CBSE Class 12 Biology Principles of Inheritance and Variation Assignment Set B

Read and download free pdf of CBSE Class 12 Biology Principles of Inheritance and Variation Assignment Set B. Get printable school Assignments for Class 12 Biology. Class 12 students should practise questions and answers given here for Chapter 5 Principles Of Inheritance And Variation Biology in Class 12 which will help them to strengthen their understanding of all important topics. Students should also download free pdf of Printable Worksheets for Class 12 Biology prepared as per the latest books and syllabus issued by NCERT, CBSE, KVS and do problems daily to score better marks in tests and examinations

Assignment for Class 12 Biology Chapter 5 Principles Of Inheritance And Variation

Class 12 Biology students should refer to the following printable assignment in Pdf for Chapter 5 Principles Of Inheritance And Variation in Class 12. This test paper with questions and answers for Class 12 Biology will be very useful for exams and help you to score good marks

Chapter 5 Principles Of Inheritance And Variation Class 12 Biology Assignment

 

POINTS TO REMEMBER

Allele : Various or slightly different forms of a gene, having same position on chromosomes.
Phenotype : The observable or external characteristics of an organism Genotype : The genetic constitution of an organism.
Monohybrid cross : A cross between two individuals of species, considering the inheritance of single pair of contrasting character e.g., a cross between pure tall (TT) and Dwarf (tt).
Dihybrid cross : A cross between two individuals of a species, considering the inheritance of two pairs of contrasting traits/characters e.g., a cross between Round and Yellow (RRYY) and wrinkled and green (rryy) pea seeds Incomplete dominance : When one of the two alleles of a gene is incompletely dominant over the other allele.
Co-dominance : When two alleles of a gene are equally dominant and express themselves even when they are together.
Multiple allelism : When a gene exists in more than two allelic forms e.g., gene for blood group exist in three allelic forms, IA, IB and i.
Aneuploidy : The phenomenon of gain or loss of one or more chromosome(s), that results due to failure of separation of homologous pair of chromosomes during meiosis. Trisomy : The condition in which a particular chromosome is present in three copies in a diploid cell/ nucleus.
Male heterogamety : When male produces two different types of gametes/ sperms e.g., In human beings X and Y.

 

Important Questions for NCERT Class 12 Biology Principles of Inheritance and Variation

 

Question. Mendel found that the F1 always resembled either one of the parents and that the trait of the other parent was not seen in them. This is due to :
(a) Segregation
(b) Dominance
(c) Partial dominance
(d) Unit factor

Answer : B

Question. Study of family history about inheritance of a particular trait in several generations of a family called
(a) Phylogeny
(b) Ontogeny
(c) Pedigree analysis
(d) Cladistics

Answer : C

Question. Symbols 5 used in pedigree analysis, represents
(a) Five offspring with unspecified sex
(b) Five diseased offspring
(c) Five unaffected offspring
(d) Five affected offsprings

Answer : C

Question. It was found that sometimes the F1 - had a phenotype that did not resemble either of the two parents and was in between the two. This is the case of :
(a) Dominance
(b) Incomplete dominance
(c) Codominance
(d) Pleiotropism

Answer : B

Question. Theoratically, the modified allele could be responsible for the production of :
(a) less efficient enzyme
(b) A non functional enzyme
(c) Non enzyme at all
(d) All the above

Answer : D

Question. How many true breeding pea plant varieties were selected by Mendel
(a) 7
(b) 14
(c) 21
(d) 28

Answer : B

Question. Regarding to pair of dominant and recessive trait which of the following combination is wrong
(a) Flower colour - Violet / white
(b) Flower position - Axial / terminal
(c) Pod shape - Inflated / constricted
(d) Seed colour - Green / yellow

Answer : D

Question. If F1 individual of genotype (Tt) go through sexual reproduction, then it's gamete (pollengrain) with genotype (T) have what chances to pollinate eggs of the genotype (T)
(a) 25 %
(b) 50 %
(c) 75 %
(d) 100 %

Answer : B

Question. Mendel proposed how many conclusions to consolidate his understanding of inheritance in monohybrid cross
(a) One
(b) Two
(c) Three
(d) None of the rules, he proposed laws / principles

