NCERT Solutions of Chapter: Cell – Structure and Functions. NCERT Solutions along with worksheets and notes for Class 8.
(1) Indicate whether the following statements ate True (T) or False (F)
(a) Unicellular organisms have one – celled body.
(b) Muscle cells are branched.
(c) The basic living unit of an organism is an organ.
(d) Amoeba has irregular shape.
(a) Unicellular organisms have one – celled body. T
(b) Muscle cells are branched. F
(c) The basic living unit of an organism is an organ. F
(d) Amoeba has irregular shape. T
(2) Make a sketch of the human nerve cell. What functions do nerve cells perform?
Ans- Nerve cells are like branch of a tree. These cells receive and transfers messages. Thus, control and coordinate the working of different parts of the body.
(3) Write short notes on the following.
(b) Nucleus of a cell
(a) Cytoplasm – A jelly like structure found in between nucleus and cell membrane which has many organelles of cells like mitochondria, golgi bodies, ribosomes etc. is called cytoplasm.
(b) Nucleus of the cell – The round body in the centre of the cell which acts as control center of the activities of the cell is called nucleus of the cell.
A membrane which is porous and separates cytoplasm and nucleus is called nuclear membrane. It allows the movement of the materials between the cytoplasm and the inside of the nucleus.
Parts of the nucleus
(i) A smaller spherical body inside the nucleus is called nucleolus.
(ii) The thread like structures of nucleus which carry genes and can be seen only when cell divides are called chromosomes.
(4) Which part of the cell contains organelles?
Ans- Cytoplasm of the cell contains organelles.
(5) Make sketches of animal and plant cells. State three differences between them.
Ans- Sketches of animal and plant cells are given below:-
Differences between plant cell and animal cell are given below:-
|SN||Plant Cell||Animal Cell|
|1.||They have cell wall.||They do not have cell wall.|
|2.||They have plastids.||They do not have plastids.|
|3.||They have a big central vacuole.||They have a small vacuoles.|
(6) State the differences between eukaryotes and prokaryotes.
Ans- Differences between eukaryotes and prokaryotes are listed below:-
|1.||These cells are found in plants.||These cells are found in bacteria.|
|2.||They have well organized nucleus.||They do not have well organized nucleus.|
|3.||They have a nucleus membrane.||They do not have nuclear membrane.|
|4.||Eg:- All organisms other than bacteria and blue green algae.||Eg:- Bacteria and blue green algae|
(7) Where are chromosomes found in a cell? State their functions?
Ans- Chromosomes are found in nucleus of ell. It is a thread like structures of nucleus which carry genes and can be seen only when cell divides. Gene is a unit of inheritance in living organisms. It transfers hereditary characteristics from parent to their offspring.
(8) ‘Cells are the basic structural units of the living organisms”. Explain.
Ans- Organs of every living organism is made up of tissues and tissues are made up of cells. Cells are responsible for the different functions like digestion, assimilation and absorption etc. Similarly, different cells of organs of plants perform different functions like absorption of water and minerals by roots and synthesis of food by leaves. Therefore, cells are the basic structural units of the living organisms.
(9)Explain why chloroplasts are found only in plant cells?
Ans- Chloroplast are found only in plant cell because they provide green colour to plants.
(10) Complete the cross word with the help of clues given bellow:-
(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.
(1) Green plastids.
(2) Formed by collection of tissues.
(4) It separates the contents of the ell from the surrounding medium.
(5) Empty structure in the cytoplasm.
(7) A group of cells.