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?
Robert Hooke
Matthias Schleiden
Robert Brown
Anton van Leeuwenhoek

Explanation:

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

Q. The cell theory was proposed by:
Watson and Crick
Pasteur and Koch
Hooke and Leeuwenhoek
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 lack a membrane-bound nucleus
Prokaryotes have a nuclear envelope

Explanation:

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

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

Explanation:

Mitochondria generate ATP through oxidative phosphorylation.

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

Explanation:

Ribosomes synthesize proteins from amino acids using mRNA as template.

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

Explanation:

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

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

Explanation:

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

Q. Lysosomes are known as:
Lipid factories
Protein factories
Powerhouses
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:
Being found only in prokaryotes
Having ribosomes attached
Having no membrane
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:
Plant cells and some algae
Fungal cells only
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
Photosynthesis
Cellular respiration

Explanation:

Chloroplasts perform photosynthesis, converting light energy into chemical energy.

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

Explanation:

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

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

Explanation:

Plant cell walls are composed mainly of cellulose.

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

Explanation:

Bacterial cell walls are made of peptidoglycan (murein).

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

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
Ribosomes, lysosomes, and vacuoles
Cellulose, chitin, and peptidoglycan
Microfilaments, intermediate filaments, and microtubules

Explanation:

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

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

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
Lipid synthesis
ATP production
DNA replication

Explanation:

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

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

Explanation:

Peroxisomes break down fatty acids and detoxify hydrogen peroxide.

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

Explanation:

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

Q. Which organelle modifies proteins with carbohydrate chains?
Mitochondria
Golgi apparatus
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 chloroplasts
The structure of ribosomes
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:
Ribosomes enter the nucleus
The cell divides
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
Lysosome
Nucleus
Cytoskeleton

Explanation:

The cytoskeleton provides structural support and maintains cell shape.

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

Explanation:

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

Popular Topics

```