Biology MCQs/Topics Chapter

AFNS Test Biology MCQs/Topics for Chapter#02–cell Structure 

You will find MCQs at the end of important Topic.

TOPIC 1: What is a Cell?

A cell is the smallest structural and functional unit of life. It is the basic building block of all living things. Every living organism — from the tiniest bacterium to the largest blue whale — is made up of cells.

The human body contains approximately 37 trillion (37,000,000,000,000) cells! Each cell is so small that you need a microscope to see it. Most human cells are about 10–20 micrometers (µm) in diameter.

Cell = Smallest structural AND functional unit of life.This fact is the most repeated statement in AFNS biology tests. You must know this by heart.

Who Discovered the Cell?

The cell was first discovered by Robert Hooke in 1665. He was looking at thin slices of cork under a compound microscope and saw tiny box-like compartments. He named them ‘cells’ because they reminded him of small rooms (cellula in Latin means ‘small room’) in a monastery.

However, Hooke saw dead cell walls, not living cells. The first person to see LIVING cells was Anton van Leeuwenhoek, who observed bacteria and protozoa in pond water and dental scrapings.

📌 EXAMPLE

Q: Q: Who first discovered the cell and what material was used?

A: Robert Hooke (1665) discovered the cell by examining thin slices of CORK under a microscope. He named the box-like units ‘cells’.

TOPIC 2: Cell Theory

Cell Theory is one of the most important theories in biology. It explains the relationship between cells and living organisms. It was developed by Matthias Schleiden, Theodor Schwann, and Rudolf Virchow in the 1800s.

Three Main Principles of Cell Theory

All living organisms are made of one or more cells.

The cell is the basic structural and functional unit of life.

All cells arise from pre-existing cells (cells come from cells — Omnis cellula e cellula). — proposed by Rudolf Virchow

KEYFACT:Scientists behind Cell Theory:• Matthias Schleiden (1838) — All plants are made of cells• Theodor Schwann (1839) — All animals are made of cells• Rudolf Virchow (1855) — All cells come from pre-existing cells’Omnis cellula e cellula’ = Every cell from a cell (Latin)

QUICKTIP: AFNS test trick: If asked who said ‘all cells come from pre-existing cells’ — the answer is Rudolf Virchow. If asked who developed cell theory for plants — Schleiden. For animals — Schwann.

TOPIC 3: Types of Cells — Prokaryotic vs Eukaryotic

The Two Major Types of Cells

All cells in the living world can be divided into two major types based on whether they have a true nucleus or not:

Prokaryotic Cell: Pro = before, Karyon = nucleus (no true nucleus,DNA is in nucleoid region )

• Very small (1–10 µm)
• no membrane-bound organelles
• Cell wall: Present (made of peptidoglycan in bacteria)
• Ribosomes: Present (smaller, 70S)

Eukaryotic Cell: Eu = true, Karyon = nucleus (has true nucleus).

• Very small (10–100 µm)
• has mitochondria, ER, Golgi body etc.
• Cell wall: Present in plants/fungi; Absent in animals
• Ribosomes: Present (larger, 80S)

KEYFACT: Most important difference to remember:Prokaryotic = NO nuclear membrane (no true nucleus) — e.g., bacteria Eukaryotic = HAS nuclear membrane (true nucleus) — e.g., human cells This comparison is asked directly in AFNS tests very frequently.

📌 EXAMPLE

Q: Q: Bacteria are examples of which type of cell?

A: Prokaryotic cells. Bacteria have no true nucleus — their DNA floats freely in the cytoplasm in a region called the nucleoid. They also lack membrane-bound organelles.

QUICKTIP Memory trick: PRO-karyotic = PROblematic (primitive) — no nuclear membrane. EU-karyotic = EUphoric (evolved) — has true nucleus. The ‘EU’ means ‘true/good’ in Greek.

