NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

 

Multiple Choice Questions.........................


Question 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. 

Solution 1:  (c) unicellular organisms respire and reproduce.

Unicellular organisms are made up of single cells that perform basic functions like respiration, digestion, and reproduction. Option a) is incorrect because tissues are made up of multiple cells, whereas in unicellular there is only one cell. Option b) is incorrect because, like all other organisms, organisms require food to survive. For locomotion, different unicellular organisms use different organs.

 

Question 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 

Solution 2:  (b) cells are microscopic

Cells are the smallest units of life that can be seen with the naked eye. The size of a cell varies from nanometer to micrometre, which necessitates the use of a microscope to see. As a result, they are referred to as microscopic structures.

 

Question 3:  Read the different combinations of terms given below:

(a) cell wall, cell membrane, nucleus, plastid

(b) cell wall, nucleus, ribosome, chromosome

(c) the cell membrane, mitochondria, ribosome, chromosome

(d) the cell membrane, ribosome, mitochondria, chloroplast.

The correct combination of terms with reference to an animal cell is _____. 

Solution 3:  (c) cell membrane, mitochondria, ribosome, chromosome 

Option a) and b) are incorrect since they contain a cell wall that is exclusive to plant cells. Option d) is incorrect since it contains chloroplasts, which are not found in animal cells. As a result, c) is the correct answer.

 

Question 4: Which one of the following term is not a part of the nucleus?

(a) ribosome

(c) chromosome

(b) nucleolus

(d) gene 

Solution 4:  (a) ribosome 

Ribosomes are cytoplasmic organelles. Chromosomes, which are made up of genes, are structures found in the nucleus. The nucleolus is a component of the nucleus that aids in the synthesis of proteins.

 

Question 5:  A suitable term for the various components of cells is

(a) tissue

(b) cell organelles

(c) chromosomes

(d) genes 

Solution 5: (b) cell organelles 

A tissue is a collection of cells that collaborate to perform a specific purpose. Chromosomes are the thread-like structures that make up the nucleus and contain all of the genes. In living species, a gene is a unit of inheritance. It regulates the transmission of a genetic trait from parents to offspring. DNA is the material that makes up genes.

 

Question 6:  The jelly-like fluid substance present in cells is called

(a) protoplasm

(b) chromosome

(c) chloroplast

(d) cytoplasm 

Solution 6:  (d) cytoplasm 

Between the cell membrane and the nucleus, there is a jelly-like material. The cytoplasm contains a variety of other cell elements, or organelles. These include mitochondria, Golgi bodies, ribosomes, and other structures.

 

Question 7:  Read the following pairs of examples of organisms:

(a) moss and sponge

(b) yeast and Amoeba

(c) bacteria and a blue-green alga

(d) penicillium and Spirogyra

The pair that belongs to the group prokaryotes is_____ 

Solution 7:  (c) bacteria and a blue-green alga 

Prokaryotes are organisms that do not have a nucleus or cell organelles. Other choices include contained eukaryotes, so the correct answer is c).

  

Question 8:  Read the following terms and select the pair that is related to the inheritance of characters.

(a) cell wall and cell membrane

(b) chromosome and mitochondria

(c) chloroplast and cell membrane

(d) chromosome and genes 

Solution 8:  (d) chromosome and genes

Chromosome and genes is related to the inheritance of characters.

 

Question 9:  Choose the correct statement:

(a) Genes are located in the chromosomes.

(b) The cell is located in the nucleus.

(c) Chromosomes are located in the nucleolus.

(d) Cell membrane surrounds the nucleus. 

Solution 9:  (a) Genes are located in the chromosomes. 

Genes are the inheritance units found in chromosomes. The nucleus is found in cells, but the nucleus is not found in cells. The nucleus, not the nucleolus, contains chromosomes. The nucleus membrane, not the cell membrane, surrounds the nucleus.

 

Question 10:  The green colour of leaves is due to presence of the pigment_____

(a) chlorophyll

(b) ribosomes

(c) mitochondria

(d) chloroplast 

Solution 10:  (a) chlorophyll 

The pigment chlorophyll is found in the chloroplasts. Chlorophyll is the green pigment that gives leaves their colour. Chlorophyll absorbs solar energy and aids in its conversion to chemical energy.

 

Question 11:   The unit of measurement used for expressing dimension (size) of cells is:

(a) centimetre

(b) millimetre

(c) micrometre

(d) metre 

Solution 11:  (c) micrometre 

The unit of measurement used for expressing dimension (size) of cells is called micrometre.

