In this article, we are providing you NCERT Exemplar Solutions for all the questions of CBSE 12 Biology chapter 1, Reproduction in Organisms.
Principle of Inheritance and Variation is one of the most important topic of Class 12 Biology. Questions from this chapter are frequently asked in CBSE Class 12 Biology Board exam as well as competitive examinations like AIIMS, NEET, etc. Due to this reason Jagranjosh.com has provided NCERT Exemplar Solutions for Class 12 Biology. All the solutions are collated in PDF format with the help of which students will be able to score a nice score in CBSE Class 12 Biology Board Exam 2019.
Few problems along with their solutions from this chapter are given follows:
Q. Distance between the genes and percentage of recombination shows
(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship
Ans. (a) a direct relationship
Crossing over separates genes away from each other, So, the distance between the genes and percentage of recombination shows an direct relationship, I.e., when genes are close together they have high linkage and exhibit low recombination frequencies, Thus, the other option are wrong as it does not show parallel or inverse relationship.
Q. The inheritance pattern of a gene over generations among humans is studied by the pedigree analysis. Character studied in the pedigree analysis is equivalent to
(a) quantitative trait
(b) Mendelian trait
(c) polygenic trait
(d) maternal trait
Ans. (b) Mendelian trait
Mendelian inheritance in humans is difficult to study. Current understanding of mendelian inheritance in humans is gained by analysis of family pedigrees or the results of matings that have already occured. By analysing a pedigree, we may be able to predict how the trait is inherited.
On the other hand, quantitative trait, polygenic trait and maternal traits are not studied by pedigree analysis.
Q. For the expression of traits genes provide only the potentiality and the environment provides the opportunity. Comment on the veracity of the statement.
Ans. Obviously, genes are not the only factors that determine phenotype. Environment also plays an important role in the expression of traits. Genes are actually quite active throughout our lives, switching their expression on and off in response to the environment. Besides the effect of internal factors like hormones and metabolism on gene expression, external factors like temperature, light, nutrition, etc., also affect the gene expression and ultimately exhibiting phenotypic changes.
So, we can say that genes provide only the potentiality and the environment provides the opportunity for the expression of traits.
Q. Discuss the genetic basis of wrinkled phenotype of pea seed.
Ans. Seed shape is determined by a single gene, with the allele (R) for round peas dominant over the allele (r) for wrinkled peas (recessive trait).
It the alleles for the gene controlling the seed shape are homozygous in a plant, it will show the character or phenotype of same alleles, i.e., -RR- round seed, rr – wrinkled seed.
On the other hand, if the alleles of gene are heterozygous. They will express the phenotype of dominant allele.
Rr - Round seed (r- wrinkled is recessive)
This is the genetic basis of wrinkled phenotype of pea seed.
Find below the links to download Class 12 Biology NCERT Exemplar Solutions for chapter 5- Principle of Inheritance and Variation:
Link to Download PDF
Multiple Choice Questions
Very Short answer type questions
Short answer type questions
Long answer types questions
Class 12 Biology NCERT Exemplar Problems:
NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. Every year, many questions from the NCERT Exemplar are directly asked in the board exams. So, it’s very important for students to practice the NCERT exemplar problems to prepare well for the board exams.
Main topics discussed in Class 12 Biology, Chapter 5- Principle of Inheritance and Variation, are:
- Mendel’s Laws of Inheritance
- Inheritance of one gene
- Inheritance of two genes
- Sex determination
- Genetic disorders.
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Note: Once you are done with all the NCERT Exemplar problems, refer the solutions given above in this article to check the correctness of your own solutions and know the right way to design perfect answers.