TOPIC 4: Plant Cell vs Animal Cell

Key Differences Between Plant and Animal Cells

Both plant and animal cells are eukaryotic, but they have important differences. These differences are very commonly tested in AFNS MCQs:

Plant Cell Features:

• Cell membrane: Present
• Cell wall: Present (made of cellulose)
• Chloroplasts: Present (for photosynthesis)
• Large central vacuole: Present (for water storage/pressure)
• Centrioles: Absent (in most plants)
• Shape: Regular/fixed shape (due to cell wall)
• Lysosomes: Rare
• Energy production: Chloroplasts + Mitochondria

Animal Cell Features: 

• Cell wall:Absent
• Cell membrane:Present
• Chloroplasts: Absent
• Large central vacuole: Small or absent
• Centrioles:Present (for cell division)
• Shape:Irregular/flexible shape
• Lysosomes: Present
• Energy production:Only Mitochondria

KEYFACT: 3 things ONLY plant cells have (animal cells lack):1. Cell wall (made of cellulose)2. Chloroplasts (for photosynthesis)3. Large central vacuole 1 thing ONLY animal cells have (plants lack):1. Centrioles (for animal cell division)

⭐ REMEMBER FOR AFNS TEST

Cellulose is the material that makes plant cell walls. It gives plants their rigid shape. Wood is mostly cellulose. This fact is frequently tested — do NOT confuse with peptidoglycan (which makes bacterial cell walls).

TOPIC 5: Cell Organelles — Structure and Function

What Are Organelles?

Organelles are tiny structures inside cells that perform specific functions. The word ‘organelle’ means ‘little organ’ — just like organs in the body each do a different job, organelles inside the cell each have a specific role.

All Major Organelles — Detailed Study

1. Nucleus — The Control Centre

The nucleus is the most important organelle in a eukaryotic cell. It controls all cell activities and contains the cell’s genetic material (DNA).

Location: Usually at centre of cell

Bounded by: Nuclear membrane (double membrane with pores)

Contains: DNA (genetic instructions), nucleolus (makes ribosomes)

Function: Controls all cell activities; stores and transmits genetic information

The nucleolus inside the nucleus makes ribosomal RNA (rRNA)

KEYFACT: Nucleus = Control centre of the cell. Contains DNA. Surrounded by nuclear membrane with pores. Has a nucleolus inside that makes ribosomes. Most repeated organelle in AFNS tests!

2. Mitochondria — The Powerhouse

Mitochondria (singular: mitochondrion) are often called the ‘powerhouse of the cell’ because they produce ATP (energy) through cellular respiration.

Shape: Oval/bean-shaped with double membrane

Inner membrane: Folded into structures called cristae (increase surface area)

Matrix: The inner fluid containing enzymes for respiration

Function: Aerobic cellular respiration — produces ATP energy from glucose + oxygen

Special feature: Has its own DNA and ribosomes (can self-replicate — endosymbiont theory)

KEYFACT

Mitochondria = Powerhouse of the cell (ATP production).Cristae = folds of inner membrane = increase surface area for more ATP production.This is one of the MOST repeated topics in AFNS biology tests.

📌 EXAMPLE

Q: Q: What is the function of cristae in mitochondria?

A: Cristae are the folds of the inner mitochondrial membrane. They increase the surface area available for the enzymes that produce ATP during cellular respiration.

3. Ribosomes — The Protein Factories

Ribosomes are the smallest organelles and the only organelles found in BOTH prokaryotic and eukaryotic cells. They are the site of protein synthesis (making proteins).

Size: 70S in prokaryotes; 80S in eukaryotes (S = Svedberg unit — measure of size)

Location: Free in cytoplasm OR attached to Rough Endoplasmic Reticulum

Structure: Made of two subunits — large subunit + small subunit

Function: Read mRNA and assemble amino acids into proteins

QUICKTIP: Antibiotics like Streptomycin and Erythromycin specifically target 70S prokaryotic ribosomes — this is why antibiotics can kill bacteria without harming human cells (which have 80S ribosomes). This is often asked in AFNS nursing-related questions!

4. Endoplasmic Reticulum (ER) — The Transport System

The Endoplasmic Reticulum is a network of membrane-enclosed tubes and sacs (cisternae) that acts as the cell’s transport and manufacturing system.

KEYFACT: RER (Rough) = has ribosomes = makes PROTEINSSER (Smooth) = no ribosomes = makes LIPIDS/STEROIDS and detoxification Rough looks rough because of ribosomes attached to it.

5. Golgi Apparatus — The Post Office

The Golgi Apparatus (also called Golgi body or Golgi complex) was discovered by Camillo Golgi in 1898. It is a stack of flattened membrane sacs called cisternae.

