Here is the completely updated `question.php`. I added the missing `$breadcrumbs` array and defined `$category_name` and `$topic_name` right before the header is included. This ensures that `header.php` generates the correct Breadcrumb Schema, page title, and meta description for single question pages. Replace your entire `question.php` with this: ```php Cell Structure & Function Questions
TestMaster MCQs

Cell Structure & Function Questions

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

Explanation:

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

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

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 lack a membrane-bound nucleus
Prokaryotes have a nuclear envelope
Prokaryotes have mitochondria

Explanation:

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

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

Explanation:

Mitochondria generate ATP through oxidative phosphorylation.

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

Explanation:

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

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

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 ribosomes attached
Producing ATP
Having no membrane
Being found only in prokaryotes

Explanation:

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

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

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?
Golgi apparatus
Ribosomes
Mitochondria
Chloroplasts

Explanation:

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

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

Explanation:

Plant cell walls are composed mainly of cellulose.

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

Explanation:

Bacterial cell walls are made of peptidoglycan (murein).

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

Explanation:

Fungal cell walls contain chitin, distinguishing them from plants.

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

Explanation:

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

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

Explanation:

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

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

Explanation:

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

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

Explanation:

Peroxisomes break down fatty acids and detoxify hydrogen peroxide.

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

Explanation:

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

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

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 DNA
The structure of ribosomes
The structure of chloroplasts

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:
The cell divides
Ribosomes enter the nucleus
mRNA is translated on ribosomes
DNA enters the cytoplasm

Explanation:

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

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

Explanation:

The cytoskeleton provides structural support and maintains cell shape.

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

Explanation:

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

Popular Topics

```