Class 9 Cell: The Building Block of Life Mock Test (CBSE)

Topics in Cell: The Building Block of Life

• Studying cells
• Cell membrane
• Cell wall
• Cell organelles
• Vacuoles
• Cell division: mitosis
• Meiosis
• Cell theory

Cell: The Building Block of Life practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following best describes the outcome of mitotic cell division?

   1. (a)Four haploid cells with genetic variation
   2. (b)Two identical diploid daughter cells
   3. (c)Two haploid cells without replication
   4. (d)Four identical diploid cells
   Show answer and step marks

   1. Correct option: (b) Two identical diploid daughter cells+1

   Answer: (b)
2. Q2Multiple choice·1 mark
   In plant cells, large central vacuoles are primarily responsible for:

   1. (a)Producing ATP through cellular respiration
   2. (b)Storing water, waste, and providing turgidity
   3. (c)Synthesizing lipids and steroids
   4. (d)Controlling cell division
   Show answer and step marks

   1. Correct option: (b) Storing water, waste, and providing turgidity+1

   Answer: (b)
3. Q3Assertion and reason·1 mark
   Assertion (A): Lysosomes are known as the suicide bags of the cell. Reason (R): They contain powerful digestive enzymes capable of breaking down cellular debris and damaged organelles.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true but Reason (R) is false.
   4. (d)Assertion (A) is false but Reason (R) is true.
   Show answer and step marks

   1. Correct option: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).+1

   Answer: (a)
4. Q4Assertion and reason·1 mark
   Assertion (A): Plant cells can withstand much greater changes in surrounding medium than animal cells without bursting. Reason (R): Plant cells possess a rigid outer cell wall that exerts pressure against the expanding cell membrane.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true but Reason (R) is false.
   4. (d)Assertion (A) is false but Reason (R) is true.
   Show answer and step marks

   1. Correct option: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).+1

   Answer: (a)
5. Q5Short answer·3 marks
   Differentiate between mitosis and meiosis based on any three distinct features, including the type of cells where they occur and the chromosome number in the resulting daughter cells.
   Show answer and step marks

   1. Type of cells: mitosis occurs in somatic (body) cells for growth and repair, whereas meiosis occurs in the germ cells of the reproductive organs (to form gametes in animals).+1
   2. Chromosome number in daughter cells: mitosis keeps the same chromosome number as the parent cell (a diploid cell gives diploid daughters), whereas meiosis halves it (diploid to haploid).+1
   3. Third difference, any one of: mitosis gives two daughter cells while meiosis gives four; mitosis gives genetically identical daughter cells while meiosis gives genetically varied ones; mitosis involves one division while meiosis involves two successive divisions; or any other valid difference.+1

   Answer: Mitosis occurs in somatic (body) cells, meiosis in germ cells of the reproductive organs. Mitosis keeps the parent's chromosome number (diploid to diploid), meiosis halves it (diploid to haploid). Plus any one of: 2 vs 4 daughter cells; identical vs genetically varied daughter cells; one division vs two successive divisions.
6. Q6Long answer·5 marks
   Cell division is a fundamental biological process required for growth, tissue repair, and gamete formation. (a) Differentiate between mitosis and meiosis in terms of the types of cells they occur in and the number of daughter cells produced. (b) Explain why mitosis is referred to as equational division. (c) State the significance of meiosis in sexually reproducing organisms.
   Show answer and step marks

   1. (a) Mitosis occurs in somatic (body) cells, whereas meiosis occurs in germ cells of the reproductive organs.+1
   2. (a) Mitosis produces two daughter cells, whereas meiosis produces four daughter cells.+1
   3. (b) Mitosis is called equational division because the chromosome number in the daughter cells remains equal to that of the parent cell.+1
   4. (c) Meiosis halves the chromosome number in gametes, so fertilisation restores it and the chromosome number stays constant from generation to generation.+1
   5. (c) Meiosis introduces genetic variation (through crossing over and the mixing of chromosomes), which helps species adapt and evolve.+1

   Answer: (a) Mitosis occurs in somatic cells and gives 2 daughter cells; meiosis occurs in germ cells and gives 4 daughter cells. (b) The daughter cells have the same chromosome number as the parent cell. (c) It halves the chromosome number in gametes so that fertilisation keeps it constant across generations, and it produces genetic variation.

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