Function: Receives proteins from RER, modifies them, packages them, and sends them to their destination

Called the ‘post office’ or ‘dispatch centre’ of the cell

Produces lysosomes

Secretes substances to outside of cell (exocytosis)

Cis face = receives from ER | Trans face = sends to destination

📌 EXAMPLE

Q: Q: Which organelle is called the ‘post office’ of the cell and why?

A: The Golgi Apparatus is called the post office because it receives proteins from the RER, modifies them (adds sugar/lipid tags), packages them into vesicles, and dispatches them to their correct destination — inside or outside the cell.

6. Lysosomes — The Digestive Bags

Lysosomes are membrane-bound organelles filled with digestive enzymes. They break down waste materials, old organelles, and foreign particles (like bacteria).

Produced by: Golgi Apparatus

Contains: About 50 types of hydrolytic (digestive) enzymes

Function: Intracellular digestion — breaks down food particles, old organelles, bacteria

Also called ‘suicidal bags’ — if lysosomes rupture inside the cell, the enzymes digest the entire cell (autolysis)

Especially abundant in white blood cells (which digest bacteria)

KEYFACT: Lysosomes = Suicidal bags of the cell (contain digestive enzymes).Made by Golgi body.Abundant in phagocytic cells like neutrophils and macrophages (white blood cells) — very relevant for nurses!

7. Vacuoles — The Storage Tanks

Vacuoles are fluid-filled, membrane-bound sacs used for storage, waste disposal, and maintaining cell pressure.

Plant cells: Large central vacuole — stores water, maintains cell turgor pressure

Animal cells: Small vacuoles for temporary storage

Food vacuoles: Store food (in Amoeba/unicellular organisms)

Contractile vacuoles: Pump out excess water (in freshwater organisms like Amoeba)

8. Chloroplasts — The Solar Panels (Plants Only)

Chloroplasts are found only in plant cells and some algae. They are the site of photosynthesis — the process of making food using sunlight.

Structure: Double membrane. Inner membrane has thylakoids (stacked into grana). Fluid inside = stroma

Contains: Chlorophyll — the green pigment that absorbs light

Function: Photosynthesis — CO₂ + H₂O + light energy → Glucose + O₂

Like mitochondria, chloroplasts have their own DNA (endosymbiont theory)

KEYFACT: Chloroplast structure:• Thylakoids = flat membrane sacs stacked in grana = light reactions of photosynthesis happen here• Stroma = fluid around thylakoids = dark reactions (Calvin cycle) happen here• Chlorophyll = green pigment inside thylakoids

9. Cell Membrane (Plasma Membrane)

The cell membrane is present in ALL cells (both prokaryotic and eukaryotic). It is the outermost boundary in animal cells. In plants, it lies just inside the cell wall.

Structure: Fluid Mosaic Model — phospholipid bilayer with proteins embedded throughout

Phospholipid: Head = hydrophilic (water-loving) | Tail = hydrophobic (water-fearing)

Functions: Controls entry and exit of substances (selective permeability)

Contains: Proteins (transport channels, receptors), cholesterol (stability)

KEYFACT

Cell membrane = Fluid Mosaic Model (Singer & Nicolson, 1972)Selectively permeable = allows some substances to pass, blocks othersPhospholipid bilayer = two layers of phospholipids with heads facing outside, tails facing inside

QUICKTIP

The Fluid Mosaic Model describes the cell membrane. ‘Fluid’ = the phospholipid bilayer is fluid (molecules can move). ‘Mosaic’ = proteins are scattered like mosaic tiles. This model was proposed by Singer and Nicolson in 1972

10. Cell Wall

The cell wall is a rigid layer outside the cell membrane. It provides structural support and protection.

Plants: Cell wall made of CELLULOSE

Fungi: Cell wall made of CHITIN

Bacteria: Cell wall made of PEPTIDOGLYCAN

Animals: NO cell wall — only cell membrane

⭐ REMEMBER FOR AFNS TEST

Cell wall composition is frequently asked in AFNS:Plant = Cellulose | Fungus = Chitin | Bacteria = Peptidoglycan | Animal = No cell wallNever confuse these — each is a separate material!

