Home
NCERT Soltions
Class 12
Biology
Principles of Inheritance and Variation
Briefly mention the contribution of T.H. Morgan in genetics.

Briefly mention the contribution of T.H. | Class 12 Biology Chapter Principles of Inheritance and Variation, Principles of Inheritance and Variation NCERT Solutions

Welcome to the NCERT Solutions for Class 12 Biology - Chapter Principles of Inheritance and Variation. This page offers a step-by-step solution to the specific question from Exercise 1, Question 9: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 9: Briefly mention the contribution of T.H. Morgan in genetics.

Answer:

Morgan’s work is based on fruit flies (Drosophila melanogaster). He formulated the chromosomal theory of linkage. He defined linkage as the co-existence of two or more genes in the same chromosome and performed dihybrid crosses in Drosophila to show that linked genes are inherited together and are located on X-chromosome. His experiments have also proved that tightly linked genes show very low recombination while loosely linked genes show higher recombination.

Other Questions of Chapter Principles of Inheritance and Variation

Q: Explain the Law of Dominance using a monohybrid cross.

Q: When a cross in made between tall plants with yellow seeds (Ttyy) and tall plant with green seed (Ttyy), what proportions of phenotype in the offspring could be expected to be (a) Tall and green. (b) Dwarf and green.

Q: Mention any two autosomal genetic disorders with their symptoms.

Q: Who had proposed the chromosomal theory of inheritance?

Q: Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?

Q: A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.

Q: What is pedigree analysis? Suggest how such an analysis, can be useful.

Q: A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?

Q: Using a Punnett square, work out the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.

Q: Define and design a test − cross?

Popular questions of class 12 Biology

Q: What is spermatogenesis? Briefly describe the process of spermatogenesis.

Q: Why is reproduction essential for organisms? Answer

Q: Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals.

Q: With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.

Q: What is DNA fingerprinting? Mention its application.

Q: What is oogenesis? Give a brief account of oogenesis.

Q: Describe the structure of a seminiferous tubule.

Q: What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.

Q: With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.

Q: What are sacred groves? What is their role in conservation?

Recently Viewed Questions of Class 12 Biology

Taking examples under each category, discuss upstream and downstream processing.

Name the first transgenic cow. Which gene was introduced in this cow?

Q: Diagrammatically represent the experimental steps in cloning and expressing an human gene (say the gene for growth hormone) into a bacterium like E. coli ?

Q: Explain what is meant by biofortification.

What is the main idea behind “Joint Forest Management Concept” introduced by the Government of India?

Q: List two essential roles of ribosome during translation.

Q: If a population growing exponentially double in size in 3 years, what is the intrinsic rate of increase (r) of the population?

Q: Try to trace the various components of human evolution (hint: brain size and function, skeletal structure, dietary preference, etc.)

Which type of food would have lactic acid bacteria. Discuss their useful application.

Give the full form of ELISA. Which disease can be detected using it? Discuss the principle underlying the test.

Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

Read the question carefully and focus on the core concept being asked.
Reference examples and data from the chapter when answering questions about Principles of Inheritance and Variation.
Review previous year question papers to get an idea of how such questions may be framed in exams.
Practice answering questions within the time limit to improve your speed and accuracy.
Discuss your answers with your teachers or peers to get feedback and improve your understanding.

Latest Blog Posts

Stay updated with our latest educational content and study tips

Government Jobs by Age Limit: Eligibility and Opportunities in 2026

Government jobs continue to be one of the most popular employment options in India because of their job security, regular salary, pension benefits, and promotion prospects. However, one of the most frequent doubts of aspirants is age eligibility. Countless candidates are discouraged from applying for Government positions – or even from preparing for them – … Read more

NEET & JEE Preparation Guide for State Board Students

After preparation for NEET and JEE, students inclined towards studying under state education boards find themselves a step behind the CBSE students. The syllabus, question pattern and level of idea of these national entrance exams varies widely from most state board syllabus. But with the correct approach, students taking the state board can hold their … Read more

Simple and Compound Interest Formulas with Questions

Interest is one of the most significant ideas in maths and financial calculations. It is very common in banking, loan applications, investments, saving account and competitive exams. Simple Interest and Compound Interest make it easier to find out how much more is earned and/or paid on a principal during the period of time. These Interest … Read more

Spoken English Course Topics for Beginners in 2026

In 2026, students, professionals, and job seekers must have a high level of spoken English. Spoken English is a beginner level course to enhance learners’ communication skills in English, their pronunciation, vocabulary, grammar structure and confidence in speaking English fluently. Today, the emphasis of spoken English courses is placed on actual conversations, everyday speech practice … Read more

View All Blog Posts

Comments

Dhiraj
Oct 21, 2019

Thank you so much

Manasi
Sep 29, 2019

Nice answers Thanks a lot!!!

Rambabu
May 05, 2019

Thanks

Rambabu
May 05, 2019

Thanks

Aadi
Mar 03, 2019

Great work... Perfect and ans in very easy way ðð

SSD
Dec 09, 2018

Thank you so much Sarah study. You all are doing a great job.It's very helpful and supportive...

anu
Oct 20, 2018

useful to me

yash
Sep 09, 2018

fantestic answer

Devesh
Jun 16, 2018

Nice answer thnx a lot