Biology

Genetics and Plant Breeding

1,240 Questions

Genetics and Plant Breeding explores the principles of heredity, chromosomal inheritance, and hybridization techniques. It includes key concepts like Mendelian genetics, gene linkage, and polygenic inheritance. This topic is essential for students tackling advanced biology or botany sections in competitive examinations.

Mendelian InheritanceChromosome TheoryGene LinkagePolygenic InheritancePlant HybridizationPopulation Genetics Equilibrium

Genetics and Plant Breeding Questions

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

In an organism punk is a sex-linked recessive trait and black hair heterozygous female is mated to white male which is not spotted, the phenotypic ratio of the offspring would be :

  1. 1/4 spotted black; 1/4 pink spotted white; 1/4 unspotted black; 1/4 uspotted white

  2. 1/2 spotted black; 1/2 pink spotted white

  3. 3/4 pink spotted black; 1/4 pink spotted white

  4. 3/4 unspotted black; 1/4 pink spotted white
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice biology inherited changes linkage and crossing over linkage and recombination genetics: inheritance

A man with pure blue eyes and pure black hair marries a woman with black eyes and red hair. (Black eyes are dominant over blue eyes and black hair over red hair). What will be the probabilities of phenotypes of the children?

  1. $50$% with black eyes and black hair, and $50$% blue eyes and black hair

  2. All will be with black eyes and black hair

  3. Both the above cases are possible
  4. $1 : 1 : 1 : 1$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Man is bbhh (blue eyes, red hair - both recessive). Woman is BBrr (black eyes dominant, red hair recessive). Their F1 progeny will all be Bbrr (black eyes, red hair). When crossed with bbhh, all offspring will be Bbrr (black eyes, red hair) in phenotype. However, the question structure suggests the man is bbhh and woman is BBHh, giving 50% black eyes with black hair and 50% blue eyes with black hair.

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

If both parents are bald and their first female child is normal, then chances of bald ness is second male child are ________________.

  1. $100$%
  2. $50$%
  3. $25$%
  4. $0$%
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Male pattern baldness is X-linked recessive. If both parents are bald, mother is X^bX^b and father is X^BY. First daughter being normal means she's X^BX^b (heterozygous carrier). Second male child receives Y from father and X from mother. With probability 1, he receives X^b from mother, making him X^bY and bald.

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

Choose the correct answer from the alternatives given.
If you had two guinea pigs of opposite sex, both homozygous, one black and one brown, but you didnt know which was the dominant characteristic, how would you find out the dominant colour?

  1. Mate them together and see what colour the offspring arethat will be the dominant colour

  2. Mate them together and see what colour the offspring arethe other will be the dominant colour

  3. Mate them together, then mate their offspring to see what colour the grandchildren arethat will be the dominant colour

  4. Mate them together, then mate their offspring to see what colour the grandchildren arethe other colour will be the dominant colour
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since both the guinea pigs are homozygous mating them will result in a heterozygous genotype in the offspring. In the heterozygous condition, the dominant allele has the ability to mask the effect of the recessive allele. Therefore, the phenotypic character that will be expressed will be the phenotype of the dominant character and the F1 progeny color will be the dominant color. So, the correct option is 'Mate them together and see what color the offspring are that will be the dominant color'.

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


A heterozygote has a .......... for the trait being studied.

  1. haploid condition, in genetic terms

  2. pair of non-identical alleles

  3. pair of identical alleles

  4. both (a) and (c)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An individual having two different alleles of a particular gene or genes, and so giving rise to varying offspring.

So, the correct option is 'pair of non-identical alleles'.