11. Centrioles / Centrosome (Animal Cells Only)

Centrioles are cylinder-shaped organelles found in animal cells (and lower plants). Two centrioles form a centrosome.

Function: Form the spindle fibres during cell division (mitosis/meiosis)

Only in animal cells — plants use other structures for cell division

Important for formation of cilia and flagella

12. Cytoskeleton

The cytoskeleton is a network of protein fibres throughout the cytoplasm that gives the cell its shape and helps in movement.

Microfilaments — thin filaments made of actin protein; involved in cell movement and shape

Microtubules — hollow tubes made of tubulin; form spindle fibres, cilia, flagella

Intermediate filaments — provide mechanical strength.

AFNS test MCQs for chapter# 02

Q1. The basic structural and functional unit of life is:

Atom

Molecule

Cell

Tissue

✔ Answer: (C) Cell

Explanation: The cell is THE basic unit — structural (makes up the body) and functional (carries out life processes). Most repeated fact in AFNS biology.

Q2. Who first discovered and named the cell?

Leeuwenhoek

Robert Hooke

Schleiden

Virchow

✔ Answer: (B) Robert Hooke

Explanation: Robert Hooke observed cork cells in 1665 and named them ‘cells’. He saw the dead cell walls, not living cells.

Q3. Which of the following is NOT a part of Cell Theory?

All organisms are made of cells

Cell is the basic unit of life

Cells are formed from non-living matter

All cells come from pre-existing cells

✔ Answer: (C) Cells are formed from non-living matter

Explanation: Cell Theory says the OPPOSITE — all cells come from PRE-EXISTING cells (Virchow). The idea that cells form from non-living matter is called spontaneous generation, which was disproved.

Q4. Rudolf Virchow’s contribution to Cell Theory was:

All plants are made of cells

All animals are made of cells

All cells arise from pre-existing cells

Cell is the basic unit of life

✔ Answer: (C) All cells arise from pre-existing cells

Explanation: Virchow (1855) stated ‘Omnis cellula e cellula’ — every cell from a cell. He added the 3rd principle to Cell Theory.

Q5. Prokaryotic cells are characterized by:

Presence of membrane-bound nucleus

Presence of mitochondria

Absence of nuclear membrane

Presence of chloroplasts

✔ Answer: (C) Absence of nuclear membrane

Explanation: Prokaryotes (pro = before + karyon = nucleus) have no true nucleus — their DNA is in a nucleoid region without a membrane. Bacteria are the best example.

Q6. Which of the following is an example of a prokaryotic cell?

Amoeba

Bacterium

Plant cell

Red blood cell

✔ Answer: (B) Bacterium

Explanation: Bacteria are the classic example of prokaryotic cells — no nuclear membrane, no membrane-bound organelles, 70S ribosomes.

Q7. The powerhouse of the cell is:

Nucleus

Ribosome

Mitochondria

Chloroplast

✔ Answer: (C) Mitochondria

Explanation: Mitochondria produce ATP through cellular respiration. They are called the ‘powerhouse’ because they generate the cell’s energy currency (ATP).

Q8. Cristae are found in which organelle?

Chloroplast

Golgi body

Mitochondria

Nucleus

✔ Answer: (C) Mitochondria

Explanation: Cristae are the folds of the inner mitochondrial membrane. They increase surface area for more ATP production during cellular respiration.

Q9. Which organelle is called the ‘suicidal bag’ of the cell?

Mitochondria

Lysosome

Ribosome

Vacuole

✔ Answer: (B) Lysosome

Explanation: Lysosomes contain digestive enzymes. If they rupture, they digest the entire cell (autolysis) — earning the nickname ‘suicidal bags’.

Q10. Ribosomes are the site of:

Lipid synthesis

Protein synthesis

ATP production

Photosynthesis

✔ Answer: (B) Protein synthesis

Explanation: Ribosomes read messenger RNA (mRNA) and link amino acids together to make proteins. They are the protein factories of the cell.

Q11. The cell organelle that modifies, packages, and dispatches proteins is:

Rough ER

Lysosome

Golgi Apparatus

Nucleus

✔ Answer: (C) Golgi Apparatus

Explanation: The Golgi Apparatus receives proteins from Rough ER, modifies them (adds sugars etc.), packages them into vesicles, and sends them to their destination.

