Class 8 Science Lesson 8 Inside Question and Answer NCERT & CBSE Board Here in this post. NCERT Class 8 Science Textbook Lesson 8 Inside Questions.
- Grade: VIII
- Lesson 8 Cell – Structure and Functions
Que. 1) Fill in the blanks.
(1) Organism are made of more than one cell are called——
(2) A billion is —— million.
(3) ——- is a unit of inheritance in living organisms.
(4) ——— us a group of similar cells performing specific functions.
(5) All organisms are made of smaller parts called——-
Que. 2) Answer the following questions.
Define the followings.
Unicellular organism -The organism have only one cell or single cell organism called unicellular organism.
Multicellular organism- The organism are made of more than one cell is called multicelluar organism.
Pseudopodia-The organism have false feet is known as pseudopodia.
Tissue-The organism are made up of smaller parts is called tissue.
Cell wall-The outer thick layer of plant cell is called cell wall.
Nuclear membrane-Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane.
Cytoplasm- The jelly like substance between the nucleus and the cell membrane is called cytoplasm.
2.) Discuss the followings.
Shape of cell- In humans there are different type of cells like some are round in shape or some are spindle in shape . components of the cell are enclosed in a membrane which provides shape to the cells of plants and animals. Mostly cells are round ,spherical or elongated. Some cells are long and pointed at both ends. They are a spindle shape. Cells sometimes are little or quite long. Some are branched cells like the nerve cell or a neuron. The nerve cell receives and transfer messages thereby helping to control and coordinate the working of different parts of the body.
Size of cell-The size of cells in living organisms may be as small as a millionth of a meter (micrometer or micron) or may be as large as a few centimeters. Most of the cells are microscopic in size and are not visible to the opened eye. Therefore they enlarged or magnified by a microscope. The smallest cell is 0.1 to 0.5 micrometer which found in The largest cell measuring 170mm into 130mm, which is the egg of an ostrich. The size of cell has no relation with the size of the body of the animal or plant. The size of the cell is related to its function.
3.) Give difference between followings.
(1) Unicellular and multicellular
|The organisms are made of only one or single cell is known as unicellular organism.
Uni- single, cellular- cell.
The organism are made of more than one or more cell is known as multicelluar organism.
Multi- many , cellular- cell.
For example- Amoeba, Paramecium
For example- human beings, plants.
(2) Prokaryotic cell and eukaryotic cell
|The cells having nuclear material without nuclear membrane are known as prokaryotic cell.||
The cell having well organized nucleus with a nuclear membrane is known as eukaryotic cell.
Prokaryotes means, pro- primitive, karyon- nuclelus ,the organism of these kind of cells are called Prokaryotes.
|Eukaryotes means ,eu- true, karyon- nucleus,the organism of these kind of cells are called Eukaryotes.|
|For example- bacteria, blue green algae.||
For example-plant cell , animal cell.
(3) Plant cell and animal cell
|The cell wall is present||
The cell wall is absent.
Vacuoles are large in size.
|Vacuoles are small in size.|
|Coloured body plastisides are present.||
Plastisides are absent.
4.) Write short note on the followings.
Cell membrane –The basic component of the cell are Known as cell membrane. It is also called plasma membrane. The cytoplasm and nucleus are enclosed within the cell membrane. The membrane separates cells from one another and also the cell from the surrounding is porous and allows the movement of substances or materials both inward and outward .cell membrane is covered with the thick covering called cell wall. Cell wall is present in plant cell.
Cytoplasm- It is jelly like structure present between the cell membrane and the nucleus. Various other components or organelles of cells are present in the cytoplasm. These are Mitochondria ,Golgi bodies, Ribosomes, etc.
Nucleus-It is an important component of the living cell. It is generally spherical and located in the centre of the cell. It can be stained and seen easily with the help of a microscope. Nucleus is separated from the cytoplasm by a membrane called nuclear membrane. This membrane allows the movement of materials between the cytoplasm and the inside of the nucleus. There are smaller spherical bodies are present called nucleolus. Nucleus contain thread like structure called chromosomes.