Inheritance is one of the most important and fascinating topics in Biology. It explains how characteristics are passed from parents to their offspring and why members of the same family often resemble each other. This chapter begins with an introduction to Genetics, the branch of biology that studies heredity and variation.
Students will learn about chromosomes and genes, the basic units of inheritance that control traits in living organisms. The foundation of modern genetics was laid by Gregor Mendel, whose experiments led to the formulation of Mendel’s Laws of Inheritance, which explain how traits are transmitted from one generation to the next.
The chapter also covers important concepts such as co-dominance and incomplete dominance, which show that inheritance is not always a simple dominant–recessive pattern. In addition, students will explore variations and evolution, understanding how genetic differences lead to diversity among organisms and contribute to the evolutionary process.
Important MCQs – Chapter 15 Inheritance
1. The branch of biology that deals with the study of inheritance is:
(a) Cytology
(b) Genetics ✅
(c) Anatomy
(d) Embryology
2. Inheritance is the transmission of ________ from parents to offspring.
(a) Hormones
(b) Traits ✅
(c) Energy
(d) Blood
3. Each human body cell contains how many chromosomes in total?
(a) 44
(b) 23
(c) 46 ✅
(d) 48
4. The number of homologous chromosome pairs in humans is:
(a) 46
(b) 22
(c) 24
(d) 23 ✅
5. Which one of the following was not a reason for Mendel choosing the pea plant?
(a) It had contrasting traits
(b) It had a long life cycle ✅
(c) It allowed self-pollination
(d) It allowed cross-pollination
6. Who proposed the Theory of Natural Selection?
(a) Mendel
(b) Watson
(c) Darwin ✅
(d) Lamarck
Short Questions – Chapter 15
1. Define genotype and phenotype.
Answer:
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Genotype is the specific combination of genes (alleles) present in an organism.
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Example: AA, Aa, or aa
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Phenotype is the observable trait or physical appearance shown by the organism due to its genotype.
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Example: Tall plant, albino, or normal pigment
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Explanation for Students:
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Genotype represents the genetic makeup which may or may not be visible.
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Phenotype represents the physical expression of the genotype that we can see or measure.
Example: A plant with genotype Aa may show the tall phenotype if “A” is dominant
2. What is meant by inheritance?
Answer:
Inheritance means the transfer of traits from parents to their offspring through genes.
Explanation:
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Traits like eye color, height, hair type are passed from parents to children through genes.
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This process ensures the continuation of species and explains why children often resemble their parents.
3. What is the Watson-Crick model of DNA?
Answer:
According to the Watson-Crick model, DNA is a double helix made of two strands with a sugar-phosphate backbone and nitrogenous base pairs:
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Adenine (A) – Thymine (T)
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Cytosine (C) – Guanine (G)
Explanation:
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The two strands are complementary and twist around each other forming a helical structure.
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The base pairing (A-T and C-G) ensures accurate replication of DNA during cell division.
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This model helps explain how genetic information is stored and transmitted in living organisms.
4. What are the outcomes of artificial selection in agriculture?
Answer:
Artificial selection in agriculture has led to:
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Improved breeds of animals such as cows, hens, and sheep
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Better plant varieties for fruits, vegetables, and cereals
Explanation:
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Farmers select desirable traits in plants and animals to produce high-yielding, disease-resistant, and nutritious varieties.
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This process ensures better productivity and meets the growing food demands of humans.
Example: Selecting cows that give more milk, or wheat varieties that are resistant to drought.
Long Questions – Chapter 15
Q1: What are Mendel’s Laws of Inheritance? Explain his experiments and importance in genetics.
Introduction:
Mendel’s Laws of Inheritance form the foundation of classical genetics. Gregor Mendel, an Austrian monk, studied how traits are passed from parents to offspring through controlled experiments on pea plants. His work helped scientists understand the patterns of inheritance.
Mendel’s Key Contributions:
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Studied traits like flower color, plant height, seed shape, and seed color
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Proposed that “factors” (now called genes) control traits
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Conducted experiments on over 28,000 pea plants (Pisum sativum)
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Laid the basic principles of inheritance still used today
Why Mendel Chose Pea Plants:
Mendel selected pea plants because:
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They had distinct and easily observable traits (e.g., tall/dwarf, round/wrinkled)
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They could self-pollinate or be cross-pollinated
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They had a short life cycle, giving faster experimental results
Methodology of Mendel’s Experiments:
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Conducted monohybrid crosses (single trait) and dihybrid crosses (two traits)
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Started with true-breeding plants to ensure consistent results
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Carefully recorded and analyzed results statistically
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Formulated laws of inheritance based on observed patterns
Importance of Mendel’s Work:
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First to explain inheritance in predictable, mathematical patterns
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Introduced the concept of dominant and recessive traits
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Laid the foundation for modern genetics
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Provided tools to predict traits in future generations
Summary:
Mendel’s experiments with pea plants became the cornerstone of genetics. His laws of inheritance explain how traits pass from parents to offspring, and his discoveries are still essential for studying genetics today.
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