12th Bio - Botany - Book Back Answers - Chapter 9 - English Medium Guides

 

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Tamil Nadu Board 12th Standard Bio-Botany - Chapter 9: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Chapter 9 – Bio-Botany from the Tamil Nadu State Board 12th Standard Bio-Botany textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Bio-Botany Chapter 9 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 12 students! Prepare well and aim for top scores. Thank you!

Unit 9 - Plant Breeding

I. Multiple Choice Questions

1. Assertion: Genetic variation provides the raw material for selection
Reason: Genetic variations are differences in genotypes of the individuals.
a) Assertion is right and reason is wrong. 
b) Assertion is wrong and reason is right. 
c) Both reason and assertion is right. 
d) Both reason and assertion is wrong.
Answer Key:
b) Assertion is wrong and reason is right. 

2. While studying the history of domestication of various cultivated plants _______ were recognized earlier
a) Centres of origin
b) Centres of domestication
c) Centres of hybrid
d) Centres of variation
Answer Key:
a) Centres of origin

3. Pick out the odd pair.
a) Mass selection - Morphological characters
b) Purline selection - Repeated self pollination
c) Clonal selection - Sexually propagated
d) Natural selection - Involves nature
Answer Key:
c) Clonal selection - Sexually propagated

4. Match Column I with Column II
Column I                 Column II 
i) William S. Gaud             I) Heterosis 
ii) Shull                 II) Mutation breeding 
iii) Cotton Mather             III) Green revolution 
iv) Muller and Stadler         IV) Natural
hybridization
a) i – I, ii – II, iii – III, iv – IV 
b) i – III, ii – I, iii – IV, iv – II
c) i – IV, ii – II, iii – I, iv – IV
d) i – II, ii – IV, iii – III, iv – I
Answer Key:
b) i – III, ii – I, iii – IV, iv – II

5. The quickest method of plant breeding is
a) Introduction 
b) Selection 
c) Hybridization 
d) Mutation breeding
Answer Key:
d) Mutation breeding

6. Desired improved variety of economically useful crops are raised by
a) Natural Selection 
b) hybridization
c) mutation 
d) biofertilisers
Answer Key:
b) hybridization

7. Plants having similar genotypes produced by plant breeding are called
a) clone 
b) haploid
c) autopolyploid 
d) genome
Answer Key:
a) clone 

8. Importing better varieties and plants from outside and acclimatising them to local environment is called
a) cloning 
b) heterosis
c) selection 
d) introduction
Answer Key:
d) introduction

9. Dwarfing gene of wheat is
a) pal 1 
b) Atomita 1
c) Norin 10 
d) pelita 2
Answer Key:
c) Norin 10 

10. Crosses between the plants of the same variety are called
a) interspecific 
b) inter varietal
c) intra varietal 
d) inter generic
Answer Key:
c) intra varietal 

11. Progeny obtained as a result of repeat self pollination a cross pollinated crop to called
a) pure line 
b) pedigree line
c) inbreed line 
d) heterosis
Answer Key:
a) pure line 

12. Jaya and Ratna are the semi dwarf varieties of 
a) wheat 
b) rice
c) cowpea 
d) mustard
Answer Key:
b) rice

13. Which one of the following are the species that are crossed to give sugarcane varieties with high sugar, high yield, thick stems and ability to grow in the sugarcane belt of North India?
a) Saccharum robustum and Saccharum officinarum
b) Saccharum barberi and Saccharum officinarum
c) Saccharum sinense and Saccharum officinarum
d) Saccharum barberi and Saccharum robustum
Answer Key:
b) Saccharum barberi and Saccharum officinarum

14. Match column I (crop) with column II (Corresponding disease resistant variety) and select the correct option from the given codes.
Column I         Column II
I) Cowpea         i) Himgiri
II) Wheat         ii) Pusa komal
III) Chilli         iii) Pusa Sadabahar
IV) Brassica     iv) Pusa Swarnim 
I     II     III     IV
a) iv     iii     ii     i
b) ii     i      iii     iv
c) ii     iv     i     iii
d) i     iii     iv     ii
Answer Key:
b) ii     i     iii     iv

