Explain the mechanism of hereditary changes. - Science and Technology 2

Short Note

Explain the mechanism of hereditary changes.


Solution 1

Hereditary changes can occur due to the following changes:

  1. Natural Selection- One allele is fixed for the population as it provides a survival advantage.
  2. Genetic Drift- Sudden change in a small population due to which genetic variability is reduced.
  3. Mutations- Sudden and inheritable changes in the genetic material that gives rise to a new allele.
  4. Recombination- When the crossing over occurs during meiosis, the sequence of alleles changes on the chromosomes.

Solution 2

The mechanism of hereditary changes is as follows:

  1. Diversity or hereditary changes occur due to genetic variation.
  2. In sexually reproducing organisms, a fusion of gametes from male and female parents occurs, the offspring always has recombined genes of both the parents. These offsprings thus show some characters of either of the parents.
  3. Also, sometimes sudden changes known as mutations occur in the genes.  A change in the position of even a single nucleotide can cause either a minor effect or a considerable alteration in the characters of an individual.
  4. If these changes (mutation) occur in the DNA of germline cells then, these changes would be inherited to the next generation.
Concept: Heredity
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Chapter 1: Heredity and Evolution - Answer the following questions


SCERT Maharashtra Question Bank 10th Standard SSC Science and Technology 2 Maharashtra State Board
Chapter 1 Heredity and Evolution
Answer the following questions | Q 1.2
Balbharati Science and Technology Part 2 10th Standard SSC Maharashtra State Board
Chapter 1 Heredity and Evolution
Exercises | Q 5.2 | Page 11


In a monohybrid cross between tall pea plants (TT) and short pea plants (tt), a scientist obtained only tall pea plants (Tt) in the F1 generation. However, on selfing the F1 generation pea plants, he obtained both tall and short plants in F2 generation. On the basis of above observations with other angiosperms also, can the scientist arrive at a law? If yes, explain the law. If not, give justification for your answer.

Define heredity.

Name the information source for making proteins in the cells.

Mendel crossed tall pea plants with dwarf pea plants in his experiment. Write his observations giving reason on the F1 and F2 generations.

A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as:

With the help of two suitable examples, explain why certain experiences and traits earned by people during their lifetime are not passed on to their next generations. When can such traits be passed on?

 What will you get in the F1 and F2 generations in the following cross?
Pure tall pea plant × Pure dwarf pea plant

What is the genotype of (i) dwarf plants, and (ii) tall plants, whose parental cross always produces tall offspring?

Pure-bred tall pea plants are first crossed with pure-bred dwarf pea plants. The pea plants obtained in F1generation are then cross-bred to produce F2 generation of pea plants.
(a) What do the plants of F1 generation look like?
(b) What is the ratio of tall plants to dwarf plants in F2 generation?
(c) Which type of plants were missing in F1 generation but reappeared in F2 generation?


A red-haired woman marries a brown-haired man, and all the children are brown haired. Explain this genetically.


Hereditary characters are transferred from parents to offspring by ______ hence they are said to be structural and functional units of heredity.

Define Heredity. Give two examples.

Who is the pioneer of modern genetics?

Write advantages of science of heredity.

____________ refers to the transmission of genetic information from parental generation to next generation.

In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of eyes of the persons having combinations 
(i) Bb and (ii) BB?

What are the components of the DNA molecule?


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