THE FUNDAMENTAL UNIT OF LIFE Flashcards
(14 cards)
Who discovered the cell and in which year?
Robert Hooke, 1665
Who discovered the nucleus of the cell and in which year?
Robert Brown,1831
Who coined the term protoplasm for the fluid substances of the cell and in which year?
Purkinje, 1839
What is cell theory?
All the plants and animals are composed of cells and cell is the basic unit of life.
Who presented the cell theory and in which year?
Schleiden(1838) Schwann(1839)
Who expanded the cell theory and in which and by saying what?
Virchow,1855,by suggesting that all cells arise from pre-existing cells.
Examples of unicellular organisms.
Amoeba, Chlamydomonas, Paramoecium and bacteria
What are the three features present in every cell?
1) plasma membrane
2) nucleus
3) chlamydomonas
Define plasma membrane.
The outermost covering of the cell that separates the contents of the cell from its exetrnl environment.
Why is plasma membrane called semi-permeable membrane?
The plasma membrane allows or permits the entry and exit of some materials in and out cell. It also prevents the movement of some material in and out of cell.It also prevents the movement of some other materials.The cell membrane therefore is called selectively permeable membrane.
Define diffusion.
The process by which gases like carbon dioxide and oxygen move and out of the cell from higher concentration region to lower concentration region is called diffusion.
Define osmosis.
Ososis is the passage of water from a region of high water concentration to the region of low water concentration through a selectively permeable membrane til equilibrium is reached.
Define hypotonic solution.
The type of solution in which the medium surrounding the cell has a higher water concentration than the cell, meaning that the outside solution is very dilute, the cell will gain water by osmosis.This type of solution is called hypotonic solution.
Define isotonic solution.
The type of solution in which the medium has exactly the same water concentration than the cell, there will be no net movement of water across the cell membrane. This type of solution is called isotonic solution.
