Class 9th Biology: Cell: The Building Block of Life MCQ Quiz, Exemplar & Detailed Explanations

Class 9th Biology — Chapter 1

Class 9th Biology: Cell: The Building Block of Life  MCQ Quiz, Exemplar & Detailed Explanations

Part A: Multiple Choice Questions (बहुविकल्पीय प्रश्न)

Q1. Which of the following is a prokaryotic cell?
(निम्नलिखित में से कौन सी प्रोकैरियोटिक कोशिका है?)

💡 Explanation: Bacteria are prokaryotes as they lack a well-defined membrane-bound nucleus and organelles. Yeast, plants, and Amoeba are eukaryotes.

Q2. The basic structural and functional unit of all living organisms is a/an:
(सभी जीवों की मूल संरचनात्मक और कार्यात्मक इकाई है:)

💡 Explanation: Cells form the fundamental building blocks of all living organisms, performing all basic life functions.

Q3. What happens to raisins if they are placed in an isotonic solution?
(यदि किशमिश को समप्रासारी (isotonic) घोल में रखा जाए तो क्या होगा?)

💡 Explanation: An isotonic solution has the same solute concentration as inside the cell, so there is no net movement of water.

Q4. Cell membranes are:
(कोशिका झिल्ली होती है:)

💡 Explanation: The plasma membrane selectively allows only specific substances to enter or leave the cell.

Q5. What happens if some grapes are placed in a strong salt solution?
(यदि कुछ अंगूरों को गाढ़े नमक के घोल में रखा जाए तो क्या होगा?)

💡 Explanation: Strong salt solution is hypertonic. Water moves out of the grapes via exoskeleton/exosmosis, causing them to shrink.

Q6. In osmosis:
(परासरण (Osmosis) में:)

💡 Explanation: Osmosis is specifically the movement of solvent molecules (water) across a Semi-Permeable Membrane (SPM).

Q7. Selective transport is the function of the:
(चयनात्मक परिवहन (Selective transport) किसका कार्य है?)

💡 Explanation: The cell membrane regulates the entry and exit of molecules through selective permeability.

Q8. Histone proteins are associated with DNA of:
(हिस्टोन प्रोटीन किसके DNA से जुड़े होते हैं?)

💡 Explanation: Histone proteins help package linear DNA in eukaryotic chromosomes. Prokaryotes lack true histones.

Q9. Respiratory enzymes in a bacterium are found associated with:
(जीवाणु में श्वसन एंजाइम किससे जुड़े होते हैं?)

💡 Explanation: Bacteria lack mitochondria; their respiratory enzymes are located on the plasma membrane folds (mesosomes).

Q10. The biggest cell is:
(सबसे बड़ी कोशिका है:)

💡 Explanation: An ostrich egg is a single cell measuring approximately 15 to 18 cm, making it the largest isolated cell.

Q11. Human erythrocytes (RBCs) lack:
(मानव लाल रक्त कोशिकाओं (RBCs) में अनुपस्थित होता है:)

💡 Explanation: Mature human RBCs lack a nucleus, mitochondria, and Golgi apparatus to provide maximum space for hemoglobin.

Q12. Nucleoid is found in:
(न्यूक्लियॉइड (Nucleoid) पाया जाता है:)

💡 Explanation: Prokaryotes lack a nuclear membrane, leaving their genetic material exposed in an undefined region called the nucleoid.

Q13. Which worker discovered the cell?
(कोशिका की खोज किस वैज्ञानिक ने की थी?)

💡 Explanation: Robert Hooke discovered dead cork cells under his primitive microscope in 1665.

Q14. Who was first to see free cells like bacteria and protozoa?
(जीवाणु और प्रोटोजोआ जैसी जीवित मुक्त कोशिकाओं को सबसे पहले किसने देखा?)

💡 Explanation: Anton van Leeuwenhoek observed living cells in pond water for the first time in 1674.

Q15. The source of genetic information is:
(आनुवंशिक जानकारी का स्रोत है:)

💡 Explanation: DNA (Deoxyribonucleic Acid) contains functional segments called genes that carry heredity information.

Q16. Who proposed the term 'protoplasm'?
('जीवद्रव्य' (Protoplasm) शब्द का प्रतिपादन किसने किया?)

💡 Explanation: J.E. Purkinje coined the term 'protoplasm' in 1839 for the fluid substance of the cell.

Q17. Chromosomes are made up of:
(गुणसूत्र बने होते हैं:)

💡 Explanation: Chromosomes consist of nucleic acid (DNA) wrapped around structural proteins (histones).

Q18. Which of the following are covered by a single membrane?
(निम्नलिखित में से कौन एकल झिल्ली (single membrane) से घिरा होता है?)

💡 Explanation: Vacuoles (and lysosomes) have a single membrane (tonoplast), whereas mitochondria, nucleus, and plastids have double membranes.

Q19. Cell wall of plants is made up of:
(पादप कोशिका भित्ति बनी होती है:)

💡 Explanation: Plant cell walls are mainly composed of cellulose, a complex carbohydrate providing structural strength.