Q12. Which organelle is responsible for photosynthesis?

Mitochondria

Lysosome

Chloroplast

Golgi body

✔ Answer: (C) Chloroplast

Explanation: Chloroplasts contain chlorophyll and are the site of photosynthesis in plant cells. They convert light energy + CO₂ + H₂O into glucose + O₂.

Q13. Cell wall in plants is made of:

Chitin

Peptidoglycan

Cellulose

Lignin

✔ Answer: (C) Cellulose

Explanation: Plant cell walls are composed of cellulose — a polysaccharide. Chitin = fungi. Peptidoglycan = bacteria. Never mix these up in AFNS tests!

Q14. Which type of endoplasmic reticulum has ribosomes on its surface?

Smooth ER

Rough ER

Both

Neither

✔ Answer: (B) Rough ER

Explanation: Rough ER looks rough because ribosomes are attached to its membrane. It is involved in making and transporting proteins.

Q15. The fluid-filled cavity in plant cells used for storage is:

Lysosome

Vacuole

Vesicle

Cytoplasm

✔ Answer: (B) Vacuole

Explanation: Plant cells have a large central vacuole that stores water, waste products, and nutrients. It also maintains turgor pressure in the cell.

Q16. Centrioles are present in which type of cells?

Plant cells

Prokaryotic cells

Animal cells

Fungal cells

✔ Answer: (C) Animal cells

Explanation: Centrioles are found in animal cells and help form spindle fibres during cell division. Most plant cells lack centrioles.

Q17. The Fluid Mosaic Model describes the structure of:

Cell wall

Nuclear membrane

Cell membrane

Mitochondrial membrane

✔ Answer: (C) Cell membrane

Explanation: The Fluid Mosaic Model (Singer & Nicolson, 1972) describes the cell membrane as a fluid phospholipid bilayer with proteins scattered (like mosaic tiles) throughout.

Q18. Osmosis is the movement of:

Any molecule from high to low concentration

Water molecules across a semi-permeable membrane

Proteins across the cell membrane

Ions using ATP energy

✔ Answer: (B) Water molecules across a semi-permeable membrane

Explanation: Osmosis is specifically the movement of WATER from dilute (high water concentration) to concentrated (low water concentration) across a semi-permeable membrane.

Q19. Which process requires ATP energy to move molecules against concentration gradient?

Diffusion

Osmosis

Active transport

Facilitated diffusion

✔ Answer: (C) Active transport

Explanation: Active transport moves molecules from LOW to HIGH concentration — against the gradient — and requires ATP energy. Example: sodium-potassium pump.

Q20. Mitosis produces how many daughter cells?

1

2

3

4

✔ Answer: (B) 2

Explanation: Mitosis = one cell division producing 2 genetically identical daughter cells. The chromosome number stays the same (diploid → diploid, 2n → 2n).

Q21. Meiosis produces how many daughter cells?

2

3

4

8

✔ Answer: (C) 4

Explanation: Meio

sis involves two divisions and produces 4 haploid daughter cells (gametes). Each has half the chromosome number of the parent cell (2n → n).

Q22. Which stage of mitosis is characterized by chromosomes aligning at the cell equator?

Prophase

Metaphase

Anaphase

Telophase

✔ Answer: (B) Metaphase

Explanation: During Metaphase, chromosomes line up along the equatorial plate (middle of cell). This is the best stage to see and count chromosomes.

Q23. The ribosome size in eukaryotic cells is:

50S

70S

80S

100S

✔ Answer: (C) 80S

Explanation: Eukaryotic ribosomes are 80S. Prokaryotic ribosomes are smaller — 70S. The ‘S’ stands for Svedberg units (sedimentation coefficient).

Q24. Which organelle produces lysosomes?

Nucleus

Rough ER

Mitochondria

Golgi Apparatus

✔ Answer: (D) Golgi Apparatus

Explanation: The Golgi apparatus produces lysosomes by budding off vesicles filled with digestive enzymes.

Q25. The green pigment found in chloroplasts is:

Haemoglobin

Chlorophyll

Carotene

Xanthophyll

✔ Answer: (B) Chlorophyll

Explanation: Chlorophyll is the primary green pigment in chloroplasts that absorbs light energy (mainly red and blue light) for photosynthesis.