question_answer

Directions : (1 - 5)

Read the passage given below and answer the following questions.

Mendel crossed tall and dwarf Pea plants to study the inheritance of one gene. He collected the seeds produced as a result of this cross and grew them to generate plants of the first hybrid generation \[\left( {{F}_{1}} \right)\]. This generation is also called the Filial progeny or the \[{{F}_{1}}\]. Mendel observed that all the progeny plants were tall, like one of its parents; none were dwarf. He made similar observations for the other pairs of traits - he found that the always resembled either one of the parents, and that the trait of the other parent was not seen in them. Mendel then self-pollinated or selfing the tall F1 plants and to his surprise found that in the \[{{F}_{2}}\] generation some of the offspring were 'dwarf '; the character that was not seen in the \[{{F}_{1}}\] generation was now expressed. The proportions of dwarf plants were 1/4th of the plants while 3/4th of the plants were tall. The tall and dwarf traits were identical to their parental type and did not show any blending or mixing that is all the offspring were either tall or dwarf, none were of in between height. Similar results were obtained with the other traits that he studied: only one of the parental traits was expressed in the \[{{F}_{1}}\] generation while at the \[{{F}_{1}}\] stage both the traits were expressed in the proportion 3 : 1. The contrasting traits did not show any blending at either \[{{F}_{1}}\] or \[{{F}_{2}}\] stage. Based on these observations, Mendel proposed that something was being stably passed down, unchanged, from parent to offspring through the gametes, over successive generations. He called these things as 'factors' (Carl Corren, 1902). Nowadays these are genes (Johannsen, 1909). Genes, therefore, are the units of inheritance. They contain the information that is required to express a particular trait, in an organism. Genes which code for a pair of contrasting traits are known as alleles (Bateson, 1905), i.e., they are slightly different forms of the same gene. If we use alphabetical symbols for each gene, then the capital letter is used for the trait expressed i.e., dominant at the \[{{F}_{1}}\] stage and the small alphabet for the other trait i.e., recessive. For example, in case of the character of height, T is used for the Tall trait and t for the 'dwarf ', and T and t are alleles of each other. Hence, in plants the pair of alleles for height would be TT, Tt or tt.

One character has how many traits

A) One

B) Two

C) Three

D) Four