ସିଟି ପରୀକ୍ଷା ୨୦୧୯..PLANT CELL & ANIMAL CELL

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Cell Structure and Function Question Answers

April 10, 2019

Cell Structure and Function Question Answers

The topics we will cover in this chapter are as follows:

Cells

Discovery of Cells

Cell Shape and Size

Cell Numbers

Basic Structure of Cell

Cell Organelles

Difference between Plant and Animal Cells

All plants and animals (small or large) are made up of same small units that are cells.

Cells

Cells are the basic building blocks of all living things. Cell is a structural and functional unit of living organisms.

Cells may be compared to bricks. Bricks are assembled to make a building. Similarly, cells are assembled to make the body of every organism. All organisms are made up of cells.

All basic chemical and physiological functions of living beings – for example, repair, growth, movement, immunity, communication, and digestion etc are carried out inside the cells.

Discoveries

Who discovered cells?

Answer: Cells were discovered by Robert Hooke. In 1665, the English scientist Robert Hooke observed slices of cork (bark of tree) which is part of bark of a tree, under a simple magnifying device. He noticed partitioned boxes or compartments in the cork slice.

The instrument used to see cells is microscope.

Microscope is an instrument which is used to magnify the very small objects, which cannot be seen with the naked eye. It was discovered by Anton van Leeuwenhoek. The Ancient microscope is the microscope which discover the cell.

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Types of cell

There are two types of cell which are as follows:

Prokaryotic Cells
The cells having nuclear material without nuclear membrane are termed as prokaryotic cells. The organisms with these kinds of cells are called prokaryotes. “Pro” means primitive and “karyon” means nucleus. Examples: bacteria and blue green algae.

Eukaryotic cells
The cells having well organised nucleus with a nuclear membrane are designated as eukaryotic cells. All organisms other than bacteria and blue green algae are called Eukaryotes. “Eu” means true and “karyon” means nucleus.

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Cells have Three Basic Characteristics

Cell Membrane

Genetic Material

Metabolic Machinery

Cell Shape and Size

The shape of the cell depends upon its function. The shape of the cell may change or remain same.

For example: The cells which are helpful in protection have different characteristics and similarly the cells involved in circulation have different characteristics.

Different shapes of Cell are as follows:

Spindle like

Flat

Oval

Irregular

Disc like

Round

Cylindrical

Cube-like

Elongated

Branched

Branched- The nerve cell is branched-shape cell. Nerve cell receives and transfers messages for helping to control and coordinate the working of different parts of the body.

Disc like

Cells which are in disc-like in shape. For example: RBC (Red blood cells).

Spindle like

These are the cells which are spindle in shape (These type of cells are narrow from ends and wider from middle). For example: Smooth muscle fiber.

Flat

Skin cells are flat.

There are few cells which can change their shape according to their requirement. For example: WBC(White blood count) and Amoeba.

Cell size

There are different sizes of cells. In animals, the smallest cell size is 0.1 micron and it is present in Mycoplasma.

The largest cell is in ostrich egg and it is 17 cm in diameter.

In man, the smallest cell is Red Blood Cell and its size is 6-8 micrometer. The longest cell is nerve cell and its size can be upto 100 microns.

The size of the cells has no relation with the size of the body of the animal or plant.

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Cell number

Unicellular: The single celled organisms are called unicellular. For example: Amoeba.

Multicellular: The organisms which have more than one cell are called multi-cellular. For example: Man.

Here is the most important question.

Question: Cells are the basic structural units of living organisms. Explain.
Answer: All the living organisms are made of cells either unicellular or multicellular. The basic functions of life like respiration, assimilation and all major metabolic activities are carried inside the cell. So, cell is known as structural and functional units of living organism.

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Cell Structure

Basic cell contains:

1. Cell membrane

The outermost membrane of the cell is called as cell membrane.

2. Protoplasm

Everything that is present in the cell except cell membrane comes under protoplasm. Protoplasm is living material of cell. Or the entire content of living cells including cytoplasm and nucleus is known as protoplasm.

Protoplasm is further divided into two parts:

Cytoplasm

Nucleus

Question: Who discovered nucleus and protoplasm?

Answer:

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