Questions - Answers
Very Short Answer Type Questions
1. What is meant by hidden hunger?
A: The suffering caused due to deficiencies of micro nutrients, proteins or vitamins due to non-affordability to buy fruits, vegetables, legumes, fish, meat etc., is called “Hidden Hunger”.
2. Name two semi-dwarf varieties of rice developed in India.
A: Jaya, Ratna.
3. Give two examples of wheat varieties introduced in India which are high yielding and disease resistant.
A: Sonalika and Kalyan Sona.
4. Give two examples of fungi used in SCP production.
A: Candida utilis (Torula yeast)
Saccharomyces cervisiae (Baker’s yeast)
Chaetomium cellulolyticum (Any two of the above)
5. Why are plants obtained by protoplast fusion called somatic hybrids?
A: The plants obtained by protoplast fusion are formed by fusing isolated protoplasts of different plants with desirable characters. As this fusion does not involve pollination or fertilization they are called somatic hybrids.
6. What is protoplast fusion?
A: The fusion of isolated protoplasts from two different varieties of plants each with a desirable character is called protoplast fusion.
7. Why is it easier to culture meristems compared to permanent tissues?
A: The meristematic cells are young and capable of cell division easily. Further the meristems are virus free and hence easy to culture them when compared to permanent tissues.
8. Why are proteins synthesised from Spirulina called single cell proteins?
A: All the proteins obtained from microorganisms like fungi, bacteria and algae are called single cell proteins. As Spirulina is a microscopic alga the proteins obtained from Spirulina are called single cell proteins.
9. A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give reasons for the advice.
A: Pulses are an important source of protein in human diet. If a person is allergic to pulses he may develop symptoms of protein deficiency and mal nutrition. Hence it was advised to take capsule of Spirulina daily as Spirulina capsule is made up of single cell protein from Spirulina.
10. Would it be wrong to refer to plants obtained through micro propagation as ‘clones’? Explain.
A: No. Plants obtained through micro propagation are genetically identical to their original or source plant. Hence they may be referred to as ‘clones’.
11. How is a somatic hybrid different from a hybrid?
A: Somatic hybrid is produced by fusing isolated protoplasts of two different varieties of plants with desirable characters. A hybrid is produced by artificial cross pollination between two parents with desirable characters.
12. What is emasculation? Why and when is it done?
A: Emasculation is the process of removing anthers from the buds of female parent selected for hybridization.
It is done before the opening of flowers to prevent self-pollination.
13. Discuss the two main limitations of plant hybridization programme.
A: * The hybrids may not combine desirable characters every time.
* Disease resistant genes are limited in number which limits plant hybridisation.
14. Give two important contributions of Dr.M.S.Swaminathan.
A: Dr.M.S.Swaminathan developed short duration high yielding varieties of rice like Basmati.
* He also developed the concept of crop cafeteria, crop scheduling and genetic improvement of the yield and quality of crops.
* He introduced Mexican variety of wheat in India.
* He initiated ‘lab to land’, food security and other environmental programmes.
15. Which two species of sugar cane were crossed for better yields?
A: Sachaarum barberi and Sachaarum officinarum.
Short Answer Type Questions
1. Suggest some of the features of plants that prevent insect and pest infestation.
A: Some features of the plants that prevent insect and pest infestation are:
Morphological:
Hairy leaves on plant parts show resistance to insect pests.
e.g.: 1: Resistance to Jassids in cotton and cereal leaf beetle in wheat.
e.g.: 2: Solid stems in wheat are not preferred by stem sawfly.
e.g.: 3: Smooth leaves of cotton do not attract boll worms.
Biochemical or Physiological:
Nectar less cotton does not attract boll worm.
High aspartic acid, low nitrogen and sugar content in maize leads to resistance to maize stem borers.
2. Give few examples of bio fortified crops. What benefits do they offer to the society?
A: Examples of bio fortified crops:
* Atlas 66 variety of wheat having high protein content.
* Iron fortified rice containing 5 times much iron.
* Β-carotene containing golden rice.
* Vitamin A enriched carrot, spinach, pumpkin.
* Vitamin C enriched bitter gourd, Bathua (Chenopodium), tomato and mustard.
* Iron and calcium enriched spinach and Bathua.
* Protein enriched broad beans, lab lab beans, french beans, garden peas.
Benefits of bio fortified crops:
These crops provide essential nutrients like proteins and aminoacids for healthy growth.
