Cell: The Unit of Life — Class 11 MCQs with Answers
Class 11 CBSE Biology · Chapter 8
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 11 CBSE Biology questions from Chapter 8, "Cell: The Unit of Life". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG apart.
To score well in "Cell: The Unit of Life", focus on diagrams, key terms and knowing NCERT line by line. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Cell: The Unit of Life, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 11 Biology mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Cell: The Unit of Life (Class 11 Biology)
The cell is the structural and functional unit of all life. This chapter traces cell theory, contrasts small prokaryotic cells with compartmentalised eukaryotic cells, and details the fluid-mosaic membrane, the cell wall and each organelle whose division of labour keeps the cell alive and working.
- Cell theory
- Given by Schleiden and Schwann and extended by Virchow: all organisms are made of cells, cells are the basic unit of life, and cells arise only from pre-existing cells.
- Prokaryotic cell
- Lacks a true nucleus and membrane-bound organelles; DNA lies naked in the nucleoid, with mesosomes, 70S ribosomes and often a glycocalyx, plasmid and flagella.
- Eukaryotic cell
- Has a membrane-bound nucleus and organelles, an endomembrane system, a cytoskeleton and 80S ribosomes; found in protists, fungi, plants and animals.
- Fluid-mosaic model
- Singer and Nicolson's model: a lipid bilayer with proteins floating like a mosaic; phospholipids give fluidity, letting the membrane act as a selectively permeable barrier.
Cell: The Unit of Life — important questions & MCQs with answers (Class 11 Biology)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
Cell theory was proposed by:
A.DarwinB.MendelC.Schleiden and Schwann✓ CorrectD.PasteurAnswer: C. Schleiden and Schwann
Explanation: Schleiden and Schwann proposed cell theory in 1838-39; Virchow later added that cells arise only from pre-existing cells. Darwin and Mendel are famous biologists too, but they worked on evolution and heredity, not cell origin.
- Q2Easy
Powerhouse of the cell:
A.NucleusB.Mitochondria✓ CorrectC.RibosomeD.LysosomeAnswer: B. Mitochondria
Explanation: Mitochondria are the powerhouse because their inner membrane hosts oxidative phosphorylation, making most cellular ATP. Ribosomes make protein and lysosomes digest waste — neither one generates energy.
- Q3Easy
Cell theory was proposed by?
A.Watson and CrickB.MendelC.Schleiden and Schwann✓ CorrectD.PasteurAnswer: C. Schleiden and Schwann
Explanation: Schleiden and Schwann proposed cell theory in 1838-39, later extended by Virchow's 'all cells from pre-existing cells'. Watson and Crick found DNA's structure a century later — a different milestone entirely.
- Q4Easy
Which is absent in prokaryotic cells?
A.RibosomesB.Cell wallC.Membrane-bound organelles✓ CorrectD.DNAAnswer: C. Membrane-bound organelles
Explanation: Prokaryotes have no membrane-bound organelles — no mitochondria, ER, Golgi or true nucleus — since they never evolved internal membrane compartments. They do have ribosomes, DNA and a cell wall, so those are wrong picks.
- Q5Easy
Powerhouse of the cell is?
A.NucleusB.Mitochondrion✓ CorrectC.RibosomeD.LysosomeAnswer: B. Mitochondrion
Explanation: Mitochondria generate ATP by oxidative phosphorylation across their folded inner membrane, earning the 'powerhouse' label. Ribosomes make protein and lysosomes digest waste — neither produces cellular energy.
- Q6Easy
Cell was first discovered by?
A.LeeuwenhoekB.Robert Hooke (1665)✓ CorrectC.SchleidenD.VirchowAnswer: B. Robert Hooke (1665)
Explanation: Robert Hooke observed dead cork cell walls under a microscope in 1665 and coined the term 'cell'. Leeuwenhoek came later and saw living cells (animalcules), which is the usual mix-up for 'first observer'.
- Q7Medium
Prokaryotes lack:
A.RibosomesB.DNAC.Cell wallD.Membrane-bound nucleus and organelles✓ CorrectAnswer: D. Membrane-bound nucleus and organelles
Explanation: Prokaryotes lack a nuclear envelope and membrane-bound organelles like mitochondria — their DNA sits free as a nucleoid. They still have DNA, a cell wall and 70S ribosomes, so those options are wrong picks.
