Plus One / 12th Bio-Zoology - Book Back Answers - Chapter 4 - English Medium
Chapter 4: Principles of Inheritance and Variation
Tamil Nadu Board 12th Standard Bio-Zoology - Chapter 4: Book Back Answers and Solutions
This post covers the book back answers and solutions for Chapter 4 – Bio-Zoology from the Tamil Nadu State Board 12th Standard Bio-Zoology textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.
We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.
By going through this material, you’ll gain a strong understanding of Bio-Zoology Chapter 4 along with the corresponding book back questions and answers (PDF format).
Question Types Covered:
- 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following
- 2 Mark Questions: Answer briefly
- 3, 4, and 5 Mark Questions: Answer in detail
All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.
All the best, Class 12 students! Prepare well and aim for top scores. Thank you!
Chapter 4: Principles of Inheritance and Variation
I. Multiple Choice Questions
1. Haemophilia is more common in males because it is a
a)Recessive character carried by Y-chromosome
b) Dominant character carried by Y-chromosome
c) Dominant trait carried by X-chromosome
d) Recessive trait carried by X-chromosome
Answer Key:
d) Recessive trait carried by X-chromosome
2. ABO blood group in man is controlled by
a) Multiple alleles
b) Lethal genes
c) Sex linked genes
d) Y-linked genes
Answer Key:
a) Multiple alleles
3. Three children of a family have blood groups A, AB and B. What could be the genotypes of their parents?
a) IA IB and Io Io
b) IA Io and IBIo
c) IB IB and IA IA
d) IA IA and Io Io
Answer Key:
b) IA Io and IBIo
4. Which of the following is not correct?
a) Three or more alleles of a trait in the population are called multiple alleles.
b) A normal gene undergoes mutations to form many alleles.
c) Multiple alleles map at different loci of a chromosome.
d) A diploid organism has only two alleles out of many in the population.
Answer Key:
c) Multiple alleles map at different loci of a chromosome.
5. Which of the following phenotypes in the progeny are possible from the parental combination AxB?
a) A and B only
b) A,B and AB only
c) AB only
d) A,B,AB and O
Answer Key:
d) A,B,AB and O
6. Which of the following phenotypes is not possible in the progeny of the parental genotypic combination IAIO X IAIB?
a) AB
b) O
c) A
d) B
Answer Key:
b) O
7. Which of the following is true about Rh factor in the offspring of a parental combination DdxDd (both Rh positive)?
a) All will be Rh positive
b) Half will be Rh positive
c) About ¾ will be Rh negative
d) About one fourth will be Rh negative
Answer Key:
d) About one fourth will be Rh negative
8. What can be the blood group of offspring when both parents have AB blood group?
a) AB only
b) A, B and AB
c) A, B, AB and O
d) A and B only
Answer Key:
b) A, B and AB
9. If the childs blood group is ‘O’ and fathers blood group is ‘A’ and mother’s blood group is ‘B’ the genotype of the parents will be
a) IA IA and IB Io
b) IA Io and IB Io
c) IA Io and IoIo
d) IoIo and IB IB
Answer Key:
b) IA Io and IB Io
10. XO type of sex determination and XY type of sex determination are examples of
a) Male heterogamety
b) Female heterogamety
c) Male homogamety
d) Both (b) and (c)
Answer Key:
a) Male heterogamety
11. In an accident there is great loss of blood and there is no time to analyse the blood group which blood can be safely transferred?
a) O and Rh negative
b) O and Rh positive
c)B and Rh negative
d) AB and Rh positive
Answer Key:
a) O and Rh negative
12. Father of a child is colourblind and mother is carrier for colourblindness, the probability of the child being colourblind is
a)25%
b) 50%
c) 100%
d) 75%
Answer Key:
b) 50%
13. A marriage between a colourblind man and a normal woman produces
a) All carrier daughters and normal sons
b) 50% carrier daughters and 50% normal daughters
c) 50% colourblind sons and 50% normal sons
d) All carrier offsprings
Answer Key:
a) All carrier daughters and normal sons
14. Down's syndrome is a genetic disorder which is caused by the presence of an extra chromosome number
a) 20
b) 21
c) 4
d) 23
Answer Key:
b) 21
15. Klinefelters’ syndrome is characterized by a karyotype of
a) XYY
b) XO
c) XXX
d) XXY
Answer Key:
d) XXY
16. Females with Turners’ syndrome have
a) Small uterus
b) Rudimentary ovaries
c) Underdeveloped breasts
d) All of these
Answer Key:
b) Rudimentary ovaries
17. Pataus’ syndrome is also referred to as
a) 13-Trisomy
b) 18-Trisomy
c) 21-Trisomy
d) None of these
Answer Key:
a) 13-Trisomy
18. “Universal Donor” and “Universal Recipients” blood group are _____ and___________respectively
a) AB, O
b) O, AB
c) A, B
d) B, A
Answer Key:
b) O, AB
19. ZW-ZZ system of sex determination occurs in
a) Fishes
b) Reptiles
c) Birds
d) All of these
Answer Key:
d) All of these
20. Co-dominant blood group is
a) A
b) AB
c) B
d) O
Answer Key:
