SSLC / 10th - Science - Book Back Answers - Biology Unit 20 - English Medium
Tamil Nadu Board 10th Standard Science - Biology Unit 20: Book Back Answers and Solutions
This post covers the book back answers and solutions for Unit 20 – Biology from the Tamil Nadu State Board 10th Standard Science 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 Biology Unit 20 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 10 students! Prepare well and aim for top scores. Thank you!
Topic: Breeding and Biotechnology
I. Choose the correct Answer
1. Which method of crop improvement can be practised by a farmer if he is inexperienced?(a) clonal selection
(b) mass selection
(c) pureline selection
(d) hybridisation
Answer Key:
(b) mass selection
2. Pusa Komal is a disease resistant variety of ______.
(a) sugarcane
(b) rice
(c) cow pea
(d) maize.
Answer Key:
(c) cow pea
3. Himgiri developed by hybridisation and selection for disease resistance against rust pathogens is a variety of:
(a) chilli
(b) maize
(c) sugarcane
(d) wheat
Answer Key:
(d) wheat
4. The miracle rice which saved millions of lives and celebrated its 50th birthday is ______.
(a) IR – 8
(b) IR – 24
(c) Atomita – 2
(d) Ponni.
Answer Key:
(a) IR – 8
5. Which of the following is used to produce products useful to humans by biotechnology techniques?
(a) enzyme from organism
(b) live organism
(c) vitamins
(d) both (a) and (b)
Answer Key:
(a) enzyme from organism
6. We can cut the DNA with the help of ______.
(a) scissors
(b) restriction endonucleases
(c) knife
(d) RNAase.
Answer Key:
(b) restriction endonucleases
7. rDNA is a:
(a) vector DNA
(b) circular DNA
(c) recombinant of vector DNA and desired DNA:
(d) satellite DNA
Answer Key:
(c) recombinant of vector DNA and desired DNA:
8. DNA fingerprinting is based on the principle of identifying ______ sequences of DNA.
(a) single-stranded
(b) mutated
(c) polymorphic
(d) repetitive.
Answer Key:
(d) repetitive
9. Organisms with modified endogenous gene or a foreign gene are also known as:
(a) transgenic organsims
(b) genetically modified
(c) mutated
(d) both (a) and (b)
Answer Key:
(a) transgenic organsims
10. In a hexaploid wheat (2n = 6x = 42) the haploid (n) and the basic (x) number of chromosomes respectively are ______.
(a) n = 7 and x = 21
(b) n = 21 and x = 21
(c) n = 7 and x = 7
(d) n = 21 and x = 7.
Answer Key:
(d) n = 21 and x = 7.
II. Fill in the blanks
1. Economically important crop plants with superior quality are raised by ………..2. A protein rich wheat variety is ………
3. ………. is the chemical used for doubling the chromosomes.
4. The scientific process which produces crop plants enriched with desirable nutrients are called ………
5. Rice normally grows well in alluvial soil, but ………… is a rice variety produced by mutation breeding that grows well in saline soil.
6. ……….. technique made it possible to genetically engineer living organism.
7. Restriction endonucleases cut the DNA molecule at specific positions known as …………
8. Similar DNA fingerprinting is obtained for ………..
9. ………… cells are undifferentiated mass of cells.
10. In gene cloning the DNA of interest is integrated in a …………
Answer Key:
1. Hybridization
2. Altas 66
3. Colchicine
4. Bio fortification
5. Atomita 2 rice
6. Recombinant
7. Phosphodiester
8. Identical twins
9. stem cells
10. bacterial cell
III. State whether the following statements are true or false. correct the statement if it is false.
1. Raphanobrassica is a tetraploid man-made genus produced by colchicine treatment.2. The process of producing an organism with more than two sets of chromosome is called mutation.
3. A group of plants produced from a single plant through vegetative or asexual reproduction are called a pureline.
4. Iron fortified rice variety determines the protein quality of the cultivated plant.
5. Golden rice is a hybrid.
6. Bt gene from bacteria can kill insects. ,
7. In vitro fertilisation means the fertilisation done inside the body.
8. DNA fingerprinting technique was developed by Alec Jeffrey.
9. Molecular scissors refers to DNA ligases.
Answer Key:
1. False – Raphanobrassica is a allotetra ploid man-made genus produced by colchicine treatment.
2. False – The process of producing an organism with more than two sets of chromosome is called polyploidy.
3. True
4. False – Iron rich rice variety determines the protein quality of the cultivated plant.
5. False – Golden rice is a genetically modified plant
6. True
7. False – In vitro fertilisation means the fertilisation done outside the body.
8. True
9. False – Molecular scissors refers to Restriction enzymes
IV. Match the following
V. Understand the assertion statement, justify the reason given and choose the correct choice
(a) Assertion is correct and reason is wrong.(b) Reason is correct and the assertion is wrong.
(c) Both assertion and reason is correct.
(d) Both assertion and reason is wrong.
1. Assertion : Hybrid is superior than either of its parents.
Reason: Hybrid vigour is lost upon inbreeding.
Answer Key:
(c) Both assertion and reason is correct.
2. Assertion: Colchicine reduces the chromosome number.
Reason: It promotes the movement of sister chromatids to the opposite poles.
Answer Key:
(d) Both assertion and reason is wrong.
3. Assertion: rDNA is superior over hybridisation techniques.
Reason: Desired genes are inserted without introducing the undesirable genes in target organisms.
Answer Key:
(a) Assertion is correct and reason is wrong.
VI. Answer in a sentence
1. Give the name of the wheat variety having higher dietary fibre and protein.Answer Key:
Triticale a hybrid of wheat having dietary fibre and protein.
2. Semi-dwarf varieties were introduced in rice. This was made possible by the presence of the dwarfing gene in rice. Name this dwarfing gene.
Answer Key:
The dwarfing gene is Sd.I.
3. Define genetic engineering.
Answer Key:
Genetic engineering is the manipulation and transfer of genes from one, organism to another organism to create a new DNA called as recombinant DNA(rDNA).
4. Name the types of stem cells?
Answer Key:
Embryonic stem cell and Adult stem cell or somatic stem cell, are the two types of stem cells.
5. What are transgenic organisms?
Answer Key:
Plants or animals expressing a modified endogenous gene or a foreign gene is known as transgenic organism.
6. State the importance of bio-fertiliser.
Answer Key:
Increasing the harvest yields, improving soil structure, better water relation, economical, eco – friendly and more efficient farms are due importance of biofertilizer.
VII. Give the answer in detail
Question 1.VIII. Numerical Problems
Question 1.IX. Hot questions
Question 1.
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