They also provide essential micronutrients like vitamins and minerals which are necessary for growth and development.
They may also contain healthier fats which improve health.
Long Answer Type Questions
1. You are a botanist working in the area of plant breeding. Describe the various steps that you will undertake to release a new variety.
A: The main steps in releasing a new variety are:
a. Collection of variability
b. Evaluation and selection of parents
c. Cross hybridization among the selected parents
d. Selection and testing of superior recombinants
e. Testing, release and commercialization of new cultivars
a. Collection of variability: Preexisting genetic variability is available from wild relatives of crop plants. Hence the wild varieties are collected and preserved for further breeding. The entire collection of plants or seeds having all the diverse alleles for all genes in a given crop is called germplasm collection.
b. Evaluation and selection of parents: The germplasm is evaluated to identify plants with desirable combination of characters. The selected plants are multiplied and used for hybridization.
c. Cross hybridization among the selected parents: Cross hybridization between two parents produces hybrids that possess desired characters of both plants. The pollen grains of desirable plant chosen as male parent are collected and placed on the stigma of the flowers selected as female parent. Emasculation is done at bud condition. It is the removal of stamens in bud condition to prevent undesirable self-pollination. Bagging the cross pollinated flowers with a polythene cover is done to prevent undesirable cross pollination.
d. Selection and testing of superior recombinants: Hybridization does not ensure combination of desirable characters every time. Only one in hundred or thousand crosses may produce the desirable combination of characters. Such plants which combine both the desirable characters and are superior to both the parents are selected and self-pollinated to reach a homozygous condition.
e. Testing, release and commercialization of new cultivars: The newly selected lines are tested in the farmer’s field under ideal fertilizer application irrigation and other crop management practices. The testing process is carried out for at least three years at different locations. The material is evaluated in comparison to the best available local crop cultivar.
2. Describe the tissue culture technique and what are the advantages of tissue culture over conventional method of plant breeding in crop improvement programmes?
A: Tissue culture Technique: The capacity of a single cell to generate a whole plant is called totipotency. The tissue culture technique is based on totipotency of plant cells and aims at production of millions of plants in a short time by growing explants on artificial nutrient medium in the laboratory. It is also called in vitro culture as it is carried out in a laboratory. Tissue culture may be defined as in vitro production of plants and plantlets by growing explants on artificial nutrient medium.
The tissue culture technique involves the following steps:
1) Preparation of nutrient medium
2) Sterilization of the medium
3) Preparation of explant
4) Inoculation of explant into the nutrient medium
5) Incubation for growth
6) Acclimatization
Preparation of nutrient medium: The nutrient medium should contain a carbon source sucrose, inorganic salts, vitamins, amino acids and growth regulators like auxins and cytokinins. Agar agar is used to make it a semi solid.
Sterilization of the medium: As the nutrient medium is rich in nutrients it attracts microorganisms hence it must be sterilized. The culture medium is autoclaved for 15 minutes at 121oC and 15 pounds pressure.
Preparation of the explant: The cells, tissues or any part of the plant used for tissue culture may be called an explant. The plant part is carefully collected, thoroughly washed with water and detergents and surface sterilized to be used as an explant.
Inoculation: The transfer of explants onto the sterilized nutrient culture medium is called inoculation and is carried out in a laminar air flow chamber under aseptic conditions.
Incubation for growth: The cultures are incubated for 3 to 4 weeks in tissue culture lab providing adequate temperature and light during which the explants utilize nutrients and undergo cell division. They produce an undifferentiated mass of cells called “Callus”. Organogenesis from callus is promoted by balancing the auxin and cytokinins ratio. A higher auxin concentration induces root production called rhizogenesis and higher cytokinins concentration induces shoot production from the callus called caulogenesis. Sometimes somatic embryos may be formed from callus which is preserved for further use as synthetic seeds.
Acclimatization: The plantlets formed are replanted in small pots with sterilized soil and manure. They are first raised under shade and gradually exposed to sunlight for further acclimatization.
Advantages of Tissue culture:
* Large numbers of plants are produced in very short time in limited space.
* Genetically identical soma clones are produces.
* Economically important plants like tomato, banana, apple, eucalyptus etc., are produced on commercial scale.
* Virus free plants are produced by using meristem cells in banana, sugarcane and potato.
* Somatic hybrids are produced by protoplasmic fusion techniques.
e.g.: Pomato.