Answer : C

Question. Which of the following is correct ?
(a) When genes are grouped on the same chromosome, some genes are very tightly linked and showed very low recombination
(b) When genes are loosely linked show very low recombination
(c) When genes are tightly linked show higher recombination
(d) When genes are loosely linked show no recombination

Answer : A

Question. In Morgan's experiment, what will be percentage of recombination in case of body colour and eye colour in Drosophila ?
(a) 37.2%
(b) 1.3%
(c) 98.7%
(d) 37.2%

Answer : B

Ques. How many true breeding pea plant varieties did Mendel select as pairs, which were similar except in one character with contrasting traits?
(a) 4
(b) 2
(c) 14
(d) 8 

Answer: C

Ques. Among the following characters, which one was not considered by Mendel in his experiments on pea?
(a) Trichomes-Glandular or non-glandular
(b) Seed-Green or yellow
(c) Pod-Inflated or constricted
(d) Stem-Tall or dwarf 

Answer: A

Ques. Which one from those given below is the period for Mendel’s hybridisation experiments?
(a) 1840-1850
(b) 1857-1869
(c) 1870-1877
(d) 1856-1863

Answer: D

Ques. In his classic experiments on pea plants, Mendel did not use
(a) seed shape
(b) flower position
(c) seed colour
(d) pod length. 

Answer: D

Ques. How many pairs of contrasting characters in pea plants were studied by Mendel in his experiments?
(a) Eight
(b) Seven
(c) Five
(d) Six 

Answer: B

Ques. Which one of the following traits of garden pea studied by Mendel was a recessive feature?
(a) Axial flower position
(b) Green seed colour
(c) Green pod colour
(d) Round seed shape 

Answer: B

Ques. The genes controlling the seven pea characters studied by Mendel are now known to be located on how many different chromosomes?
(a) Seven
(b) Six
(c) Five
(d) Four 

Answer: D

Ques. According to Mendelism, which character shows dominance?
(a) Terminal position of flower
(b) Green colour in seed coat
(c) Wrinkled seeds
(d) Green pod colour

Answer: D

Ques. First geneticist/father of genetics was
(a) De Vries
(b) Mendel
(c) Darwin
(d) Morgan. 

Answer: B

Ques. Which contribute to the success of Mendel?
(a) Qualitative analysis of data
(b) Observation of distinct inherited traits
(c) His knowledge of biology
(d) Consideration of one character at one time

Answer: D

Ques. Identify the wrong statement with reference to the gene ‘I’ that controls ABO blood groups.
(a) The gene (I) has three alleles.
(b) A person will have only two of the three alleles.
(c) When IA and IB are present together, they express same type of sugar.
(d) Allele i does not produce any sugar.

Answer: C

Ques. In Antirrhinum (Snapdragon), a red flower was crossed with a white flower and in F1 generation all pink flowers were obtained. When pink flowers were selfed, the F2 generation showed white, red and pink flowers. Choose the incorrect statements from the following.
(a) Law of segregation does not apply in this experiment.
(b) This experiment does not follow the Principle of Dominance.
(c) Pink colour in F1 is due to incomplete dominance.
(d) Ratio of F2 is 1/4 (red) : 2/4 (pink) : 1/4 (white).

Answer: A

Ques. The genotypes of a husband and wife are IAIB and IAi. Among the blood types of their children, how many different genotypes and phenotypes are possible?
(a) 3 genotypes; 4 phenotypes
(b) 4 genotypes; 3 phenotypes
(c) 4 genotypes; 4 phenotypes
(d) 3 genotypes; 3 phenotypes 

Answer: B

Ques. A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the F1 plants were selfed the resulting genotypes were in the ratio of
(a) 3 : 1 : : Tall : Dwarf
(b) 3 : 1 : : Dwarf : Tall
(c) 1 : 2 : 1 : : Tall homozygous : Tall heterozygous : Dwarf
(d) 1 : 2 : 1 : : Tall heterozygous : Tall homozygous : Dwarf. 

