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Science practice

Biology - Cell Structure & Function Questions with Answers

Cell structure questions cover the cell theory, prokaryotic and eukaryotic cells, the nucleus, cell organelles, plant versus animal cells and the movement of substances by diffusion and osmosis, as in NCERT class 8 and 9. RRB Group D, ALP, NTPC and SSC papers mostly ask for the function of an organelle, the scientist linked to a discovery, or a difference between plant and animal cells. Tip: link each organelle to one function word, such as mitochondria with energy.

Formulas and key facts

  • Cell was first observed by Robert Hooke in 1665, in a thin slice of cork
  • Cell theory: Schleiden and Schwann proposed that all plants and animals are made of cells; Virchow added that new cells arise from existing cells
  • Robert Brown discovered the nucleus in 1831
  • Mitochondria: site of aerobic respiration and release of energy as ATP; called the powerhouse of the cell
  • Ribosomes: sites of protein synthesis; present in both prokaryotic and eukaryotic cells
  • Rough ER has ribosomes on it; smooth ER helps in making fats (lipids) and in detoxification
  • Golgi apparatus: packaging, storage and dispatch of materials; also helps form lysosomes
  • Lysosomes: digestive enzymes, waste disposal; called suicide bags
  • Plastids (chloroplasts) are found only in plant cells; chloroplasts contain chlorophyll for photosynthesis
  • Cell wall (made of cellulose) is present in plant cells and absent in animal cells
  • Prokaryotes have no true nucleus or membrane-bound organelles; eukaryotes have both
  • Osmosis is the movement of water across a selectively permeable membrane from a region of higher water concentration to a lower one

Worked examples

Q1. Which cell organelle is the main site of ATP production?

  1. ATP is the energy currency produced during aerobic respiration.
  2. Aerobic respiration takes place in mitochondria.
  3. Chloroplasts make food, not ATP for general use; ribosomes make proteins.

Answer: Mitochondria

Q2. A plant cell is placed in a strong salt solution. What happens to it and why?

  1. The salt solution has a lower water concentration than the cell sap, so it is hypertonic to the cell.
  2. Water moves out of the cell by osmosis through the cell membrane.
  3. The cell contents shrink away from the cell wall. This is called plasmolysis.

Answer: The cell loses water and undergoes plasmolysis

Q3. Consider these statements. (i) Ribosomes are present in both prokaryotic and eukaryotic cells. (ii) The Golgi apparatus is involved in the formation of lysosomes. (iii) Animal cells have a cellulose cell wall. Which statements are correct?

  1. Statement (i): ribosomes make proteins in all cells, so it is true.
  2. Statement (ii): NCERT states the Golgi apparatus is involved in forming lysosomes, so it is true.
  3. Statement (iii): cell walls of cellulose are found in plant cells, not animal cells, so it is false.

Answer: (i) and (ii) only

Shortcuts that save time

  • Read statement-type questions by eliminating the clearly false statement first. Words such as 'only' and 'always' in an option are usually the trap, and eliminating them avoids a negative mark.
  • Learn organelles as one-word pairs: mitochondria with energy, ribosomes with protein, lysosomes with digestion, Golgi with packaging, nucleus with control, chloroplast with food.
  • Scientist questions have a fixed set: Hooke for cell, Brown for nucleus, Schleiden and Schwann for cell theory, Virchow for new cells from old cells. Skip the question if you are unsure instead of guessing among these four names.

Where this appears

RRB Group DGeneral Science section
RRB ALPGeneral Science section
RRB NTPCGeneral Awareness section
SSC CGLGeneral Awareness section

Biology - Cell Structure & Function

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Biology - Cell Structure & Function questions with answers

10 sample questions from this topic with the correct option and the solution.

  1. Q1. The cellular organelles are suspended in a jelly called _________.

    1. Cytoplasm
    2. Lumen
    3. Stroma
    4. Nucleoplasm

    Answer: (A) Cytoplasm

    Solution
    Cytoplasm is the jelly-like fluid inside the cell, enclosed by the cell membrane, in which the cell organelles are suspended. Nucleoplasm is the fluid inside the nucleus and stroma is the fluid inside chloroplasts, so they do not hold all the organelles.

