Page 391 - General Knowledge

GENERAL KNOWLEDGE 2019

GENERAL SCIENCE: BIOLOGY

1. CELL
 Structural and functional unit of all living organisms.
 Smallest unit of life and called as building block of life.
 Cytology – Branch of biology that deals with study of cell.
 Robert Hooke- Coined the term ‗Cell‘ and discovered ‗cell wall’ in 1665.
 Leeuwenhoek – Discovered first living cell.

Types of Cells
 Two types of cells – Prokaryotic and Eukaryotic.

Prokaryotic Cell Eukaryotic Cell
Simplest, Complex in
primitive in nature
nature.
Lacks nuclear Nucleus present
envelope. in nuclear
envelope.
Cell organelles – Cell organelles –
present absent
Single Many uncovered
uncovered chromosomes
chromosome present.
present.
Cell division – Cell division –
direct. occurs by
meiosis.

Cell Wall
 Present in plant cells and absent in animals.
 Composed of cellulose in plants and chitin in fungi.
 Non-living.
 Main function – Provides shape and rigidity to the cell.

Plasma membrane
 Plasmalemma – a thin membrane that encloses the contents of the cell.
 Composed of proteins and phospholipid molecules.
 Provides passage for various substances.
 Observed only via microscope.
 Outermost covering of the cell.

Mitochondria
 Discovered by R Altman in 1880.
 Coined by Carl Benda.
 Known as as Power house of the cell.
 Bound by a double membrane.

387 | P a g e shop.ssbcrack.com