Answer: C

Ques. A gene showing co-dominance has
(a) alleles that are recessive to each other
(b) both alleles independently expressed in the heterozygote
(c) one allele dominant on the other
(d) alleles tightly linked on the same chromosome.

Answer: B

Ques. Alleles are
(a) different molecular forms of a gene
(b) heterozygotes
(c) different phenotype
(d) true breeding homozygotes. 

Answer: A

Ques. Multiple alleles are present
(a) at the same locus of the chromosome
(b) on non-sister chromatids
(c) on different chromosomes
(d) at different loci on the same chromosome.

Answer: A

Ques. A man with blood group ‘A’ marries a woman with blood group ‘B’. What are all the possible blood groups of their offspring?
(a) A, B, AB and O
(b) O only
(c) A and B only
(d) A, B and AB only

Answer: A

Ques. If two persons with ‘AB’ blood group marry and have sufficiently large number of children, these children could be classified as ‘A’ blood group: ‘AB’ blood group : ‘B’ blood group in 1 : 2 : 1 ratio. Modern technique of protein  lectrophoresis reveals presence of both ‘A’ and ‘B’ type proteins in ‘AB’ blood group individuals. This in an example of
(a) partial dominance
(b) complete dominance
(c) codominance
(d) incomplete dominance.

Answer: C

Ques. Which idea is depicted by a cross in which the F1 generation resembles both the parents?
(a) Inheritance of one gene
(b) Co-dominance
(c) Incomplete dominance
(d) Complete dominance 

Answer: B

Ques. F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1 : 2 : 1. It represents a case of
(a) co-dominance
(b) dihybrid cross
(c) monohybrid cross with complete dominance
(d) monohybrid cross with incomplete dominance.

Answer: D

Ques. A test cross is carried out to
(a) determine the genotype of a plant at F2
(b) predict whether two traits are linked
(c) assess the number of alleles of a gene
(d) determine whether two species or varieties will breed successfully. 

Answer: A

Ques. Test cross in plants or in Drosophila involves crossing
(a) between two genotypes with recessive trait
(b) between two F1 hybrids
(c) the F1 hybrid with a double recessive genotype
(d) between two genotypes with dominant trait.

Answer: C

Ques. ABO blood groups in humans are controlled by the gene I. It has three alleles - IA, IB and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?
(a) Three
(b) One
(c) Four
(d) Two

Answer: C

Very Short Answer Type Questions

Question. What is the cross between the progeny of F1 and the homozygous recessive parent called? How is it useful?
Answer : When a progeny of F1 is crossed with the homozygous recessive parent, it is called test cross.
Test cross between pure dominant (A) and hybrid dominant (B) individuals with recessive parent is shown below Such a cross is useful to determine the genotype of an unknown trait, i.e., whether it is heterozygous or homozygous dominant for the trait.

Question. A person has to perform crosses for the purpose of studying inheritance of a few traits/characters. What should be the criteria for selecting the organisms?
Answer : The criteria for selecting the organism to study inheritance are
(i) Easily visible and different traits
(ii) Short life span
(iii) Simple pollination procedure
(iv) Organisms must be true breeds
(v) Mating of gametes has to be random
(vi) Can be easily manipulated

Question. The pedigree chart given below shows a particular trait which is absent in parents but present in the next generation irrespective of sexes. Draw your conclusion on the basis of the pedigree.
Answer : The pedigree chart shows that the trait is autosome linked and recessive in nature. But, the parents are carriers (i.e., heterozygous) hence, among the offsprings only few show the trait irrespective of sex. The other offsprings are either normal or carrier.

Question. In order to obtain the F1-generation Mendel pollinated a pure-breeding tall plant with a pure-breeding dwarf plant. But for getting the F2-generation, he simply self-pollinated the tall F1 plants. Why?
Answer : Characters segregate during gamete formation. Pure-breeding parents give rise to F1 with heterozygous conditions. Only self-pollination of heterozygotes can result in all possible recombinations of characters in progeny as mating is random.

