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I want 9 th class state textbook Ch1 Cell its structure and functions notes.. Please,who have written,plz answer by keeping the pics, I'll mark them as the Brainliest...No spam plz..
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Answer:
Cell:
(i) In the living organisms, Cells are basic structural units.
(ii) Cells may be compared to bricks. Bricks are assembled to make a building. Similarly, cells are assembled to make the body of every organism.
(iii) It is the basic structural and functional unit of life. All organisms are made up of cells
(iv) Sub cellular structures of cell include organelles, the plasma membrane, and, if present, the nucleus.
(v) Size of the cell is 1 to 100 micrometer.
(vi) Cells are produced by the division of pre existing cell. Each cell contains genetic material that is passed down during reproduction process.
(v) Cells in the living organisms are complex living structures unlike non-living bricks.
(vi) All basic chemical and physiological functions like repairing, growth, excretion movement, immunity, communication, and digestion - are happen inside of cells.
Discovery of the Cell:
(i) In 1665, the English scientist Robert Hooke observed slices of cork which is part of bark of the tress, under a simple magnifying device. He noticed partitioned boxes or compartments in the cork slice.
Cork cells as observed by Robert Hooke
(ii) These boxes looked like a honeycomb. He also noticed that these boxes were separated from the other by a wall or partition. Hooke named them ‘cell’ for each box. Hooke observed as boxes or cells in the cork were actually dead cells. These boxes appeared like a honeycomb.
Over the next 170 years, research led to the formation of the cell theory, first proposed by the German botanist Matthias Jacob Schleiden and the German physiologist Theodore Schwann in 1838 and formalized by the German researcher Rudolf Virchow in 1858.
Types of cell:
1. Prokaryotic Cells:
The cells having nuclear material without nuclear membrane are termed prokaryotic cells. The organisms with these kinds of cells are called prokaryotes (pro: primitive; karyon: nucleus). Examples: bacteria and blue green algae.
2. Eukaryotic cells:
The cells having well organised nucleus with a nuclear membrane are designated as eukaryotic cells. All organisms other than bacteria and blue green algae are called Eukaryotes. (Eu : true; karyon: nucleus).
Organisms Show Variety in Cell Number, Shape and Size:
Millions of living organisms have cells with different shapes and sizes. Their organs also vary in shape, size and number of cells.
(i) Human body has trillions of cells which vary in different size and shapes. Different groups of cells perform a variety of functions. Organisms made of more than one cell are called multicellular organisms. An organism with billions of cells Starts life as a single fertilized egg cell. The fertilised egg cell multiplies by dividing process and the number of cells increases for development.
(ii) The single-celled organisms are made up of single cell called unicellular organisms. A single celled organism performs all the necessary functions that multicellular organisms perform.