Heredity is a chapter in the CBSE Class 10 Science syllabus from Science. This chapter hub brings together revision notes, practice questions, worksheets, flashcards, formula sheet to help students learn, practice, and revise Heredity effectively.

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Heredity

NCERT Class 10 Science Chapter 8: Heredity (Pages 128–133)

Summary of Heredity

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Heredity at a Glance

Board

CBSE

Class

Class 10

Subject

Science

Book

Science

Chapter

8

Pages

128133

Resources

7 study resources

Heredity Summary

In this chapter, we explore heredity, which is the process through which traits and characteristics are transmitted from parents to their offspring. Understanding heredity is crucial because it explains the similarities and differences we see among individuals within a species. We begin by discussing how variations occur during reproduction, whether it is asexual or sexual. Asexual reproduction, like that of bacteria, results in offspring that are nearly identical to the parent, with only minor genetic variations due to errors during DNA replication. In contrast, sexual reproduction leads to a wider variety of traits as it mixes genetic material from two parents. The chapter also touches on the principles of inheritance as introduced by Gregor Mendel, a scientist known for his experiments with pea plants. Mendel discovered that traits can be dominant or recessive. For example, if tallness is a dominant trait, then a plant only needs one copy of the tallness gene to express that trait. However, if a plant has two copies of a recessive gene for shortness, it will exhibit the short trait. This principle leads us to the conclusion that traits can be inherited separately, allowing new combinations to appear in offspring. Moreover, the discussion covers how the environment impacts which traits are favored for survival, introducing concepts of natural selection. For instance, individuals with traits that better suit their environment are more likely to survive and reproduce, passing on those advantageous characteristics. We also learn about sex determination, primarily through human genetics. Each parent contributes chromosomes to their child, with the mother always providing an X chromosome, while the father can provide either an X or a Y chromosome, determining the child’s sex. Understanding these mechanisms allows us to see that genetics plays a foundational role in not only individual traits but also in the diversity and adaptability of species over generations. By mastering these concepts, students will gain insight into the biological processes that govern life and evolution.

Heredity Revision Guide

Download the Heredity revision guide with key points, summaries, and quick revision notes for CBSE Class 10 Science.

Key Points

1

Define heredity with an example.

Heredity is the transmission of traits from parents to offspring. For example, a child may inherit eye color from their parents.

2

Explain variation in heredity.

Variation refers to differences in traits among individuals of a species, caused by genetic differences and environmental factors.

3

State Mendel's law of dominance.

Mendel's law states that in a pair of contrasting traits, one will be dominant and the other recessive. Dominant traits are expressed in the F1 generation.

4

Describe Mendel's law of segregation.

This law states that alleles for a trait separate during gamete formation, so each gamete carries only one allele for each trait.

5

Explain Mendel's law of independent assortment.

Genes for different traits are inherited independently of each other, leading to new trait combinations in offspring.

6

Define dominant and recessive traits.

Dominant traits are expressed even if only one allele is present, while recessive traits require two alleles to be expressed.

7

What is a gene?

A gene is a segment of DNA that codes for a specific protein, determining a particular trait in an organism.

8

Explain the concept of alleles.

Alleles are different versions of the same gene that can result in variations of the trait controlled by that gene.

9

Describe the genotype and phenotype.

Genotype is the genetic makeup of an organism, while phenotype is the physical expression of those genes.

10

How is sex determined in humans?

Sex is determined by the sex chromosomes: XX for females and XY for males. The father's sperm determines the child's sex.

11

What are sex chromosomes?

Sex chromosomes are the X and Y chromosomes that determine the sex of an individual. Females have XX, and males have XY.

12

Explain the role of DNA in heredity.

DNA carries genetic information that is passed from parents to offspring, determining inherited traits.

13

What is a chromosome?

A chromosome is a long DNA molecule with part or all of the genetic material of an organism.

14

Describe the process of DNA copying.

DNA copying is the process by which DNA replicates itself, ensuring genetic information is passed accurately during cell division.

15

What causes genetic variation?

Genetic variation is caused by mutations, recombination during sexual reproduction, and random fertilization.

16

Explain the importance of variation.

Variation is crucial for the survival of species as it allows adaptation to changing environments and evolution.

17

What is a monohybrid cross?

A monohybrid cross is a genetic cross between individuals differing in one trait, used to study inheritance patterns.

18

What is a dihybrid cross?

A dihybrid cross is a genetic cross between individuals differing in two traits, showing independent assortment of genes.

19

How do traits get expressed?

Traits are expressed through proteins synthesized based on genetic instructions, influenced by dominant and recessive alleles.

20

What is the significance of Mendel's experiments?

Mendel's experiments laid the foundation for genetics, explaining how traits are inherited and predicting inheritance patterns.

Heredity Practice Questions & Answers

Practice important questions and exam-style problems from Heredity. These questions cover key topics from the CBSE Class 10 Science syllabus.

How to practice: Start with the questions below to test your understanding of Heredity. Use the revision guide to review concepts you find difficult, then come back and retry the questions for better retention.

View all 198 Heredity questions
Q9

Explain the rule of inheritance of traits in human beings.

Single Answer MCQ
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Q10

What is the difference between free and attached earlobes?

Single Answer MCQ
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Q11

How can the inheritance of earlobe types be correlated with parents' earlobe types?

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Q12

How does the environment influence the selection of genetic variants?

Single Answer MCQ
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Q13

What is the role of genetic factors in determining traits?

Single Answer MCQ
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Q14

How does the concept of heredity relate to evolutionary processes?

Single Answer MCQ
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Q15

Discuss the importance of genetic variation in heredity.

Single Answer MCQ
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Q16

How does Mendel's theory of inheritance explain the expression of traits in offspring?

Single Answer MCQ
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Q17

What are the different visible characters of garden peas that Mendel studied?

Single Answer MCQ
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Q18

How did Mendel determine the pattern of inheritance in pea plants?

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Q19

Explain the difference between the F1 and F2 generations in Mendel's experiments.

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Q20

How did Mendel's knowledge of science and mathematics help him in studying heredity?

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Q21

What is the significance of keeping count of individuals exhibiting a particular trait in each generation?

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Q22

How does Mendel's experiment with pea plants demonstrate the laws of inheritance?

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Q23

What is the ratio of dominant and recessive traits in the F2 generation according to Mendel's experiments?

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Q24

How do dominant and recessive traits influence the expression of traits in offspring?

Single Answer MCQ
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Q25

Discuss the inheritance of traits over two generations as shown in Figure 8.3.

Single Answer MCQ
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Q26

What is heredity?

Single Answer MCQ
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Q27

Explain the concept of inheritance of traits.

