Mention the advantages of selecting pea plant for experiment by Mendel.
Solution and Explanation
Mendel selected pea plants to carry out his study on the inheritance of characters from parents to offspring.
He selected a pea plant because of the following features.
(a) Peas have many visible contrasting characters such as tall/dwarf plants round/wrinkled seeds green/yellow pod purple/white flowers etc.
(b) Peas have bisexual flowers and therefore undergo self pollination easily. Thus pea plants produce offsprings with same traits generation after generation.
(c) In pea plants cross pollination can be easily achieved by emasculation in which the stamen of the flower is removed without affecting the pistil.
(d) Pea plants have a short life span and produce many seeds in one generation.
Top Questions on Principles of Inheritance and Variation
- Assertion (A): A male individual always inherits haemophilia from his mother.
Reason (R): The gene for haemophilia lies on X-chromosome.- CBSE CLASS XII - 2025
- Biology
- Principles of Inheritance and Variation
In a certain population, the frequency of three genotypes is as follows:
Genotypes: PP Pp pp
Frequency: 22% 62% 16%
Choose the option that shows the frequency of P and p alleles correctly:- CBSE CLASS XII - 2025
- Biology
- Principles of Inheritance and Variation
- Which of the following conditions correctly describes the manner of determining the sex in the given options?
- CBSE CLASS XII - 2025
- Biology
- Principles of Inheritance and Variation
- Answer the following questions:
- Write the scientific name of the fruit fly.
- Why did Morgan prefer to work with fruit flies for his experiments? State two reasons.
- CBSE CLASS XII - 2025
- Biology
- Principles of Inheritance and Variation
- Assertion (A): Human male is referred to as heterogametic.
Reason (R): The male produces millions of sperms of the same kind.- CBSE CLASS XII - 2025
- Biology
- Principles of Inheritance and Variation
Questions Asked in CBSE CLASS XII exam
Read the given passage carefully and answer the questions that follow :
In agriculturally important countries, agro products are exchanged for manufactured goods, whereas industrialised nations export machinery and finished products and import food grains and other raw materials. Foreign investment can boost trade in developing countries which lack in capital required for the development of mining, oil drilling, heavy engineering, lumbering and plantation agriculture. By developing such capital intensive industries in developing countries, the industrial nations ensure import of food stuffs, minerals and create markets for their finished products. This entire cycle steps up the volume of trade between nations.
- CBSE CLASS XII - 2025
- International Trade
Study the following graph carefully and answer the following questions
- CBSE CLASS XII - 2025
- Population Geography
Study the map of the Rhine waterway and answer the questions that follow :
- CBSE CLASS XII - 2025
- Transport and Communication
Study the following table carefully and answer the questions that follow :
India – Trends of Urbanisation
Year Number of Towns/UAs Urban Population (in Thousands) % of Total Population Decennial Growth (%) 1931 2,072 33,456.0 11.99 19.12 1941 2,250 44,153.3 13.86 31.97 1951 2,843 62,443.7 17.29 41.42 1961 2,365 78,936.6 17.97 26.41 1971 2,590 1,09,114 19.91 38.23 1981 3,378 1,59,463 23.34 46.14 1991 4,689 2,17,611 25.71 36.47 2001 5,161 2,85,355 27.78 31.13 - CBSE CLASS XII - 2025
- Population Geography
- “In India, water resources are getting polluted with industrial effluents, domestic waste, and insecticides used in agriculture.” Evaluate the statement.
- CBSE CLASS XII - 2025
- Water Resources
Notes on Principles of Inheritance and Variation
Concepts Used:
Principles of Inheritance and Variation - Mutation
A Mutation is a change in the sequence of our DNA base pairs caused by numerous environmental stimuli such as UV light or mistakes during DNA replication. Germline mutations take place in the eggs and sperm and can be passed onto offspring, whereas somatic mutations take place in body cells and are not passed on.
Types of Mutations
There are three types of mutations, which are as follows:
Silent mutation
It refers to any change in DNA sequence that has no effect on the amino acid sequence in a protein or the functions that a protein performs. There is no phenotypic indication that a mutation has occurred.
Nonsense mutation
When there is a change in the sequence of base pairs due to a point mutation, that results in a stop codon. This leads to a protein that is either shortened or non-functional.
Missense mutation
A missense mutation occurs when a point mutation causes a change in the codon, which then codes for another amino acid.
The mutation is caused by the following factors:
Internal Causes
When DNA copies incorrectly, the majority of mutations occur. Evolution occurs as a result of all of these mutations. DNA makes a copy of itself during cell division. When a copy of DNA isn't flawless, it's called a mutation since it differs somewhat from the original DNA.
External Causes
When certain chemicals or radiations are used to break down DNA, it causes the DNA to break down. The thymine dimers are broken by UV radiation, resulting in altered DNA.