NCERT Exemplar Solution Class 8 Science Chapter 8
NCERT Exemplar Solution Class 8 Science Chapter 8 Cell- Structure and Functions all Questions Answer Solution. NCERT Exemplar Class 8 Science Chapter 8 Solution PDF.
NCERT Exemplar Solution Class 8 Science Chapter 8: Overview
NCERT Exemplar Solution Class 8 Science Chapter 8 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
8 |
Subject |
Science |
Chapter |
8 |
Chapter Name |
Cell- Structure and Functions |
NCERT Exemplar Solution Class 8 Science Chapter 8 Cell- Structure and Functions
Multiple Choice Questions
1) Choose the correct statement with respect to unicellular organisms:
a) In unicellular organisms, tissues work in co-ordination to perform different functions.
b) Unicellular organisms do not require food.
c) Unicellular organisms respire and reproduce.
d) All unicellular organisms move by cilia.
Answer:- c) Unicellular organisms respire and reproduce.
The only correct statement given above is unicellular organisms respire and reproduce. All the other are wrong.
2) Majority of cells cannot be seen directly with our naked eyes because:
a) Organisms are generally unicellular.
b) Cells are microscopic.
c) Cells are present only inside the body.
d) Cells are grouped into tissues.
Answer:- b) cells are microscopic.
Cells are so minute that they cannot seen with naked eyes. We can see it with the help of microscope.
3) Read the different combinations of terms given below.
a) Cell wall, cell membrane, nucleus, plastid
b) Cell wall, nucleus, ribosome, chromosome
c) Cell membrane, mitochondria, ribosome, chromosome.
d) Cell membrane, ribosome, mitochondria, chloroplast.
The correct combination of terms with reference to an animal cell is __________.
Answer:- c) cell membrane, mitochondria, ribosome, chromosome.
The correct combination of terms with reference to an animal cell is cell membrane, mitochondria, ribosome and Chromosome. Other pairs has some wrong organelle.
4) Which one of the following term is not a part of the Nucleus?
a) Ribosome
b) Nucleolus
c) Chromosome
d) Gene
Answer:- a) Ribosome
Ribosomes are present out of the nucleus in the cell.
5) A suitable term for the various components of cells is
a) Tissue
b) Cell organelles
c) Chromosomes
d) Genes
Answer:- b) Cell organelles
Tissues, chromosomes and genes are meant for other functions. Cell organelles are the term for the components of the cells.
6) The jelly-like fluid substance present in cells is called
a) Protoplasm
b) Chromosome
c) Chloroplast
d) Cytoplasm
Answer:- d) Cytoplasm
Cytoplasm is present in the cell which is a jelly like fluid substance. All the other organelles float in these fluid.
7) Read the following pairs of examples of organisms.
a) Moss and sponge
b) Yeast and Amoeba
c) Bacteria and blue-green alga
d) Penicillium and spirogyra.
The pair that belongs to the group prokaryotes is ______________.
Answer:- c) Bacteria and blue green alga
Bacteria and blue green alga both belongs to the prokaryotes. Other set does not have both prokaryotes.
8) Read the following terms and select the pair that is related to inheritance of characters.
a) Cell wall and cell membrane
b) Chromosome and mitochondria
c) Chloroplast and cell membrane
d) Chromosome and genes
Answer:- d) chromosome and genes
Genes are transporters of hereditary characters which are present in the Chromosomes.
9) Choose the correct statement:
a) Genes are located in the chromosomes.
b) Cell is located in the Nucleus.
c) Chromosomes are located in the nucleolus.
d) Cell membrane surrounds the Nucleus.
Answer:- a) Genes are located in the chromosomes.
Genes are present in the Chromosomes which are the transporters of the hereditary characters from parents to the offspring.
10) Green colour of leaves is due to presence of the pigment___________
a) Chlorophyll
b) Ribosomes
c) Mitochondria
d) Chloroplast
Answer:- a) chlorophyll
Chlorophyll is a pigment which is present in the leaves responsible for the green colour of it. Ribosomes, mitochondria and Chloroplast are the cell organelles present in the cell.
11) The unit of measurement used for expressing dimension (size) of cells is :
a) Centimetre
b) Millimetre
c) Micrometre
d) Metre
Answer:- c) Micrometres
As the cells are microscopic the measurement used for expressing dimension of the cell is micrometre. Centimetre, millimetre and metre are used to measure length of large size.
12) The most important function of cell membrane is that it:
a) Controls the entry and exit of materials from cells.
b) Controls only the entry of materials into cells.
c) Controls only the exit of materials from cells.
d) Allows entry and exit of materials without any control.
Answer:- a) Controls the entry and exit of materials from cells.
Cell membrane is the outermost covering of the cell which gives the shape to the cell, it protects to cell and the main function is to control the entry and exit of materials from cells.
