Genetics is the study of heredity and variations. The variations are the differences that exist between individuals belonging to the same species. In other words, variations mat be defined as the appearance of new characters in the offsprings which are not found in their parents and might be appeared due to the combining of two alleles coming from two different parents. The variations in sexually reproducing organisms such as animals, plants can be easily observed. An asexually produced organism has one parent and inherits all traits. It is indeed a carbon copy of the parent and is called a clone. Types of variations: Somatic variations: These variations influence the body cells. They appear after birth and are also called acquired characters. These are non-heritable variations. These variations are formed due to environmental factors, use and disuse of organs. Germinal variations: These are heritable variations mostly formed in reproductive cells. Germinal variations are of two types: Continuous variations and discontinuous variations. Continuous variations are formed due to the recombination of alleles as found in sexual reproduction. Discontinuous variations are caused due to the change in the structure or number of chromosomes.

Mutation is a phenomenon which results in alteration of DNA sequences and consequently results in changes in the genotype and the phenotype of an organism. In addition to recombination, mutation is another phenomenon that leads to variation in DNA. One DNA helix runs continuously from one end to the other in each chromatid, in a highly supercoiled form. Therefore, loss (deletions) or gain (insertion/duplication) of a segment of DNA, result in alteration in chromosomes. Since genes are known to be located on chromosomes, alteration in chromosomes results in abnormalities or aberrations. Chromosomal aberrations are commonly observed in cancer cells. In addition to the above, mutation also arise due to change in a single base pair of DNA. This is known as point mutation. A classical example of such a mutation is sickle cell anaemia. Deletions and insertions of base pairs of DNA, causes frame-shift mutations.

Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 1

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Define pedigree chart.

Important Questions on Genetics - Some Basic Fundamentals

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 1

Define variations.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 1

Define mutation.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 2

State the three Mendel's laws of inheritance.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 3

Does the sex of the child depend on the father or it is just a matter of chance? Discuss.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 4

Distinguish between the karyotype and karyokinesis.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 4

Distinguish between the autosomes and sex chromosomes.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 4

Distinguish between the homozygous and heterozygous chromosomes.

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Concise Biology Part-II Class 10>Chapter 3 - Genetics - Some Basic Fundamentals>Review Questions>Q 1

In a certain species of animals, black fur (B) is dominant over brown fur (b). Predict the genotypic and phenotypic ratios of the offspring when both parents are 'Bb' or have heterozygous black fur.

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