Chapter 10.2, Problem 7MI

Summary Introduction

To fill:

The blanks in the given paragraph and analyze Mendel’s experiment with green- seed and yellow- seed pea plants

Introduction:

The study of heredity is called genetics. Gregor Mendel was a mathematician who studied how some characteristics are passed from parent to offspring while others do not. Heredity is passing on of characteristics from parent to offspring. These characteristics are known as traits. He carefully selected his pea plants and controlled his experiments by studying only one trait at a time.

Answer to Problem 7MI

S.No.	Term
1	True breeding
2	studying only one trait at a time
3	100
4	0
5	self- fertilize
6	F2
7	75
8	25
9	Alleles
10	Dominant
11	Recessive

Explanation of Solution

Mendel carefully controlled his experiments and the peas he used. He studied only one trait at a time to control variables. He analyzed his data mathematically. He used tall pea plants and short pea plants from a population of plants that had been tall and short respectively for many generations. Such plants are called true breeding plants.

Mendel selected two pea plants which produced green seeds and yellow seeds respectively. He crossed pollinated them to obtain hybrids. The offspring in the first generation or F₁generation were all yellow seeds plants and no green seed plants were produced. The F₁offspring were 100 percent yellow and 0 percent green. When he allowed these hybrid yellow seed plants to self −fertilize, he obtained both yellow and green seed plants in second generation. The F₂generation had 75 % yellow seed plants and 25% green seed plants. This means three- fourths of the plants in second generation were yellow- seed plants and one- fourth plants were green- seed plants. The green train reappeared in second generation.

From his experiments Mendel concluded that each organism has two factors that control each of its traits. These factors are genes and are located on chromosomes. Genes exist in alternate form called alleles. Each pea plant had two alleles of the gene that determined the seed color. So a plant could have two alleles for green color or two alleles for yellow color or one allele for green color and one for yellow color. Mendel called the trait that was observed in F₁ as the dominant trait and the trait that disappeared in F₁ but reappeared in F₂ generation as recessive trait.