The NCERT Exemplar Class 12 Solutions provide answers in a detailed and clear language so that students can understand the concepts without any further help. The Principles of Inheritance and Variation chapter also introduces genetic diseases such as haemophilia, sickle cell anaemia, and colour blindness, and autosomal versus sex-linked inheritance. Topics like chromosomal theory of inheritance, gene interaction, mutations, genetic recombination, and variations are included in the NCERT Exemplar Class 12 Biology Solutions Chapter 5 Principles of Inheritance and Variation.
NCERT Exemplar Class 12 Biology Solutions Chapter 5 Principles of Inheritance and Variation
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CBSE Class 12th Exam Date:01 Jan' 26 - 14 Feb' 26
The NCERT Exemplar Class 12 Biology Solutions Chapter 5 Principles of Inheritance and Variation helps students in understanding how characteristics are inherited by one generation from another. The chapter starts with Mendel's experiments on pea plants by using Law of Dominance, the Law of Segregation, and the Law of Independent Assortment. The NCERT Exemplar Solutions allow students to build a strong foundation in the subject, making it easier for them to solve different types of questions with confidence and perform well in both school and competitive exams such as NEET.
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NCERT Exemplar Class 12 Biology Solutions Chapter 5
The chapter Principles of Inheritance and Variation helps students learn how characters are passed from one generation to the next and also explains important ideas like Mendel’s experiments, genes, and how variations happen. The questions are present in many formats like MCQs, short and long answers. Practising these helps students understand the concepts clearly and prepare well for exams. The NCERT Exemplar Class 12 Biology Solutions consist of different types of questions, such as MCQs, long and short answers, and diagram-based questions that allow students to revise and prepare efficiently.
Get NCERT Exemplar Class 12 Biology Chapter 5 (MCQs)
Question:1
All genes located on the same chromosome:
a. Form different groups depending upon their relative distance
b. Form one linkage group
c. Will not be from any linkage groups
d. Form interactive groups that affect the phenotype
Answer:
The answer is option (b) Form one linkage group
Explanation: Closer genes are more likely to form linkages, as the linkage is decided by the vicinity of two genes. Morgan showed that genes form one linkage group when they are located on the same chromosome. Thus, (b) is the answer.
Question:2
Conditions of a karyotype 2n +1, 2n –1 and 2n + 2, 2n – 2 are called:
a. Aneuploidy
b. Polyploidy
c. Allopolyploidy
d. Monosomy
Answer:
The answer is option (a) Aneuploidy
Explanation: Aneuploidy is the condition in which loss or gain of chromosomes is observed due to the failure of the separation of chromatids during the cycle of cell division. Hence, (a) is the correct option
Question:3
Distance between the genes and the percentage of recombination show:
a. a direct relationship
b. an inverse relationship
c. a parallel relationship
d. no relationship
Answer:
The answer is option (b) an inverse relationship
Explanation: Reduced distance between genes increases the probability of recombination, which shows an inverse relationship. Hence, (b) is the correct option.
Question:4
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:
a. Autosomal dominant
b. Autosomal recessive
c. Sex-linked dominant
d. Sex-linked recessive
Answer:
The answer is option (d) Sex-linked recessive
Explanation: Here, the X chromosome has the flawed gene, but the carriers of the disease are females and it is manifested in males. Thus, it is referred to as a sex-linked recessive disease. One example of such a disease is Haemophilia, which is known as an X-linked recessive disease.
Question:5
In sickle cell anaemia, glutamic acid is replaced by valine. Which one of the following triplets codes for valine?
a. G G G
b. A A G
c. G A A
d. G U G
Answer:
The answer is option (d) G U G
Explanation: At the sixth codon of the beta-globin gene, single-base substitution takes place from GAG to GUG. Due to this, in the globin protein, replacement of glutamic acid with valine is seen. Hence, GUG is the code for valine.
Question:6
The person having genotype |A|B would show the blood group as AB. This is because of:
a. Pleiotropy
b. Co-dominance
c. Segregation
d. Incomplete dominance
Answer:
The answer is option (b) Co-dominance
Explanation: Most commonly found in ABO blood grouping, co-dominance is when the F1 generation resembles both parents. Here, the result is the AB group because both A and B sugars are dominant.
Question:7
zzzwype of sex determination is seen in:
a. Platypus
b. Snails
c. Cockroach
d. Peacock
Answer:
The answer is option (d) Peacock
Explanation: Sex determination of the type ZZZW is observed in birds. Males have a ZZ combination and females have a ZW combination.
