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Chapter Analysis
Intermediate8 pages • EnglishQuick Summary
The chapter on heredity in Class 10 Science explores the mechanisms of inheritance and variation, highlighting how traits are transmitted from parents to offspring. It discusses Mendelian genetics, explaining how dominant and recessive traits are expressed. Concepts such as sex determination and the role of chromosomes in passing genetic information are also covered. The chapter provides insight into the significance of genetic variations in evolution and survival.
Key Topics
- •Mendelian genetics
- •Dominant and recessive traits
- •Sex determination
- •Chromosome functions
- •Genetic variation
- •Inheritance patterns
- •Role of DNA in heredity
Learning Objectives
- ✓Understand the basic principles of Mendelian genetics
- ✓Describe how traits are inherited and expressed
- ✓Explain the concept of dominance and recessiveness
- ✓Understand the process of sex determination in humans
- ✓Explore the role of genetic variation in evolution
- ✓Identify different patterns of inheritance
Questions in Chapter
How do Mendel’s experiments show that traits may be dominant or recessive?
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How do Mendel’s experiments show that traits are inherited independently?
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A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
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How is the sex of the child determined in human beings?
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A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
Answer: (d) TtWw
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A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
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Outline a project which aims to find the dominant coat colour in dogs.
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How is the equal genetic contribution of male and female parents ensured in the progeny?
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Additional Practice Questions
Explain the concept of genetic variability and its importance in evolution.
mediumAnswer: Genetic variability refers to the differences in DNA sequences among individuals within a population. It is important for evolution as it provides the raw material for natural selection, allowing populations to adapt to changing environments and survive different challenges.
How do environmental factors influence the expression of traits?
mediumAnswer: Environmental factors can affect the expression of traits by influencing gene activity. For example, the temperature can affect the coloration of fur in some animals or the sex determination in reptiles. These interactions can significantly impact an organism's phenotype.
Describe the process of meiosis and its role in heredity.
hardAnswer: Meiosis is the process of cell division that reduces the chromosome number by half, producing four genetically different haploid cells. It ensures genetic diversity through independent assortment and crossing over, playing a crucial role in heredity by passing down unique genetic variations to the offspring.
What evidence supports the chromosomal theory of inheritance?
mediumAnswer: The chromosomal theory of inheritance is supported by evidence such as the observation that chromosomes behave in ways consistent with Mendel's laws of inheritance, as seen under the microscope during cell division, and the correlation between genetic traits and chromosomal locations discovered through experiments like fruit fly linkage studies.
How do genetic mutations affect an organism? Provide examples.
mediumAnswer: Genetic mutations can have various effects ranging from neutral to harmful or even beneficial changes. For example, a mutation might cause a disease like cystic fibrosis, confer a survival advantage like antibiotic resistance in bacteria, or result in neutral variation like different eye colors in humans.
NCERT Exemplar
AvailablePractice with NCERT Exemplar problems and solutions for this chapter. Exemplar problems are designed to help you master the concepts with advanced-level questions.
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