ZOOLOGY: CELL BIOLOGY AND HISTOLOGY (ZOODSM-151) FYUG Even Semester Exam, 2025
Subject: Zoology | Course No: ZOODSM-151 | Semester: 2nd Semester (FYUG)
Full Marks: 70 | Pass Marks: 28 | Year: 2025
UNIT-I
Question 1 (a) 2 Marks
Compare the ribosomes of prokaryotic and eukaryotic cells.
- Prokaryotic cells contain 70S ribosomes, consisting of a 50S large subunit and a 30S small subunit.
- Eukaryotic cells contain 80S ribosomes, consisting of a 60S large subunit and a 40S small subunit.
Question 1 (b) 2 Marks
Mention the important functions of plasma membrane.
- Acts as a semi-permeable barrier that regulates the entry and exit of molecules.
- Provides structural support and facilitates cell signaling and communication.
Question 1 (c) 2 Marks
What are tight junctions?
Tight junctions are specialized intercellular connection sites where the membranes of two adjacent cells are fused together to form a barrier that prevents the leakage of fluids and solutes between cells.
Question 2 (a) 10 Marks
Explain the different types of membrane transport mechanism in cells, highlighting their significance.
Membrane transport is essential for maintaining cellular homeostasis. The primary mechanisms include:
- Passive Transport: Movement along the concentration gradient without energy. Includes simple diffusion, osmosis, and facilitated diffusion (using carrier/channel proteins).
- Active Transport: Movement against the concentration gradient using ATP. Includes primary active transport (e.g., Sodium-Potassium pump) and secondary active transport.
- Vesicular Transport: Transport of large particles via endocytosis (taking in) and exocytosis (releasing out).
Significance: These mechanisms ensure the cell receives nutrients, removes waste, and maintains electrochemical gradients necessary for nerve impulses and muscle contraction.
Question 2 (b) 10 Marks
Describe the composition of plasma membrane. Add a note on structure and function of desmosomes.
The plasma membrane follows the Fluid Mosaic Model:
- Lipids: Primarily phospholipids arranged in a bilayer, along with cholesterol for fluidity.
- Proteins: Integral proteins (spanning the bilayer) and peripheral proteins (attached to surfaces).
- Carbohydrates: Attached to lipids or proteins as glycolipids/glycoproteins for cell recognition.
Desmosomes: These are "spot-weld" junctions that mechanically attach cells to each other, providing structural integrity to tissues like skin and heart muscle.
UNIT-II
Question 3 (a) 2 Marks
Differentiate between RER and SER.
| Rough Endoplasmic Reticulum (RER) | Smooth Endoplasmic Reticulum (SER) |
|---|---|
| Studded with ribosomes. | Lacks ribosomes. |
| Primarily involved in protein synthesis. | Involved in lipid synthesis and detoxification. |
Question 4 (a) 10 Marks
Describe the structure of mitochondria with suitable diagram. Add a note on its functions.
Structure: Double-membrane organelle. The outer membrane is smooth, while the inner membrane is folded into cristae. The interior space is the matrix containing mitochondrial DNA and ribosomes.
Functions: Known as the "powerhouse of the cell," it is the site of cellular respiration and ATP production. It also plays a role in calcium storage and apoptosis.
Question 4 (b) 10 Marks
Describe the structure and function of peroxisomes. Add a note on function of lysosomes.
Peroxisomes: Small, membrane-bound organelles containing oxidative enzymes like catalase. They break down long-chain fatty acids and detoxify harmful substances (like hydrogen peroxide) into water and oxygen.
Lysosomes: These are the "suicidal bags" of the cell, containing hydrolytic enzymes used for intracellular digestion, recycling of old organelles (autophagy), and breaking down foreign substances.
UNIT-III
Question 5 (a) 2 Marks
What do you mean by cell cycle?
The cell cycle is the series of events that take place in a cell leading to its division and duplication of its DNA to produce two daughter cells.
Question 6 (a) 10 Marks
Describe the structure of microtubules with diagram. Add a note on functions of microtubules.
Structure: Hollow tubes about 25nm in diameter, made of alpha and beta-tubulin dimers arranged into 13 protofilaments.
Functions:
- Maintaining cell shape and structural support.
- Intracellular transport of organelles (acting as tracks).
- Formation of spindle fibers during cell division.
UNIT-IV
Question 8 (b) 10 Marks
Describe various components of blood and explain their functions.
- Plasma: The liquid component that carries nutrients, hormones, and waste products.
- Red Blood Cells (Erythrocytes): Carry oxygen using hemoglobin.
- White Blood Cells (Leukocytes): Play a key role in the immune system.
- Platelets (Thrombocytes): Essential for blood clotting.
UNIT-V
Question 10 (a) 10 Marks
Describe the ultrastructure of skeletal muscle with suitable diagram. Add a note on function of skeletal muscle.
Structure: Composed of long, cylindrical, multinucleated fibers with visible striations. Striations are caused by the arrangement of actin (thin) and myosin (thick) filaments into sarcomeres.
Function: Facilitates voluntary movements, maintains posture, and generates body heat through contraction.