NCERT Class 8 Science Exemplar Chapter 8 - Cell - Structure and Functions

Chapter 8 - 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.
Answer:
c) unicellular organisms respire and reproduce.

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
Answer:
b) cells are microscopic

Question 3: Read the different combinations of terms given below: The correct combination of terms with reference to an animal cell is _____.
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.
Answer:
c) cell membrane, mitochondria, ribosome, chromosome

Question 4: Which one of the following term is not a part of the nucleus?
a) ribosome
b) nucleolus
c) chromosome
d) gene
Answer:
a) ribosomes

Question 5: A suitable term for the various components of cells is
a) tissue
b) cell organelles
c) chromosomes
d) genes
Answer:
b) cell organelles

Question 6: The jelly-like fluid substance present in cells is called
a) protoplasm
b) chromosome
c) chloroplast
d) cytoplasm
Answer:
d) cytoplasm

Question 7: Read the following pairs of examples of organisms: The pair that belongs to the group prokaryotes is_____
a) moss and sponge
b) yeast and Amoeba
c) bacteria and blue-green alga
d) penicillium and Spirogyra
Answer:
c) bacteria and blue-green alga

Question 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

Question 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.

Question 10: Green colour of leaves is due to presence of the pigment_____
a) chlorophyll
b) ribosomes
c) mitochondria
d) chloroplast
Answer:
a) chlorophyll

Question 11: The unit of measurement used for expressing dimension (size) of cells is:
a) centimetre
b) millimetre
c) micrometre
d) metre
Answer:
c) micrometre

Question 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.

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
Answer:
c) nerve cells

Question 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

Question 15: The thread-like structures present in the nucleus are
a) nucleolus
b) chromosomes
c) genes
d) ribosomes
Answer:
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
Answer:
c) A single cell can perform all the functions in a unicellular organism.

Question 17: Which of the following is not a cell?
a) Red Blood Corpuscle (RBC)
b) bacterium
c) spermatozoa
d) virus
Answer:
d) virus

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
Answer:
a) cell wall

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
Answer:
d) a bacterial cell

Question 20: Cheek cells do not have _______
a) cell membrane
b) nucleus
c) golgi apparatus
d) plastids
Answer:
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 nucleus.
Answer:
d) Prokaryotes do not have nucleus.

Question 22: Which of the following statements are true for eukaryotic cells?
i) They do not have a nuclear membrane.
ii) They 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

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 a tissue have similar structure.
d) Shape of all types of cells is round.
Answer:
c) Cells of a tissue have similar structure.

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

Very Short Answer Questions
Question 25: In leaves, name the cell organelle and pigment that is responsible for green colour.
Answer:
The cell organelle and pigment that is responsible for green colour in leaves is chloroplast and chlorophyll.

Question 26: The instrument used to observe cells is ________
Answer:
The instrument that is used to observe cells is microscope.

Question 27: We do not sense any pain when we clip our nails or cut our hair. Why?
Answer:
We do not sense any pain when we clip our nails or cut our hair because the nails and hair are dead cells. They don’t contain nerve cells in them.

Question 28: In a cell, where are the genes located?
Answer:
The genes are located in the chromosomes of the nucleus of the cell.

Question 29: Amoeba and Paramecium belong to which category of organisms?
Answer:
Amoeba and Paramecium belong to unicellular and eukaryotic category of organisms. They also belong to the family of protozoans.

Question 30: What are the functions of cell wall in plant cells?
Answer:
Plant cells need protection against variation in temperature, high wind speed, atmospheric moisture etc. They are exposed to the variations because they can't move. That is why plants need cell wall.

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”
Answer:
No, the statement is completely wrong; the statement should be “Unicellular and Multicellular organisms respire.”

Question 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 - site of photosynthesis
B. Cell membrane - controls the movement of materials into and out of cells.
C. Nucleus - controls the activities of cells
D. Chromosome - carries hereditary characters

Question 33: Observe the following diagram given as Fig. 8.1.
Answer the following questions.
A. Does it represent a plant cell or an animal cell?
B. Does it represent a prokaryotic cell or an eukaryotic cell?
Answer:

A. It represents an animal cell.
B. It represents an eukaryotic cell.

Question 34: Label the parts A to E in the given as Fig. 8.2 diagram.
Answer:
A - Cell wall
B - Cell membrane
C - Nucleus
D - Cytoplasm
E - Vacuole


Question 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
Answer:

• Cell
→ RBC
→ WBC
→ Nerve cell

• Tissue
→ Blood
→ Muscle
→ Nerve

• Organ
→ Blood vessels
→ Heart
→ Hand
→ Brain

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 offsprings. Who am I? ...................
Answer:

A. Nucleus
B. Cell membrane
C. Genes/Chromosomes

Question 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 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:

a) cell wall
b) cell membrane
c) cytoplasm
d) cell organelles
e) nucleus
f) chromosomes

Long Answer Questions
Question 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:
Cells consist of many organelles, yet we do not call any of these organelles as structural and functional unit of living organisms because the cell organelles have specific structures and perform specific functions but they cannot be called structural and functional units of living organisms. This is so because they can perform their functions only when they are within a living cell. They cannot function outside the cell as an independent unit.

Question 39: Why do plant cells have an additional layer surrounding the cell membrane? What is this layer known as?
Answer:
The additional layer that the plant cells have is the cell wall. Plant cells need protection against variation in temperature, high wind speed, atmospheric moisture etc. They are exposed to the variations because they can't move. That is why plants need cell wall.

Question 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:
The size of the cell has no relation with the size of its body of the plant or animal. It is not necessary that the cells in an elephant be much bigger than those in rats. The size of the cell is related to its function. Example: The nerve cells, both in an elephant and rats are long and branched. They perform the same function i.e. transferring the messages.

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