b) AB
21. Which of the following is incorrect regarding ZW-ZZ type of sex determination?
a) It occurs in birds and some reptiles
b) Females are homogametic and males are heterogametic
c) Males produce one types of gamete
d) It occurs in gypsy moth
Answer Key:
b) Females are homogametic and males are heterogametic
a)Recessive character carried by Y-chromosome
b) Dominant character carried by Y-chromosome
c) Dominant trait carried by X-chromosome
d) Recessive trait carried by X-chromosome
Answer Key:
d) Recessive trait carried by X-chromosome
2. ABO blood group in man is controlled by
a) Multiple alleles
b) Lethal genes
c) Sex linked genes
d) Y-linked genes
Answer Key:
a) Multiple alleles
3. Three children of a family have blood groups A, AB and B. What could be the genotypes of their parents?
a) IA IB and Io Io
b) IA Io and IBIo
c) IB IB and IA IA
d) IA IA and Io Io
Answer Key:
b) IA Io and IBIo
4. Which of the following is not correct?
a) Three or more alleles of a trait in the population are called multiple alleles.
b) A normal gene undergoes mutations to form many alleles.
c) Multiple alleles map at different loci of a chromosome.
d) A diploid organism has only two alleles out of many in the population.
Answer Key:
c) Multiple alleles map at different loci of a chromosome.
5. Which of the following phenotypes in the progeny are possible from the parental combination AxB?
a) A and B only
b) A,B and AB only
c) AB only
d) A,B,AB and O
Answer Key:
d) A,B,AB and O
6. Which of the following phenotypes is not possible in the progeny of the parental genotypic combination IAIO X IAIB?
a) AB
b) O
c) A
d) B
Answer Key:
b) O
7. Which of the following is true about Rh factor in the offspring of a parental combination DdxDd (both Rh positive)?
a) All will be Rh positive
b) Half will be Rh positive
c) About ¾ will be Rh negative
d) About one fourth will be Rh negative
Answer Key:
d) About one fourth will be Rh negative
8. What can be the blood group of offspring when both parents have AB blood group?
a) AB only
b) A, B and AB
c) A, B, AB and O
d) A and B only
Answer Key:
b) A, B and AB
9. If the childs blood group is ‘O’ and fathers blood group is ‘A’ and mother’s blood group is ‘B’ the genotype of the parents will be
a) IA IA and IB Io
b) IA Io and IB Io
c) IA Io and IoIo
d) IoIo and IB IB
Answer Key:
b) IA Io and IB Io
10. XO type of sex determination and XY type of sex determination are examples of
a) Male heterogamety
b) Female heterogamety
c) Male homogamety
d) Both (b) and (c)
Answer Key:
a) Male heterogamety
11. In an accident there is great loss of blood and there is no time to analyse the blood group which blood can be safely transferred?
a) O and Rh negative
b) O and Rh positive
c)B and Rh negative
d) AB and Rh positive
Answer Key:
a) O and Rh negative
12. Father of a child is colourblind and mother is carrier for colourblindness, the probability of the child being colourblind is
a)25%
b) 50%
c) 100%
d) 75%
Answer Key:
b) 50%
13. A marriage between a colourblind man and a normal woman produces
a) All carrier daughters and normal sons
b) 50% carrier daughters and 50% normal daughters
c) 50% colourblind sons and 50% normal sons
d) All carrier offsprings
Answer Key:
a) All carrier daughters and normal sons
14. Down's syndrome is a genetic disorder which is caused by the presence of an extra chromosome number
a) 20
b) 21
c) 4
d) 23
Answer Key:
b) 21
15. Klinefelters’ syndrome is characterized by a karyotype of
a) XYY
b) XO
c) XXX
d) XXY
Answer Key:
d) XXY
16. Females with Turners’ syndrome have
a) Small uterus
b) Rudimentary ovaries
c) Underdeveloped breasts
d) All of these
Answer Key:
b) Rudimentary ovaries
17. Pataus’ syndrome is also referred to as
a) 13-Trisomy
b) 18-Trisomy
c) 21-Trisomy
d) None of these
Answer Key:
a) 13-Trisomy
18. “Universal Donor” and “Universal Recipients” blood group are _____ and___________respectively
a) AB, O
b) O, AB
c) A, B
d) B, A
Answer Key:
b) O, AB
19. ZW-ZZ system of sex determination occurs in
a) Fishes
b) Reptiles
c) Birds
d) All of these
Answer Key:
d) All of these
20. Co-dominant blood group is
a) A
b) AB
c) B
d) O
Answer Key:
b) AB
21. Which of the following is incorrect regarding ZW-ZZ type of sex determination?
a) It occurs in birds and some reptiles
b) Females are homogametic and males are heterogametic
c) Males produce one types of gamete
d) It occurs in gypsy moth
Answer Key:
b) Females are homogametic and males are heterogametic
II. Short answer questions
12th bio zoolgy III. Long answer questions
12th bio zology
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