13) Paheli accidentally placed her hand over a flame and immediately pulled it back. She felt the sensation of heat and reacted due to the action of
a) Blood cells
b) Skin surface
c) Nerve cells
d) Nucleus of cells
Answer:- c) Nerve cells
Nerve cells or neurones are the receivers and transporters of messages to the brain. Due to nerve cells we feel the sensation.
14) Of the following parts of a cell listed below, name the part that is common to plant cell, animal cell and a bacterial cell.
a) Chloroplast
b) Cell wall
c) Cell membrane
d) Nucleus
Answer:- c) cell membrane
Cell membrane is common in plant, animal and bacterial cell. Other organelles are not present in all of the three.
15) The thread like structures present in the nucleus are
a) Nucleolus
b) Chromosomes
c) Genes
d) Ribosomes
Answer:- b) Chromosomes
Chromosomes are thread like in appearance these are present in nucleus. They are the carriers of the genes .
16) Identify the statement which is true for cells.
a) Cells can be easily seen with naked eyes.
b) Insect’s egg is not a cell.
c) A single cell can perform all the functions in a unicellular organism.
d) The size and shape of cells is uniform in multicellular organisms.
Answer:- c) A single cell can perform organism functions in a unicellular organism.
Unicellular is the single celled organism. As it is single celled organism, it performs all the functions alone
a) Red blood corpuscles (RBC)
b) Bacterium
c) Spermatozoa
d) Virus
Answer:- d) Virus.
17) Which of the following is not a cell ?
Viruses are not made up of cells. These are mainly made up of protein. These also cannot reproduce by itself. It reproduces with the help of host cell.
18) Which of the following feature will help you in distinguished a plant cell from an animal cell?
a) Cell wall
b) Cell membrane
c) Mitochondria
d) Nucleus
Answer:- a) cell wall
Cell wall is present in plant cell but not in Animal cell.
19) Under a microscope paheli Observes a cell that has a cell wall but no distinct Nucleus. The cell that she observes is
a) A plant cell
b) An animal cell
c) A nerve cell
d) A bacterial cell
Answer:- d) A bacterial cell.
Bacterial cell has a cell wall like an plant cell nut it does not have a well organised Nucleus.
20) Cheek cells do not have _________
a) Cell membrane
b) Nucleus
c) Golgi apparatus
d) Plastids
Answer:- d) Plastids
Cheek cells does not have plastids . Plastids are found in the leaf cells of plant. These Coloured body are only found in the plant cells.
21) Identify the correct statement.
a) Tissue is a group of dissimilar cells.
b) An organ consists of similar cells.
c) Vacuoles are not found in plant cells.
d) Prokaryotes do not have nucleus.
Answer:- d) Prokaryotes do not have Nucleus.
Prokaryotes do not have well organised Nucleus. They lack in nuclear membrane therefore it is named as prokaryotes.
22) Which of the following statements are true for eukaryotic cells ?
i) They do not have a nuclear membrane.
ii) That have a well organised Nucleus.
iii) They have a nuclear membrane.
iv) Blue green algae are eukaryotic cells.
a) II and IV
b) II and III
c) I and II
d) I and IV
Answer:- b) II and III
Eukaryotic cells are known as cells which have nuclear membrane and well organised Nucleus.
23) Identify the correct statement about cells.
a) All the cells have Nucleus
b) Cells of an organ have similar structure.
c) Cells of a tissue have similar structure.
d) Shape of all types of cells is round.
Answer:- c) cells of a tissue have similar structure.
The correct statement about cell is that cells of a tissue have similar structure. All the other statement have wrong words.
24) The table given below has certain terms and four blank spaces named A, B, C, and D.
Cell
|
Feature/ part | Function |
Amoeba
|
A | Movement |
Plant cell
|
Plastid | B |
C
|
Spindle shaped | Contraction |
Nerve cell
|
D | Stimuli and response |
From the options given below choose the correct combination of terms.
a) A- pseudopodia; B- Respirations; C- Muscle cell; D- Branched
b) A- pseudopodia; B- photosynthesis; C- muscle cell; D- Branched
c) A- contractile vacuole; B- photosynthesis, C- Blood cell; D- spindle shaped
d) A- pseudopodia; B- photosynthesis; C- cheek cell; D- spindle shaped
Answer:- b) A- pseudopodia, B- photosynthesis, C- muscle cell, D- Branched
These is the correct combination of term.
Movement in amoeba takes place with the help of pseudopodia.
Plastids in the plant cell helps in the function of photosynthesis.
Spindle shaped muscle cells help in contraction.
Branched nerve cells are responsible for stimuli and response.
Very Short Answer Questions
25) leaves, name the cell organelle and pigment that is responsible for green colour.
Answer:- chloroplast is the cell organelle and chlorophyll is the pigment in the leaves which is responsible for green colour.
26) The instrument used to observe cells is ___________
Answer:- The instrument used to observe cells is microscope.