Question:8
A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both parents?
a. TT and Tt
b. Tt and Tt
c. TT and TT
d. Tt and tt
Answer:
The answer is option (b) Tt and Tt
Explanation: In the case of Tt and Tt (option (b)), a few of the offspring will be dwarfs (TT, Tt, tt), and most of them are going to be tall (TT, Tt). In case of option (a) and (c), the offspring will be all tall and in option (d), one of the parents is a dwarf. Hence, (b) is the correct option.
Question:9
In a dihybrid cross, if you get a 9:3:3:1 ratio, it denotes that:
a. The alleles of two genes are interacting with each other
b. It is a multigenic inheritance
c. It is a case of multiple allelism
d. The alleles of two genes are segregating independently
Answer:
The answer is option (d). The alleles of two genes are segregating independently.
Explanation: A 9:3:3:1 ratio is the result of a dihybrid cross when two genes assort independently during gamete formation, as explained by Mendel’s law of independent assortment.
Question:10
Which of the following will not result in variations among siblings?
a. Independent assortment of genes
b. Crossing over
c. Linkage
d. Mutation
Answer:
The answer is option (c) Linkage
Explanation: Whenever two genes are in close proximity and located on the same chromosome, linkage takes place irrespective of the variation.
Question:11
Mendel's Law of independent assortment holds good for genes situated on the:
a. non-homologous chromosomes
b. homologous chromosomes
c. extranuclear genetic element
d. same chromosome
Answer:
The answer is option (a) Non-homologous chromosomes
Explanation: Mendel's law of independent assortment applies when genes are located on different (non-homologous) chromosomes, allowing them to assort independently during gamete formation.
Question:12
Occasionally, a single gene may express more than one effect. The phenomenon is called:
a. multiple allelism
b. mosaicism
c. pleiotropy
d. polygeny
Answer:
The answer is option (c) Pleiotropy
Explanation: Pleiotropy is the phenomenon in which a single gene expresses more than one effect occasionally.
Question:13
In a certain taxon of insects, some have 17 chromosomes and the others have 18 chromosomes. The 17 and 18 chromosome-bearing organisms are:
a. males and females, respectively
b. females and males, respectively
c. all males
d. all females
Answer:
The answer is option (a) Males and females, respectively
Explanation: Males have a single X chromosome while females have pairs of X chromosomes. This is XO sex determination, which is seen in such insects. Hence, (a) is the answer.
Question:14
The inheritance pattern of a gene over generations among humans is studied by pedigree analysis. Character studied in the pedigree analysis is equivalent to:
b. Mendelian trait
c. polygenic trait
d. maternal trait
Answer:
The answer is option (b) Mendelian trait
Explanation: Pedigree analysis can be used to trace the Mendelian disorders and the pattern of their inheritance.
Question:15
It is said that Mendel proposed that the factor controlling any character is discrete and independent. His proposition was based on the
a. Results of the F3 generation of a cross.
b. observations that the offspring of a cross made between the plants having two contrasting characters show only one character without any blending.
c. self-pollination of F1 offspring
d. cross-pollination of F1 generation with recessive parent
Answer:
The answer is option (b), observations that the offspring of a cross made between the plants having two contrasting characters show only one character without any blending.
Explanation: It was observed by Mendel that when two pairs of varying characters are analysed during a dihybrid cross, the behaviour of a particular character is independent of another character. Hence, the correct answer is (b).
Question:16
Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross involving these two genes, the F1 heterozygote is crossed with the homozygous recessive parental type (aa bb). What would be the ratio of offspring in the next generation?
a. 1: 1 : 1: 1
b. 9 : 3 : 3: 1
c. 3: 1
d. 1: 1
Answer:
The answer is option (a) 1:1:1:1
Explanation: Since genes A and B are linked, but a test cross is performed with a double recessive parent, the four types of gametes (parental and recombinant) are produced in equal proportion, giving a 1:1:1:1 ratio.
Question:17
In the F2 generation of a Mendelian dihybrid cross, the number of phenotypes and genotypes is:
a. phenotypes – 4; genotypes – 16
b. phenotypes – 9; genotypes – 4
c. phenotypes – 4; genotypes – 8
d. phenotypes – 4; genotypes – 9
Answer:
The answer is the option (d) Phenotypes – 4; genotypes - 9
Explanation: For example, consider a dihybrid cross between wrinkled green (rryy) and round yellow (RRYY). The phenotypes were as follows: round green, round yellow, wrinkled green and wrinkled yellow and the genotypes were: rryy, rrYy, rrYY, Rryy, RrYy, RrYY, RRyy, RRYy, and RRYY. Hence, the correct option is (d).
