CHAPTER 8
CELL STRUCTURE AND FUNCTIONS
This article brings you the CBSE Class 8 Science solution of CHAPTER 8 'CELL STRUCTURE AND FUNCTIONS '. This will help students to easily understand the answer of textbook questions of Chapter 8 Cell structure and function and some important keypoints are also given which helps students to easily go through the CHAPTER 8 CELL STRUCTURE AND FUNCTIONS.
IMPORTANT KEYPOINTS OF CHAPTER 8 CELL STRUCTURE AND FUNCTIONS.
a)Cell:- Cell is the smallest unit of the living body.
b)Cell Membrane:-Outer covering of the cell is known as Cell Membrane.
c)Cell Wall:- Protective layer of the plant cell which present outer to the cell membrane only in plants cell.
d) Chloroplast :-Green colour plastids which contain chlorophyll are known as Chloroplast.
e) Chromosomes :-Thread like structure which is present in the nucleus of cell contain parentile information are known as Chromosomes.
f)Eukaryotes:- Cell which contains proper nucleus with nucleus membrane and other organelles with their outer covering are known as Eukaryotes.
g)Gene:- Gene is a unit of inheritance in living organism,it control transfer of characters from parents to offspring.
h)Multicellular Organisms: - The organism which are having more than one cell is known as Multicellular.
i) Nucleus:- Spherical structure of the cell it present in the centre of the cell is known as Nucleus.
j) Plastids :-Coloured bodies present only in plant cell provide colour to different parts of plants are known as Plastids.
k) Prokaryotes:- The cell which are not having proper nucleus( nucleus with membrane) are known as Prokaryotes.
l)Tissue:- Tissue is a group of cell.
m)Unicellular:-Organisms which are hving only single cell are known as Unicellular.
n) Vacuole:- A blank structure of the cell is known as Vacuole.
Textbook questions of CHAPTER 8 'CELL STRUCTURE AND FUNCTIONS
Ques 1. Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one celled body.(T/F)
(b) Muscle cells are branched.(T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape.(T/F)
Ans. (a) True
(b) False
(c) False
(d) True
Ques 2. Make a sketch of the human nerve cell. What function do nerve cells perform?
Ans. The nerve cell receives and transfers messages, thereby helping to control and coordinate the working of different parts of the body.
Ques 3. Write a short notes on the following.
(a) Cytoplasm
(b) Nucleus of a cell
Ans. (a) Cytoplasm:- The cytoplasm is a fluid that contains all the cell organelles such as the Mitochondria, Ribosomes , Golgi Bodies etc. It is present between the nucleus and the plasma membrane .It helps in the exchange of materials between cell organelles.It is made up of eighty percent water and is usually clear and colourless.
(b) The nucleus of a cell:- Nucleus is an important component of the living cell.It is a generally spherical and located in the centre of the cell.The nucleus contain thread like structure called chromosomes.
Ques 4. Which part of the cell contains organelles?
Ans. Cytoplasm, gelatinous fluid inside a cell contains various organelles like mitochondria, golgi bodies, ribosomes etc.
Ques 5. Make s sketch of animal and plant cell. State three differences between them.
Ans.
| Plant cell | Animal cell |
| They are large in size | They are smaller than plant cells |
| The cell wall is present | The cell wall is absent |
| Vacuoles are large | Vacuoles are small |
| Plastids could be seen | Except for Euglena, Plastids could not be seen in animal cells. |
Ques 6. State the difference between eukaryotes and prokaryotes.
Ans. Prokaryotes:- The cells having nuclear material without nuclear membrane are termed as prokaryotic cells. The organisms with these kinds of cells are called prokaryotes.
Example:- Bacteria and blue green algae.
Eukaryotes:- The cells having a well organised nucleus with a nuclear membrane are termed as Eukaryotic cells. The organisms with these kinds of cells are called eukaryotes.
Example: onion cells and cheek cells.
Ques 7. Where are chromosomes found in a cell? State their functions.
Ans. Chromosomes are found in the nucleus of the cell. These carry genes and help in inheritance or transfer of characters from the parents to the offspring.
Ques 8. 'Cells are the basic structural unit of living organisms'.Explain.
Ans. a) Cells are morphological and physiological unit of all living organisms.
b) Properties of given organism depend on those of its individual cells.
c)Cell originates from pre- existing cells.
d)Cell maintains ontinuity through genetic material.
Ques 9. Explain why chloroplasts are found only in plant cells?
Ans. Chloroplasts are found in plant cells only because chloroplasts contain chlorophyll which is essential for photosynthesis. Chlorophyll which is essential for photosynthesis. Chlorophyll traps cell energy and use it to prepare food for plants.
10. Complete the crossword with the help of clues given below.
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
Ans:-
Across
Chlorophyll
Organelle
Protoplasm
Genes
Down
Chloroplasts
Organ
Membrane
Vacuole
Tissue
This is the complete solution of CHAPTER 8 CELL STRUCTURE AND FUNCTION of NCERT SCIENCE of CLASS 8.This will helps students to understand the topics completly.
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