The Fundamental Unit of Life Test - 21

The Term endocytosis is composed of two term, i.e. ‘endo’ means towards inside and ‘cytosis’ means movement related to cell.

Cell wall of plants is made up of cellulose whereas cell wall of bacteria is mainly made up of peptidoglycan.

Camillo Golgi carried out ‘black reaction’ which involved use of silver nitrate. This helped him in staining individual nerve and cell structures.

Nucleus, mitochondria and plastids are the cell organelles present in eukaryotic cells that contain their own DNA.

Food is produced in plants inside chloroplasts. Hence, chloroplast is called the kitchen of the cell.

Lipid molecules in the cell are sythesized by smooth endoplasmic reticulum.

This postulation of Virchow made an addition to the earlier cell theory.

The cell theory, that all the plants and animals are composed of cells and that the cell is the basic unit of life, was presented by two biologists, M.J. Schleiden (1838) and Theodore Schwann (1839).

A prokaryotic cell is the cell that lacks all the membrane bound cell organelles such as a well developed nucleus, mitochondria, plastids, ER, Golgi apparatus etc. However ribosomes are not surrounded by membrane therefore they are present in prokaryotic cells. The prokaryotic cells are characteristic of prokaryotes e.g., bacteria, cyanobacteria, etc.

Other cell organelles are membrane – bound.

1 µm = \(10^{–6} m\)

Golgi apparatus is involved in the formation of lysosomes. Endoplasmic reticulum provides the precursors of enzymes to Golgi apparatus required for the formation of lysosomes.

Robert Hooke was the first to observe cells but he observed dead cells of cork. It was Leeuwenhoek who was the first to observe living cells.

Plasma membrane is a living, thin, elastic, selectively permeable membrane which chemically consists of lipids (20-79%), proteins (20-70%), carbohydrates (1-5%) and water (20%). Chitin sugar is not present in the plasma membrane of plants.

The radiant energy of sunlight is converted to chemical energy and is stored as ATP.