Question:18
Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group, respectively. What would be the genotype of both mother and father?
a. Mother is homozygous for ‘A’ blood group, and father is heterozygous for ‘B’
b. Mother is heterozygous for ‘A’ blood group, and father is homozygous for ‘B’
c. Both mother and father are heterozygous for ‘A’ and ‘B’ blood groups, respectively
d. Both mother and father are homozygous for the ‘A’ and ‘B’ blood groups, respectively
Answer:
The answer is option (c) Both mother and father are heterozygous for the ‘A’ and ‘B’ blood groups, respectively
Explanation: Offspring ii (O blood group) is the feasible phenotype of parents, and IAi (A blood group) and IBi (B blood group) are the feasible genotypes of the parents.
Question:2
Answer:
Yes, the results would have been completely different if the characters chosen were located on the same chromosome. In his experiments on Drosophila, Morgan found that the ratio of phenotype in the F1 generation was different from that in Mendel’s observation because the characters were on the same chromosome.
Question:4
Answer:
The following criteria should be followed for selecting the organisms:
Question:5
Answer:
The breeding between parents is shown in the first row, and the number of progenies is depicted by the second row. The figure shows two female and three male children, with one girl and one boy affected by some kind of genetic disease. From the figure, it can be concluded that the nature of the trait is recessive and autosome-linked in nature.
Question:7
Genes contain the information that is required to express a particular trait.” Explain.
Answer:
The fact that genes are responsible for inheritance was discovered after the discovery of chromosomes. Before that, genes were not in the knowledge of the scientists. Only after Mendel’s period was it known that the information on the expression of a particular trait is contained in the genes.
Question:8
How do the alleles of a particular gene differ from each other? Explain its significance.
Answer:
Alleles are genes which code for a pair of contrasting characters, and these are different from each other within a pair. However, the slight difference is not noticeable as character or phenotype, but as the absence or presence of a molecule of a substance like a sugar polymer. The substance is present on gene I, which regulates the ABO blood grouping.
Alleles are vital because they help in identifying whether a particular trait is recessive or dominant or even co-dominant (in some cases).
Question:9
Answer:
The usage of particular letters is only meant for convenience. Generally, the character is shown by the first letter of a particular trait, and a different case of the same letter is used to show the contrasting character. Conventionally, a capital letter depicts the dominant trait, and a lowercase letter depicts the recessive trait.
Question:10
Answer:
Genes carry the potential for the expression of a trait, i.e. phenotype and are responsible for inheritance. Phenotype depends on many factors. If a trait gets combined with a dominant one, it may become recessive, and the survival depends on the natural selection process. Therefore, the opportunity for expression of a particular trait is provided by and depends on the environment.
Question:11
Answer:
The genotype of the F1 generation is depicted by the following Punnett Square:
abd (From Parent 2) | |
AbD (From Parent 1) | AabbDd |
abD (From Parent 1) | aabbDd |
So, the offspring produced will have two types of genotypes
- AabbDd
- aabbDd
Question:12
Answer:
The Y chromosome, which is present in males, determines the sex of the human child. Hence, it is evident that the father is responsible for having a male or a female child. Therefore, a mother should not be blamed at all for the same. However, the probability of X or Y chromosome making its way to the zygote is equal, i.e. 50-50. Hence, no one is to be blamed or rewarded for that. A female child is as important as a male child.
Question:13
Discuss the genetic basis of wrinkled phenotype of pea seed.
Answer:
Generally, seeds dry before dispersal and germination. The amount of starch in the seed decides whether the seed will be round or wrinkled, and the relative amount of starch is looked after by a gene. If there is less than the required starch in the seed, it will be wrinkled. In pea plants, a mutant gene’s enzymes are responsible for reducing the amount of starch in seeds and hence, the seeds become wrinkled.
Question:15
How does a mutagen induce mutation? Explain with example.
Answer:
The mutation is induced by physical and chemical factors called mutagens. During replication, the base-pair sequence in the DNA is altered to induce mutation.