Single Answer MCQ
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Q28

How are genes related to heredity?

Single Answer MCQ
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Q29

Describe Mendel's contributions to the study of heredity.

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Q30

What are dominant and recessive traits?

Single Answer MCQ
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Q31

How do dominant and recessive traits influence the expression of traits in offspring?

Single Answer MCQ
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Q32

Explain the difference between genotype and phenotype.

Single Answer MCQ
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Q33

How does the environment influence the expression of inherited traits?

Single Answer MCQ
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Q34

What is the significance of Mendel's experiments with garden peas?

Single Answer MCQ
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Q35

How did Mendel determine the inheritance patterns of traits in garden peas?

Single Answer MCQ
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Q36

Describe the process of self-pollination in plants.

Single Answer MCQ
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Q37

How does the presence of two copies of genes influence the inheritance of traits?

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Q38

What is the role of DNA in the inheritance of traits?

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Q39

How do parents contribute to the genetic makeup of their offspring?

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Q40

Explain the concept of free and attached earlobes as an example of inherited traits.

Single Answer MCQ
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Q41

How can the inheritance of earlobe types be used to suggest possible rules for inheritance of traits?

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Q42

Discuss the importance of studying heredity in understanding evolution.

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Q43

How do variations in traits contribute to the survival of species?

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Q44

What are some examples of inherited traits in humans?

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Q45

How can the study of heredity help in predicting the likelihood of certain traits in offspring?

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Q46

What are some factors that can influence the expression of inherited traits?

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Q47

How do Mendel's laws of inheritance apply to human genetics?

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Q48

Explain the significance of Mendel's experiments in understanding heredity.

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Q49

How can the study of heredity help in breeding programs for plants and animals?

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Q50

Discuss the ethical implications of genetic testing and manipulation in the context of heredity.

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Q51

What is the main result of sexual reproduction compared to asexual reproduction?

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Q52

Which of the following processes introduces variations among individuals in populations?

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Q53

In a population where variation exists, which trait is likely to persist over generations?

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Q54

Which term describes the genetic information inherited from both parents?

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Q55

What effect does a high mutation rate have on a species' variation?

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Q56

How do environmental factors influence the survival of variations in a population?

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Q57

What role did Mendel's experiments play in understanding inheritance?

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Q58

Which of the following increases genetic diversity the most in a population?

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Q59

What would result from a population with very low genetic variation?

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Q60

Which of the following is a common misconception about genetic variation?

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Q61

What is an example of a trait that can have multiple variations in a population?

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Q62

Which reproductive strategy is less likely to promote genetic diversity?

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Q63

What is the significance of variations within a population for evolution?

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Q64

In terms of genetic diversity, what advantage does sexual reproduction have over asexual reproduction?

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Q65

What type of trait is determined by multiple genes rather than a single gene?

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Q66

What is the primary source of genetic variation in sexual reproduction?

Single Answer MCQ
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Q67

Which of Mendel's laws states that alleles segregate independently during gamete formation?

Single Answer MCQ
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Q68

In pea plants, round seeds (R) are dominant over wrinkled seeds (r). What would be the expected phenotypic ratio of the offspring from a cross between a heterozygous round seed plant and a homozygous wrinkled seed plant?

Single Answer MCQ
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Q69

If a person has blood type O, what are the possible genotypes of their parents?

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Q70

Which of the following statements best describes a dominant trait?

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Q71

What kind of genetic trait is an example of incomplete dominance?

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Q72

Which of the following best explains the role of mutations in heredity?

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Q73

If a tall plant (TT) is crossed with a short plant (tt), what will be the genotype of the F1 offspring?

Single Answer MCQ
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Q74

How is sex determined in human beings?

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Q75

If a characteristic is controlled by a single gene with two alleles, what are the only possible genotypes?

Single Answer MCQ
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Q76

Which type of inheritance describes a trait that is influenced by multiple genes?

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Q77

What is the expected outcome if two heterozygous tall pea plants (Tt) are crossed?

Single Answer MCQ
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Q78

If a trait is recessive, when will it be expressed in the phenotype?

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Q79

What type of trait is determined by the interaction of genes and environment?

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Q80

What is the primary factor that Mendel determined was responsible for the inheritance of traits in pea plants?

Single Answer MCQ
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Q81

Which type of traits did Mendel observe in his pea plant experiments that always showed dominance over others?

Single Answer MCQ
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Q82

In Mendel's experiments, the F2 generation from a monohybrid cross displayed what ratio of dominant to recessive traits?

Single Answer MCQ
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Q83

How do variations within a population benefit a species in terms of survival?

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Q84

If a trait has a frequency of 10% in a population, what can we infer about this trait compared to a trait with a frequency of 60%?

Single Answer MCQ
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Q85

What is the expected phenotypic ratio from the F2 generation of a dihybrid cross according to Mendelian principles?

Single Answer MCQ
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Q86

Mendel's laws are based on which type of organism?

Single Answer MCQ
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Q87

What do we call traits that require two recessive alleles to be expressed?

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Q88

If a plant's genotype is Tt, what phenotype would be expressed?

Single Answer MCQ
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Q89

Which of the following is NOT a component of Mendel's law of segregation?

Single Answer MCQ
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Q90

What term describes the genetic makeup of an organism?

Single Answer MCQ
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Q91

In Mendelian genetics, traits that are shown equally in the phenotype of both homozygous genotypes are known as what?

Single Answer MCQ
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Q92

Which inheritance pattern does NOT produce a 1:2:1 ratio in the F2 generation?

Single Answer MCQ
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Q93

When analyzing traits in a Punnett square, what does each box represent?

Single Answer MCQ
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Q94

What role does environmental influence play in the expression of genetic traits?

Single Answer MCQ
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Q95

What is the primary source of variation in sexually reproducing organisms?

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Q96

In asexually reproducing organisms, variations mainly arise due to:

Single Answer MCQ
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Q97

Which type of reproduction typically leads to greater genetic variation in a population?

Single Answer MCQ
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Q98

Why are traits that are advantageous more likely to persist in a population?

Single Answer MCQ
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Q99

When offspring inherit traits from both parents, this process is referred to as:

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Q100

How does sexual reproduction contribute to evolution?

Single Answer MCQ
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Q101

Which term describes the mixing of genetic material during sexual reproduction?

Single Answer MCQ
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Q102

In genetic terms, what does variation refer to?

Single Answer MCQ
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Q103

Which process increases genetic variation through the reshuffling of alleles?

Single Answer MCQ
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Q104

Which is an example of a trait that can show variation within a population?

Single Answer MCQ
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Q105

What role do mutations play in variation?

Single Answer MCQ
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Q106

What type of selection favors extreme phenotypes over intermediate phenotypes?

