Page 94 - Science Class 08

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i Cells are basic independent units of life.
i A cell has several organelles that are made up of molecules.
i Cells are common to all organisms that can be unicellular or multicellular.
i Various organisms have different types of cells. The cells of the same organism differ in its
various organs and organ systems.

i Cells differ in number, shape and size.
i A cell has three chief parts– outer membrane, central nucleus and the cytoplasm in-between
these two parts.
i Both plants and animals are made up of cells.

i There is much common in animal and plant cells, but there are some points of difference too.
i Cells keep dying (older ones) and forming (new-ones).
i Cells keep growing in size and increasing in number to effect overall growth of the
organism.

i Death of a cell affects its tissue which affects the organ. In its turn, the defective organ
affects its system and finally the system badly affects the organism.

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A. Tick (3) the correct op on.
1. The addi onal organelles found in plant cells containing pigments are:
(a) vacuoles (b) plas ds
(c) lysosomes (d) nucleus

2. The addi onal feature in a plant cell that gives it strength:
(a) membrane (b) nucleus
(c) cell-wall (d) all of these
3. The cytoplasm of a plant cell has vacuoles:

(a) only one (b) two
(c) several (d) no vacuoles
B. Write the correct term for.

1. the smallest structural unit of an organism : _______________________
2. the object observed by Robert Hooke to discover cells : _______________________
3. an organism with one body-cell only : _______________________
4. an organism with many body-cells : _______________________

5. the outermost part of a cell : _______________________
6. the central core of a cell : _______________________
7. the liquid between the membrane and the nucleus : _______________________
8. the many segments of DNA : _______________________

94 Science-8