Class 9 Science - BIHAR
Cell: The Building Block of Life
The chapter 'Cell: The Building Block of Life' introduces Class 9 Bihar Board students to the fundamental structural and functional unit of all living organisms. Students will explore the historical discovery of cells by Robert Hooke, the differences between plant and animal cells, and the detailed structures of cell organelles such as the nucleus, mitochondria, ribosomes, and the Golgi apparatus. Understanding cell division (mitosis and meiosis) is also emphasized. This chapter is crucial for BSEB exams as it forms the base for all advanced biological concepts in higher classes and frequently features in objective and short-answer questions.
Start Learning FreeKey Concepts
Discovery of Cell
Robert Hooke discovered cells in 1665 using a primitive microscope to observe a thin slice of cork, naming the tiny box-like compartments 'cells'.
Prokaryotic vs Eukaryotic Cells
Prokaryotic cells lack a well-defined, membrane-bound nucleus (e.g., bacteria), whereas eukaryotic cells possess a true, membrane-bound nucleus and organized organelles (e.g., plant and animal cells).
Plasma Membrane and Cell Wall
The plasma membrane is a selectively permeable membrane present in all cells, while plant cells additionally have a rigid outer cell wall made of cellulose for protection and support.
Cell Organelles
Specialized structures within a cell that perform specific functions, such as mitochondria (powerhouse of the cell) and chloroplasts (sites of photosynthesis in plants).
Cytoplasm and Nucleus
Cytoplasm is the jelly-like fluid filling the cell, and the nucleus acts as the control center, storing hereditary material (DNA).
Important Formulas
Board Exam Info
In the Bihar School Examination Board (BSEB) Class 9 Science exams, this chapter typically carries around 6 to 8 marks. Questions usually include objective (multiple-choice) questions about cell organelles, short-answer questions on differences between plant and animal cells, and diagrams of animal or plant cells.
Frequently Asked Questions
Why is the cell called the structural and functional unit of life?
It is called the structural unit because all living organisms are made up of cells, and the functional unit because all life processes (like respiration, digestion, and excretion) occur inside cells.
What is the difference between a plant cell and an animal cell?
Plant cells have a rigid cell wall and large central vacuoles, and they contain plastids (like chloroplasts) for photosynthesis. Animal cells lack cell walls and plastids, and they have small, temporary vacuoles.
Why is mitochondria called the powerhouse of the cell?
Mitochondria are called the powerhouse of the cell because they produce energy in the form of ATP (Adenosine Triphosphate) through cellular respiration.
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