The fundamental unit of life
37) The membrane-bound cell organelles are absent in prokaryotic cells.
38) Differences between plant cell and animal cell.
Plant cell | Animal cell | |
1 | Plant cells are generally large in size. | Animal cells are smaller than plant cells. |
2 | Plant cells possess plastids. | Animal cells lack plastids. |
3 | Cell wall is present | Cell wall is absent. |
4 | Mature plant cells possess a large, central and permanent vacuole. | Animal cells possess many small and temporary vacuoles. |
5 | Centrosome and centrioles are absent in plant cells. | Centrosome and centrioles are present in animal cells. |
39) The basic structural organization of the cell helps it to perform important functions like respiration, nutrition, excretion and protein synthesis.
1) Cell - An autonomous self-replicating structure that forms the structural, functional and biological unit of all living organisms.
2) Prokaryotic cell – A cell characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes.
2) Nucleoid – An undefined nuclear region of the prokaryotic cell, containing the genetic material (nucleic acids).
3) Eukaryotic cell – A cell containing a membrane-bounded nucleus and membrane-bounded organelles.
4) Unicellular organism – Organism having only one cell.
5) Multicellular organism - Organism consisting of more than one cell, wherein the differentiated cells perform specialized functions in the organism.
6) Diffusion – The spontaneous movement of a substance from a region of its higher concentration to a region of its lower concentration.
7) Osmosis – The movement of water through a semi-permeable membrane from a region of high water concentration to a region of low water concentration.
8) Hypertonic solution - A solution that has a higher solute concentration than the one to which it is compared (eg - some kind of cell).
9) Hypotonic solution - A solution that has a lower solute concentration than the one to which it is compared (eg - some kind of cell).
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