Single Answer MCQ
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Q107

How does the environment impact the survival of variations in a species?

Single Answer MCQ
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Q108

What is a possible effect of inbreeding on a population's variation?

Single Answer MCQ
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Q109

What process determines which traits are passed on in a population?

Single Answer MCQ
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Q110

Why do species that reproduce sexually tend to have more diverse traits?

Single Answer MCQ
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Q111

What is the basic unit of heredity that carries genetic information?

Single Answer MCQ
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Q112

In Mendel's experiments, what was the phenotype of the F1 generation when true-breeding tall plants were crossed with true-breeding short plants?

Single Answer MCQ
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Q113

What is meant by a dominant trait?

Single Answer MCQ
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Q114

Which of the following represents a homozygous recessive genotype?

Single Answer MCQ
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Q115

When a tall plant (Tt) is crossed with a short plant (tt), what is the expected phenotypic ratio in the offspring?

Single Answer MCQ
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Q116

How do Mendel's laws of inheritance apply to independent assortment?

Single Answer MCQ
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Q117

In humans, what determines the sex of the child?

Single Answer MCQ
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Q118

What genotype is responsible for a person with blood type O?

Single Answer MCQ
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Q119

What term describes the observable characteristics of an organism?

Single Answer MCQ
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Q120

Which of the following statements best describes mutations?

Single Answer MCQ
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Q121

What is a phenotype ratio expected from a dihybrid cross of heterozygous parents (TtYy x TtYy) in the F2 generation?

Single Answer MCQ
Q-00040245
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Q122

How does asexual reproduction influence genetic variation?

Single Answer MCQ
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Q123

What role do alleles play in determining traits?

Single Answer MCQ
Q-00040247
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Q124

In a pedigree chart, what does a filled circle or square represent?

Single Answer MCQ
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Q125

If a mutation occurs in a germ cell, what can be its consequence?

Single Answer MCQ
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Q126

In humans, which blood type is considered a universal donor?

Single Answer MCQ
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Q127

What is a dominant trait?

Single Answer MCQ
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Q128

In Mendel's pea experiments, what was observed in the F1 generation?

Single Answer MCQ
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Q129

What does the term 'recessive trait' signify?

Single Answer MCQ
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Q130

How can variations in a population promote survival?

Single Answer MCQ
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Q131

Which generation in Mendel's experiments displayed a 3:1 ratio?

Single Answer MCQ
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Q132

What role do genes play in heredity?

Single Answer MCQ
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Q133

If trait A occurs in 10% of a population and trait B in 60%, which trait is likely older?

Single Answer MCQ
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Q134

What is the phenotype of an individual?

Single Answer MCQ
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Q135

What can be concluded if a trait is found in a 1:2:1 ratio in F2 generation?

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Q136

Which of the following statements about genes is true?

Single Answer MCQ
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Q137

What did Mendel's experiments primarily focus on?

Single Answer MCQ
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Q138

What is the significance of genetic variation in evolution?

Single Answer MCQ
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Q139

Which term refers to the genetic makeup of an individual?

Single Answer MCQ
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Q140

What is a trait that is expressed when at least one dominant allele is present called?

Single Answer MCQ
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Q141

Why might an organism with a harmful trait still survive in a population?

Single Answer MCQ
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Q142

Choose the correct statements with reference to chromosomes: (i) carry hereditary information from parents to next generation. (ii) are thread-like structures located inside the nucleus of an animal cell. (iii) always exist in pairs in human gametes. (iv) are involved in the process of cell division.

Single Answer MCQ
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Q143

A couple are parents to 4 daughters in a sequence, and do not have any son. Does this indicate that the husband does not produced Y-chromosome bearing sperms? Explain.

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Q144

What are the chances of this couple bearing yet another daughter? Show with the help of a cross.

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Q145

Mendel crossed tall pea plant with short pea plant and obtained all the tall plants in the F1 generation. Why only tall pea plants were observed in F1 progeny?

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Q146

By which method did Mendel obtain F2 progeny?

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Q147

Write one difference between dominant and recessive trait.

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Q148

Write two observations made by Mendel about F1 progeny.

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Q149

Mendel crossed tall pea plant with short pea plant and obtained all the tall plants in the F1 generation. Why only tall pea plants were observed in F1 progeny?

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Q150

Write one difference between dominant and recessive trait.

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Q151

By which method did Mendel obtain F2 progeny?

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Q152

Write two observations made by Mendel about F1 progeny.

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Q153

The genotype of green stemmed tomato plant is denoted by 'GG' and that of purple stemmed tomato plant as 'gg'. Hybrid of a cross between these two were self-pollinated to obtain F2 progeny. What will be the ratio of GG, Gg and gg in this F2 progeny?

Single Answer MCQ
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Q154

Variation is useful for the survival of species over time. Explain this statement with the help of an example.

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Q155

Giving two examples, justify the statement that the sex of the offspring in all animals is not always genetically determined.

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Q156

Differentiate between the sex chromosomes of male and female human beings.

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Q157

The genotype of green stemmed tomato plant is denoted by ‘GG’ and that of purple stemmed tomato plant as ‘gg’. Hybrid of a cross between these two were self-pollinated to obtain F2 progeny. What will be the ratio of GG, Gg and gg in this F2 progeny?

Single Answer MCQ
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Q158

Do all variations in a species have equal chances of surviving in the environment in which they find themselves? Explain.

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Q159

Giving two examples, justify the statement that the sex of the offspring in all animals is not always genetically determined.

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Q160

Differentiate between the sex chromosomes of male and female human beings.

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Q161

The genotype of green stemmed tomato plant is denoted by ‘GG’ and that of purple stemmed tomato plant as ‘gg’. Hybrid of a cross between these two were self-pollinated to obtain F2 progeny. What will be the ratio of GG, Gg and gg in this F2 progeny?

Single Answer MCQ
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Q162

Do all variations in a species have equal chances of surviving in the environment in which they find themselves? Explain.

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Q163

Giving two examples, justify the statement that the sex of the offspring in all animals is not always genetically determined.

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Q164

Differentiate between the sex chromosomes of male and female human beings.

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Q165

Show the cross and observations made by Mendel when he crossed pure tall pea plant with a pure short pea plant to get F1 progeny.

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Q166

Sex is determined by different factors in various species. However, in human beings, it is determined genetically. Which amongst the following option(s) is/are correct for human beings? (i) Gamete carrying X chromosome from female parent. (ii) Gamete carrying X chromosome from male parent. (iii) Gamete carrying Y chromosome from male parent.

Single Answer MCQ
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Q167

Mendel crossed tall pea plant with short pea plant and obtained all tall plants in the F1 generation. Why only tall pea plants were observed in F1 progeny?

