Molecular Inheritance and Gene Expression : 12th Class Biology Q Ans Lesson 23 – NIOS
INTEXT QUESTIONS 23.1
- Expand the abbreviation DNA.
Ans. Deoxyribonucleic acdi - Name the scientists who confirmed that DNA was the genetic material in
bacterial transformation.
Ans. Avery, Mcleod and McCarty - Name the sugar and the nitrogenous bases found in DNA
Ans. Deoxyribose, Adenine, Guanine, Thymine, Cytosine
INTEXT QUESTIONS 23.2
- In which direction does DNA polymerase proceed to catalyse DNA replicaiton5′ to 3′ or 3′ to 5′?
Ans. In 5’-3’ direction - What is a primer ……………. a DNA molecule or an RNA molecule?
Ana. RNA molecule - Name the four enzymes needed for DNA replication.
Ans. Helicase, DNA polymerase, DNA ligase, Topoisomerase - Which enzyme joins the okazaki pieces to form a complete DNA strand?
Ans. DNA ligase
INTEXT QUESTIONS 23.3
- What is central dogma in molecular Biology?
Ans. The transfer of information from genes to the site of protein synthesis
constitutes the central dogma. - Which molecule is synthesised during transcription?
Ans. Cistronic DNA - What is a codon? What is meant by ‘code is degenerate’?
Ans. Sequence of three bases in the genes. - Where in the cell does translation occur?
Ans. Nucleus - Name the three types of RNA that participate in protein synthesis.
Ans. mRNA, tRNA, hnRNA
INTEXT QUESTIONS 23.4
- Name the components of an operon.
……………………………………………………………………………………………………………. - What is mutation? When is a mutation called a transition mutation?
Ans. A heritable change in the structure, content and organization of genetic material is called mutation. When in a DNA sequence a purine is replaced by purine and pyrimidine is replaced by pyrimidine. - Why is “silent mutation” called so? Heredity
Ans. A silent mutation in a gene does not bring about a change in the synthesis of the coded protien. - What are mutagens?
Ans. Agents that cause mutation in the genetic material are called mutagens. Mutagens belong to two categories
a) Radiations : x-ray, UV rays, α radiations.
b) Chemical : Mustard gas, Actinomycin D - Name a chemical which causes mutation in the heredity material.
………………………………………………………………
TERMINAL EXERCISES
- How did Hershey and Chase prove that DNA is the hereditary material?
- Explain (i) Transduction and (2) Lysogeny
- Describe the Watson and Crick model of DNA.
- Explain how replication takes place.
- Write a note on Central Dogma
- State the properties of the genetic code.
- Explain transcription in Eukaryotes and processing of hnRNA.
- What do you mean by regulation of genes?
- Explain how the lac operon gets switched on in the presence of lactose in E.coli.
- Name three levels at which regulation takes place in a eukaryotic cell.
- Write notes on :
(i) Types of mutations
(ii) Okazaki fragments
(iii) Chain termination during translation
NIOS 12th class biology Q Ans
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- Tissues & Others Level of Organization : 12th Class Biology Question Answer Lesson 5 – NIOS
- Root System : 12th Class Biology Question Answer Lesson 6 – NIOS
- Shoot System : 12th Class Biology Question Answer Lesson 7 – NIOS
- Absorption, Transport & Water Loss (Transpiration) in Plants : 12th Class Biology Q Ans Lesson 8 – NIOS
- Nutrition in Plants – Mineral Nutrition : 12th Class Biology Question Answer Lesson 9 – NIOS
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- Nutrition and Digestion : 12th Class Biology Question Answer Lesson 13 – NIOS
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- Circulation of Body Fluids : 12th Class Biology Question Answer Lesson 15 – NIOS
- Locomotion and Movement : 12th Class Biology Question Answer Lesson 16 – NIOS
- Coordination & Control : The Nervous & Endocrine Systems | 12th Class Biology Q Ans Lesson 17 – NIOS
- Homeostasis : The Steady State – 12th Class Biology Q Ans Lesson 18 – NIOS
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- Previous:Growth and Development in Plants : 12th Class Biology Question Answer Lesson 20 – NIOS
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- Principles of Genetics : 12th Class Biology Question Answer Lesson 22 – NIOS
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