- Q8Medium
Ribosomes are the site of:
A.PhotosynthesisB.Protein synthesis✓ CorrectC.RespirationD.ExcretionAnswer: B. Protein synthesis
Explanation: Ribosomes translate mRNA into protein, whether free in the cytoplasm or bound to rough ER. Respiration happens in mitochondria and photosynthesis in chloroplasts — ribosomes never process energy or light.
- Q9Medium
Modern cell theory does NOT include?
A.All living organisms are made of cellsB.Cells arise from pre-existing cellsC.Cell is the basic unit of structure and functionD.All cells contain chloroplasts✓ CorrectAnswer: D. All cells contain chloroplasts
Explanation: Modern cell theory says all organisms are made of cells and cells arise from pre-existing cells — it says nothing about chloroplasts, which occur only in plant and algal cells, never in animal or fungal ones.
- Q10Medium
Mesosomes in bacteria are?
A.Plasma membrane invaginations involved in respiration/replication✓ CorrectB.DNA moleculesC.Storage granulesD.Cell wall extensionsAnswer: A. Plasma membrane invaginations involved in respiration/replication
Explanation: Mesosomes are infoldings of the bacterial plasma membrane that increase surface area for respiration, DNA replication and cell wall formation. They are membrane structures, not DNA or storage granules.
- Q11Medium
Inner mitochondrial membrane folds are called?
A.GranaB.Cristae✓ CorrectC.ThylakoidsD.CisternaeAnswer: B. Cristae
Explanation: Cristae are the folds of the mitochondrion's inner membrane that increase surface area for the electron transport chain, while the fluid matrix inside holds Krebs cycle enzymes. Grana and thylakoids are the chloroplast's structures, not the mitochondrion's.
- Q12Hard
Assertion: Bacteria contain 70S ribosomes. Reason: 70S ribosomes are made up of 50S and 30S subunits.
A.Both true; R explains AB.A true, R falseC.Both true; R doesn't explain A✓ CorrectD.A false, R trueAnswer: C. Both true; R doesn't explain A
Explanation: Bacteria do have 70S ribosomes, and 70S ribosomes are indeed built from 50S and 30S subunits — both statements are true, but the subunit composition just describes what a 70S ribosome is, not why bacteria specifically possess that type.
- Q13Hard
Chloroplasts perform:
A.DigestionB.RespirationC.Photosynthesis✓ CorrectD.ExcretionAnswer: C. Photosynthesis
Explanation: Chloroplasts trap light energy and fix CO2 into sugars during photosynthesis, using their thylakoid membranes. Respiration is the mitochondrion's job — the two are often swapped since both handle cell energy.
- Q14Hard
Assertion: Mycoplasmas can grow without a cell wall. Reason: Their plasma membrane is reinforced with sterols.
A.A true, R falseB.Both true; R doesn't explain AC.Both true; R explains A✓ CorrectD.A false, R trueAnswer: C. Both true; R explains A
Explanation: Mycoplasmas genuinely lack a cell wall yet survive because their plasma membrane is reinforced with sterols for extra rigidity — the reason directly explains the assertion, since sterols compensate for the wall's missing mechanical support.
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Start this chapter free →Cell: The Unit of Life — FAQs
What are the key concepts in Class 11 Biology Cell: The Unit of Life?+
The cell is the structural and functional unit of all life. This chapter traces cell theory, contrasts small prokaryotic cells with compartmentalised eukaryotic cells, and details the fluid-mosaic membrane, the cell wall and each organelle whose division of labour keeps the cell alive and working. Key ideas include Cell theory, Prokaryotic cell, Eukaryotic cell, Fluid-mosaic model.
What does Class 11 Biology Chapter 8 (Cell: The Unit of Life) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Cell: The Unit of Life": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, MHT-CET and NEET UG.
Are these "Cell: The Unit of Life" questions free to practise?+
Yes. Sign in with Google to practise "Cell: The Unit of Life" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Cell: The Unit of Life" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Cell: The Unit of Life" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Cell: The Unit of Life" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Cell: The Unit of Life (Class 11 Biology)?+
The questions that matter most test Cell theory, Prokaryotic cell, Eukaryotic cell, Fluid-mosaic model. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Cell: The Unit of Life?+
Yes — Class 11 Biology Cell: The Unit of Life has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.