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Q168

By which method did Mendel obtain F2 progeny?

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Q169

Write one difference between dominant and recessive trait.

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Q170

Write two observations made by Mendel about F1 progeny.

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Q171

Show the cross and observations made by Mendel when he crossed pure tall pea plant with a pure short pea plant to get F1 progeny.

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Q172

Round, green seeded pea plant (RRyy) was crossed with wrinkled, yellow seeded pea plant (rrYY), and F1 progeny is produced. All plants of F1 progeny will have:

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Q173

“The sex of the children in the human beings will be determined by what they inherit from their father.” Explain this statement.

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Q174

A tall pea plant (TT) is crossed with a dwarf pea plant (tt). Find out F1 and F2 progeny. Also mention the processes that lead to the formation of F1 and F2 progeny during the cross.

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Q175

Identify the traits that cannot be transmitted from parents to the off-springs: (i) Swimming technique (ii) Blood group (iii) Eye colour (iv) Dancing skills

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Q176

Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds were crossed with each other which produced F1 progeny that have only round yellow (RrYy) seeds. When F1 plants are self-pollinated, the F2 progeny will have which new combination of characters as compared to the parents: (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green

Single Answer MCQ
Q-00206610
View explanation
Q177

Study the given table about a cross between red-flowered and white-flowered pea plants. Depict the information given in the table in the form of a cross.

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Q-00206620
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Q178

Using the given table, deduce the F2 phenotypic ratio and genotypic ratio.

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Q-00206622
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Q179

Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds were crossed with each other which produced F1 progeny that have only round yellow (RrYy) seeds. When F1 plants are self-pollinated, the F2 progeny will have which new combination of characters, as compared to the parents: (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green. Correct options are:

Single Answer MCQ
Q-00206689
View explanation
Q180

Study the given table and answer: Parents: A pea plant with red flowers was crossed with a pea plant with white flowers. F1: 30 seeds were sown and all bore plants with red flowers. F2: 44 seeds were sown, 33 plants bore red flowers and 11 plants bore white flowers. Depict the information given in the table in the form of a cross.

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Q-00206699
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Q181

Study the given table and answer: Deduce the F2 phenotypic ratio/F2 ratio showing external look as well as genotypic/genetic makeup ratio.

Text
Q-00206700
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Q182

Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds were crossed with each other which produced F1 progeny that have only round yellow (RrYy) seeds. When F1 plants are self-pollinated, the F2 progeny will have which new combination of characters, as compared to the parents: (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green Correct options are:

Single Answer MCQ
Q-00206776
View explanation
Q183

Assertion (A): Variations are not often seen in off-springs produced by asexual reproduction. Reason (R): DNA molecule generated by replication is not similar to the original DNA.

Single Answer MCQ
Q-00206779
View explanation
Q184

What is the probability of obtaining tall plants with white flowers in F2 progeny?

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Q-00206783
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Q185

Use the following information for Pea plants: Dominant allele for tall plants – T; Recessive allele for short plants – t; Dominant allele for purple flowers – P; Recessive allele for white flowers – p. Perform a cross between pure plant dominant for both the traits with another plant which is recessive for both the traits and work out the progeny upto F2 generation.

Text
Q-00206785
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Q186

When a human egg is fertilized by a sperm having ‘Y’ chromosome, the zygote has the following combination of chromosomes:

Single Answer MCQ
Q-00206855
View explanation
Q187

Assertion (A): Bacteria that can withstand heat have better chances of survival in a heat wave. Reason (R): Accumulation of variations in a species increases the chances of its survival in changing environment.

Single Answer MCQ
Q-00206858
View explanation
Q188

Based on Mendel’s experiment show the cross between round, yellow seeds of pea plant (RRYY) with wrinkled and green seeds of pea plant (rryy) upto F2 generation. Write the number of seeds/plants with following genetic (Genotype) makeup in F2 generation: (i) RRYY (ii) rryy

Text
Q-00206864
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Q189

The number of chromosomes in parents and offspring of a particular species undergoing sexual reproduction remains constant due to:

Single Answer MCQ
Q-00206919
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Q190

A blue colour flower (BB) bearing plant is crossed with a plant with white coloured flowers (bb). State the colour of the flowers expected in the F1 progeny.

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Q-00206925
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Q191

If the F1 plants are self-pollinated, what must be the percentage of white flower plants in the F2 generation?

Text
Q-00206927
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Q192

State the expected ratio of genotypes BB and bb in F2 progeny.

Text
Q-00206928
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Q193

When a human egg is fertilized by a sperm having ‘Y’ chromosome, the zygote has the following combination of chromosomes:

Single Answer MCQ
Q-00206979
View explanation
Q194

When a human egg is fertilized by a sperm having Y chromosome, the zygote has the following combination of chromosomes.

Single Answer MCQ
Q-00207071
View explanation
Q195

Assertion (A): Bacteria that can withstand heat have better chances of survival in a heat wave. Reason (R): Accumulation of variations in a species increases the chances of its survival in changing environment.

Single Answer MCQ
Q-00207073
View explanation
Q196

Show a cross between a pea plant having round and green seed with a pea plant having wrinkled and yellow seeds up to F2 generation.

Text
Q-00207083
View explanation
Q197

Write down the results of F2 generation.

Text
Q-00207084
View explanation
Q198

A cross made between two pea plants produces 50% tall and 50% short pea plants. The gene combination of the parental pea plants must be:

Single Answer MCQ
Q-00209013
View explanation

Heredity Practice Worksheets

Download and practice Heredity worksheets to improve problem-solving accuracy and speed for CBSE Class 10 Science exams.

Heredity - Practice Worksheet

This worksheet covers essential long-answer questions to help you build confidence in Heredity from Science for Class X (Science).

Practice

Questions

1

Explain the concept of heredity and its significance in the continuity of life.

Heredity refers to the passing of traits from parents to offspring through genes. It ensures the continuity of life by transmitting genetic information that determines the physical and biological characteristics of organisms. Genes, which are segments of DNA, carry instructions for the synthesis of proteins that influence traits. For example, in humans, traits like eye color, hair texture, and height are inherited. The process of heredity is crucial for the survival of species as it allows for the transmission of advantageous traits that can help organisms adapt to their environment. Variations arising from heredity contribute to biodiversity and the evolution of species. Mendel's experiments with pea plants laid the foundation for understanding heredity, showing how traits are inherited in predictable patterns. Heredity also plays a role in medicine, helping in the understanding of genetic disorders and their inheritance patterns. Thus, heredity is fundamental to the study of biology and the understanding of life's continuity.

2

Describe Mendel's experiments with pea plants and how they contributed to the understanding of heredity.

