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519 questions in this collection · Page 26 of 52
Question 251 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
In Drosophila melanogaster, a single mating could produce a large number of progeny flies, and they complete their life cycle in about _______ weeks.
Drosophila melanogaster complete their life cycle in about two weeks, and a single mating could produce a large number of progeny flies.
Question 252 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Morgan observed 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, which he described as physical association or _______.
Morgan coined the term linkage to describe this physical association of genes on a chromosome.
Question 253 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
The generation of non-parental gene combinations due to the physical association of genes is described by Morgan using the term _______.
Morgan coined the term recombination to describe the generation of non-parental gene combinations.
Question 254 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Morgan found that the genes white and yellow in Drosophila were very tightly linked and showed only _______ per cent recombination.
The genes white and yellow were very tightly linked and showed only 1.3 per cent recombination.
Question 255 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Morgan's student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the _______ between genes.
Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes.
Question 256 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Traits such as human height or skin colour, which are controlled by three or more genes, are called _______ traits.
Traits generally controlled by three or more genes are called as polygenic traits.
Question 257 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
Besides the involvement of multiple genes, _______ inheritance also takes into account the influence of environment.
Besides the involvement of multiple genes, polygenic inheritance also takes into account the influence of environment.
Question 258 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
The underlying mechanism of pleiotropy in most cases is the effect of a gene on _______ pathways which contribute towards different phenotypes.
The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contribute towards different phenotypes.
Question 259 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
The initial clue about the genetic/chromosomal mechanism of sex determination came from the cytological observations made in a number of _______.
The initial clue about the genetic/chromosomal mechanism of sex determination can be traced back to some of the experiments carried out in insects.
Question 260 of 519
📘 CLASS XII
Principles Of Inheritance And Variation
In 1891, Henking traced a specific nuclear structure during spermatogenesis in a few insects and named it the _______ body, which was later identified as the X-chromosome.
Henking (1891) could trace a specific nuclear structure all through spermatogenesis in a few insects, and he gave a name to this structure as the X body.