Class 8 Science - Chapter Cell - Structure and Functions NCERT Solutions | Write short notes on the following: (a)
Write short notes on the following:
(a) Cytoplasm
(b) Nucleus of a cell
- Cytoplasm: Cytoplasm is a fluid like substance which fills the cell and it is present between the plasma membrane and the nucleus. In cytoplasm, cell organelles like ribosomes, mitochondria and golgi bodies are suspended. Exchange of material between cell organelles is done with the help of cytoplasm.
- Nucleus of a cell: The spherical structure is present in the center of the cell called as nucleus. It is composed of the following components:
- Nuclear membrane: A double layered membrane which separates the contents of the nucleus from the cytoplasm is known as nuclear membrane. Pores that are present in the nuclear membrane which allows the transfer of specific substance in and out of the nucleus.
- Nucleolus: The spherical bodies which are not bounded by a membrane called as nucleolus.
- Chromosomes: The thread like structure which carry genes. Genes have the necessary information for the transfer of different characteristics from parents to the offspring. Therefore, inheritance mainly depends on the chromosomes.
More Questions From Class 8 Science - Chapter Cell - Structure and Functions
- Q:-
Make sketches of animal and plant cells. State three differences between them.
- Q:-
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.
- Q:-
Make a sketch of the human nerve cell. What function do nerve cells perform?
- Q:-
Explain why chloroplasts are found only in plant cells?
- Q:-
Where are chromosomes found in a cell? State their function.
- Q:-
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) - Q:-
‘Cells are the basic structural units of living organisms’. Explain.
- Q:-
State the difference between eukaryotes and prokaryotes.
- Q:-
Which part of the cell contains organelles?
Popular Questions of Class 8 Science
- Q:-
Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen - Q:-
Fill in the blanks
(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.
(b) The passage of an electric current through a solution causes ______________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the terminal of the battery.
(d) The process of depositing a layer ofany desired metal on another material by means of electricity is called . - Q:-
Give two examples each of situations in which you push or pull to change the state of motion of objects.
- Q:-
Fill in the blanks:
(a) Friction opposes the _____________ between the surfaces in contact with each other.
(b) Friction depends on the _____________ of surfaces. (c) Friction produces __________.
(d) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction. - Q:-
List conditions under which combustion can take place.
- Q:-
Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth. - Q:-
Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called .
(b) Species found only in a particular area is known as .
(c) Migratory birds fly to far away places because of changes. - Q:-
Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.
- Q:-
What are the different ways in which water gets contaminated ?
- Q:-
Explain the importance of reproduction in organisms.
Recently Viewed Questions of Class 8 Science
- Q:-
If wheat is sown in the kharif season, what would happen? Discuss.
- Q:-
Complete the word puzzle:
Down
1. Species on the verge of extinction.
2. A book carrying information about endangered species.
5. Consequence of deforestation.
Across
1. Species which have vanished.
3. Species found only in a particular habitat.
4. Variety of plants, animals and microorganisms found in an area.
- Q:-
Explain how deforestation leads to reduced rainfall.
- Q:-
Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct? If not, correct it.
- Q:-
(a) Find out the position of the image of an object situated at A in the plane mirror (Fig. 16.21).
(b) Can Paheli at B see this image?
(c) Can Boojho at C see this image?
(d) When Paheli moves from B to C, where does the image of A move?
- Q:-
The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accomodate?
- Q:-
Boojho stands at A just on the side of a plane mirror as shown in Fig. 16.20. Can he see himself in the mirror? Also can he see the image of objects situated at P, Q and R?
- Q:-
Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?
- Q:-
Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. 16.19. Draw the reflected ray from the second mirror.
- Q:-
Do all the stars in the sky move? Explain.
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