Gregor Mendel, known as the father of genetics, conducted experiments with pea plants to study heredity. He chose pea plants because they have easily distinguishable traits and can self-pollinate. Mendel cross-pollinated pea plants with contrasting traits, such as tall and short plants, and observed the traits in the offspring. He found that the first generation (F1) exhibited only one of the parental traits, which he called the dominant trait. The recessive trait reappeared in the second generation (F2) in a 3:1 ratio. This led Mendel to propose the laws of inheritance: the Law of Segregation and the Law of Independent Assortment. The Law of Segregation states that alleles separate during gamete formation, and the Law of Independent Assortment states that alleles for different traits are inherited independently. Mendel's work was groundbreaking because it provided a mathematical basis for heredity, showing that traits are inherited in discrete units (genes). His experiments laid the foundation for modern genetics and our understanding of how traits are passed from parents to offspring.

3

What are dominant and recessive traits? Give examples from Mendel's experiments.

Dominant traits are those that are expressed in the phenotype even if only one copy of the gene is present. Recessive traits are expressed only when two copies of the gene are present. In Mendel's experiments, the tall trait in pea plants was dominant, while the short trait was recessive. When Mendel crossed purebred tall plants (TT) with purebred short plants (tt), all F1 offspring were tall (Tt), showing the dominance of the tall trait. In the F2 generation, the recessive short trait reappeared in a 1:3 ratio. Another example is the flower color in pea plants: violet flowers (dominant) and white flowers (recessive). When purebred violet-flowered plants were crossed with purebred white-flowered plants, all F1 offspring had violet flowers. In the F2 generation, white flowers reappeared. These examples illustrate how dominant traits mask recessive traits in heterozygous individuals. Understanding dominant and recessive traits is essential for predicting the inheritance patterns of genetic disorders and breeding plants and animals.

4

How do variations arise during reproduction and why are they important for species?

Variations arise during reproduction due to genetic recombination, mutations, and environmental factors. In sexual reproduction, variations result from the shuffling of genes during meiosis and fertilization, leading to unique combinations of traits in offspring. Mutations, which are changes in DNA, can also introduce new variations. Environmental factors, such as radiation and chemicals, can induce mutations. Variations are crucial for the survival and evolution of species because they provide the raw material for natural selection. For example, in a changing environment, individuals with advantageous variations are more likely to survive and reproduce, passing those traits to future generations. This process leads to adaptation and speciation. Variations also contribute to biodiversity, ensuring that species can withstand diseases and environmental changes. Without variations, species would be more vulnerable to extinction. Thus, variations play a vital role in the continuity and evolution of life.

5

Explain the mechanism of sex determination in human beings.

In humans, sex determination is genetic and depends on the sex chromosomes inherited from the parents. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). During reproduction, females produce eggs with an X chromosome, while males produce sperm with either an X or a Y chromosome. If a sperm carrying an X chromosome fertilizes the egg, the resulting zygote will be XX (female). If a sperm carrying a Y chromosome fertilizes the egg, the zygote will be XY (male). Thus, the father's sperm determines the sex of the child. The Y chromosome contains the SRY gene, which triggers the development of male characteristics. In the absence of the Y chromosome, female characteristics develop. This mechanism ensures a roughly equal ratio of males and females in the population. Understanding sex determination is important for studying genetic disorders linked to sex chromosomes, such as color blindness and hemophilia.

6

What is the difference between genotype and phenotype? Provide examples.

Genotype refers to the genetic makeup of an organism, representing the alleles it carries for a particular trait. Phenotype refers to the observable characteristics or traits of an organism, resulting from the interaction of its genotype with the environment. For example, in pea plants, the genotype for tallness can be TT (homozygous dominant) or Tt (heterozygous), both resulting in the tall phenotype. The genotype tt (homozygous recessive) results in the short phenotype. Another example is human blood groups: the genotype IAIA or IAi results in blood group A (phenotype), while ii results in blood group O. The phenotype can also be influenced by environmental factors, such as nutrition affecting height. Understanding the difference between genotype and phenotype is essential for studying inheritance patterns and predicting the outcomes of genetic crosses. It also helps in understanding how traits are expressed and how they can vary within a population.

7

How do Mendel's laws of inheritance explain the inheritance of traits?

Mendel's laws of inheritance explain how traits are passed from parents to offspring. The Law of Segregation states that alleles for a trait separate during gamete formation, so each gamete carries only one allele for each trait. This explains why recessive traits can reappear in later generations. The Law of Independent Assortment states that alleles for different traits are inherited independently of each other, leading to new combinations of traits in offspring. For example, in pea plants, the inheritance of seed shape (round or wrinkled) is independent of seed color (yellow or green). These laws are based on Mendel's experiments with pea plants, where he observed predictable ratios of traits in offspring. The laws apply to sexually reproducing organisms and provide the foundation for understanding genetic inheritance. They help predict the probability of traits appearing in offspring and explain the diversity of traits in populations. Mendel's laws are fundamental to genetics and are used in breeding programs and genetic counseling.

8

What is the role of chromosomes in heredity?

Chromosomes play a crucial role in heredity by carrying genetic information in the form of DNA. Each chromosome contains many genes, which are segments of DNA that code for proteins. During reproduction, chromosomes are passed from parents to offspring, ensuring the transmission of genetic traits. In sexually reproducing organisms, chromosomes come in pairs, with one set inherited from each parent. For example, humans have 23 pairs of chromosomes, including one pair of sex chromosomes (XX or XY). During meiosis, chromosomes are shuffled and recombined, creating genetic variation in gametes. Fertilization restores the diploid number of chromosomes in the zygote. Chromosomes also ensure the stability of genetic information by accurately replicating and segregating during cell division. Mutations in chromosomes can lead to genetic disorders or variations. Thus, chromosomes are essential for the inheritance of traits and the continuity of genetic information across generations.

9

Explain how traits are expressed in organisms.

Traits are expressed in organisms through the interaction of genes and the environment. Genes provide the instructions for making proteins, which influence traits. For example, the gene for eye color codes for proteins that determine pigment production. The expression of traits depends on whether the alleles are dominant or recessive. Dominant alleles are expressed even if only one copy is present, while recessive alleles require two copies for expression. Environmental factors, such as nutrition and sunlight, can also affect trait expression. For instance, height is influenced by both genetic factors and nutrition. The process of gene expression involves transcription and translation, where DNA is converted into RNA and then into proteins. Proteins perform various functions that result in observable traits. Understanding trait expression is important for studying inheritance patterns, genetic disorders, and the development of organisms. It also helps in biotechnology, where genes can be manipulated to produce desired traits.

10

How does sexual reproduction contribute to genetic variation?

