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
Anton van Leeuwenhoek
Matthias Schleiden
Robert Brown

Explanation:

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

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

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'?
Golgi apparatus
Nucleus
Mitochondria
Ribosome

Explanation:

Mitochondria generate ATP through oxidative phosphorylation.

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

Explanation:

Ribosomes synthesize proteins from amino acids using mRNA as template.

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

Explanation:

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

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

Explanation:

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

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

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

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
Plant cells and some algae
Bacterial cells only

Explanation:

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

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

Explanation:

Chloroplasts perform photosynthesis, converting light energy into chemical energy.

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

Explanation:

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

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

Explanation:

Plant cell walls are composed mainly of cellulose.

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

Explanation:

Bacterial cell walls are made of peptidoglycan (murein).

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

Explanation:

Fungal cell walls contain chitin, distinguishing them from plants.

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

Explanation:

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

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

Explanation:

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

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

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
Store water
Synthesize proteins

Explanation:

Peroxisomes break down fatty acids and detoxify hydrogen peroxide.

Q. The central vacuole is found predominantly in:
Bacterial cells
Fungal cells only
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?
Ribosome
Mitochondria
Golgi apparatus
Nucleus

Explanation:

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

Q. The fluid mosaic model describes:
The structure of chloroplasts
The structure of ribosomes
The structure of the cell membrane
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:
mRNA is translated on ribosomes
Ribosomes enter the nucleus
DNA enters the cytoplasm
The cell divides

Explanation:

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

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

Explanation:

The cytoskeleton provides structural support and maintains cell shape.

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

Explanation:

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

Popular Topics

```