Cell Structure and Function (Class 8 Science)

This MCQ chapter covers the fundamental concepts of cell biology, organelles, and their functions. Master the structure of plant and animal cells to excel

Cell Structure and Function (Class 8 Science)

This MCQ chapter covers the fundamental concepts of cell biology, organelles, and their functions. Master the structure of plant and animal cells to excel

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TL;DR: This MCQ chapter covers the fundamental concepts of cell biology, organelles, and their functions. Master the structure of plant and animal cells to e…

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This MCQ chapter covers the fundamental concepts of cell biology, organelles, and their functions. Master the structure of plant and animal cells to excel

Cell Structure and Function MCQs with Answers & Explanations

Q1. Which organelle is called the powerhouse of the cell?

  1. Nucleus
  2. Mitochondria ✓ (correct)
  3. Chloroplast
  4. Ribosome

Explanation: Mitochondria is called the powerhouse of the cell because it produces ATP through cellular respiration, providing energy for all cellular activities.

Q2. What is the main function of the nucleus?

  1. Energy production
  2. Photosynthesis
  3. DNA storage and regulation of cellular activities ✓ (correct)
  4. Protein synthesis

Explanation: The nucleus contains DNA and controls all cellular activities by regulating gene expression. It is the command center of the cell.

Q3. Which of the following is found only in plant cells?

  1. Centrioles
  2. Mitochondria
  3. Ribosomes
  4. Chloroplast ✓ (correct)

Explanation: Chloroplasts are found only in plant cells. They contain chlorophyll for photosynthesis. Animal cells lack chloroplasts.

Q4. What does the cell membrane control?

  1. Movement of substances in and out of the cell ✓ (correct)
  2. DNA replication
  3. Protein storage
  4. Photosynthesis

Explanation: The cell membrane is selectively permeable and controls the movement of substances into and out of the cell, protecting the cell from its environment.

Q5. Which organelle is responsible for protein synthesis?

  1. Golgi apparatus
  2. Ribosome ✓ (correct)
  3. Smooth endoplasmic reticulum
  4. Rough endoplasmic reticulum

Explanation: Ribosomes are sites of protein synthesis. They read mRNA and link amino acids together to form proteins in all cells.

Q6. What is the main component of the cell wall in plant cells?

  1. Lipid
  2. Protein
  3. Cellulose ✓ (correct)
  4. Starch

Explanation: Cell walls in plant cells are composed primarily of cellulose. Cellulose provides structural support and rigidity to the plant cell.

Q7. Which organelle stores water, nutrients, and waste in plant cells?

  1. Mitochondria
  2. Chloroplast
  3. Nucleus
  4. Vacuole ✓ (correct)

Explanation: The large central vacuole in plant cells stores water, nutrients, minerals, and waste products. It helps maintain turgor pressure.

Q8. What is the function of the rough endoplasmic reticulum?

  1. Synthesis of proteins for secretion ✓ (correct)
  2. Detoxification
  3. Synthesis of lipids
  4. Storage of calcium

Explanation: The rough endoplasmic reticulum (RER) is studded with ribosomes and synthesizes proteins that are transported out of the cell for secretion.

Q9. Which organelle is involved in the breakdown of harmful substances?

  1. Ribosome
  2. Lysosome ✓ (correct)
  3. Centrosome
  4. Golgi apparatus

Explanation: Lysosomes contain digestive enzymes that break down harmful substances, pathogens, and cellular waste. They are called suicide bags of the cell.

Q10. What is the function of centrioles in animal cells?

  1. Storage of water
  2. Protein synthesis
  3. Help in cell division ✓ (correct)
  4. Photosynthesis

Explanation: Centrioles are found in animal cells and help organize the spindle fibers during cell division, assisting in the movement of chromosomes.

Q11. Who discovered the cell, and what was he actually looking at?

  1. Anton von Leeuwenhoek, looking at pond water
  2. Robert Brown, looking at an onion peel
  3. Rudolf Virchow, looking at animal tissue
  4. Robert Hooke, looking at a thin slice of cork ✓ (correct)

Explanation: Robert Hooke observed a thin slice of cork under his own microscope in 1665 and saw box-like compartments, which he named cells. Cork is dead tissue, so what he actually saw were the empty walls left behind, not living cells.