Sexual reproduction contributes to genetic variation through several mechanisms. During meiosis, homologous chromosomes exchange segments in a process called crossing over, creating new combinations of alleles. Independent assortment of chromosomes during meiosis results in gametes with unique combinations of genes. Fertilization combines genetic material from two parents, further increasing variation. For example, in humans, each parent can produce 2^23 different gametes, leading to immense genetic diversity in offspring. Sexual reproduction also allows for the recombination of beneficial mutations, enhancing adaptability. Variations provide the raw material for natural selection, enabling species to evolve and survive in changing environments. Without sexual reproduction, populations would have less genetic diversity, making them more susceptible to diseases and environmental changes. Thus, sexual reproduction is a key driver of genetic variation and evolution, ensuring the survival and diversity of species.

Heredity - Mastery Worksheet

This worksheet challenges you with deeper, multi-concept long-answer questions from Heredity to prepare for higher-weightage questions in Class X Science.

Mastery

Questions

1

Explain how variations are created and inherited during reproduction, with examples from both asexual and sexual reproduction.

Variations are created during reproduction through mechanisms like DNA copying errors in asexual reproduction and the combination of genetic material from two parents in sexual reproduction. In asexual reproduction, variations are minimal and arise due to small inaccuracies in DNA copying, as seen in bacteria dividing. In sexual reproduction, greater diversity is generated due to the combination of genes from both parents, leading to traits like tallness or shortness in pea plants. This diversity is crucial for the survival of species in changing environments.

2

Compare and contrast dominant and recessive traits with examples from Mendel's experiments.

Dominant traits are expressed even if only one copy of the gene is present, while recessive traits require two copies to be expressed. In Mendel's experiments, tallness (T) was dominant over shortness (t), and round seeds (R) were dominant over wrinkled seeds (r). For example, a plant with Tt genotype would be tall, showing the dominant trait, while only tt plants would be short, showing the recessive trait.

3

Describe Mendel's contributions to the understanding of heredity, including his experiments with pea plants.

Mendel contributed the foundational principles of heredity through his experiments with pea plants. He demonstrated that traits are inherited as discrete units (now known as genes) and introduced the concepts of dominant and recessive traits. By crossing tall and short pea plants, he observed that the first generation (F1) was all tall, showing dominance. The second generation (F2) showed a 3:1 ratio of tall to short plants, illustrating the segregation of alleles.

4

How do traits get expressed at the molecular level? Discuss the role of genes and proteins in trait expression.

Traits are expressed through the synthesis of proteins, which are coded by genes. For example, the gene for plant height may code for an enzyme involved in hormone production. Efficient enzyme activity leads to more hormone production, resulting in a tall plant. If the gene has a mutation making the enzyme less efficient, less hormone is produced, leading to a short plant. Thus, genes control traits by determining the type and efficiency of proteins synthesized.

5

Explain the concept of independent inheritance with reference to Mendel's dihybrid cross experiment.

Independent inheritance refers to the separate inheritance of two different traits, as demonstrated in Mendel's dihybrid cross. When Mendel crossed pea plants with round yellow seeds (RRYY) and wrinkled green seeds (rryy), the F1 generation all had round yellow seeds (RrYy). The F2 generation showed a 9:3:3:1 ratio, indicating that seed shape and color are inherited independently, leading to new combinations like round green and wrinkled yellow seeds.

6

Discuss how the sex of a child is determined in human beings, including the role of sex chromosomes.

In humans, sex is determined by the sex chromosomes inherited from the parents. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The mother always contributes an X chromosome, while the father can contribute either an X or a Y. If the sperm carrying an X chromosome fertilizes the egg, the child will be female (XX). If the sperm carries a Y chromosome, the child will be male (XY).

7

Analyze the significance of variations in the survival of species, providing examples.

Variations are crucial for the survival of species as they enable adaptation to changing environments. For example, bacteria with heat-resistant variations survive better during heat waves. Similarly, in peppered moths, dark-colored variants became more common in polluted areas as they were better camouflaged against predators. Such adaptations ensure the survival and reproduction of individuals with beneficial traits, driving evolutionary processes.

8

Compare the inheritance patterns in sexually and asexually reproducing organisms.

In sexually reproducing organisms, offspring inherit genetic material from both parents, leading to greater genetic diversity. Traits are inherited according to Mendelian principles, with dominant and recessive alleles. In asexually reproducing organisms, offspring are genetically identical to the parent, with variations arising only from mutations during DNA replication. This results in less genetic diversity compared to sexual reproduction.

9

Explain the concept of a 'test cross' and its importance in genetics.

A test cross is used to determine the genotype of an individual showing a dominant trait by crossing it with a homozygous recessive individual. If all offspring show the dominant trait, the individual is homozygous dominant. If some offspring show the recessive trait, the individual is heterozygous. This is important for understanding inheritance patterns and predicting the genotypes of future generations.

10

Discuss common misconceptions about heredity and how Mendel's experiments helped clarify them.

A common misconception is that traits blend in offspring, but Mendel's experiments showed that traits are inherited as discrete units. Another misconception is that all traits are equally likely to be expressed, but Mendel demonstrated dominant and recessive traits. His work clarified that traits segregate independently and are not blended, laying the foundation for modern genetics.

Heredity - Challenge Worksheet

The final worksheet presents challenging long-answer questions that test your depth of understanding and exam-readiness for Heredity in Class X.

Challenge

Questions

1

Evaluate the implications of Mendel's laws of inheritance in predicting the traits of offspring in a dihybrid cross.

Mendel's laws, including the Law of Segregation and the Law of Independent Assortment, predict that traits are inherited independently and that each parent contributes one allele for each trait. In a dihybrid cross, these laws explain the 9:3:3:1 phenotypic ratio observed in the F2 generation, demonstrating how traits are inherited separately. Examples include the inheritance of seed shape and color in peas. Counterpoints might consider linkage, where genes close together on a chromosome may not assort independently.

2

Analyze how environmental factors can influence the expression of genetic traits, using examples from the chapter.

Environmental factors can influence gene expression, such as temperature determining sex in some reptiles or sunlight affecting plant growth. This shows that while genes provide the blueprint, the environment can modify how these genes are expressed. For instance, identical genetic makeup can result in different phenotypes under varying environmental conditions, highlighting the concept of phenotypic plasticity.

3

Discuss the significance of genetic variation in the survival of species, with reference to Darwin's theory of natural selection.

Genetic variation is crucial for the survival of species as it provides the raw material for natural selection. Variations that confer advantages in a specific environment increase an organism's chances of survival and reproduction. Over time, these advantageous traits become more common in the population. Examples include antibiotic resistance in bacteria or camouflage in moths. Counterpoints might discuss scenarios where high variation does not guarantee survival if changes in the environment are too rapid.

