'False'.

All genes located on the same chromosome

botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

  1. Form different groups depending upon their relative distance

  2. Form one linkage group

  3. Will not from any linkage groups

  4. Form interactive groups that affect the phenotype

Show answer
Correct Option: B
Explanation:

All the genes located on a single chromosome, are inherited together. So, they constitute a linkage group. They don't move independently during the process of cell division. They always in a group. They form a set of genes on different loci in a single chromosome. But the chromosome should not be a cross over one.

So, option B is the correct answer.