Question. Genes contain the information that is required to express a particular trait.’ Explain.
Answer : Genes contain the information required to express a particular trait can be explained by the following experiment.
G Beadle and E Tatum set an experiment to prove that one gene possess a particular trait and is responsible for the production of one enzyme or protein. They performed their experiment on Neurospora crassa which were nutritionally mutant. It was proved that a single protein contains several polypeptide and each polypeptide is controlled by separate gene. Thus, each gene expresses a particular trait. This theory was called one-gane-one enzyme or one gene-one polypeptide hypothesis.
But after the discovery of cistron (the functional unit of gene), the theory was named as one-cistron-one polypeptide hypothesis.

Question. Do you think Mendel’s Laws of inheritance would have been different in the characters that he chose were located on the same chromosome.
Answer : If the characters are present on the same chromosome they would not assort independently as they are linked on the same chromosome. Percentage of linkage depends on the distance between the genes. With linkage no conclusive laws can be drown.

Question. For the expression of traits genes provide only the potentiality and the environment provides the opportunity. Comment on the veracity of the statement.
Answer : 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.

Question. A, B, D are three independently assorting genes with their recessive alleles a, b, d, respectively. A cross was made between individuals of Aa bb DD genotype with aa bb dd. Find out the type of genotypes of the offspring produced.
Answer : The given cross Aa bb DD X aa bb dd, is a trihybrid cross, Accordingly the type of offspring produced would be,  (Image 91)

Short Answer Type Questions

Question. In a Mendelian monohybrid cross, the F2-generation shows identical genotypic and phenotypic ratios. What does it tell us about the nature of alleles involved? Justify your answer. 
Answer : In case of incomplete dominance, a monohybrid cross shows the result as follows Here, the phenotypic and genotypic both ratios are the same. So, we can conclude that when genotypic and phenotypic ratios are the same, alleles show incomplete dominance. i.e., none of the two alleles shows dominance thus producing hybrid intermediate from the expression of two homozygous alleles.

Question. Name a disorder, give the karyotype and write the symptoms, a human suffers from as a result of monosomy of the sex chromosome. 
Answer : Turner’s syndrome is a disorder caused by the absence of one of the X-chromosomes. Its karyotype will be 45 + XO. Symptoms are:
(i) Sterile females
(ii) Rudimentary ovaries
(iii) Lack of secondary sexual characters.

Question. Name a disorder, give the karyotype and write the symptoms where a human male suffers as a result of an additional X-chromosome.
Answer : Klinefelter’s syndrome. The karyotype is 44 + XXY. Symptoms are:
(i) Sex of the individual is masculine but possesses feminine characters.
(ii) Gynaecomastia, i.e., development of breasts.
(iii) Poor beard growth and often sterile.
(iv) Feminine pitched voice.

Question. Name the phenomenon that leads to situations like ‘XO’ abnormality in humAnswer : How do humans with ‘XO’ abnormality suffer? Explain. 
Answer : Absence of one X chromosome due to non segregation of chromatids during cell division leads
to XO abnormality. These are sterile female with rudimentary ovaries. They have shield-shaped
thorax, webbed neck, poor development of breasts, short stature, small uterus and puffy fingers.

Question. Which chromosome carries the mutated gene causing β-thalassemia? What are the problems  caused by the mutation? 
Answer : Chromosome number 11 carries the mutant gene causing β-thalassemia. It causes formation of abnormal haemoglobin molecules, resulting into anaemia.

Question. Give the chromosomal constitution and the resulting sex in each of the following syndromes:
(i) Turner’s syndrome
(ii) Klinefelter’s syndrome 
Answer : (i) XO, female
(ii) XXY, male with female characters

Question. If a father and son are both defective in red-green colour vision, is it likely that the son inherited the trait from his father? Comment.
Answer : Gene for colourblindness is X-chromosome linked, and sons receive their sole X-chromosome from their mother, not from their father. Male to male inheritances is not possible for X-linked traits in humans
In the given case the mother of the son must be a carrier (heterozygous) for colour blindness gene, thus transmitting the gene to her son.