Q20. Which structure is called the kitchen of the cell?
(किस संरचना को कोशिका की 'रसोई' कहा जाता है?)

💡 Explanation: Chloroplasts perform photosynthesis to synthesize food (glucose) for plant cells.

Q21. Which of the following is used by animal cells to connect to neighboring cells for direct communication?
(जंतु कोशिकाएँ आपस में संचार हेतु किसका उपयोग करती हैं?)

💡 Explanation: Desmosomes (and gap junctions) connect adjacent animal cells, whereas plasmodesmata are found in plant cells.

Q22. Adenosine Triphosphate (ATP) is a type of:
(एडीनोसिन ट्राईफॉस्फेट (ATP) एक प्रकार का है:)

💡 Explanation: ATP is a nucleoside triphosphate, consisting of an adenine base, ribose sugar, and three phosphate groups.

Q23. Artificial cells are defined as:
(कृत्रिम कोशिकाओं (Artificial cells) को किस प्रकार परिभाषित किया जाता है?)

💡 Explanation: Artificial cells are engineered particles that encapsulate biological contents to mimic cellular functions.

Q24. Which of the following is a key similarity between mitosis and meiosis?
(समसूत्री और अर्धसूत्री विभाजन में मुख्य समानता क्या है?)

💡 Explanation: Sister chromatids separate during Anaphase in mitosis and Anaphase II in meiosis.

Q25. The abnormal growth of cells in the body is known as:
(शरीर में कोशिकाओं की असामान्य वृद्धि कहलाती है:)

💡 Explanation: Uncontrolled cellular division leads to cancerous tumors and malignant growths.

Q26. What was a major breakthrough of Prof. Arun Kumar Sharma's techniques?
(प्रोफेसर अरुण कुमार शर्मा की तकनीकों की मुख्य उपलब्धि क्या थी?)

💡 Explanation: Prof. A.K. Sharma developed techniques to induce cell division in adult tissue cells to study chromosome structure.

Q27. What is the fundamental mechanism of disease in Leigh syndrome patients?
(लीघ सिंड्रोम के रोगियों में बीमारी का मुख्य कारण क्या है?)

💡 Explanation: Leigh syndrome is a neurometabolic disorder caused by defects in mitochondrial oxidative phosphorylation.

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Part B: NCERT Exemplar Questions

Q1 (Exemplar). Which of the following can be made into crystal?

💡 Explanation: Viruses are acellular nucleoprotein particles that can be crystallized outside host cells.

Q2 (Exemplar). A cell will swell if:

💡 Explanation: When surrounding water concentration is higher (hypotonic solution), water enters the cell via endosmosis, swelling it.

Q3 (Exemplar). Chromosomes are made up of:

💡 Explanation: Chromosomes are composed of DNA molecules wrapped around histone protein complexes.

Q4 (Exemplar). Which of these options are NOT a function of ribosomes?
(i) Protein manufacture    (ii) Enzyme manufacture
(iii) Hormone manufacture    (iv) Starch manufacture

💡 Explanation: Ribosomes synthesize proteins and protein-based enzymes. Hormones (often steroidal) and starch are not made by ribosomes.

Q5 (Exemplar). Which of these is NOT related to endoplasmic reticulum?

💡 Explanation: Mitochondria are the powerhouse/sites of energy generation (ATP), not the ER.

Q6 (Exemplar). Select the correct definition of osmosis:

💡 Explanation: Osmosis requires a semipermeable membrane for movement of solvent water molecules.

Q7 (Exemplar). Plasmolysis in a plant cell is defined as:

💡 Explanation: Hypertonic conditions pull water out of plant cells, shrinking the protoplasm away from the cell wall.

Q8 (Exemplar). Which of the following are covered by a single membrane?

💡 Explanation: Lysosomes and vacuoles have single membranes, whereas mitochondria, plastids, and nucleus are double-membraned.

Q9 (Exemplar). Find out the false sentence:

💡 Explanation: Protoplasm includes Cytoplasm + Nucleus. Cytoplasm alone is not protoplasm.

Q10 (Exemplar). Proteins and lipids essential for building cell membrane are manufactured by:

💡 Explanation: RER produces proteins, SER produces lipids, together helping membrane biogenesis.

Q11 (Exemplar). The undefined nuclear region of prokaryotes is known as:

💡 Explanation: Prokaryotic nuclear region without a nuclear envelope is called a nucleoid.

Q12 (Exemplar). Cell organelle involved in forming complex sugars from simple sugars is:

💡 Explanation: Golgi bodies modify, package, and convert simple sugars into complex carbohydrates.

Q13 (Exemplar). Which of the following is NOT a function of the vacuole?

💡 Explanation: Vacuoles do not assist in movement or locomotion.

Q14 (Exemplar). Amoeba acquires its food through a process termed:

💡 Explanation: Membrane flexibility allows Amoeba to engulf food particles via endocytosis (phagocytosis).

Q15 (Exemplar). Cell wall of which one of these is NOT made up of cellulose?

💡 Explanation: Bacterial cell walls are composed of peptidoglycan, not cellulose.

