Answers and bookmarks are saved in this browser, across visits. They do not sync to your account.
519 questions in this collection · Page 2 of 52
Question 11 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Who were the three scientists that independently rediscovered Mendel's results in 1900?
In 1900, three scientists—de Vries, Correns, and von Tschermak—independently rediscovered Mendel’s results on the inheritance of characters.
Question 12 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Who noted that the behaviour of chromosomes was parallel to the behaviour of genes and used it to explain Mendel's laws?
In 1902, Walter Sutton and Theodore Boveri noted that the behaviour of chromosomes was parallel to the behaviour of genes and used chromosome movement to explain Mendel’s laws.
Question 13 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
The synthesis of Mendelian principles with the knowledge of chromosomal segregation is known as:
Sutton united the knowledge of chromosomal segregation with Mendelian principles and called it the chromosomal theory of inheritance.
Question 14 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Who provided experimental verification for the Chromosomal Theory of Inheritance?
Experimental verification of the chromosomal theory of inheritance was provided by Thomas Hunt Morgan and his colleagues through their work with fruit flies, Drosophila melanogaster.
Question 15 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Which organism did T.H. Morgan use for his genetic studies?
Morgan worked with the tiny fruit flies, Drosophila melanogaster, which were found very suitable for such studies.
Question 16 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Morgan observed that when two genes in a dihybrid cross were on the same chromosome, the proportion of parental gene combinations was:
Morgan saw that when two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. He attributed this to the physical association or linkage of the two genes.
Question 17 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
The term coined by Morgan to describe the physical association of genes on a chromosome is:
Morgan coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations.
Question 18 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Which student of Morgan used the frequency of recombination between gene pairs to measure the distance between genes and create genetic maps?
Morgan's student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and ‘mapped’ their position on the chromosome.
Question 19 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Traits like human height and skin colour, which show a continuous range of variation, are generally controlled by three or more genes. Such traits are called:
Traits that are generally controlled by three or more genes are called polygenic traits. They are not distinct in their occurrence and are spread across a gradient, like human height or skin colour.
Question 20 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
In polygenic inheritance, the phenotype reflects the contribution of each allele, meaning the effect of each allele is:
In a polygenic trait, the phenotype reflects the contribution of each allele; i.e., the effect of each allele is additive. The number of each type of allele in the genotype determines the phenotype, such as the darkness or lightness of skin.