4

Explain the mechanism of sex determination in humans and compare it with another species where sex determination is environmentally influenced.

In humans, sex is genetically determined by the inheritance of X or Y chromosomes from the father, leading to XX (female) or XY (male) offspring. In contrast, some reptiles like turtles have temperature-dependent sex determination, where the incubation temperature of eggs influences the sex of the offspring. This comparison highlights the diversity in sex determination mechanisms across species and the role of genetics versus environment in development.

5

Critically assess the statement 'All mutations are harmful' using examples from genetic studies.

While many mutations can be harmful, leading to diseases or disorders, some are neutral or even beneficial. Beneficial mutations can provide advantages such as resistance to diseases (e.g., sickle cell anemia offering malaria resistance) or adaptation to new environments. This demonstrates the dual nature of mutations in evolution, serving as a source of genetic diversity essential for natural selection.

6

Explore the ethical dilemmas posed by genetic engineering in humans, referencing the principles of heredity.

Genetic engineering offers potential benefits like curing genetic diseases but raises ethical concerns such as designer babies, genetic discrimination, and unintended consequences on genetic diversity. The principles of heredity remind us that changes made to the germ line would be passed to future generations, making the stakes of such interventions particularly high. Balancing innovation with ethical considerations is crucial.

7

Compare and contrast the inheritance patterns of autosomal dominant and recessive traits, providing examples of each.

Autosomal dominant traits require only one copy of the allele to be expressed (e.g., Huntington's disease), while recessive traits require two copies (e.g., cystic fibrosis). Dominant traits often appear in every generation, whereas recessive traits can skip generations and appear when both parents are carriers. This distinction is crucial for genetic counseling and understanding disease transmission.

8

Investigate the role of chromosomes in inheritance, explaining how chromosomal abnormalities can lead to genetic disorders.

Chromosomes carry genetic information in the form of genes. Abnormalities, such as nondisjunction during meiosis, can lead to disorders like Down syndrome (trisomy 21) or Turner syndrome (monosomy X). These conditions illustrate the importance of precise chromosome segregation for normal development and how errors can have significant phenotypic consequences.

9

Debate the potential impacts of cloning on genetic diversity, using principles of heredity and evolution.

Cloning creates genetically identical organisms, potentially reducing genetic diversity, which is vital for species' adaptability and survival. While cloning can preserve desirable traits, it may also increase vulnerability to diseases and environmental changes. This tension highlights the importance of genetic diversity for evolutionary resilience and the risks of over-reliance on cloning.

10

Construct a scenario where a new trait emerges in a population due to a mutation, and predict its spread under different environmental conditions.

A mutation conferring drought resistance in plants could arise in a population. In arid conditions, this trait would likely spread rapidly as resistant plants survive and reproduce more effectively. In contrast, in wet environments, the trait might offer no advantage or even a disadvantage, limiting its spread. This scenario demonstrates how environmental pressures shape the distribution of genetic traits within populations.

Heredity Formula Sheet

Use this Class 10 Science Heredity Formula Sheet for quick revision before school exams and CBSE exams. It brings together the important formulas, key concepts, and worked examples in one place so students can revise faster and download a printable PDF for offline study.

Important Formulas

1

F1 Generation: TT (Tall) x tt (Short) → All Tt (Tall)

TT represents homozygous tall, tt represents homozygous short, and Tt represents heterozygous tall. This shows dominance of tall trait over short.

2

F2 Generation Ratio: 1 (TT) : 2 (Tt) : 1 (tt)

This ratio demonstrates Mendelian inheritance patterns, showing 3 tall (TT or Tt) to 1 short (tt) plant.

3

Dihybrid Cross Ratio: 9:3:3:1

Represents the phenotypic ratio for two traits independently assorting, e.g., seed shape and color in peas.

4

Sex Determination: XX (Female) x XY (Male)

Females contribute an X chromosome; males contribute either X or Y, determining the offspring's sex.

5

Probability of Sex: 50% Male (XY), 50% Female (XX)

Based on the equal chance of a sperm carrying an X or Y chromosome fertilizing an X-bearing egg.

6

Gene Expression: Dominant (T) vs. Recessive (t)

Dominant traits are expressed when at least one dominant allele is present; recessive traits require two recessive alleles.

7

Phenotypic Ratio in Monohybrid Cross: 3:1

Shows the ratio of dominant to recessive phenotypes in the F2 generation.

8

Genotypic Ratio in Monohybrid Cross: 1:2:1

Represents the ratio of homozygous dominant:heterozygous:homozygous recessive genotypes in the F2 generation.

9

Law of Segregation

Alleles separate during gamete formation, ensuring each gamete carries only one allele for each gene.

10

Law of Independent Assortment

Genes for different traits are inherited independently of one another, leading to varied combinations in offspring.

Worked Examples

1

Punnett Square for Monohybrid Cross

A grid used to predict the genotype and phenotype combinations of offspring from parental alleles.

2

Punnett Square for Dihybrid Cross

Extends the monohybrid concept to two traits, predicting more complex inheritance patterns.

3

Blood Group Inheritance: IA, IB, i

IA and IB are codominant; i is recessive. Determines blood groups A, B, AB, or O.

4

Chromosome Pairing: 22 Autosomes + 1 Sex Chromosome Pair

Humans have 23 chromosome pairs, with sex determined by the 23rd pair (XX or XY).

5

Mutation Rate and Variation

Mutations during DNA copying introduce variations, some of which may be inherited.

6

Environmental Influence on Traits

Some traits are influenced by both genetic and environmental factors, e.g., height and nutrition.

7

Genetic Diversity Calculation

Diversity increases with the number of gene combinations possible through sexual reproduction.

8

Homozygous vs. Heterozygous

Homozygous individuals have identical alleles (TT or tt); heterozygous have different alleles (Tt).

9

Pedigree Analysis Symbols

Standard symbols represent males, females, affected individuals, and carriers in genetic diagrams.

10

Test Cross: Tt x tt

Used to determine the genotype of a dominant phenotype individual by crossing with a homozygous recessive.

Explore More Heredity Resources

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Heredity Frequently Asked Questions

Learn about heredity in this comprehensive chapter, covering the principles of genetic inheritance, variations, and the role of Gregor Mendel's experiments in understanding traits.

