GENETICS

Detailed Study:

Brief Revision:

https://www.youtube.com/watch?v=fFh-q1aq5DE&list=PLhf4hr_x5XyQWQNFIfhh589X9WCqEf1J4&index=2

Frequently Tested Topics:

  • Genotype and Phenotype

  • Punnett Square and Sex-Linked Inheritance

  • Mendel's Experiments

  • Mendel's Laws of Inheritance

*Note that other aspects of the chapter are equally important.

Important Past Questions

  • State whether true or false. If false rewrite the correct form by changing the first or last word only. 

i) The theory of Inheritance of Acquired characters was proposed by Watson and Crick.  (2019)

ii) Nitrogen bonds are present between the complementary nitrogenous bases of DNA. (2018)

iii) Chromosomes other than the pair of sex chromosomes are called alleles. (2010)

  • Give appropriate biological/technical terms for:

i) The condition in which a pair of chromosomes carry similar alleles of a particular character. (2018)

ii) The complex consisting of a DNA strand and a core of histones. (2018)

iii) The suppressed allele of a gene. (2012, 2017)

iv) The repeating components of each DNA strand lengthwise. (2016)

v) An alteration in the genetic material that can be inherited. (2014, 2016)

  • Write the difference between the following on the basis of what is given in the brackets:

i) Monohybrid and Dihybrid cross (phenotypic ratio) (2011)

ii) Genotype and Phenotype (definition) (2010)

  • Name the four nitrogenous bases in a DNA molecule. (2010, 2013, 2019)

  • __________ is the scientific name of garden pea, which Mendel used for his experiments. (2015, 2018)

  • The recessive gene is the one that expresses itself in:

A) heterozygous condition B) homozygous condition C) F2 generation D) Y-linked inheritance

  • State Mendel's Law of:

Dominance (2010, 2017, 2019)

Independent Assortment (2013, 2016)

Segregation of Gametes (2018)

  • In Mendel's experiments with pea plants:

i) tall pea plants (T) are dominant over dwarf pea plants (t). (2019)

      1. What is the phenotype and genotype of the F1​ generation if a homozygous tall plant is crossed with            a homozygous dwarf plant?

      2. Draw a Punnett square board to show the gametes and offspring when both the parents are                      heterozygous for tallness.

      3. What is the phenotypic and genotypic ratio of the above cross?

ii) axial flowers (A) are dominant over terminal flowers (a). (2017)

      1. What is the phenotype and genotype of the F1​ generation if a plant bearing pure axial flowers is                crossed with a plant bearing pure terminal flowers?

      2. Draw a Punnett square board to show the gametes and offspring when both the parents are                      heterozygous for axial flowers.

      3. Write the possible combinations of gametes that can be obtained if two F1 hybrid plants are                      crossed.

iii) round seeds (R) are dominant over wrinkled seeds (r). (2015)

      1. What is the phenotype and genotype of the F2 generation?

      2. Draw a Punnett square board to show the gametes and offspring when both the parents are                      heterozygous for round seeds. (Rr)

      3. What is the phenotypic and genotypic ratio of the above cross?

  • What is dihybrid cross? (2019)

  • Name 2 genetic disorders commonly seen in human males. (2017)

  • Name the sex chromosomes in human males and females. (2015)

  • Briefly explain the term

i) Mutation. (2018)

ii) Gene. (2013)

  • What is the number of chromosomes in the gametes of human beings? (2018)

  • Name any one X-linked disease found in humans. (2010)

  • Name the unit of heredity. (2010)

  • A pea plant which is homozygous for Green pods which are inflated [GGII] is crossed with a homozygous plant for yellow pods which are constricted[ggii]. Answer the following questions:
    i) Give the phenotype and genotype of the F1​ generation.
    Which type of pollination has occurred to produce F1​ generation?

       ii) Write the phenotypic ratio of the F2 generation.

       iii) Write the possible combinations of the gametes that can be obtained if two F1 hybrid plants are                crossed.

  • A homozygous tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf (t) plant bearing white (r) flowers. (2016)

       i) Give the genotype and phenotype of the plants of F1​ generation.

       ii) Mention the possible combinations of the gametes that can be obtained from the F1 hybrid plant.

       iii) Mention the phenotypes of the offsprings obtained in F2 generation.

       iv) What is the phenotypic ratio obtained in F2 generation?   

  • A pure tall plant (TT) is crossed with a pure dwarf plant. (2010)

i) Draw Punnett squares to show 1) F1 generation and 2) F2 generation.

ii) Give the phenotype of the F2 generation.

iii) Give the phenotypic and genotypic ratio of the F1 and F2 generation. 

DIAGRAM BASED QUESTIONS

Given below is a schematic diagram showing Mendel's Experiment on sweet pea plants having axial flowers with round seeds (AARR) and Terminal flowers with wrinkled seeds (aarr). Study the same and answer the questions that follow : (2010)
(i) Give the phenotype of F1​ progeny.
(ii) Give the phenotypes of F2​ progeny produced upon by the self-pollination of F1​ progeny.
(iii) Give the phenotype ratio of F2​ progeny.
(iv) Name and explain the law induced by Mendel on the basis of the above observation.

image_2021-04-21_222315.png

Given below is a diagram of a double helical structure of DNA.
i) Name the four nit

image_2021-04-21_222631.png