NCERT Solution //class 8// Science // Chapter 8- Cell structure and functions

NCERT solutions of class 8 >Science > Chapter 8 - Cell structure and functions 
NCERT Solution //class 8// Science // Chapter 8-  Cell structure and functions



1 .   Indicate whether the following statements are true or false

a)  Unicellular organisms have one -celled body.    
Answer. - True
b) Muscle cells are branched
Answer. -True
c) The basic living unit of an organism is an organ
Answer-. False
d) Amoeba has irregular shape
Answer . True
 
2. Make a sketch of human nerve cell what function do nerve cell perform? 
Answer .

       Function of nerve cells-
 Nerve cell carry the signal of sensation from different body parts to brain or  it again carry the reverse signal from brain to other body parts.

3. Write a short notes on following
 a) Cytoplasm - 
           The space present between the nuclear membrane and plasma membrane is filled with the translucent jelly like fluid which is called cytoplasm. All cell organelles are embedded in cytoplasm. It contain different types of reserved food materials ,enzymes ,excretory materials etc.

b) Nucleus of a cell - 
      It is a controlled center of the cell.  It is spherical and located in the center of the cell . It is surrounded by a membrane called nuclear membrane .Nuclear membrane separate the cytoplasm and nuclear material , inside the nucleus a genetic material is found in the form of chromosome they carry genes it helps in inherit and transfer of characters from parents to the offspring
.nucleus contain a jelly like structure called nucleoplasm .

4. Which part of the cell contains organelles? 
 Answer-. The cytoplasm part of the cell contains cell organelles like mitochondria ,chloroplast ,nucleus ,lysosomes etc.

5. Make sketches of animal and plant cell state three difference between them? 
Answer . 

  Animal cell - 1. The outer covering of the
animal cell is plasma membrane.
2. Nucleus present in the animal cell is in centre.
3. Centromere is present in animal cell.

Plant Cell


1. The outer covering of plant cell is cell wall.
2. Nucleus present in the plant cell is in the Periphery  .
3. Plastids are present in only plant cells

6. State the difference between eukaryotes and prokaryotes
Answer-. Eukaryotes- 
    1. Eukaryotes content to true nucleus nuclear membrane is present and more than one chromosome is present.
2. Membrane bound organelles are present.
3. Cell divides by mitosis or by meiosis
4. Example- all organisms other than bacteria and blue green algae.

Prokaryotes 
1. In this type of organism not true nucleus found ,single chromosome ,nuclear membrane absent.
2. Membrane bound organelles are absent.
3. Cell divides by simple fission.
4. Example- bacteria and blue green algae

7. Where are chromosome found in cell state their function? 
Answer. -Chromosomes are found in the cell in the nucleus
Function- Chromosome carries genes . Genes help in inheritance or transfer of characters from parents to the offspring

8.  Cell are the basic structural unit of living organism explain? 

Answer. -  A cell is capable of carrying out all the life functions such as nutrition ,excretion ,respiration etc . Hence a cell is called the functional unit of life additionally the cell is the smallest unit of life and all the living beings are made up of cells therefore a cell is called the structural unit of life.

9.  Explain why chloroplast are found only in plant cells? 

 Answer-.   Chloroplast is a green coloured plastids .It  contain chlorophyll ,chloroplast manufactured the food in plant  by the process of photosynthesis .and animals are unable to do the photosynthesis  that's why chloroplast only found in plant cell.

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 content of the cell from the surrounding medium
5. Empty structure in the cytoplasm
7. A group of cells


Comments

Post a Comment

Text

Popular posts from this blog

NCERT solution for class 6 || Science || Chapter 13 - Fun with magnets

  NCERT solution > class 6 > Science  Chapter 13 - Fun with magnets  Exercise  Q1. Fill in the blanks in the following.  i) Artificial magnet are made in different shapes such as  H orse shoe and cylindrical ii) The materials which are attracted towards a magnet are called Magnetic materials  iii) Paper is not Magnetic material . iv) In olden days sailor used to find direction by suspending a piece of Magnet   v) A magnet always has Two poles.  Q2. State whether the following statements are true or false  i) Cylindical magnet has only one pole  ii) Artificial magnets were discovered in Greece . iii) Similar poles of a magnet repel each other . iv) Maximum iron filings stick in the middle of the bar magnet when it is brought them near.  v) Bar magnets always point towards north south direction. vi) Compass can be used to find east west direction at any place . vii) Rubber is a magnetic material . Answer - i) fals...
Read more

NCERT solution for class 6 || science || chapter 14 - Water

 NCERT solutions>  Class 6 > Science  NCERT solution for class 6 || science || chapter 14 -  Water Chapter 14 -Water   Exercise  Q1. Fill up  the blanks in the following  a) The process of changing of water into its vapour is called evaporation b) The process of changing water vapour into water is called condensation  c) No rainfall for a year or more may lead to drought in that region . d) Excessive rain may cause floods . Q2. State for each of the following whether it is  due to evaporation or condensation  . a) Water drops appear on the outer surface of  a glass containing cold water. b) Steam rising from wet clothes while they are iron  c) Fog appearing on a cold winter morning  d) Blackboard dries up after wiping it  e) Steam rising from ala hot girdle when water is sprinkled on it . Answer -  a) Condensation  b) Evaporation  c) Condensation  d) Evaporation  e) Evaporati...
Read more