Tag: cell-the basic unit of life

• All the living organism is made up of cells which constitute some organic and inorganic molecules and perform all the life process like nutrition (autotrophic or heterotrophic), reproduction (sexual or asexual), excretion. 
• Each cell arises from pre-existing cells, they divide and increase their numbers and has a certain life span, thus they undergo aging and then death. Thus, the correct answer is option D.

• In unicellular (single-celled) organisms, the single cell performs all life processes for survival such as nutrition, transport, excretion, and reproduction. 
• They do not depend on another cell for function and thus exist independently.

• Cells are called an amazing world in itself because all the living organisms are made up of cells and also all the functions taking place inside the body of organisms are performed by cells. 
• These have the specialized enzymes, which catalyze the biochemical reaction and regulates the specialized functions of the body such as the conversion of nutrients into the energy, reproduction in unicellular and division or replication in multicellular.

Robert Hooke was an English scientist who coined the term cell for the Honeycomb structures he saw in a cork slice. Through he didn't see the inside of a cell, he discovered the cell and coined the term. He used a primitive compound microscope . He only saw cell walls as it a dead tissue. He discovered it in $1665$. The first man to witness a live cell under microscope was Antonie Philips van Leeuwenhoek in $1674$.

A micrometre is also known as a micron. It is an SI derived unit of length. Its value is 1×10$^{−6}$ metres or one millionth of a metre. Thus the correct answer is option B.

Living organisations have capacity to reproduce for ex animals give both to young ones of their kind, either directly or through egg.

• Endoplasmic reticulum (ER) is a system of membrane-lined channels found in all eukaryotic cells except mature erythrocytes. 
• Endoplasmic reticulum was discovered by Porter and Thompson (1945). 
• The name endoplasmic reticulum was given by Porter in 1953.
  Hence, option A is correct.

Lysosomes are small vesicles containing hydrolyzing enzymes and surrounded by a single membrane of lipids. They were discovered by Christian de Duve in 1955 but were named and observed under an electron microscope by Novikoff in 1956.