Class 10 Biology Worksheet Heredity and Evolution

Biology is a fascinating subject that explains how life works, and in Class 10, one of the most interesting topics you study is “Heredity and Evolution.” This topic helps us understand how traits are passed from one generation to another and how living organisms have evolved over millions of years. Let us explore the key concepts in this chapter and create a helpful worksheet to reinforce your learning.

What is Heredity?

Heredity is the process through which parents pass traits to their offspring. For example, you might have inherited your eye color, hair type, or even certain habits from your parents. The study of heredity is called genetics.

Key Terms in Heredity:

1. Gene: A unit of inheritance found in chromosomes. It carries information about a specific trait.
2. DNA (Deoxyribonucleic Acid): The molecule that contains genetic information.
3. Chromosome: A thread-like structure in the nucleus that contains DNA.
4. Allele: Different forms of the same gene. For example, the gene for eye color might have alleles for brown, blue, or green eyes.

Example Question:

1. What is the role of DNA in heredity?

Laws of Inheritance

Gregor Mendel, known as the “Father of Genetics,” discovered the basic principles of heredity. He conducted experiments with pea plants to explain how traits are inherited.

Mendel’s Laws

1. Law of Dominance: Some traits (dominant) can mask others (recessive).
2. Law of Segregation: During reproduction, alleles separate, and each offspring gets one allele from each parent.
3. Law of Independent Assortment: Traits are inherited independently of each other.

Example Question: 2. Define Mendel’s Law of Segregation and explain it with an example.

What is Evolution?

Evolution is the process through which species change over time. It explains the diversity of life on Earth. Charles Darwin’s theory of natural selection is the most widely accepted explanation of evolution.

Key Concepts in Evolution:

1. Natural Selection: Organisms that are better adapted to their environment survive and reproduce.
2. Speciation: The formation of new species due to evolution.
3. Fossils: Remains or impressions of ancient organisms that help us study evolution.
4. Homologous and Analogous Organs:

• • Homologous organs have a similar structure but different functions (e.g., human arm and bat wing).
  • Analogous organs have different structures but similar functions (e.g., wings of a bird and wings of an insect).

Example Question: 3. What is natural selection? Give an example.

Differences Between Heredity and Evolution

Example Question: 4. List two differences between heredity and evolution.

Worksheet for Class 10 Heredity and Evolution

Use this worksheet to test your understanding of the chapter.

Section A: Fill in the Blanks

1. The basic unit of inheritance is the _______.
2. Traits that mask other traits are called _______ traits.
3. _______ is the molecule that carries genetic information.
4. The theory of evolution by natural selection was proposed by _______.

Section B: Match the Following

Section C: Short Answer Questions

1. What are homologous and analogous organs? Give examples of each.
2. Explain speciation with an example.
3. Why are fossils important in understanding evolution?

Section D: Long Answer Questions

1. Describe Mendel’s experiments with pea plants. What conclusions did he draw?
2. Explain how natural selection leads to the evolution of species. Use an example to support your answer.
3. Discuss the importance of genetic variation in evolution.

Section E: True or False

1. Natural selection is the process by which organisms best adapted to their environment survive and reproduce.
2. All traits inherited from parents are dominant.
3. Fossils provide evidence for the evolution of species.
4. Analogous organs have similar structures but different functions.
5. The study of genetics began with Charles Darwin’s experiments.

Section F: Multiple Choice Questions

1. Which of the following is a dominant trait in pea plants as per Mendel’s experiments?
   a) Green seed color
   b) Wrinkled seeds
   c) Tall stem
   d) White flower
2. What are the thread-like structures in the nucleus called?
   a) Genes
   b) Chromosomes
   c) Alleles
   d) DNA
3. Which concept explains the development of a new species?
   a) Mutation
   b) Speciation
   c) Natural selection
   d) Fossilization
4. Homologous organs indicate:
   a) Common ancestry
   b) Independent evolution
   c) Similar functions
   d) None of the above
5. The study of heredity is called:
   a) Evolution
   b) Fossilology
   c) Genetics
   d) Anthropology

Section G: Diagram-Based Questions

1. Draw a Punnett square to show the inheritance of traits in a monohybrid cross between a tall pea plant (TT) and a short pea plant (tt). Mention the genotype and phenotype ratios.
2. Label the following parts on a diagram of the DNA structure: Phosphate group, Sugar, Base pair.
3. Observe a provided image of homologous organs (e.g., human arm and bat wing). Write a short note explaining their structure and function.

Section H: Assertion and Reasoning

1. Assertion (A): Fossils are important evidence of evolution.
   Reason (R): Fossils show transitional forms between species.
   • Options:
     a) Both A and R are true, and R is the correct explanation of A.
     b) Both A and R are true, but R is not the correct explanation of A.
     c) A is true, but R is false.
     d) A is false, but R is true.
2. Assertion (A): Mendel\u2019s laws apply to all living organisms.
   Reason (R): Mendel\u2019s experiments were conducted on pea plants.
   • Options:
     a) Both A and R are true, and R is the correct explanation of A.
     b) Both A and R are true, but R is not the correct explanation of A.
     c) A is true, but R is false.
     d) A is false, but R is true.

Section I: Case-Based Questions

1. A population of moths changes color from light to dark due to industrial pollution.
   Questions:
   a) Which concept of evolution does this represent?
   b) How does natural selection play a role in this example?
2. A farmer notices that crossing red-flowered plants with white-flowered plants always results in pink-flowered offspring.
   Questions:
   a) What type of inheritance is this?
   b) Explain how this differs from Mendelian inheritance.