Tag: the cell structure

In 1809, Lamarck concluded that all living beings are formed of cells. Living substance was first observed by Corti in 1772 and was named sarcode by Dujardin in 1835. Dutrochet believed in the individuality of cells, i.e., living organisms are made up of a number of individual cells.

A multicellular organism attains its multicellularity from a single cell. Single totipotent cell undergo number of mitotic and meiotic divisions to give rise to a multicellular structure where cells undergo differentiation to a particular function. Some of the cells are undifferentiated such as stem cells which can give rise to any type of cells of the body. Also multicellular organisms undergoes dedifferentiation process where a differentiated cell revert back to totipotent cell and can again differentiate to a particular type of cell witha particular function. So Multicellular organisms posses all these type of cells so Answer D is correct.

In short a gamete is an egg cell (female gamete) or a sperm (male gamete). This is an example of anisogamy or heterogamy, the condition in which females and males produce gametes of different sizes. This is the case in humans, the human ovum has approximately 100,000 times the volume of a single human sperm cell. 

Schleiden and Schwann presented a cell theory which proposed that each cell is itself is an organism which has all attributes of life. Each cell is living its individual life as well as the as a group of tissue which has become an integral part of plant. So Schleiden while observing plant cells discovered this double life of each cell. So option A is correct.

The average size of a human cell is about 100 μm in diameter. The smallest of which is the red blood cell, and it also has not nucleus.