Ans) Offspring of same parents do not exactly resemble each other as well as their parents.

Ans) Heredity and Heredity Characters “The transfer of characters in living organisms from one generation to another generation is called heredity and the characters so transferred are called heredity characters.

Ans) Mendel choosen the pea plant for their experiments because: –

• Pea plant is bisexual, self pollinated annual plant.
• It has short life cycle and can be easily grown everywhere, due to short life cycle, can be studied many generation in short terms.
• Many contrasting characters are found in it and artificial cross pollination can be done easily in it.

Ans) In human there are 23 pairs of chromosomes out of which 22 pairs are similar in both male and female but the 23rd pair called sex chromosome is different in male that is (XY) while in female that is (XX).

Ans) Mendel crossed a pair having two contrasting characters by dihybrid cross and observed that the characters of one gamete transmitted to next generation seperately in F2 generation where four types of offsprings were arisen in which two were similar to parents and two different from parents. Thus the mendel’s experiment shows that traits are inherited independently.

Ans) According to this law, when a pair having different alleles is crossed only dominant characters will appear in the first generation. This tendency is called Dominance and the law is called Mendel’s Law of Dominance.

Ans) According to this law, when a pair of contrasting characters is taken in parent generation, both the characters remain present in F1 generation but get segregated in F2 generation as pure without contaminating one another. This tendency is called segregation or purity of gametes and the law is called Mendel’s Law of Segregation or Law of Purity of Gametes.

Ans) According to this law, mendel crossed a pair having two contrasting characters by dihybrid cross and observed that the characters of one gamete transmitted to next generation separately without affecting the characters of other gamete; the characters assorted independently. Therefore this tendency is called independent assortment and the law is called Mendel’s Law of Independent Assortment.

Ans) “A long thread like structure contained in nucleus of all eukaryotic cells and whose hereditary material remains in some specific structure are called chromosomes.” Or

“The filamentous linkage structures carrying linear sequence of genes visible in the nucleus during the cell division and multiplied by frequent cell division and maintain their morphological structure as functions are called chromosomes.”

Ans) Following are the functions and importance of chromosomes: –

• Play important role in heredity.
• They are responsible for protein synthesis.
• Play important role in structure and activities of the body.
• New cells are produced by the replication of chromosomes.

Ans) The sex in children is determined by 23rd pair of chromosome called sex chromosomes therefore chromosomes play an important role in sex determination.

Ans) Sex determination in human by line diagram: –

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