Tag: linkage and crossing over

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

Out of three characters on chromosome no. 4, two characters indicate linkage and not mentioned by Mendel. These characters were

  1. Pod form - stem length

  2. Pod form - pod position

  3. Pod form - pod colour

  4. Pod position - stem length
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The chromosome no. 4 of pea plant carries genes for flower position, pod form and plant height. Out of these three genes, the two genes namely the gene for pod form and the one for plant height are closely placed on the chromosome that they show linkage. However, the gene for flower position is located far apart from the other two genes and do not show linkage. Hence, option A is correct. 

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

How many linkage groups are present in human male?

  1. 24

  2. 23

  3. 46

  4. 22
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Humans can have 2 linkage groups based on gender. 
Male have 22 pairs of autosomes and 1X and 1Y. So, in all 24 linkage groups. 
While females have 22 pairs autosomes and 1X pair. So, total 23 linkage groups
Thus, the correct answer is '24'.
Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Lack of independent assortment between two genes A and B would be due to

  1. Crossing over

  2. Linkage

  3. Recombination

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Crossing over is the process of exchange of genetic material between non-sister chromatids of homologous chromosomes to produce new genetics combinations or variations; it does not interfere with an independent assortment of genes. Option A is incorrect. The linkage is the tendency of closely placed genes on a chromosome to stay together during inheritance and do not assort independently; it produces more parental combination and less/no new combinations of the gene. The linkage is indirectly proportional to the distance between genes; the less the distance between the genes, the more linkage due to lack of independent assortment between them. Option B is correct. Recombination is new arrangements of genes on chromosomes which is carried out by independent assortment and crossing over; thus recombination is the result of independent assortment which makes option D is incorrect. Option B is correct.
Multiple choice botany chromosomal basis of inheritance linkage and crossing over linkage and recombination genetics: inheritance

Number of linkage groups in Pisum sativum is 

  1. 4

  2. 5

  3. 7

  4. 10
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The total number of linkage groups in an organism equals to the number of autosomes in its haploid cell. Pisum sativum has seven pairs of chromosomes which mean that the number of autosomes in its haploid cell is 7. Hence, a total number of linkage groups will be 7 provided all the genes are mapped. So, the correct answer is option C.

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

Linkage was first observed in

  1. Field pea

  2. Sweet pea

  3. Pea

  4. Grass pea
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The phenomenon of linkage was first observed by Bateson and Punnet in 1906 in sweet pea (Lathyrus odoratus). Linkage describes the way in which two genes that are located close to each other on a chromosome are often inherited together. Hence option B is correct.

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

In a long-term study of a population of a self-pollinated plant, it was observed that an allele, which significantly enhanced vegetative growth and production of flowers in the plant, did not expand in distribuation over subsequent generations in the population. This could be because the allele is

  1. Dominant lethal in nature

  2. Tightly linked to a gene that allows formation to large number of seeds in each plant

  3. Linked to a gene that suppresses development of axillary branches

  4. Tightly linked to a gene that suppresses development of pollen mother cells in the plant
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the case of self pollinated plants, the self pollen pollinates on the stigma. The allele involved in the production of pollen affects the progeny plants in the subsequent generations. The allele for the formation of pollen from pollen mother cells and the allele for vegetative growth and production of flowers are tightly linked. So, when the plants did not show enhanced growth and flowering, it can be said that this gene also suppresses development of pollen mother cells which will thereby affect the distribution in the next generations. 

Thus, the correct answer is option D.  

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

Linkage gene do not show

  1. independent assortment

  2. 9:3:3:1

  3. segregation

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Linked gene do not show :

Correct option is (D) All of the above .
Linked gene violates independent assortment , having the phenotype ratio 9;3;3;1. Linked gene is also influenced by the segregation.
Hence, option D is correct.

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

Genes located very close to one another on same chromosome tend to be transmitted together and are called as

  1. Allomorphs

  2. identical genes

  3. Linked genes

  4. recessive genes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Genes that are sufficiently close together on a chromosome will tend to "stick together," and the alleles of those genes that are together on a chromosome will tend to be inherited as a pair more often than not. This phenomenon is called genetic linkage. These genes are called as linked genes that are likely to be inherited together because they are physically close to one another on the same chromosome.

So, the correct answer is 'Linked genes'.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

The primary biological importance of sex in organisms is that it

  1. Is essential for organismic reproduction

  2. Is essential for cellular reproduction

  3. Causes new mutations to occur in offspring

  4. Promotes genetic variability in offspring
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The primary biological advantage of sexual reproduction over asexual reproduction is the generation of genetic diversity through recombination and independent assortment, which aids in adaptation.

Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

P is the daughter of Q. R has only two children - P and S. T is the brother of U. S is married to V. R has only two daughters. X is the father of Q. T is married to P. W is married to X. R is the son of Y. Who among the following is the mother of Q?

  1. W

  2. Y

  3. R

  4. X
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

X is the father of Q. W is married to X. Therefore, W is the mother of Q.