Access NCERT Exemplar Class 12 Biology Chapter 5 (Short Answer Questions)
Question:1
Answer:
The alleles segregate and go to each of the parents when plants of F1 generation reproduce without a cross. The segregation is random with equal probability of a particular allele going to either of the parental gametes. Thus, genotype and phenotype in the F2 generation are identical. So, there will be 50% of plants with a pure genotype and 50% of plants with a mixed genotype.
Question:2
Can a child have blood group O if his parents have blood group ‘A’ and ‘B’? Explain.
Answer:
Yes, it is possible for a child to have blood group O if the parents have blood group A and B. If genotypes of the parents are IAi and IBi, then gametes can have one of the genotypes from i, IA or IB. The child’s genotype will be ii if fertilisation of gametes occurs with i, and hence the child will have blood group O.
Question:3
Answer:
First discovered and described by Langdon Down in 1866, Down syndrome refers to the presence of an additional copy of the 21st chromosome. It is a chromosomal disorder. A person with this condition has:
distinct facial appearance with a partially opened mouth and furrowed tongue
small round head
delayed physical and mental development
short stature
broad palm
According to studies, with advancing maternal age, the chances of Down syndrome in the child. This is because cells get older with the age of the mother, and the ova are present since birth in females. Various physicochemical exposures also lead to increased chances.
Question:4
How was it concluded that genes are located on chromosomes?
Answer:
The behaviour of chromosomes and genes was studied during meiosis by Walter Sutton and Theodor Boveri, and they observed similar movement in chromosomes and genes. Hence, it was proposed by them that genes are located on chromosomes.
Question:5
Answer:
Incomplete dominance of a particular trait over another is sometimes seen which results in the manifestation of both characters in some way. For example, consider the genotype of red flowers to be RR and that of yellow flowers to be rr. In F1 generation, all progenies have the genotype as Rr. Hence, orange flowers are produced by all plants in F1 generation because red colour does not completely dominate the yellow colour.
Question:6
What are the characteristic features of a true-breeding line?
Answer:
The characteristic features of a true-breeding line are:
Question:7
Answer:
TtRr and ttrr are the genotypes of the two parents.
The four offspring types are:
Question:8
Answer:
The genes with photo-pigments are located on X chromosome, and if the gene is destroyed or missing, it results in colour blindness. Chances of this disease are much higher in males than in females because males have only one X chromosome; hence, there is no second X chromosome to compensate for the defect, like in females. Females have colour blindness if the defect is in both their X chromosomes.
Question:10
Discuss why Drosophila has been used extensively for genetic studies.
Answer:
Drosophila is ideal for genetic studies because:
Its life cycle is completed in two weeks.
Many offspring are produced through a single mating.
It can be in a laboratory.
It exhibits sexual dimorphism and many hereditary variations.
Question:11
How do genes and chromosomes share similarities from genetic studies?
Answer:
From the point of view of genetic studies, the similarities in genes and chromosomes are:
Both genes and chromosomes are found in pairs.
Independent segregation is observed in independent pairs.
Segregation takes place when the gamete is formed, and only one pair is transmitted to the gamete.
Question:12
What is recombination? Discuss the applications of recombination from genetic engineering.
Answer:
Recombination is a combination of genes which is different from the parental gene combination. It can occur either naturally during meiosis or artificially through genetic engineering, which is used for recombining different species to produce beneficial products for humans. For example, production of BT cotton, BT brinjal, and vaccines like hepatitis B was done with genetic engineering.
Question:13
What is artificial selection? Do you think it affects the process of natural selection? How?
Answer:
The selective breeding of animals and plants is called artificial selection. It is done to include advantageous traits in plants and animals, and it can be natural or artificial. However, ethically, artificial selection is wrong. But according to the law of survival of the fittest, only the varieties which are fit to survive will survive in artificial selection. Therefore, it will not affect the process of natural selection.
Question:14
With the help of an example, differentiate between incomplete dominance and co-dominance.
Answer:
Incomplete dominance | Co-dominance |
In the F1 generation, there is a partial manifestation of phenotypes from both parents. | In the F1 generation, there is a complete manifestation of phenotypes from both parents. |
Example: F1 generation results in pink flowers when snapdragon plants with red flowers and white flowers are crossed. | Example: Co-dominance is shown in ABO blood grouping in humans. |
Question:15
Answer:
A single pair of alleles, i.e. HbA and HbS, controls sickle cell anaemia. The offspring may suffer from this disease if both parents are heterozygous (HbAHbS). But the offspring should be homozygous (HbSHbS) because a heterozygote carries this disease. However, it persists in humans because, in adaptation, heterozygous individuals are advantageous.
