Biology

Genetics and Plant Breeding

1,177 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 plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

A cybrid is hybrid carrying

  1. Genomes and cytoplams of two different plants

  2. Cytoplasms of two different plants

  3. Cytoplasms of two different plants but genome of one plant

  4. Genomes of two different plants

  5. Cytoplasms of several plants but genomes of two plants.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A cybrid (cytoplasmic hybrid) is produced by the fusion of a protoplast containing a nucleus and cytoplasm with a cytoplast (a cell without a nucleus). Thus, it contains the cytoplasm of both parents but the nuclear genome of only one.

Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

During hybridisation, offspring with hybrid vigour superior to both parents are self pollinated for a few successive generations to .............

  1. Retain their parental characters

  2. Remove their parental characters

  3. Get homozygosity

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

Self-pollination of hybrid offspring over several generations leads to the segregation of alleles and an increase in homozygosity, which helps in stabilizing the desired traits.

Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

Consider the following statements: Hybrid plants can show.
a. Sterility
b. Mosaicism
c. Crossing over
d. Vigour
e. Homozygosis
Which of the statements are correct?

  1. $2, 3$ and $5$
  2. $2, 4$ and $5$
  3. $1, 2$ and $4$
  4. $1, 3$ and $4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hybrid plants can exhibit sterility due to meiotic irregularities, mosaicism from somatic mutations or chromosomal variation, and hybrid vigor (heterosis). Crossing over is a normal meiotic process occurring in all sexually reproducing plants, not uniquely a hybrid feature, and hybrids are typically heterozygous rather than homozygotic.

Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

A breeder crossed a pure bred all plant having white flowers to a pure bred short plant having blue flowers. He obtained $202\ F _{1}$ progeny and found that they are all tall having white flowers. Upon selfing there $F _{1}$ plants, he obtained a progeny of $2160$ plants. Approximately, how many of these are likely to be short and having blue flowers?

  1. $1215$
  2. $405$
  3. $540$
  4. $135$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is a dihybrid cross. The F1 generation is heterozygous for both traits (TtWw). In the F2 generation, the probability of a short (tt) blue (ww) plant is 1/4 * 1/4 = 1/16. For 2160 plants, 2160 / 16 = 135.

Multiple choice botany plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

In high yielding hybrid crop varieties to exploit hybrid vigour, the farmers need to purchase fresh hybrid seed every year because 

  1. They are not allowed to grow their own seed.

  2. Hybrid vigour is lost due to inbreeding depression.

  3. It is cheaper to purchase fresh seed.

  4. Government has accepted Dunkel's proposals.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hybrid vigour will be lost due to inbreeding depression. The increase in the level of production traits due to crossing is called hybrid vigour or heterosis. The term hybrid vigour points at the vigour, which is a real factor that can bee seen by the naked eye, in comparison to pure breeding. The other word heterosis is derived from heterozygosity and points toward the direction form where the effect arises. The direction of the effect of crossing is opposite the effect of inbreeding. Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding - ie., breeding of related individuals. Population biological fitness refers to its ability to survive and reproduce itself.

Multiple choice biology breeding and biotechnology method of plant breeding for crop improvement plant breeding for food production biotechnology

The hybrids are generally found to be superior to their parents, it is because of

  1. Homozygosity

  2. Hybrid vigour

  3. Parents are generally weak

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heterosis is also called as hybrid vigour. It is the increase in such characteristics as size, growth rate, fertility and yield of a hybrid organism over those of its parents. Plant and animal breeders exploit heterosis by mating two different pure-bred lines that have certain desirable traits. Because of this, hybrids are generally found to be superior to their parents. Thus, the correct answer is option B.

Multiple choice biology breeding and biotechnology method of plant breeding for crop improvement plant breeding for food production biotechnology

IR-36 was developed through breeding of

  1. Six rice varieties and Oryza nivara

  2. 13 rice varieties and Oryza nivara

  3. Oryza sativa and O. indica

  4. Oryza indica and O. nivara
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gurdev S. Khush crossed 13 varieties of rice from Oryza nivara to develop IR - 36 which was resistant to grassy stunt virus.