 

Question 12:  The most important function of the 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. 

Solution 12:  (a) controls the entry and exit of materials from cells.

The cell membrane allows material to enter and exit cells more easily. The cell membrane also gives the cells their shape.

 

Question 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 

Solution 13:  (c) nerve cells

Paheli felt heat and responded as a result of the nerve cells' reaction to the stimulus. Nerve cells are specialised cells that receive and transmit signals from one portion to another. They respond to stimuli by generating signals through axons.

 

Question 14:  Which of the following cell organelle is found in all plant cells, animal cells and also in bacterial cells?

(a) chloroplast

(b) cell wall

(c) cell membrane

(d) nucleus 

Solution 14:  (c) cell membrane 

Only plant cells have chloroplasts and cell walls. Since a bacterial cell lacks a nucleus, the correct response is (c) cell membrane.

 

Question 15: The thread-like structures present in the nucleus are

(a) nucleolus

(b) chromosomes

(c) genes

(d) ribosomes 

Solution 15:  (b) chromosomes

On the nucleus, there is a spherical body called the nucleolus. On chromosomes are genes that aid in the inheritance or transition of characters from parents to offspring. In the cytoplasm, ribosomes can be found. As a result, the correct answer is (b) chromosomes.

 

Question 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 

Solution 16:  (c) A single cell can perform all the functions in a unicellular organism.

Option a) is incorrect since cells can only be seen with microscopes. Option b) is incorrect since an insect's egg is a cell. Option d) is incorrect since cells in multicellular organisms vary in size and form.

 

Question 17: Which of the following is not a cell?

(a) Red Blood Corpuscle (RBC)

(b) bacterium

(c) spermatozoa

(d) virus 

Solution 17:  (d) virus

The virus is classified as a hybrid of living and non-living organisms. Since it cannot replicate or conduct life processes outside of the host cell, it is not considered a cell.

 

Question 18:  Which of the following feature will help you in distinguishing a plant cell from an animal cell?

(a) cell wall

(b) cell membrane

(c) mitochondria

(d) nucleus 

Solution 18:  (a) cell wall

Only plant cells have a cell wall, while all plant and animal cells have a cell wall, mitochondria, and nucleus. As a result, the cell wall can help differentiate between plant and animal cells.

 

Question 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 

Solution 19:  (d) a bacterial cell

Bacterial cells are prokaryotes, meaning they lack a nucleus and cell organelles. As a result, the correct answer is (d) a bacterial cell.

 

Question 20:  Cheek cells do not have _______

(a) cell membrane

(b) nucleus

(c) golgi apparatus

(d) plastids 

Solution 20:  (d) plastids

Plastids can only be found in plant cells. Since cheek cells are only found in animals, the response is (d) plastids.

 

Question 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 a nucleus. 

Solution 21:  (d) Prokaryotes do not have a nucleus. 

Prokaryotes are organisms that do not have a nucleus or cell organelles.

                                                                     

Question 22:  Which of the following statements are not true for eukaryotic cells?

(a) They do not have a nuclear membrane.

(b) They have a well-organised nucleus.

(c) They have a nuclear membrane.

(d) Blue-green algae are eukaryotic cells 

Solution 22:  (iv) Blue-green algae are eukaryotic cells

Since blue-green algae are a type of bacteria known as a prokaryote, statement d) is not true.

 

Question 23:  Identify the correct statement about cells.

(a) All the cells have nucleus.

(b) Cells of an organ have similar structure.

(c) Cells of tissue have a similar structure.

(d) The shape of all types of cells is round. 

Solution 23:  (c) Cells of tissue have a similar structure.

Only eukaryotic cells have a well-defined nucleus, so option a) is incorrect. Statement b) is wrong since an organ's cells are made up of different types of cells. Option d) is wrong since cells come in a number of shapes and sizes.

 

Question 24:  The table given below has certain terms and four blank spaces named A, B, C and D.

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

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

Solution 24: 

(b) A-Pseudopodia; B-Photosynthesis; C-Muscle cell; D-Branched

A. Pseudopodia:

Amoeba uses pseudopods for movement and as a tool for capturing prey.

B. Photosynthesis:

Plastids are major organelles in plant cells that contain chlorophyll and are capable of photosynthesis.

C. Muscle Cell:  

Muscle cells have a spindle-like shape and are involved in contraction and relaxation.

D. Branched: 

Nerve cells are active components of the nervous system that respond to stimuli. They are long, branched, and active.

 

Very Short Answer Questions...............


