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Cell Structure & Function Questions

Home Science Cell Structure & Function
Q. Which scientist first observed cells in 1665 using a microscope?
Robert Brown
Anton van Leeuwenhoek
Robert Hooke
Matthias Schleiden

Explanation:

Robert Hooke observed cork cells in 1665, coining the term 'cell'.

Q. The cell theory was proposed by:
Hooke and Leeuwenhoek
Pasteur and Koch
Watson and Crick
Schleiden and Schwann

Explanation:

Schleiden and Schwann (1838–39) formulated cell theory; Virchow later added 'omnis cellula e cellula'.

Q. Which of the following is a key feature distinguishing prokaryotes from eukaryotes?
Prokaryotes are always multicellular
Prokaryotes have mitochondria
Prokaryotes have a nuclear envelope
Prokaryotes lack a membrane-bound nucleus

Explanation:

Prokaryotes lack a membrane-bound nucleus; eukaryotes have one.

Q. Which organelle is known as the 'powerhouse of the cell'?
Nucleus
Ribosome
Golgi apparatus
Mitochondria

Explanation:

Mitochondria generate ATP through oxidative phosphorylation.

Q. The site of protein synthesis in a cell is the:
Ribosome
Golgi apparatus
Lysosome
Nucleus

Explanation:

Ribosomes synthesize proteins from amino acids using mRNA as template.

Q. The nucleus contains which genetic material?
Lipids
DNA
Only RNA
Proteins only

Explanation:

The nucleus houses the cell's DNA, which contains the genetic code.

Q. Which organelle is responsible for packaging and modifying proteins?
Ribosome
Golgi apparatus
Lysosome
Mitochondria

Explanation:

The Golgi apparatus modifies, sorts, and packages proteins from the ER.

Q. Lysosomes are known as:
Protein factories
Suicide bags
Lipid factories
Powerhouses

Explanation:

Lysosomes contain digestive enzymes and are the cell's 'suicide bags' or garbage disposal system.

Q. The rough endoplasmic reticulum differs from smooth ER by:
Having no membrane
Having ribosomes attached
Being found only in prokaryotes
Producing ATP

Explanation:

Rough ER has ribosomes attached for protein synthesis; smooth ER lacks ribosomes and is involved in lipid synthesis.

Q. Chloroplasts are found in:
Animal cells only
Fungal cells only
Bacterial cells only
Plant cells and some algae

Explanation:

Chloroplasts occur in plant cells and some algae — not in animal cells.

Q. Chloroplasts are the site of:
Protein synthesis
Lipid breakdown
Cellular respiration
Photosynthesis

Explanation:

Chloroplasts perform photosynthesis, converting light energy into chemical energy.

Q. Which organelle is absent in animal cells?
Chloroplasts
Ribosomes
Mitochondria
Golgi apparatus

Explanation:

Chloroplasts are absent in animal cells; mitochondria are present in both.

Q. The cell wall of plant cells is primarily made of:
Peptidoglycan
Cellulose
Chitin
Phospholipid

Explanation:

Plant cell walls are composed mainly of cellulose.

Q. The cell wall of bacteria is primarily made of:
Peptidoglycan
Chitin
Lignin
Cellulose

Explanation:

Bacterial cell walls are made of peptidoglycan (murein).

Q. Fungal cell walls are mainly composed of:
Chitin
Lignin
Peptidoglycan
Cellulose

Explanation:

Fungal cell walls contain chitin, distinguishing them from plants.

Q. The cytoskeleton is made up of which three main components?
Cellulose, chitin, and peptidoglycan
Nucleic acids, lipids, and proteins
Ribosomes, lysosomes, and vacuoles
Microfilaments, intermediate filaments, and microtubules

Explanation:

The cytoskeleton consists of microfilaments, intermediate filaments, and microtubules.

Q. Which of the following is NOT membrane-bound?
Nucleus
Mitochondria
Ribosome
Golgi apparatus

Explanation:

Ribosomes are non-membrane-bound organelles found free or attached to ER.

Q. The nucleolus is the site of:
ATP production
DNA replication
rRNA synthesis and ribosome assembly
Lipid synthesis

Explanation:

The nucleolus is where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins.

Q. Peroxisomes function primarily to:
Synthesize proteins
Store water
Break down fatty acids and detoxify
Produce ATP

Explanation:

Peroxisomes break down fatty acids and detoxify hydrogen peroxide.

Q. The central vacuole is found predominantly in:
Fungal cells only
Bacterial cells
Plant cells
Animal cells

Explanation:

Plant cells have large central vacuoles for storage, turgor, and waste management.

Q. Which organelle modifies proteins with carbohydrate chains?
Nucleus
Mitochondria
Ribosome
Golgi apparatus

Explanation:

The Golgi apparatus performs glycosylation — adding carbohydrate chains to proteins.

Q. The fluid mosaic model describes:
The structure of the cell membrane
The structure of ribosomes
The structure of chloroplasts
The structure of DNA

Explanation:

The fluid mosaic model (Singer & Nicolson, 1972) describes the cell membrane as a fluid phospholipid bilayer with embedded proteins.

Q. Protein synthesis begins in the cytoplasm when:
DNA enters the cytoplasm
The cell divides
mRNA is translated on ribosomes
Ribosomes enter the nucleus

Explanation:

Translation begins on free ribosomes; proteins destined for secretion move to the ER.

Q. Which cellular component is responsible for maintaining cell shape?
Lysosome
Cytoskeleton
Golgi apparatus
Nucleus

Explanation:

The cytoskeleton provides structural support and maintains cell shape.

Q. The endosymbiotic theory explains the origin of:
Golgi and ER
Cell wall and membrane
Mitochondria and chloroplasts
Nucleus and ribosomes

Explanation:

The endosymbiotic theory proposes that mitochondria and chloroplasts evolved from engulfed prokaryotes.

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