Multiple choice biology breeding and biotechnology method of plant breeding for crop improvement plant breeding for food production biotechnology

Match the columns:

I II
a Mutation breeding 1 Johannsen
b Inbreeding depression 2 Karpechenko
c Pureline selection 3 Darwin
d Intergeneric hybridization 4 Staddler
5 Shull

  1. a-4, b-2, c-5, d-1

  2. a-4, b-5, c-2, d-1

  3. a-4, b-5, c-1, d-2

  4. a-5, b-4, c-1, d-2.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mutation breeding is associated with Staddler (4), Inbreeding depression with Shull (5), Pureline selection with Johannsen (1), and Intergeneric hybridization with Karpechenko (2).

Multiple choice botany seeds - structure and germination what is a seed? seeds seed

In view of the suicides committed by the poor farmers towards raising the commercial $F1$ hybrid seeds, a plant breeder wishes to supply them the hybrid seeds at a chapter cost. Which One of the following type of genetic stocks can be choose?

  1. Inbred lines

  2. Back-cross progeny

  3. Male sterile lines

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

Inbred lines are genetically uniform and stable. By using inbred lines, farmers can save seeds for subsequent seasons, avoiding the need to purchase expensive F1 hybrid seeds every year, which lose their vigor in the F2 generation.

Multiple choice zoology biotechnology and its applications transgenic animals transgenic organisms applications of biotechnology

Inbreeding for five generations led to production of homozygous transgenic mice. However, these homozygous males or females were infertile. Which of the following approaches is most preferable and economical to obtain heterozygous transgenic animals continuously?

  1. More transgenic founder (1st animal) should be generated.

  2. Crossing (breeding) of transgenic mice with wild type mice in earlier generations should be done for continued production of transgenic heterozygous offsprings

  3. Inbreeding should be avoided after 5th generation

  4. Homozygous transgenic mice should be mated with heterozygous transgenic mice for continued production of transgenic heterozygous offsprings.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Interbreeding of particular species for a larger amount of time causes the recessive traits to appear in the offspring and those result in infertility. Inbreeding is not recommended and cross-breeding is required. When the transgenic mice are inbred for very large duration infertility is caused.

To get heterozygous transgenic mice crossbreeding should be done with the wild-type.
So, the correct option is 'Crossing (breeding) of transgenic mice with wild type mice in earlier generations should be done for continued production of transgenic heterozygous offsprings'

Multiple choice zoology biotechnology and its applications transgenic animals transgenic organisms applications of biotechnology

Mule is a product of

  1. Breeding

  2. Mutation

  3. Hybridisation

  4. Interspecific hybridisation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An interspecific hybrid is the product of mating between parents of two different species. A mule is the offspring of a male donkey and a female horse (mare). Mules are more patient, sure-footed, hardy and long-lived than horses, and they are considered less obstinate, faster, and more intelligent than donkeys.

So, the correct answer is 'Interspecific hybridisation'

Multiple choice botany pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

Cross-pollination is advantageous because it results in

  1. Formation of weaker progeny

  2. Formation of better progeny

  3. Formation of male off-spring

  4. Formation of female offspring
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cross-pollination is advantageous because it results in formation of better progeny. The transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and wind are agents of cross-pollination.

Advantages of cross pollination:
  • Progeny shows enhanced vigor.
  • Offsprings are more viable and resistant.
  • There is a possibility to get new desirable characters.
  • Yield of crop can be maintained.
  • It helps in evolution.
  • Undesirable characters of the plant can be eliminated.

Multiple choice botany pollination, fertilization and development of endosperm and embryo types of pollination cross pollination pollination and its types

One plant produces only female white flower, if it produce pink flower in the next generation then which one of the following is possible?

  1. Double fertilisation

  2. Self pollination

  3. Cross pollination

  4. No fertilisation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If it produces a pink flower in the next generation then cross-pollination might have occurred.

Cross-pollination - The transfer of pollen from the male reproductive organ (an anther or a male cone) of one plant to the female reproductive organ (a stigma or a female cone) of another plant. Insects and wind are agents of cross-pollination.
Double fertilization is a complex fertilization mechanism of flowering plants (angiosperms). This process involves the joining of a female gametophyte (megagametophyte, also called the embryo sac) with two male gametes (sperm).
There are two types of self-pollination: In autogamy, pollen is transferred to the stigma of the same flower. In geitonogamy, pollen is transferred from the anther of one flower to the stigma of another flower on the same flowering plant or from microsporangium to ovule within a single (monoecious) Gymnosperm.
Therefore, the correct answer is option C.