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Know the NCERT Exemplar Class 12 Biology Solutions Chapter 5 (Long Answer Questions)
Question:1
Answer:
The cross between a dwarf plant with white flowers (ttrr) and a tall plant with red flowers (TTRR) is depicted by the Punnett Square shown below:
Plants of the F1 generation will produce red flowers and will be tall. When they are permitted to self-pollinate, the F2 generation’s phenotype can be depicted by following a Punnett Square.
Here, the ratio is 9:3:3:1, which is the standard dihybrid ratio, also shown as:
Tall plant red flower = 9
Tall plant, white flower = 3
Dwarf plant red flower = 3
Dwarf plant white flower = 1
This ratio stands true only when the contrasting characters have their genes on distinct chromosomes. This is because of the fact that there will be interaction if the characters are on the same chromosome.
Question:2
Answer:
1. In humans, males are called heterogametic because they have X and Y chromosomes in their 23rd pair of chromosomes. On the other hand, females are called homogametic as they have two chromosomes, i.e. XX chromosomes in their 23rd pair of chromosomes. However, in birds, the scenario is quite the opposite. Male birds have ZZ chromosomes and female birds have ZW chromosomes. Hence, in cases like these, males are homogametic, and females are heterogametic.
2. The sex of an unborn child is determined by the 23rd pair of chromosomes in humans. The males have X and Y chromosomes, and females have X and X chromosomes in that pair. So, when the ovum is fertilised with the sperm containing the X chromosome, the result is a female child, and when it is fertilised with the Y chromosome, the result is a male child. In some animals, like crocodiles, sex is determined by temperature. Male crocodiles are born if eggs are brooded at high temperatures.
Question:3
Answer:
The pedigree analysis shown below depicts the colour blindness in offspring:
The F1 generation depicts two female children and one male child. One of the female children might be a carrier, and the male child will suffer from colour blindness.
The P generation depicts a normal husband and a career wife.
About 8% of males are colour blind, while only 0.5% of females are colour blind. This is because only one X chromosome is present in males. If that one X chromosome carries the defect, the boy will suffer from colour blindness. But in females, there are two X chromosomes which help in the compensation of a deficiency in one of the chromosomes. Thus, females are generally carriers of the disease and rarely the sufferers.
Question:4
Discuss in detail the contributions of Morgan and Sturvant in the area of genetics.
Answer:
Sturtevant was one of the students of Morgan. Morgan has carried out several experiments related to genetics. Some of their contributions are:
In the various dihybrid crosses of Drosophila carried out by Morgan, it was observed by him that the phenotypic ratio did not resemble the standard ratio, which was observed by Mendel. Morgan and his group noticed that the genes did not show independent segregation when they were located on the same chromosome, as they were aware that genes were located on the X chromosome. Morgan termed the interaction of genes on the same chromosome as linkage and the generation of non-parental combinations as recombination. On the same chromosome, the probability of parental combination is much higher than that of non-parental combination.
Sturtevant discovered that on the same chromosome, recombination or lack of recombination was largely dependent on the relative distance between the two genes. There was no recombination when genes were tightly linked, and the chances of recombination were higher when genes had a large distance between them.
Contributions made by Morgan and his group, including Sturtevant, contributed hugely to the development of genetic mapping.
Question:5
Define aneuploidy. How is it different from polyploidy? Describe the individuals who have followed chromosomal abnormalities.
a. Trisomy of the 21st Chromosome
b. XXY
c. XO
Answer:
Aneuploidy is a condition in which a gain or loss of a chromosome is seen during cell division due to the failure of chromatid segregation. On the other hand, an increase in the number of chromosome sets caused due to the failure of cytokinesis after telophase is called polyploidy. This condition is mostly seen in plants and rarely seen in animals.
Trisomy of the 21st chromosome: First discovered and described by Langdon Down in 1866, it refers to the presence of an additional copy of the 21st chromosome. It is known as Down syndrome. A person with this condition has a distinct facial appearance with a partially opened mouth and a small, round head. Physical and mental development is delayed in such individuals.
XXY: In this condition, a karyotype of 47 is caused due to an additional copy of the X chromosome. It is a genetic disorder and is called Klinefelter’s syndrome. In this case, three chromosomes (XXY) are present in the 23rd set of chromosomes. A person suffering from this disorder is sterile and has enlarged breasts (gynecomastia) with overall masculine development.