Q12. Which of these organisms is unicellular?

  1. Amoeba ✓ (correct)
  2. Onion
  3. Earthworm
  4. Mango tree

Explanation: Amoeba is made of a single cell that performs every life function on its own. The others are multicellular, built from many cells with different jobs.

Q13. Which cell is able to change its shape as it moves?

  1. Nerve cell
  2. Amoeba ✓ (correct)
  3. Red blood cell
  4. Muscle cell

Explanation: Amoeba has no fixed shape and pushes out pseudopodia to move and to capture food. Among human cells the white blood cell can also change shape.

Q14. The longest cell in the human body is the:

  1. Red blood cell
  2. Muscle cell
  3. Nerve cell ✓ (correct)
  4. Bone cell

Explanation: Nerve cells are the longest cells in the human body — some run more than a metre — because they carry messages over long distances.

Q15. Which part of the cell controls the entry and exit of substances?

  1. Cell wall
  2. Vacuole
  3. Nucleus
  4. Cell membrane ✓ (correct)

Explanation: The cell membrane, also called the plasma membrane, surrounds every cell and is selectively permeable, so it decides what may pass in or out. It is present in both plant and animal cells.

Q16. A cell wall is present in:

  1. Plant cells only ✓ (correct)
  2. Both plant and animal cells
  3. Animal cells only
  4. Neither

Explanation: Only plant cells have a cell wall, made mainly of cellulose, lying outside the cell membrane. It gives the plant cell its rigid, fixed shape and protects it.

Q17. Which structure gives green colour to plant leaves?

  1. Vacuole
  2. Chloroplast ✓ (correct)
  3. Chromoplast
  4. Leucoplast

Explanation: Chloroplasts are plastids containing the green pigment chlorophyll. They trap sunlight for photosynthesis, and their pigment is what makes leaves look green.

Q18. The large central vacuole is a characteristic feature of:

  1. All cells equally
  2. Bacterial cells
  3. Plant cells ✓ (correct)
  4. Animal cells

Explanation: Plant cells have one large central vacuole that can occupy most of the cell and keeps it firm. Animal cells have vacuoles too, but they are small and numerous.

Q19. A cell whose nucleus has NO nuclear membrane around it is called:

  1. Multicellular
  2. Eukaryotic
  3. Unicellular
  4. Prokaryotic ✓ (correct)

Explanation: In a prokaryotic cell, such as a bacterium, the nuclear material lies free in the cytoplasm without a surrounding nuclear membrane. Cells with a proper membrane-bound nucleus are eukaryotic.

Q20. Chromosomes are found inside the:

  1. Nucleus ✓ (correct)
  2. Cytoplasm
  3. Cell membrane
  4. Vacuole

Explanation: Chromosomes lie within the nucleus and carry genes, which pass characters from parents to offspring. They become visible as thread-like structures when the cell divides.

Q21. The jelly-like substance between the nucleus and the cell membrane is:

  1. Plasma
  2. Cytoplasm ✓ (correct)
  3. Protoplasm
  4. Chlorophyll

Explanation: Cytoplasm is the jelly-like substance filling the space between the cell membrane and the nucleus, and it holds the various organelles. Cytoplasm together with the nucleus makes up the protoplasm.

Q22. Why is the cell called the structural and functional unit of living organisms?

  1. Because cells are visible to the naked eye
  2. Because only plants are made of cells
  3. Because every organism is built from cells and every life process happens inside them ✓ (correct)
  4. Because all cells are exactly the same size

Explanation: Every living organism is built from one or many cells, and all the activities that keep it alive take place within those cells. That is why the cell is described as both the structural and the functional unit of life.

Frequently Asked Questions

What is the difference between prokaryotic and eukaryotic cells?

Eukaryotic cells have a nucleus and membrane-bound organelles (animals, plants, fungi), while prokaryotic cells lack a nucleus and organelles (bacteria, archaea). Eukaryotic cells are more complex and larger.

How do plant and animal cells differ?

Plant cells have cell wall, large vacuole, and chloroplasts, while animal cells lack these structures. Animal cells have centrioles which plant cells lack. Both have cell membrane, nucleus, mitochondria, and ribosomes.

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