Question 25:  In leaves, name the cell organelle and pigment that is responsible for green colour. 

Solution 25:   In leaves, Chloroplast and Chlorophyll are responsible for green colour.

 

Question 26:  The instrument used to observe cells is ________ 

Solution 26:  Microscope is the instrument used to observe cells.

 

Question 27:  We do not sense any pain when we clip our nails or cut our hair. Why? 

Solution 27:   Dead cells make up nails and hairs, which are not related to nerve cells. As a consequence, when we cut our nails or hair, we don't feel any discomfort.

 

Question 28:  In a cell, where are the genes located? 

Solution 28:   Chromosomes, which are found inside the nucleus, contain genes.

 

Question 29:  Amoeba and Paramecium belong to which category of organisms? 

Solution 29:  Amoeba and Paramecium belong to Protozoan’s.

 

Question 30:  What are the functions of the cell wall in plant cells? 

Solution 30:   The functions of the cell wall in plant cells are as follows:

  • Provides a layer of security.
  • Gives the cell its shape.
  • Keep an eye on the cell's expansion.
  • Preventing the cell from losing water.
  • Gives the cell strength and rigidity.


Short Answer Questions...............


Question 31:  Is the following statement correct? If it is wrong, correct the statement Statement :

“Unicellular organisms do not respire, only multicellular organisms respire” 

Solution 31:  The argument is incorrect since all living things breathe and go through the process of respiration.

 

Question 32:  Match the terms given in column I with their functions given in column II and fill the blanks given below the table:

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

Solution 32:

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions


Question 33:  Observe the following diagram given in the below figure:

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

Answer the following questions.

A. Does it represent a plant cell or an animal cell?

B. Does it represent a prokaryotic cell or a eukaryotic cell? 

Solution 33:  

A. An animal cell is depicted in the illustration.

B. It represents a eukaryotic cell.

 

Question 34:  Label the parts A to E in the below given diagram.

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

Solution 34:


NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions


Question 35:  Classify the following terms into cells, tissues and organs and write in the tabular column given below.

RBC, blood vessels, blood, WBC, Nerve cell, muscle, brain, heart, hand, nerve.

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

Solution 35:

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

 

Question 36:  Read the following statements and write the appropriate term against each statement.

A. I control the functions of a cell. Who am I? __________

B. I am like a policeman. I do not allow anything and everything to get in and out of the cell. Who am I? __________

C. I transfer characters from parents to offspring. Who am I? _________ 

Solution 36:

A. Nucleus

B. Cell membrane

C. Genes/Chromosomes

 

Question 37:  Fill in the blanks with the terms given in the box below:

NCERT Exemplar Solutions Class 8 Science Cell Structure and Functions

The outermost layer of 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)______. 

Solution 37:   The outermost layer of plant cells is the (a) cell wall beneath which is the (b) cell membrane. The term (c) cytoplasm refers to the jelly-like substance containing all the (d) cell organelles. The (e) nucleus contains thread-like structures called (f) chromosomes.

 

Long Answer Questions...............


Question 38:  Cells consist of many organelles, yet we do not call any of these organelles as a structural and functional unit of living organisms. Explain. 

Solution 38:   Cell organelles such as mitochondria, ribosomes, and nuclei have unique roles and perform specific functions, but they cannot be referred to as the cell's functional unit. This is due to the fact that they can only perform basic functions inside a living cell. They are unable to work as a team. The nuclei, on the other hand, have their own life. It's the tiniest, most structurally important, and most useful unit of life.

 

Question 39:  Why do plant cells have an additional layer surrounding the cell membrane? What is this layer known as? 

Solution 39:   Since plants cannot move, they need protection from changes in temperature, high wind speeds, atmospheric moisture, and other factors. A plant cell has a special membrane called the cell wall for this function. The outline of the plant cell is also given by this additional membrane.

  

Question 40:  The size of the cells of an organism has no relation with the size of its body. Do you agree? Give the reason for your answer. 

Solution 40:   Size of the cells of an organism has no relation with the size of its body because the cell size of a rat. The size of an organism's cells has little bearing on the size of its body, as a rat's cell and an elephant's cell are identical in size. Cell organelles such as mitochondria, Golgi complex, ribosomes, nucleus, and others have unique roles and perform specific functions in a cell, but they are not structural or functional components of living organisms. This is due to the fact that they can only operate within a living cell. They are unable to operate as self-contained units. The nuclei, on the other hand, have their own life. It is life's tiniest structural and functional unit.