Question. Discuss why Drosophila has been used extensively for genetical studies?
Answer : Morgan worked with the tiny fruit flies, Drosophila melanogaster, which were found to be suitable for genetical studies due to the following characteristics
(i) They could be grown on simple synthetic medium in the laboratory.
(ii) They complete their life-cycle in about two weeks.
(iii) A single mating could produce a large number of progeny flies.
(iv) A clear differentiation of the sexes– the male and female flies are easily distinguishable.
(v) It has many types of variations (hereditary) that can be seen with low power microscopes.

Question. Can a child have blood group ‘O’ if his parents have blood group ‘A’ and ‘B’ Explain.
Answer : A child have blood group O in the following two cases Case I When father is IA i and mother is IB i.  (Image 93)
The offsprings will have the above possible blood groups, i.e., AB, A, B and O. Thus, a child can have blood group ‘O’ if parents have heterozygous alleles for group ‘A’ and ‘B’.

Question. What is Down's syndrome? Give its symptoms and cause. Why is it that the chances of having a child with Down's syndrome increases if the age of the mother exceeds forty years?
Answer : Down's syndrome is a human genetic disorder caused due to trisomy of chromosome number 21. Such individuals are aneuploid and have 41 chromosomes, i.e., (2n+1)
Symptoms of down’s syndrome are
(i) Mental retardation
(ii) Growth abnormalities
(iii) Constantly open mouth
(iv) Dwarfness, etc., gonads and genitalia under developed The reason for the disorder is the non-disjunction (failure to separate) of homologous
chromosome (a pair 21 during meiotic division. The chances of having a child with Down's syndrome increases with the age of the mother (+40) because age adversely affects meiotic chromosome behaviour. Meiosis in the egg cells is not completed, until after fertilisation. During this long gap (till meiosis is not completed) egg cells are arrested in prophase I and chromosomes are unpaired. The greater the time they remain upaired greater the chance for unpairing and chromosome non-disjunction.

Question. What are the characteristic features of a true-breeding line?
Answer : True breeding is a stable trait inheritance and expression for several generations as a result of continuous self-pollination.
Characteristic features of a true-breeding line
(i) They are used as parents in artificial hybridisation as they provide gametes with all similar traits.
(ii) Homozygous recessive plants are used in test cross to determine the genotype.

Question. In peas,tallness is dominant over dwarfness, and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated with a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny in numbers mentioned against them
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White = 128
Mention the genotypes of the two parents and of the four offspring types.
Answer : The result shows that the four types of offspring are in a ratio of 1:1:1:1. Such a result is observed in a test cross progeny of a dihybrid cross.
The cross can be represented as
Parents Tall and red (TtRr) × Dwarf and white (ttrr)

QUESTIONS

1. Give any two reasons for the selection of pea plants by Mendel for his experiments.
2. Name any one plant that shows the phenomenon of incomplete dominance during the inheritance of its flower colour.
3. Name the base change and the amino acid change, responsible for sickle cell anaemia.
4. Name the disorder with the following chromosome complement.
(i) 22 pairs of autosomes + X X Y
(ii) 22 pairs of autosomes + 21st chromosome + XY.
5. A haemophilic man marries a normal homozygous woman. What is the probability that their daughter will be haemophilic?
6. A test is performed to know whether the given plant is homozygous dominant or heterozygous. Name the test and phenotypic ratio of this test for a monohybrid cross.
7. Identify the sex of organism as male or female in which the sex chromosome are found as
(i) ZW in bird (ii) XY in Drosophila (iii) ZZ in birds. (iv) XO in grasshopper.
8. Mention two differences between Turner's syndrome and Klinefelter's syndome.
9. The human male never passes on the gene for haemophilia to his son. Why is it so?
10. Mention four reasons why Drosophila was chosen by Morgan for his experiments in genetics. 
11. Differentiate between point mutation and frameshift mutations.

 

Chapter 02 Sexual Reproduction In Flowering Plants
CBSE Class 12 Biology Sexual Reproduction in Flowering Plants Set A

More Study Material

CBSE Class 12 Biology Chapter 5 Principles Of Inheritance And Variation Assignment

We hope you liked the above assignment for Chapter 5 Principles Of Inheritance And Variation which has been designed as per the latest syllabus for Class 12 Biology released by CBSE. Students of Class 12 should download and practice the above Assignments for Class 12 Biology regularly. We have provided all types of questions like MCQs, short answer questions, objective questions and long answer questions in the Class 12 Biology practice sheet in Pdf. All questions have been designed for Biology by looking into the pattern of problems asked in previous year examinations. 

