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 plant breeding method of plant breeding for crop improvement plant breeding for food production biotechnology

Norin-10 gene is

  1. Dwarf gene of rice

  2. Dwarf gene of wheat

  3. Dwarf gene of tomato

  4. Smut resistant gene of wheat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Rht-B1b and Rht-D1b dwarfing genes were derived from Norin-10, which was a semi-dwarf variety bred in Japan and released in 1935 (Gale and Youssefian, 1985). Norin-10 was used in US breeding programs in the 1950s in order to improve lodging resistance in winter wheat, in which lodging was a serious problem when high rates of nitrogen fertilizers were applied. A selection from a cross of Norin-10 with the US variety, Brevor was particularly promising and was used by Borlaug in the development of the green revolution wheat varieties. Wheat Norin-10 is a semi-dwarf wheat cultivar with very large ears that was bred at an experimental station in Iwate Prefecture, Japan. Norin-10 helped developing countries, such as India and Pakistan, to increase the productivity of their crops from approximately 60% during the green revolution. Thus, the correct answer is option B.

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

Crosses between the plants of the same variety are called as

  1. Interspecific

  2. Intervarietal

  3. Intravarietal

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

In intravarietal hybridization, the crosses are made between the plants of same variety. Thus, option C is correct.

Intervarietal hybridization is in which parents involved in hybridization belong to the same species. In crop improvement programme this type of hybridization is commonly used. E.g., crossing of two varieties of wheat or other crops. 
Interspecific hybrids are bred by mating two species, normally from within the same genus.
Hybrids between different genera (such as between sheep and goats) are known as intergeneric hybrids.

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

Hexaploid or moderm wheat developed through ______________.

  1. Hybridomas

  2. Chromosome doubling

  3. Hybridisation

  4. Hybridisation and chromosome doubling
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Modern hexaploid wheat (Triticum aestivum) arose through the combination of hybridization between different wild grass species followed by spontaneous chromosome doubling (polyploidy) to restore fertility.

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

Majority of improved Indian Rice varieties have arisen from a cross between

  1. Oryza sativa indica $\times$ Oryza nivara
  2. Oryza sativa indica $\times$ O. sativa japonica
  3. O. sativa japonica $\times$ O. nivara
  4. O. rufipogon $\times$ O. nivara.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Improved Indian rice varieties, such as those developed during the Green Revolution, were primarily derived from crosses between the indica subspecies (native to India) and the japonica subspecies (known for high yield).

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

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.