XO: Lack of an X chromosome causes this genetic disorder of ploidy of 45 (XO). It is known as Turner’s syndrome. Such females have rudimentary ovaries and are sterile. The absence of secondary sexual characters is also seen.
NCERT Exemplar Class 12 Solutions Subject-wise:
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Download EBookApproach to Solve Questions of NCERT Exemplar Class 12 Biology Solutions Chapter 5
This chapter consists of a mix of direct, conceptual, and application questions. To answer the questions effectively in the chapter Principles of Inheritance and Variation, students can follow the steps given below
Read the NCERT textbook and Exemplar thoroughly to grasp Mendel's experiments, inheritance laws (dominance, segregation, independent assortment), and deviations such as incomplete dominance and linkage.
Practice in drawing and labelling Punnett squares for monohybrid and dihybrid crosses, and diagrams illustrating chromosomal sex determination.
Learn key words such as gene, allele, homozygous, heterozygous, genotype, phenotype, linkage, recombination, and mutation.
Complete all NCERT Exemplar Class 12 Biology Solutions Chapter 5, concentrating on key areas such as Mendelian ratios, blood group inheritance, genetic disorders (such as haemophilia, sickle cell anaemia, and Down's syndrome), and chromosomal basis of inheritance.
The experiments and works of scientists such as Gregor Mendel (inheritance laws), Sutton and Boveri (chromosomal inheritance theory), and Thomas Hunt Morgan (linkage and recombination) need to be read thoroughly.
Also, read the NCERT Solution subject-wise
Important topics of Principles of Inheritance and Variation Class 12 NCERT Exemplar
This chapter explains how traits are passed from one generation to the next and why variations occur among individuals. Given below are the important topics from the Principles of Inheritance and Variation chapter.
● Mendel’s Laws of Inheritance
● Inheritance of One Gene
● Inheritance of Two Genes
● Sex Determination
● Mutation
● Genetic Disorder
Must Read NCERT Notes subject-wise
Advantages of NCERT Exemplar Class 12 Biology Chapter 5 Solutions
Solving exemplar questions helps students understand the principles of genetics with clarity and accuracy. The chapter Principles of Inheritance and Variation explains how characters are passed from one generation to another.
- NCERT Exemplar Class 12 Biology Chapter 5 Solutions gives a clear understanding of Mendel's Laws, monohybrid and dihybrid crosses, along with suitable examples.
- Students can practice numerical and pedigree-based questions, which are frequently asked in the board and competitive exams like NEET.
- Exemplar solutions allow them to prepare the difficult topics like gene interactions, incomplete dominance, codominance, and polygenic inheritance easily.
- All the answers are explained in a clear and step-by-step manner, which saves time and makes it easier for students to understand without any confusion.
Important Question from Principles of Inheritance and Variation Class 12 NCERT Exemplar
Principles of Inheritance and Variation is a key chapter for NEET and board examinations that describes how characteristics and traits are inherited from one generation to the next. It is centred on the basic genetic laws identified by Mendel and branches out into more detailed patterns of inheritance.
Question 1:
Which of the following is an example of incomplete dominance?
A) A cross between red and white snapdragon flowers producing pink flowers
B) Human blood group AB expresses both A and B antigens
C) Height in humans shows continuous variation
D) Sickle cell anaemia affecting multiple traits
Answer: The correct answer is option (A), A cross between red and white snapdragon flowers producing pink flowers
Explanation:
Incomplete dominance occurs when neither allele is completely dominant, resulting in a heterozygous phenotype that is intermediate between the two parents. In snapdragons, crossing red (RR) and white (rr) flowers produces pink (Rr) flowers, demonstrating incomplete dominance.
Also, check the NCERT Books and the NCERT Syllabus here
NCERT Exemplar Class 12 Biology Chapter Wise
Find all chapter-wise practice questions and solutions in the table below to strengthen your concepts and prepare effectively for exams.
Frequently Asked Questions (FAQs)
Q: What is a linkage group and how are genes on the same chromosome inherited?
A:
A linkage group is a set of genes located on the same chromosome that tend to be inherited together. All genes on the same chromosome form one linkage group, which corresponds to the number of chromosomes in the organism.
Q: What is aneuploidy and how does it arise?