  2. Q2. The cytoplasmic strands that connect one cell to the other are known as ________.

    1. Spindle Fibre
    2. Endoplasmic Reticulum
    3. Centriole
    4. Plasmodesmata

    Answer: (D) Plasmodesmata

    Solution
    Plasmodesmata are fine cytoplasmic strands that pass through the cell walls of adjacent plant cells and connect their cytoplasm. They allow transport of materials and communication between cells. Spindle fibres, endoplasmic reticulum and centrioles do not connect one cell to another.

  3. Q3. The branch of science that studies cells is called ________.

    1. Cytology
    2. Entomology
    3. Homoplastic
    4. Hormonology

    Answer: (A) Cytology

    Solution
    Cytology is the branch of biology that deals with the study of cells, including their structure, function and life cycle. Entomology is the study of insects, while the other two terms are not branches that study cells.

  4. Q4. The fluid content inside the plasma membrane, which also contains many specialised cell organelles, is called:

    1. plasmin
    2. nucleoplasm
    3. vacuoplasm
    4. cytoplasm

    Answer: (D) cytoplasm

    Solution
    The fluid content enclosed by the plasma membrane, in which the cell organelles are suspended, is called cytoplasm. Nucleoplasm is the fluid inside the nucleus only, while plasmin and vacuoplasm are not the name for this cell fluid. Hence the answer is cytoplasm.

  5. Q5. The Golgi apparatus is associated with which of the following organelles?

    1. Mitochondria
    2. Endoplasmic reticulum
    3. Plastids
    4. Nucleus

    Answer: (B) Endoplasmic reticulum

    Solution
    The Golgi apparatus works closely with the endoplasmic reticulum. Proteins and lipids made in the endoplasmic reticulum are sent in transport vesicles to the Golgi apparatus, where they are modified, sorted and packaged for secretion or delivery to other parts of the cell. This functional link makes the endoplasmic reticulum the associated organelle.

  6. Q6. The division of labour occurs in:

    1. only unicellular organisms
    2. only multicellular organisms
    3. neither unicellular nor in multicellular organism
    4. both unicellular and multicellular organisms

    Answer: (D) both unicellular and multicellular organisms

    Solution
    Division of labour means different parts of an organism perform different functions. In unicellular organisms, different organelles carry out different tasks within the single cell. In multicellular organisms, different cells, tissues and organs specialise in different functions. So division of labour occurs in both.

  7. Q7. The electrons present in the _________ of an atom are known as the valence electrons.

    1. Outermost shell
    2. Second shell
    3. First shell
    4. Penultimate shell

    Answer: (A) Outermost shell

    Solution
    Valence electrons are the electrons present in the outermost shell of an atom. These electrons take part in chemical bonding and decide the chemical properties and valency of the element. Hence the outermost shell is the correct answer.

  8. Q8. The dense structure inside the nucleus that produces ribosomes is called the _____.

    1. nucleolus
    2. lysosome
    3. centrosome
    4. mitochondria

    Answer: (A) nucleolus

    Solution
    The nucleolus is a dense, membrane-less structure inside the nucleus where ribosomal RNA is made and ribosome subunits are assembled. Lysosomes digest waste, centrosomes help in cell division, and mitochondria produce energy. So the answer is nucleolus.

  9. Q9. The external layer of pollen is made of Exine _________, which is a highly resistant organic matter.

    1. Microcolonin
    2. Intine
    3. Sporopollenin
    4. Microscope Tetraed

    Answer: (C) Sporopollenin

    Solution
    The outer wall of a pollen grain, the exine, is made of sporopollenin. It is one of the most resistant organic materials known and withstands high temperature, strong acids and alkalis. This is why pollen is well preserved as fossils. So the correct answer is Sporopollenin.

  10. Q10. Select the statement regarding cell organelles that is INCORRECT.

    1. Each cell organelle performs a special function.
    2. They are found in Prokaryotic cells.
    3. They are found in Eukaryotic cells.
    4. They are membrane-bound structures.

    Answer: (B) They are found in Prokaryotic cells.

    Solution
    Membrane-bound cell organelles such as mitochondria, Golgi apparatus and endoplasmic reticulum are found only in eukaryotic cells. Prokaryotic cells lack a true nucleus and membrane-bound organelles. Therefore the statement that they are found in prokaryotic cells is incorrect.