27) We do not sense any pain when we clip our nails or cut our hair. Why?
Answer:-
We don’t feel painwhen we cut our nails or hairs this is because our hair and nails are made up of dead cells. They don’t have nerve cells in it. Therefore we don’t have feel anything on cutting nails and hairs.
28) In a cell, where are the genes located?
Answer:- genes are hereditary transporters which are located in the Chromosomes, in nucleus of the cell.
29) Amoeba and paramecium belong to which category of organisms?
Answer:- Amoeba and paramecium belongs to the Eukaryotic cell i.e unicellular. These belongs to protozoa group.
30) What are the functions of cell wall in the plant cells?
Answer:-
The Function of the cell wall is to protect the cell and cell organelles. Another function of the cell wall it to give shape to the cell.
Short Answer Questions
31) Is the following statement correct? If it is wrong, correct the statement.
Statement : “ Unicellular organisms do not respire, only multicellular organisms respire”
Answer:- The given statement is wrong.
The correct statement is –
“ Unicellular and multicellular both the organisms respire”
32) Match the terms given in column I with their functions given in column II and fill the blanks given below the table:
Column I
|
Column II |
A. Chloroplast
|
i) Carries hereditary characters |
B. Cell membrane | ii) Controls the activities of cells |
C. Nucleus
|
iii) Site of photosynthesis |
D. Chromosome
|
iv) Controls the movement of materials into and out of cells. |
A-_______; B-_________; C-_______;
D-_________.
Answer:-
A) Chloroplast→ iii) site of photosynthesis
B) cell membrane → iv) controls the Movement of material Into and out of cells.
C) nucleus → ii) controls the activities of cell
D) Chromosome→ i) carries hereditary Characters.
33) Observe the following diagram given as fig. 8.1
Answer the following questions.
Fig. 8.1
A-Does it represent a plant cell or an animal cell?
Answer:- it is an animal cell.
B-Does it represent a prokaryotic cell or an eukaryotic cell?
Answer:- It is a Eukaryotic cell.
34) Label the parts A to E in the given as fig. 8.2 diagram.
Answer:-
35) Classify the following terms into cells, tissues and organs and write in the tabular Column given below.
RBC, WBC, Nerve cell, blood, muscle, blood vessels, brain, heart, hand.
Cell
|
Tissue | Organ |
_________
|
_________ | __________ |
__________
|
__________ | __________ |
__________
|
___________ | __________ |
Answer:-
Cell
|
Tissues | Organ |
RBC |
Blood |
Blood vessels |
WBC |
Muscle |
Heart |
Nerve cell |
Nerve |
Hand
Brain |
36) Read the following statements and write the appropriate term against each statement.
I control the functions of a cell. Who am I?
Answer:- It is a Nucleus.
Nucleus control all the functions of the cell.
I am like a policeman. I do not allow anything and everything to get in and out of the cell. Who am I?
Answer:- it is a cell membrane.
Cell membrane allow the important materials to in and out of the cell. And restrict the foreign material.
I transfer characters from parents to offsprings. Who am I?
Answer:- it is an Genes / chromosomes.
Genes transfer all the hereditary characters from parents to offspring.
37) Fill in the blanks with the terms given in the box below:
Nucleus , chromosomes, cell wall, cell membrane, protoplasm, cytoplasm, ribosome, cell organelles
The outermost layer of the plant cells is the _____(a) _____ beneath which is the _____(b) _____ . The term _____(c) ______ refers to the jelly -like substance containing all the ____(d) ____. The _____(e) _____ contains thread like structures called _____(f) _______.
Answer:-
The outermost layer of the plant cell is the cell wall beneath which is the cell membrane. The term cytoplasm refers to the jelly like substance containing all the cell organelles . The nucleus contains thread like structures called chromosomes.
Long Answer Questions
38) Cells consist of many organelles, yet we do not call any of these organelles as structural and functional unit of living organisms. Explain.
Answer:- Cell organelles perform many functions and have specific structure but though they cannot called as an structural and functional unit of living organism. Because these organelles can perform the specific Functions only when these are into the cell. If these are placed outside then they cannot perform any function as an independent unit.
39) Why do plant cells have an additional layer surrounding the cell membrane? What is this layer known as ?
Answer:- The additional layer surrounding the cell membrane is necessary for the protection of the plant cell. Plants cannot move from their place. Therefore they need more protection against heat of sun-light, high speed wind, atmospheric moisture, heavy waterfall etc. They are always exposed in every conditions thus they need more protection. Therefore they have an extra layer of surrounding to cell membrane.
40) The size of the cells of an organism has no relation with the size of its body. Do you agree? Give reason for your answer.
Answer:- Yes, I agree with the statement, That the cell of an organism has no relation with the size of its body. The cells in the body of human beings is not so much bigger than the cells present in the rat. The size of the cell in an organism is related to the function which is to be performed.