Cell: Structure and Function

What you'll learn

A clear, from-scratch guide to the NCERT Class 11 chapter on the cell: the cell theory and its history, the key differences between prokaryotic and eukaryotic cells, and the structure and function of every major organelle, with tables, contrasts and a worked example to lock it in.

This chapter has

Cell: Structure and Function — solved practice questions

8 Class 11 Biology questions with step-by-step solutions. Attempt each, then reveal the answer.

1. Q1medium

   The cell theory, which states that all plants and animals are composed of cells, was proposed by:

   • ARobert Hooke and Robert Brown
   • BRudolf Virchow alone
   • CWatson and Crick
   • DM. Schleiden and T. Schwann
   Show answer & solution

   Correct answer: (D) M. Schleiden and T. Schwann

   Matthias Schleiden (1838) and Theodor Schwann (1839) together formulated the cell theory; it was later modified by Rudolf Virchow.

2. Q2medium

   The idea that new cells arise from pre-existing cells ('Omnis cellula-e cellula') was contributed by:

   • ARudolf Virchow
   • BRobert Hooke
   • CAnton von Leeuwenhoek
   • DTheodor Schwann
   Show answer & solution

   Correct answer: (A) Rudolf Virchow

   Rudolf Virchow (1855) explained that cells divide and new cells are formed from pre-existing cells, thereby completing the cell theory.

3. Q3medium

   According to the widely accepted fluid mosaic model, the plasma membrane was described by:

   • ASinger and Nicolson
   • BRobertson
   • CCamillo Golgi
   • DGeorge Palade
   Show answer & solution

   Correct answer: (A) Singer and Nicolson

   Singer and Nicolson (1972) proposed the fluid mosaic model, in which proteins float in a bilayer of phospholipids, giving the membrane its quasi-fluid nature.

4. Q4medium

   Which of the following is regarded as the smallest living cell?

   • AEscherichia coli
   • BHuman red blood cell
   • CMycoplasma (PPLO)
   • DOstrich egg
   Show answer & solution

   Correct answer: (C) Mycoplasma (PPLO)

   Mycoplasmas (PPLO) are the smallest living cells, about 0.3 micrometre in diameter, and notably lack a cell wall.

5. Q5medium

   Ribosomes present in a prokaryotic cell are of the type:

   • A80S
   • B60S
   • C40S
   • D70S
   Show answer & solution

   Correct answer: (D) 70S

   Prokaryotic ribosomes are 70S (made of 50S and 30S subunits), whereas eukaryotic cytoplasmic ribosomes are 80S.

6. Q6easy

   Ribosomes are the cellular site for the synthesis of:

   • Alipids
   • Bproteins
   • Ccarbohydrates
   • Dnucleic acids
   Show answer & solution

   Correct answer: (B) proteins

   Ribosomes, made of ribosomal RNA and proteins, are the sites of protein synthesis (translation) and are not bound by any membrane.

7. Q7easy

   Mitochondria are commonly called the 'power houses' of the cell because they:

   • Asynthesise proteins
   • Bstore genetic information
   • Cproduce ATP through aerobic respiration
   • Ddigest worn-out organelles
   Show answer & solution

   Correct answer: (C) produce ATP through aerobic respiration

   Mitochondria are the sites of aerobic respiration and release energy in the form of ATP, hence the name 'power houses' of the cell.

8. Q8medium

   The infoldings of the inner membrane of a mitochondrion are called:

   • Agrana
   • Bthylakoids
   • Ccisternae
   • Dcristae
   Show answer & solution

   Correct answer: (D) cristae

   The inner mitochondrial membrane is folded into cristae, which increase the surface area available for the enzymes and F1 particles of ATP synthesis.

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