A:
Aneuploidy refers to the condition where an organism has one or more extra or missing chromosomes (e.g., 2n+1, 2n–1). It arises due to the non-disjunction of chromosomes during cell division, leading to the gain or loss of chromosomes.
Q: How is the distance between genes related to recombination frequency?
A:
The distance between genes on a chromosome shows a direct relationship with the percentage of recombination. The further apart two genes are, the higher the chance of recombination between them during meiosis.
Q: Why is solving NCERT Exemplar problems important for this chapter?
A:
Solving NCERT Exemplar problems helps students understand a variety of question types, including MCQs, match the following, Punnett square problems, and conceptual questions. This practice strengthens conceptual understanding and prepares students for board and competitive exams like NEET.
Q: What types of questions are included in the NCERT Exemplar for this chapter?
A:
The exemplar includes multiple-choice questions, very short answers, short answers, long answers, and fill-in-the-blanks. These cover both fundamental concepts and higher-order thinking skills, ensuring comprehensive exam preparation.
Q: How do multiple alleles affect inheritance patterns?
A:
Multiple alleles are more than two different gene forms occupying the same position. They affect inheritance by producing additional genetic variations, such as human blood groups (A, B, O). In contrast to simple Mendelian inheritance, multiple alleles show codominance or dominance relationships. This leads to a broader array of phenotypic expressions within a population.
Q: How do chromosomal disorders differ from genetic disorders?
A:
Chromosomal disorders are caused by chromosome number or structural abnormalities, for example, Down syndrome (trisomy 21). Genetic disorders are caused by mutations in a particular gene, for instance, sickle cell anaemia or cystic fibrosis. Chromosomal disorders involve several genes, whereas genetic disorders involve single-gene mutations. Both have an effect on health but vary regarding their cause and pattern of inheritance.
Q: How does polygenic inheritance influence traits like human skin color?
A:
Polygenic inheritance involves multiple genes controlling a single trait, leading to a wide range of variations. Human skin colour is influenced by several genes that regulate melanin production. The combined effect of these genes results in a spectrum of skin tones rather than distinct categories. Environmental factors like sunlight can also modify the expression of these traits.
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You can get the Class 11 English Syllabus 2025-26 from the Careers360 website. This resource also provides details about exam dates, previous year papers, exam paper analysis, exam patterns, preparation tips and many more. you search in this site or you can ask question we will provide you the direct link to your query.
LINK: https://school.careers360.com/boards/cbse/cbse-class-11-english-syllabus
Hello,
No, it’s not true that GSEB (Gujarat Board) students get first preference in college admissions.
Your daughter can continue with CBSE, as all recognized boards CBSE, ICSE, and State Boards (like GSEB) which are equally accepted for college admissions across India.
However, state quota seats in Gujarat colleges (like medical or engineering) may give slight preference to GSEB students for state-level counselling, not for all courses.
So, keep her in CBSE unless she plans to apply only under Gujarat state quota. For national-level exams like JEE or NEET, CBSE is equally valid and widely preferred.
Hope it helps.
Hello,
The Central Board of Secondary Education (CBSE) releases the previous year's question papers for Class 12.
You can download these CBSE Class 12 previous year question papers from this link : CBSE Class 12 previous year question papers (http://CBSE%20Class%2012%20previous%20year%20question%20papers)
Hope it helps !
Hi dear candidate,
On our official website, you can download the class 12th practice question paper for all the commerce subjects (accountancy, economics, business studies and English) in PDF format with solutions as well.
Kindly refer to the link attached below to download:
CBSE Class 12 Accountancy Question Paper 2025
CBSE Class 12 Economics Sample Paper 2025-26 Out! Download 12th Economics SQP and MS PDF
CBSE Class 12 Business Studies Question Paper 2025
CBSE Class 12 English Sample Papers 2025-26 Out – Download PDF, Marking Scheme
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Hello,
Since you have passed 10th and 12th from Delhi and your residency is Delhi, but your domicile is UP, here’s how NEET counselling works:
1. Counselling Eligibility: For UP NEET counselling, your UP domicile makes you eligible, regardless of where your schooling was. You can participate in UP state counselling according to your NEET rank.
2. Delhi Counselling: For Delhi state quota, usually 10th/12th + residency matters. Since your school and residency are in Delhi, you might also be eligible for Delhi state quota, but it depends on specific state rules.
So, having a Delhi Aadhaar will not automatically reject you in UP counselling as long as you have a UP domicile certificate.
Hope you understand.
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