Heredity primarily involves the transmission of genetic information from parents to offspring through reproduction. This can occur via asexual reproduction, where an organism replicates itself, or sexual reproduction, where genetic material from two parents combines, resulting in offspring with varied traits due to genetic recombination.
Variations arise during reproduction through processes like DNA mutation during replication and genetic recombination in sexual reproduction. These processes can introduce new traits, allowing populations to adapt to changing environments and leading to evolutionary change over generations.
Gregor Mendel is known as the father of modern genetics. He conducted experiments with pea plants to study inheritance patterns. His work led to the discovery of the concepts of dominant and recessive traits and established the foundational laws of inheritance, which describe how traits are passed from parents to offspring.
Dominant traits are those that are expressed in the phenotype even if only one copy of the gene is present. Recessive traits require two copies of the gene for expression. For example, in Mendel's experiments, the tall plant trait was dominant, while the short plant trait was recessive.
Traits are inherited via genes, which are segments of DNA. Each parent contributes one allele for each gene, resulting in two alleles per trait in the offspring. The combination of these alleles determines the expression of the trait, be it dominant or recessive.
Genetic variation is crucial as it allows populations to adapt to environmental changes. Variants can confer advantages, such as resistance to diseases or adaptation to new habitats, increasing the likelihood of survival and reproduction in changing conditions.
Sexual reproduction increases genetic diversity by combining genetic material from two parents. This mixing of alleles creates unique genetic combinations in offspring, enhancing the adaptability and survival of the population in varying environments.
Inherited traits are characteristics or attributes that are passed down from parents to offspring through genes. These traits can include physical attributes like eye color, height, and even certain behaviors, influenced by the genetic makeup provided by both parents.
Environmental factors can affect genetic expression, leading to variations in traits even among individuals with the same genetic makeup. For example, temperature can influence the development of traits like fur color in some animals.
Genotype refers to the genetic composition of an organism, including all alleles inherited. Phenotype is the visible or expressed traits of an individual, which result from the interaction of the genotype with the environment.
Yes, traits can skip generations if they are recessive. An offspring may inherit a recessive trait from parents who are carriers, but if the dominant trait is expressed in that generation, the trait may not appear until future descendants inherit two copies of the recessive allele.
Mendel conducted a series of cross-breeding experiments with pea plants, analyzing traits such as seed shape and flower color. He documented the ratios of different traits in the offspring, leading to his formulation of the laws of independent assortment and segregation.
To determine if a trait is dominant, one can observe its expression in offspring when crossing individuals. If the trait appears even when only one parent carries the allele, it is likely dominant. Observing inheritance patterns over generations helps confirm this.
Mendel's law of segregation states that during the formation of gametes, the two alleles for a trait segregate from each other, ensuring that each gamete carries only one allele. This principle is fundamental to understanding genetic inheritance.
Meiosis is the process of cell division that results in gametes with half the number of chromosomes. This process introduces genetic variability through crossing over and independent assortment, where chromosomes are randomly sorted into gametes, creating diverse genetic combinations.
Studying heredity is vital for understanding evolution, genetic disorders, and biodiversity. It provides insights into how traits are passed down and evolve over time, informing agriculture, medicine, and conservation efforts.
Heredity provides the mechanism for passing genetic information to offspring, which is essential for evolution. Variation in traits due to heredity affects an organism's fitness, influencing natural selection and species adaptation over generations.
Traits that enhance an organism's ability to adapt to its environment can improve its fitness, defined as its ability to survive and reproduce. Beneficial traits may be favored by natural selection, becoming more prevalent in the population over time.
A genetic marker is a specific DNA sequence with a known location on a chromosome that can be used to identify individuals or species. They are crucial for tracking inheritance patterns and studying genetic diseases.
Sex-linked traits are associated with genes located on sex chromosomes. In humans, males with only one X chromosome will express any recessive traits present, whereas females, with two X chromosomes, require both to express a recessive trait, leading to differences in expression between genders.
Activities such as observing earlobe shapes among peers, analyzing family tree traits, and conducting simple breeding experiments with plants can effectively illustrate the principles of heredity and inheritance in a hands-on manner.
Challenges in genetic inheritance include the expression of undesirable recessive traits, genetic disorders, and the effects of mutations. These factors can lead to health issues and affect gene pools, impacting population survival.
Phenotypic variation refers to the observable differences in traits among individuals within a population. This variation may arise from genetic differences, environmental influences, or a combination of both, contributing to diversity within species.

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Heredity Flashcards

Revise key terms and definitions from Heredity with interactive flashcards. Quick recall practice for CBSE Class 10 Science.

These flash cards cover important concepts from Heredity in Science for Class 10 (Science).

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What is heredity?

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Heredity is the process by which traits and characteristics are passed from parents to offspring through genes.

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2/19

What are Mendelian traits?

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Mendelian traits are characteristics that are determined by single genes, following the laws of inheritance established by Gregor Mendel.

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3/19

What is the difference between dominant and recessive traits?

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Dominant traits are expressed when at least one dominant allele is present, while recessive traits require two recessive alleles to be expressed.

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4/19

What does the law of segregation state?

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The law of segregation states that during gamete formation, the two alleles for a trait separate, so each gamete receives only one allele.

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What is the difference between phenotype and genotype?

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Phenotype is the observable traits of an organism, while genotype is the genetic makeup that determines those traits.

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Give an example of genetic variation.

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An example of genetic variation is the different earlobe types in humans, such as free or attached earlobes.

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What is the difference between homozygous and heterozygous?

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Homozygous means having two identical alleles for a trait, while heterozygous means having two different alleles for that trait.

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What is a Punnett square used for?

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A Punnett square is used to predict the genotypes and phenotypes of offspring from a genetic cross.

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What is the role of meiosis in heredity?

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Meiosis is the process that produces gametes with half the number of chromosomes, maintaining the chromosome number across generations during reproduction.

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What is a gene?

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A gene is a segment of DNA that contains the instructions for making a specific protein, which in turn influences a trait.

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What are chromosomes?

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Chromosomes are structures made of DNA that carry genetic information. Humans have 23 pairs, with one pair being the sex chromosomes.

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How is sex determined in humans?

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In humans, sex is determined by the presence of X and Y chromosomes; females are XX and males are XY.

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What are vestigial structures?

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Vestigial structures are remnants of organs or structures that had a function in early ancestors but are largely reduced or unused in modern species.

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What is natural selection?

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Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring.

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What is a characteristic of asexual reproduction?

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Asexual reproduction produces offspring that are genetically identical to the parent, with very little genetic variation.

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What is genetic drift?

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Genetic drift is a change in the frequency of a gene variant (allele) in a population due to random sampling of organisms.

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How do environmental factors influence evolution?

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Environmental factors can select for or against certain traits, leading to changes in the population over generations.

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What is a genetic carrier?

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A genetic carrier is an individual who has one copy of a recessive allele that does not manifest in their phenotype but can be passed on to offspring.

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What is hybridization?

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Hybridization is the process of crossing different species or varieties to produce offspring with desired traits.

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