Class 9 Science - ODISHA
Cell: The Building Block of Life
In the chapter 'Cell: The Building Block of Life', Class 9 Odisha BSE students will explore the fundamental structural and functional unit of all living organisms. This chapter covers the discovery of cells by Robert Hooke, the difference between unicellular and multicellular organisms, and the detailed micro-structure of plant and animal cells. You will study cell organelles like the nucleus, mitochondria, ribosomes, and the differences between prokaryotic and eukaryotic cells. Understanding this chapter is crucial for board exams as it forms the baseline for all advanced biological concepts in later classes and frequently features in short notes, diagram-based questions, and differential comparisons.
Start Learning FreeKey Concepts
Discovery of the Cell
Cells were first discovered by Robert Hooke in 1665 using a primitive microscope while observing a thin slice of cork.
Plasma Membrane and Cell Wall
The plasma membrane is a selectively permeable outer covering of the cell, while plant cells have an additional rigid outer layer called the cell wall made of cellulose.
Nucleus
Often called the brain of the cell, the nucleus contains genetic material (DNA) and controls all cellular activities.
Prokaryotic vs Eukaryotic Cells
Prokaryotic cells lack a well-defined, membrane-bound nucleus (e.g., bacteria), whereas eukaryotic cells have a true membrane-bound nucleus and organelles.
Cytoplasm and Cell Organelles
Cytoplasm is the jelly-like substance inside the cell where various specialized structures called organelles, such as mitochondria and chloroplasts, perform specific functions.
Important Formulas
Board Exam Info
This chapter typically carries around 6 to 8 marks in the Odisha BSE Class 9 Science annual examination. Common question types include diagram labeling (plant vs animal cell), differentiating between prokaryotes and eukaryotes, and short-answer questions on specific cell organelles like mitochondria and vacuoles.
Frequently Asked Questions
Why is the cell called the structural and functional unit of life?
It is called structural because all living bodies are made up of cells, and functional because all basic life processes like respiration, digestion, and excretion occur inside the cell.
What is the main difference between plant and animal cells?
Plant cells have a rigid cell wall, plastids, and a large central vacuole, whereas animal cells lack a cell wall, do not have plastids, and have smaller, temporary vacuoles.
Why are mitochondria called the powerhouse of the cell?
Mitochondria are called the powerhouse of the cell because they generate chemical energy in the form of ATP (Adenosine Triphosphate) required for various cellular activities.
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