Heredity and Evolution

The scientist can come to two different laws, namely the law of dominance and the law of segregation, under the situation described in the topic (or the law of purity of gametes). This can be explained with the help of the following crosses: In the F1 hybrid two dissimilar alleles are present for one character, i.e., …

In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F1 generation. However, on selfing the F1 generation pea plants, he obtained both tall and short plants in the F2 generation. Based on the above observations with other angiosperms also, can the scientist arrive at a law? If yes, explain the law. If not, give a justification for your answer. (Delhi 2016) Read More »

  Mendel crossed the pea plant for two contrasting characters under consideration.  The feature that showed in the F1 generation was dominant, whereas the one that did not was recessive. Later, he selfed the F1 generation plants and recovered, resulting in the F2 generation having a clear proportion of both parental features. Mendel determined from …

How did Mendel interpret his result to show that traits may be dominant or recessive? Describe briefly. (Delhi 2016) Read More »

Mendel’s monohybrid cross showed that only one of two contrasting traits shows itself in the offspring of the first generation. As a result, it can be determined that the characteristic expressed in the F1 generation are dominant and the trait that does not is recessive. The dominant gene or allele and the recessive gene or allele are …

In one of his experiments with pea plants Mendel observed that when a pure tall pea plant is crossed with a pure dwarf pea plant, in the first generation, F1 only tall plants appear.
(a) What happens to the traits of the dwarf plants in this case?
(b) When the F, generation plants were self-fertilised, he observed that in the plants of the second generation, F2 both tall plants and dwarf plants were present. Why did it happen? Explain briefly. (Delhi 2016) Read More »

Mendel started by selecting two pure-line plants. Then he crossed such plants with different characteristics. He observed that only one of the two opposing characters—which he termed dominant—appeared in the F1 generation and that the other was recessive. Later, when he selfed the F1 plants, he observed that both features did indeed arise but in …

How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism? (AI 2017) Read More »

Mendel’s dihybrid cross showed that each trait expressed independently of the other when two pairs of characteristics or characters were taken into account. Mendel was able to develop the Law of Independent Assortment, which deals with the independent transfer of traits. The given cross could provide a clear explanation for this: F2 generation ratio : …

How did Mendels experiments show that different traits are inherited independently? Explain. (Delhi 2017) Read More »

Mendel decided to conduct a series of hybridization experiments on the garden pea (Pisum sativum).He first selected two pure line plants—a tall plant with the gene TT and a short plant with the gene TT—and crossed them to create new plants with contrasting characteristics. He saw that only one of the two opposing characters manifested in …

Name the plant Mendel used for his experiment. What type of progeny was obtained by Mendel in F1 and F2 generations when he crossed the tall and short plants? Write the ratio he obtained in F2 generation plants. (Delhi 2019) Read More »

(a) Only tall plants are obtained in the F1 offspring when a tall plant (TT) crosses with a short tea plant (tt). This is due to the fact that only one of two contrasting features is present in the offspring of the first generation. The characteristic that shows in the F1 generation is therefore dominant, …

(a) Why is the F1 progeny always of tall plants when a tall plant is crossed with a short pea plant? (b) How is F2 progeny obtained by self-pollination of F1 progeny different from F1 progeny? Give reason for this observation. (c) State a conclusion that can be drawn on the basis of this observation. (AI 2020) Read More »

(a) (i) Colour of the stem in F1 progeny The colour in the F1 progeny is green stemmed as green stem colour is dominant. (ii) F1 progeny on self pollination F2 generation Green stemmed: Brown stemmed 3;1 It means 25% of F2 progeny are brown stemmed rose plant. (iii) Ratio of GG and Gg in …

A green-stemmed rose plant denoted by GG and a brown-stemmed rose plant denoted by gg is allowed to undergo a cross with each other.
(a) List your observations regarding (i) the Colour of the stem in their F1 progeny
(ii) Percentage of brown stemmed plants in F2 progeny if plants are self-pollinated.
(iii) Ratio of GG and Gg in the F2 progeny.
(b) Based on the findings of this cross, what conclusion can be drawn? (AI 2020) Read More »

(a) Mendel performed crosses between two qualities to observe how they interacted and how their inheritance patterns differed. When two character pairings were taken into consideration for Mendel’s dihybrid cross, it was found that each characteristic expressed independently of the other. (b) An example of a cross between parents would be a round yellow and …

(a) Why did Mendel carry out an experiment to study inheritance of two traits in garden pea?
(b) What were his findings with respect to inheritance of traits in F1 and F2 generation?
(c) State the ratio obtained in the F2 generation in the above mentioned experiment. (AI 2020) Read More »

An acquired trait is a trait (or characteristic) of an organism that is “not inherited” but instead arises in reaction to the environment. For instance, all of a group of mice’s progeny will have tails if they are naturally bred. Now, if these mice’s tails are surgically removed after each generation, tail-less mice won’t be …

Write a difference between inherited traits and acquired traits giving one example of each. (Delhi 2013C) Read More »