Heredity is the study of the transmission of genes from parents to offspring and the laws governing such a transmission. Along with genetic characters, variations also appear during the transmission. Branch of biology that deals with the study of heredity and variations are called genetics.

DNA is a genetic material present in all living organisms. It is a double helix. It contains deoxyribose sugar, nitrogen bases and a phosphate group. It is located in the nucleus of the cell. The DNA is enclosed by a chromosome with histone proteins.

Answer the following: What will be the ratio in F 2 generation in Mendel's dihybrid cross?

A dihybrid cross is a cross between two individuals that are both heterozygous for two different traits. As an example, let's look at pea plants and say the two different traits we're examining are colour and shape of seeds. Mendel observed that the F2 progeny of his dihybrid cross had a 9:3:3:1 ratio and produced nine plants with round, yellow seeds, three plants with round, green seeds, three plants with wrinkled, yellow seeds and one plant with wrinkled, green seeds.

Rounded seeds (dominant trait) were crossed with wrinkled seeds (recessive trait). (i)What type of seeds will be produced in F 1 generation? (ii)By self-pollination in F 1 seeds, what percentage of seeds will be rounded shape in F 2 generation? Explain with diagram.

Mendel’s work went virtually unnoticed by the scientific community, which incorrectly believed that the process of inheritance involved a blending of parental traits that produced an intermediate physical appearance in offspring. This hypothetical process appeared to be correct because of what we know now as continuous variation. A monohybrid cross is one in which both parents are heterozygous (or a hybrid) for a single (mono) trait. Dominant refers to the relationship between two versions of a gene. A recessive trait is a trait that is expressed when an organism has two recessive alleles, or forms of a gene. Seed shape was one of the traits Mendel studied in his first set of experiments. (i) - Rounded seeds will be produced in F 1 generation. (ii) - The F 2 generation results from self-pollination of F 1 plants, and contained 75 % rounded seeds.

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In humans, women have a perfect pair of sex chromosomes, both called .

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Important Questions on Heredity and Evolution

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How do Mendel's experiments show that traits may be dominant or recessive?

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Answer the following:

Why do all gametes formed in females have only X chromosomes?

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Gauri hurts her hand in an accident and two fingers had to be cut off. Her child is born with all the fingers on his hand. What conclusion can you draw from this?

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Where are the genes found?

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Define the heredity.

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Where is DNA found?

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Answer the following:

Name:

The sex chromosome boys inherit from their father.

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The inheritance or transmission of characters from one generation to another is called

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Flow chart of sex determination in humans is given below. Information to be filled in the blanks a, b and c respectively are :

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Answer the following:

What will be the ratio in F₂ generation in Mendel's dihybrid cross?

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What is the relation of Genetics with Human Welfare?

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What are Genetics? Explain Mendel law of dominance with line diagram.

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How do Mendel's experiments show that traits may be dominant or recessive?

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Rounded seeds (dominant trait) were crossed with wrinkled seeds (recessive trait).
(i)What type of seeds will be produced in F₁ generation?
(ii)By self-pollination in F₁ seeds, what percentage of seeds will be rounded shape in F₂ generation? Explain with diagram.

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What do you mean by acquired characters? Are acquired characters inherited? Discuss.

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Describe any three types of chromosomes based on the position of the centromere.

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The genotypic ratio in F2 generation of monohybrid cross will be

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Select the correct alternative from those given below each statement and write the completed statement: