Class 11 Biology - TAMILNADU
Cell: The Unit of Life
The chapter 'Cell: The Unit of Life' from Tamil Nadu Samacheer Kalvi Class 11 Biology explores the fundamental structural and functional unit of all living organisms. Students will learn the Cell Theory, differences between prokaryotic and eukaryotic cells, and the detailed ultrastructure of plant and animal cells. Key topics include the plasma membrane, cell wall, endomembrane system, mitochondria, plastids, ribosomes, and the nucleus. Mastering this chapter is crucial for board exams as it forms the biological foundation for higher-level topics like cell division, plant physiology, and human physiology, frequently appearing in both theory and practical evaluations.
Start Learning FreeKey Concepts
Cell Theory
Formulated by Schleiden, Schwann, and later expanded by Rudolf Virchow, it states that all living things are composed of cells and pre-existing cells arise from pre-existing cells.
Prokaryotic vs Eukaryotic Cells
Prokaryotic cells lack a true nucleus and membrane-bound organelles (e.g., bacteria), whereas eukaryotic cells possess a well-defined nucleus and various membrane-bound organelles (e.g., plant and animal cells).
Endomembrane System
A coordinated group of membranous organelles including the endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles that function together in protein and lipid synthesis and transport.
Mitochondria and Plastids
Mitochondria are the powerhouse of the cell responsible for ATP production, while plastids (like chloroplasts) are pigment-containing organelles found in plants crucial for photosynthesis.
Fluid Mosaic Model
Proposed by Singer and Nicolson, this model describes the plasma membrane as a fluid phospholipid bilayer with mosaic protein molecules floating within it.
Important Formulas
Board Exam Info
In the Tamil Nadu Samacheer Kalvi Class 11 Biology (Botany and Zoology) board examinations, this chapter typically carries around 6 to 9 marks. Questions frequently include 1-mark objective queries, 2-mark and 3-mark short answers (such as functions of organelles or differences between prokaryotes and eukaryotes), and 5-mark long-answer questions requiring a well-labeled diagram of an ultrastructure like a plant cell, animal cell, mitochondrion, or chloroplast.
Frequently Asked Questions
Why is the cell called the structural and functional unit of life?
A cell is called the structural unit because it forms the basic body plan of all organisms, and the functional unit because all vital metabolic activities and life processes occur within it.
What is the main difference between 70S and 80S ribosomes?
70S ribosomes are smaller and found in prokaryotic cells, mitochondria, and chloroplasts, whereas 80S ribosomes are larger and found in the cytoplasm and on the rough endoplasmic reticulum of eukaryotic cells.
Are mitochondria present in plant cells?
Yes, mitochondria are present in both plant and animal cells because both require cellular respiration and ATP production to carry out life activities.
Learn Cell: The Unit of Life with Your AI Tutor
10 different ways to study this chapter. Free for 3 chapters per day.
Lecture
Key Points
Interactive
Quiz
Flashcards