Q16 (Exemplar). Silver nitrate solution is used to study:

💡 Explanation: Camillo Golgi developed the silver nitrate staining technique ('black reaction') to visualize Golgi apparatus.

Q17 (Exemplar). Organelle other than nucleus, containing DNA is:

💡 Explanation: Mitochondria and plastids contain their own circular DNA and ribosomes.

Q18 (Exemplar). Kitchen of the cell is:

💡 Explanation: Chloroplasts synthesize glucose during photosynthesis.

Q19 (Exemplar). "Cell arises from pre-existing cell" was stated by:

💡 Explanation: Rudolf Virchow expanded cell theory in 1855 stating 'Omnis cellula-e cellula'.

Q20 (Exemplar). Cell theory was proposed by:

💡 Explanation: Matthias Schleiden (1838) and Theodor Schwann (1839) formulated the original cell theory.

Q21 (Exemplar). The only cell organelle seen in prokaryotic cell is:

💡 Explanation: Prokaryotes lack membrane-bound organelles; 70S ribosomes are present.

Q22 (Exemplar). Organelle without a cell membrane is:

💡 Explanation: Ribosomes are non-membrane-bound ribonucleoprotein particles.

Q23 (Exemplar). 1 μm is equal to:

💡 Explanation: 1 micrometer (μm) = 10⁻⁶ meters.

Q24 (Exemplar). Living cells were discovered by:

💡 Explanation: Leeuwenhoek was the first to observe free living cells in pond water.

Q25 (Exemplar). Lipid molecules in the cell are synthesised by:

💡 Explanation: Smooth Endoplasmic Reticulum (SER) manufactures fats/lipids.

Q26 (Exemplar). Lysosomes arise from:

💡 Explanation: Hydrolytic enzymes packaged into vesicles bud off from Golgi apparatus to form lysosomes.

Q27 (Exemplar). Select the odd one out:

💡 Explanation: Plant cell membranes do not contain chitin; plant cell walls consist of cellulose.

Q28 (Exemplar). Which cell organelle plays a crucial role in detoxifying many poisons and drugs?

💡 Explanation: SER in liver cells detoxifies drugs and chemical toxins.

Q29 (Exemplar). Find out the correct sentence:

💡 Explanation: Lysosomal digestive enzymes are proteins synthesized by Rough Endoplasmic Reticulum (RER).

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Part C: Assertion and Reason Questions

Directions:
(a) Both A and R are true and R is correct explanation of A.
(b) Both A and R are true but R is NOT correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Q1 (A/R).
Assertion (A): The basic structural and functional unit of life is cell.
Reason (R): It performs functions like respiration, nutrition, waste clearance, and protein synthesis.

💡 Explanation: Since all metabolic activities necessary for life occur inside cells, the cell is the functional unit.

Q2 (A/R).
Assertion (A): Movement of substances across plasma membrane occurs through diffusion.
Reason (R): Plasma membrane is selectively permeable in nature.

💡 Explanation: Assertion is false because movement across membranes involves active transport and osmosis alongside simple diffusion.

Q3 (A/R).
Assertion (A): A cell swells up when present in a hypotonic solution.
Reason (R): More water molecules enter the cell than they leave.

💡 Explanation: Endosmosis occurs in hypotonic media because outer water concentration is higher.

Q4 (A/R).
Assertion (A): Cells with membrane-bound organelles are called eukaryotic.
Reason (R): Cells lacking membrane-bound organelles are called prokaryotic.

💡 Explanation: Both statements are individually true definitions, but R does not explain why eukaryotic cells are defined as such.

Q5 (A/R).
Assertion (A): Ribosomes are present in both eukaryotes and prokaryotes.
Reason (R): Ribosomes are not the sites of protein synthesis.

💡 Explanation: Assertion is true, but Reason is false because ribosomes ARE the primary sites of protein synthesis.

Q6 (A/R).
Assertion (A): Chromosomes are visible under a microscope when cell is about to divide.
Reason (R): In a non-dividing cell, DNA is present as part of chromatin material.

💡 Explanation: Both are correct statements regarding cellular DNA structure during dividing vs non-dividing phases.

Q7 (A/R).
Assertion (A): Passive transport does not involve metabolic energy.
Reason (R): It occurs due to concentration gradient of materials.

💡 Explanation: Passive transport moves substances down their concentration gradient without consuming cellular ATP energy.

Q8 (A/R).
Assertion (A): Inner membrane of mitochondria is folded into cristae.
Reason (R): The cristae help to decrease the surface area.

💡 Explanation: Cristae INCREASE surface area for ATP generation, making the Reason statement false.

Q9 (A/R).
Assertion (A): Plant cells have a single large vacuole.
Reason (R): Vacuole is responsible for ingestion of food substance.

💡 Explanation: Plant vacuoles store cell sap and maintain turgidity, they do not ingest food particles.

Q10 (A/R).
Assertion (A): Endoplasmic reticulum with ribosomes on surface is called SER.
Reason (R): SER is involved in lipid synthesis.

💡 Explanation: Assertion is false (ER with ribosomes is RER, not SER). Reason is true.