Question

Approximately how many cells are present in the body of an adult person?
A. ${10^{14}}$
B. ${10^{15}}$
C. ${10^{18}}$
D. ${10^{21}}$

Answer 1

Hint: The cell is known as the basic structural, functional unit of all living organisms. A cell can be defined as a living organism’s smallest unit. It is also called the “building block” of the living organisms since this makes the tissue, organ, organ system. The study of the cell is called cell biology or cytology.

Complete answer:
Every living organism is made up of this basic unit of life that is a cell. The number of cells in particular organisms varies. Depending on the number they are classified as unicellular organisms and multicellular organisms. Cells are microscopic that can be observed only under a microscope. Unicellular organisms are those that are made up of a single cell. Example- Bacteria. Multicellular organisms are those that are made up of more than one cell. Example – Plants, Animals.
The basic structure of the cell contains the following components. The cell membrane, Nucleus, Mitochondria, Endoplasmic reticulum, Golgi bodies, lysosomes, etc. They are called the cell organelles. The covering of the cell is called the cell membrane. In the case of plants, there is an extra outer cover that is the cell wall. This is the toughest wall of the plant. In the case of animals, the cell wall is absent. In-plant there is the presence of an organelle called the chloroplast that synthesizes food. This makes plant producers. But this is absent in animals.
Life in the case of sexually reproducing organisms arises by the fusion of male and female gamete. These single cells fuse and give rise to multicellular organisms. An adult human body has approximately 100000 million cells. It will be ${10^{14}}$.

The correct answer is option A.

Note:
As a person ages, the number of healthy cells will decrease. In the new-born infant, the number of cells is approximately 26,000,000,000. As a person becomes old the number of cells will be less and eventually, it will lead to death.