Question 1:
The Chromosomes Are Divided Into Halves at the Time of Formation of Gametes in Individuals. Why Do You Think This Happens?
Answers:
- The gametes from two different individuals combine to form a zygote which develops into a new individual.
- If the chromosomes were not halved at the time of formation of gametes, then the number of chromosomes would be doubled in the new individual.
- It may lead to genetic mutations, which may result in genetic disorders or the expression of any unknown trait.
- Hence, nature has made a mechanism for the continuity of the basic gene pattern of a species.
Question 2:
Why Can Only a Pea Plant Be Crossed With Another Pea Plant, Not a Gram Plant?
Answers:
- The crossing can be done only between individuals of similar species.
- The reason is that gametes of individuals belonging to different species are not compatible. Hence, they would not lead to the formation of a zygote or a new individual.
- The same theory applies to animals too.The same theory applies to animals too.
Question 3:
Define Species.
Answers:
A group of individuals with the same characteristics that can be crossed together to form fertile offspring is called a species.
Question 4:
What Do You Understand by the Term Hybrid?
Answers:
An individual produced due to the crossing of two genetically different individuals is called a hybrid.
For example, a mule is obtained by the cross between a donkey and a horse.
Question 5:
What Is a Gene? State the Essential Characteristics of a Gene?
Answers:
- Gene is the structural and functional unit of inheritance.
- It should possess the following characteristics—
- It should be located in the cells of an individual.
- It should be able to store genetic information.
- It should be physically ad chemically stable.
- It should be able to express itself in an individual.
- It should be able to undergo gradual changes which would bring necessary changes in a species for its survival.