Principles Of Inheritance

Question 1

Gregor Mendel, conducted hybridisation experiments on garden peas for……….and proposed the laws of inheritance in living organisms

Answer 1

seven years
(1856-1863)

Question 2

Assertion: Mendel experiment had large credibility to the data that he collected
Reason: His experiments had a large sampling size

Answer 2

Both are correct and correct explanation

Question 3

Statement 1: A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations
Statement 2: Mendel selected 14 true-breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.

Answer 3

Both are correct

Question 4

It was developed by a British geneticist, Reginald C. Punnett.

Answer 4

Punnett square

Question 5

The inheritance of flower colour in the dog flower (snapdragon or Antirrhinum sp.) is a good example to understand………

Answer 5

incomplete dominance

Question 6

Mendel published his work on inheritance of characters in……..

Answer 6

1865

Question 7

Reasons for failure of Mendel’s work

Answer 7

Firstly, communication was not easy (as it is now) in those days and his work could not be widely publicised.

Secondly, his concept of genes as stable and discrete units that controlled the expression of traits and, of the pair of alleles which did not ‘blend’ with each other, was not accepted by his contemporaries as an explanation for the apparently continuous variation seen in nature.

Thirdly, Mendel’s approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time.

Finally, though Mendel’s work suggested that factors (genes) were discrete units, he could not provide any physical proof for the existence of factors or say what they were made of.

Question 8

Statement 1: By 1905 the chromosome movement during meiosis had been worked out.
Statement 2: 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

Answer 8

Statement 1 is false and 2 is true

In year 1902 chromosome movement…………

Question 9

Independent pairs segregate independently of each other this refers to……

Answer 9

Gene

Question 10

One pair segregates independently of another pair it refers to………

Answer 10

Chromosome

Question 11

Morgan worked with the tiny fruit flies, Drosophila melanogaster (which were found very suitable for such studies.
Why?

Answer 11

1. They could be grown on simple synthetic medium in the laboratory. 2. They complete their life cycle in about two weeks [14-15 days] and a single mating could produce a large number of progeny flies.
2. There was a clear differentiation of the sexes – the male and female flies are easily distinguishable.
3. It has many types of hereditary variations that can be seen with low power microscopes.

Question 12

Morgan hybridised
females to
males

Answer 12

Females; yellow-bodied, white-eyed
Males: brown-bodied, red-eyed

Question 13

Genes for white and yellow were very tightly linked and showed only ………… percent recombination while white and miniature wing showed…………per cent recombination.

Answer 13

1.3 percent

37.2 percent