Assignment for Biology CBSE Class 12 Chapter 5 Principles Of Inheritance And Variation

Our team of expert teachers have referred to NCERT book for Class 12 Biology to design the Biology Class 12 Assignments. If you practice at least one test paper daily, you will get higher marks in Class 12 exams this year. Daily practice of Biology course notes and related study material will help you to clear all your doubts and have stronger understanding of all concepts. You can download all Revision notes for Class 12 Biology also from www.studiestoday.com absolutely free of cost.

Chapter 5 Principles Of Inheritance And Variation Assignment Biology CBSE Class 12

All questions and their answers for the assignment given above for Class 12 Biology have been developed as per the latest curriculum and books issued for the current academic year. The students of Class 12 can rest assured that the best teachers have designed the questions of Biology so that you are able to revise the entire syllabus if you do the assignments. Lot of MCQ questions for Class 12 Biology have also been given in the worksheets and assignments for regular use. All study material for Class 12 Biology students have been given on studiestoday.

Chapter 5 Principles Of Inheritance And Variation Assignment CBSE Class 12 Biology

Regular assignment practice helps to get a more comprehensive understanding of Chapter 5 Principles Of Inheritance And Variation concepts. Assignments play a crucial role in understanding Chapter 5 Principles Of Inheritance And Variation in CBSE Class 12. Students can download all the assignments of the same chapter in Class 12 Biology in Pdf format. You can print them or read them online on your computer or mobile.

CBSE Biology Class 12 Chapter 5 Principles Of Inheritance And Variation Assignment

CBSE Class 12 Biology latest books have been used for coming up with the latest questions and solutions for the above assignment. If you have revised all concepts relating to Chapter 5 Principles Of Inheritance And Variation then you should attempt all questions given in the test sheets above. We have also provided lot of Worksheets for Class 12 Biology which you can use to further make your self stronger in Biology

Where can I download in PDF assignments for CBSE Class 12 Biology Chapter 5 Principles Of Inheritance And Variation

You can download free Pdf assignments for CBSE Class 12 Biology Chapter 5 Principles Of Inheritance And Variation from StudiesToday.com

The assignments for Chapter 5 Principles Of Inheritance And Variation Class 12 Biology for have been made based on which syllabus

The Chapter 5 Principles Of Inheritance And Variation Class 12 Biology Assignments have been designed based on latest CBSE syllabus for Class 12 Biology issued for the current academic year

Can I download and print these printable assignments for Biology Chapter 5 Principles Of Inheritance And Variation Class 12

Yes, These printable assignments for Chapter 5 Principles Of Inheritance And Variation Class 12 Biology are free to download and print

How many topics are covered in Chapter 5 Principles Of Inheritance And Variation Biology assignments for Class 12

All topics given in Chapter 5 Principles Of Inheritance And Variation Biology Class 12 Book for the current academic year have been covered in the given assignment

Is there any charge for this assignment for Chapter 5 Principles Of Inheritance And Variation Biology Class 12

No, all Printable Assignments for Chapter 5 Principles Of Inheritance And Variation Class 12 Biology have been given for free and can be downloaded in Pdf format

How can I download the printable test assignments for Chapter 5 Principles Of Inheritance And Variation Biology Class 12

Just click on the View or Download button below, then another window with the Pdf will be visible, just click on the Pdf icon to download the free assignments for Chapter 5 Principles Of Inheritance And Variation Class 12 Biology

Are these assignments available for all chapters in Class 12 Biology

Yes, apart from Biology you can download free assignments for all subjects in Class 12

Can I download solved assignments for Chapter 5 Principles Of Inheritance And Variation CBSE Class 12 Biology

Our team of expert teachers at studiestoday.com have provided all answers for the practice questions which have been given in Class 12 Biology Chapter 5 Principles Of Inheritance And Variation assignments