15. A wheat variety, Atlas 66 which has been used as a donor for improving cultivated wheat, which is rich in
a) iron 
b) carbohydrates
c) proteins 
d) vitamins
Answer Key:
c) proteins 

16. Which one of the following crop varieties correct matches with its resistance to a disease?

Variety	Resistance to disease
a) Pusa Komal	Bacterial blight
b) Pusa Sadabahar	White rust
c) Pusa Shubhra	Chilli mosaic virus
d) Brassica	Pusa swarnim

Answer Key:
a) Pusa Komal    Bacterial blight

17. Which of the following is incorrectly paired?
a) Wheat - Himgiri
b) Milch breed - Sahiwal
c) Rice - Ratna
d) Pusa Komal – Brassica
Answer Key:
d) Pusa Komal – Brassica

18. Match list I with list II 

List I	List II
Biofertilizer	Organisms
i) Free living N2	a) Aspergillus
ii) Symbiotic N2	b) Amanita
iii) P Solubilizing	c) Anabaena azollae
iv) P Mobilizing	d) Azotobactor

a. ic, iia, iiib, ivd 
b. id, iic, iiia, ivb.
c. ia, iic, iiib, ivd 
d. ib, iia, iiid, ivc.
Answer Key:
b. id, iic, iiia, ivb.

II. Short Answer Questions

1.Differentlate primary introduction from secondary introduction.

Primary introduction	Secondary introduction
The introduced variety is well adapted to the new environment without any alternation to the original genotype	The introduced variety is subjected to selection to isolate a superior variety.

 
2.How are microbial Innoculants used to increase the soil fertility?

• Microbial innoculants also called biofertilizers,
• Biofertilizers are defined as preparations containing living cells of efficient strains of microorganisms.
• It helps crop plants uptake of nutrients by their interactions in the rhizosphere when applied through seed or soil.
• Bio-fertilisers containing rhizobium bacteria are called rhizobium bio fertilizer culture.
• Symbiotic bacteria that reside inside the root nodules.
• It convert the atmospheric nitrogen into a bio available form to the plants.
• This nitrogen fixing bacterium applied it multiplies and fixes the atmospheric nitrogen in the soil.
• Rhizobium is best suited for the increase the soil fertility in paddy fields.
• So it increases the yield by 15-40%.

 
3. What are the different types of hybridization?

• The different types of Hybridization are
• i. Intravarietal hybridization
• The cross made between the plants of same variety
• ii. Intervarietal hybridization
• This crosses are useful only in the self-pollinated crops.
• The cross made between two different varieties of the same species
• This improving self-pollinated and cross pollinated crops
• iii. Interspecific hybridization
• The cross made between two different species belongs to the same genus.
• It is commonly used for transferring the genes of disease, Insect, pest and drought resistance from one species to another. 
• Example: Gossypium hirsutum x Gossypium arboreum - Deviraj.
• iv. Intergeneric hybridization
• The crosses are made between the plants belonging to two different genera.
• Disadvantages
• Hybrid sterility, time consuming and expensive procedure.
• Example: Raphanobrassica, Triticale.

 
4. Explain the best suited type followed by plant breeders at present?

• 1. Genetic Engineering
• 2. Plant tissue culture
• 3. Protoplasmic fussion
• 4. Molecular marking
• 5. DNA fingerprinting.

 
5. Write a note on heterosis.

• G.H. Shull first to use the term heterosis.
• The superiority of the F1 hybrid in performance over its parents is called heterosis ar hybrid vigour
• Heterosis can be classified as:
• 1. Euheterosis
• 2. Psucdoheterosis
• Progeny possess superiority over parents in vegetative growth but not in yield and adaptation

 
6. List out the new breeding techniques involved in developing new traits in plant breeding.

• New breeding techniques (NBT) are a collection of methods that could increase and accelerate the development of new traits in plant breeding.
• genome editing, to modify DNA at specific locations within the plants to produce new traits in crop plants.

 

III. Long Answer Questions

12th bio botany

IV. Exercise

12thbio botany