Cell the Unit of Life — Class 11 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 11 Biology chapter "Cell the Unit of Life" — 8 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Cell the Unit of Life" — 8 important questions with detailed answers for CBSE board ex…
By Syllab.in · Updated
Key Questions Covered:
- State the cell theory and explain its significance.
- Differentiate between prokaryotic and eukaryotic cells.
- Describe the structure and function of the cell membrane (plasma membrane).
- What is the nucleus? Describe its structure and functions.
- Describe the structure and function of mitochondria.
- What is the endoplasmic reticulum? Distinguish between rough and smooth ER.
- + 2 more questions in the full chapter
Solutions Summary:
| Question | Status |
|---|---|
| State the cell theory and explain its significance. | ✓ Solved |
| Differentiate between prokaryotic and eukaryotic cells. | ✓ Solved |
| Describe the structure and function of the cell membrane … | ✓ Solved |
| What is the nucleus? Describe its structure and functions. | ✓ Solved |
| Describe the structure and function of mitochondria. | ✓ Solved |
| What is the endoplasmic reticulum? Distinguish between ro… | ✓ Solved |
Showing 6 of 8 questions
Q1: State the cell theory and explain its significance.
Cell theory has three main postulates:
1. All living organisms are composed of one or more cells.
2. The cell is the fundamental unit of life; it is the basic organizational level of living things.
3. All cells arise from pre-existing cells by cell division.
Significance:
1. Unifies all life forms; shows that cells are common to all organisms.
2. Establishes cell as the smallest unit capable of independent life and growth.
3. Explains reproduction and growth at the cellular level.
4. Forms the...
Q2: Differentiate between prokaryotic and eukaryotic cells.
Prokaryotic cells (bacteria, cyanobacteria):
1. Nucleus: Absent; genetic material (DNA) in nucleoid region, not membrane-bound.
2. Organelles: No membrane-bound organelles; ribosomes (70S) present.
3. Size: Generally smaller (0.5-5 μm).
4. Cell wall: Present in most; composed of peptidoglycan.
5. Flagella: Simple, made of protein flagellin; rotate for movement.
6. Reproduction: By binary fission (asexual).
7. Ribosomes: 70S (smaller).
Eukaryotic cells (animals, plants, fungi, protists):
1. Nucl...
Q3: Describe the structure and function of the cell membrane (plasma membrane).
The cell membrane (plasma membrane) is a selectively permeable barrier separating the cell from its environment. Structure (Fluid Mosaic Model):
1. Phospholipid bilayer:
- Two layers of phospholipid molecules arranged tail-to-tail.
- Hydrophobic fatty acid tails face inward; hydrophilic phosphate heads face outward.
- Forms basic structural framework; provides barrier.
2. Proteins:
- Integral proteins: Span entire membrane; transport substances, receive signals.
- Peripheral proteins: Attached...
Q4: What is the nucleus? Describe its structure and functions.
The nucleus is a membrane-bound organelle containing genetic information (DNA). It controls cell activities and inheritance. Structure:
1. Nuclear envelope (nuclear membrane):
- Double membrane (outer and inner lipid bilayers).
- Perforated by nuclear pores (allow selective transport of large molecules and RNA).
- Connected to endoplasmic reticulum.
2. Nucleoplasm (nucleosol):
- Gel-like matrix inside nucleus.
- Contains DNA, proteins, and RNA.
3. Chromatin:
- Complex of DNA and histone prote...
Q5: Describe the structure and function of mitochondria.
Mitochondria are double-membrane bound organelles responsible for energy production. Structure:
1. Outer membrane:
- Smooth, permeable to most molecules.
- Surrounds entire organelle.
2. Intermembrane space:
- Region between outer and inner membrane.
- Contains enzymes and cytochrome c.
3. Inner membrane:
- Highly folded into cristae (singular: crista).
- Impermeable to many molecules; selectively permeable.
- Contains enzymes of electron transport chain.
4. Matrix (stroma):
- Inner compartm...
Q6: What is the endoplasmic reticulum? Distinguish between rough and smooth ER.
Endoplasmic reticulum (ER) is an extensive network of membranous tubules and sacs continuous with the nuclear envelope and cell membrane. It is the site of synthesis and transport of molecules.
Rough endoplasmic reticulum (RER):
1. Studded with ribosomes on outer (cytoplasmic) surface; gives rough appearance.
2. Functions:
- Synthesis of proteins destined for secretion (secretory proteins).
- Synthesis of membrane proteins and organellar proteins.
- Synthesis of enzymes for lysosomes.
...
Showing 6 of 8 questions. Visit the full page for complete solutions.
More Class 11 Biology NCERT Solutions
- Animal Kingdom — Class 11 Biology NCERT Solutions
- Plant Kingdom — Class 11 Biology NCERT Solutions
- Morphology of Flowering Plants — Class 11 Biology NCERT Solutions
- Anatomy of Flowering Plants — Class 11 Biology NCERT Solutions
- Biomolecules — Class 11 Biology NCERT Solutions
- Cell Cycle and Cell Division — Class 11 Biology NCERT Solutions
- Photosynthesis in Higher Plants — Class 11 Biology NCERT Solutions
- Respiration in Plants — Class 11 Biology NCERT Solutions
- Breathing and Exchange of Gases — Class 11 Biology NCERT Solutions
- Body Fluids and Circulation — Class 11 Biology NCERT Solutions
- Excretory Products and Their Elimination — Class 11 Biology NCERT Solutions
- Neural Control and Coordination — Class 11 Biology NCERT Solutions
- Chemical Coordination and Integration — Class 11 Biology NCERT Solutions