Tag: cell as structural and functional unit

• The first characteristic of a living thing is that they are made up of cells. A cell is a basic building block of all organisms. 
• It is the smallest unit of organization in a biosphere. A cell performs the life process to maintains the survival of an organism.

Cells can be prokaryotic or eukaryotic. If the cells have dispersed nucleus i.e., nucleoid then these are called as prokaryotic cells. Eukaryotes are organisms, whose cells are organized into complex structures by internal membranes and a cytoskeleton.
So, the correct answer is option C.

• Cells are called the structural and functional unit of life 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. Cells provide specific conditions, for the occurrence of the metabolic reactions. These have specialized enzymes, which catalyze the biochemical reaction and regulates the functions of the body.

• Tissues are the group of cells, which may be similar or dissimilar in structures, but coordinates to perform specialized functions e.g., xylem.

The first man to witness a live cell under a microscope was Antonie van Leeuwenhoek, who described the algae, Spirogyra, in 1674. He named that cell as animalcules. He is also known as father of microbiology, as he was first to study the microorganism.
So, the correct answer is option D.

• The cell is considered to be the basic unit of life in many pathological processes. 
• In addition, the phenomenon of energy flow occurs in cells in processes that are part of the function known as metabolism. 
• Cells contain hereditary information (DNA), which is passed from cell to cell during cell division and from one generation to next. Thus, the correct answer is option D

Antonie van Leeuwenhoek (1632-1723) described cells in a drop of pond water using a microscope made by him. He was the first person to observe bacteria and protozoa. By observing the movement of bacteria or protozoa he named them animalcules. Therefore, the correct answer is option A.

The size of cells and microorganisms are too small to observe by naked eyes. It was impossible to study them but with the invention of the microscope, cells became visible and many new discoveries were made about them. Therefore, the correct answer is option D.

Cytology is the branch of science which, deals with the study of form, structure, and contents of cells as observed under the microscope. The term was coined by Hertwig in 1893. Cytology has enormous application in genetics, biomedical research etc. It is used for diagnosis and screening of various diseases. It can also be for the study of the genetic composition of a living organism.

Virus are non-living crystallisable entities which replicate in other living cells. They do not have a cellular structure and are an exception to cell theory.