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Page No 40:

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:

All unicellular organisms respire and reproduce. unicellular organisms are single-celled organisms that perform all the basic functions of digestion, respiration, reproduction like multicellular organisms.

Hence, the correct answer is option (c).

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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:

Cells cannot be seen directly with our naked eyes because they are microscopic. Cells are small, basic, and structural units of life that can only be seen under the microscope. 

Hence, the correct answer is option (b).

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Question 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:

The correct combination of terms related to an animal's cell is the cell membrane, mitochondria, ribosome, and chromosome. An animal cell is a eukaryotic cell that contains a cell membrane that allows the movement of selected particles across the cell. They have a well-defined nucleus and thread-like structures called chromosomes are present in the nucleus. Mitochondria are called the powerhouse of the cell as they provide energy to the cell. Ribosomes are required for protein synthesis. 

Hence, the correct answer is option (c).
 

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Question 4:

Which one of the following term is not a part of the nucleus?
(a) ribosome 
(b) nucleolus
(c) chromosome
(d) gene

Answer:

 Ribosome is not a part of the nucleus. The nucleolus, chromosome, and gene are part of the nucleus. The nucleus acts as a control center of a cell. 

Hence, the correct answer is option (a).

 

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Question 5:

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

Answer:

Cell organelles are suitable terms for the various components of cells. They are small structures that are present in the cytoplasm. For example- mitochondria, nucleus, chloroplast, cell membrane. 

Hence, the correct answer is option (b).

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Question 6:

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

Answer:

The cytoplasm is a jelly-like substance that is present between the cell membrane and the nucleus. Other cell organelles are present in the cytoplasm.

Hence, the correct answer is option (d).



Page No 41:

Question 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:

The pair that belongs to the group prokaryotes is bacteria and blue-green alga. Prokaryotes are single-celled organisms that lack a true nucleus and other cell organelles.

Hence, the correct answer is option (c).

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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:

Chromosomes and genes are related to the inheritance of characters. Chromosomes are thread-like structures present in the nucleus and genes are present in the chromosomes that help in the transfer or inheritance of characters from parents to offspring.

Hence, the correct answer is option (d).

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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:

Chromosomes are thread-like structures present in the nucleus and genes are present on the chromosomes that help in the inheritance of characters from parents to offspring.

Hence, the correct answer is option (a).

Page No 41:

Question 10:

Green colour of leaves is due to presence of the pigment_____
(a) chlorophyll 
(b) ribosomes
(c) mitochondria
(d) chloroplast

Answer:

The green colour of leaves is due to the presence of chlorophyll pigment. It is present in the chloroplast of the leaves that is responsible for photosynthesis.

Hence, the correct answer is option (a).

Page No 41:

Question 11:

The unit of measurement used for expressing dimension (size) of cells is:
(a) centimeter 
(b) millimeter
(c) micrometer
(d) meter

Answer:

A micrometer ( 1 micrometer=10-6meter) is a unit of measurement used for expressing the dimension of cells. The cells are microscopic and are not visible by naked eyes. 

Hence, the correct answer is option (c).

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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:

The cell membrane controls the entry and exit of materials from cells (selectively permeable in nature) and it is also called the plasma membrane. This membrane allows the movement of material inward and outward of the cell. It separates the cell from one another as well as the cell from the surrounding medium.

Hence, the correct answer is option (a).

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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:

The sensation of heat and reaction is due to the action of nerve cells. The nerve cells receive and transfer messages and responsible for control and coordination of the different parts of the body.

Hence, the correct answer is option (c).

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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:

The cell membrane is present in all plant cells, animal cells, and bacterial cells. It separates the cell from one another and also from the surrounding medium. This membrane allows the movement of material both inward and outward of the cell. 

Hence, the correct answer is option (c).



Page No 42:

Question 15:

The thread-like structures present in the nucleus are
(a) nucleolus
(b) chromosomes
 (c) genes
(d) ribosomes

Answer:

Chromosomes are the thread-like structures present in the nucleus. They carry genes that are responsible for inheritance of characters from parents to their offsprings.

Hence, the correct answer is option (b).

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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:

A single cell can perform all the functions in unicellular organisms such as digestion, respiration, excretion, and reproduction that are necessary for life. As cells are the basic structural and functional unit of life. Prokaryotes are made up of single cells. 

Hence, the correct answer is option (c).

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Question 17:

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

Answer:

The virus is not a cell. It acts as a non-living particle when present outside the host cell. It only replicates when present in the host cell. So, it acts as an intermediate between non-living and living. 

Hence, the correct answer is option (d).

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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:

Cell wall is absent in animal cells. It is present in plant cells. Cell membrane, mitochondria and nucleus are present in all eukaryotic cells.

Hence, the correct answer is option (a).

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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:

Bacterial cell is a prokaryotic cell that contains cell wall but lacks a true nucleus and other cell organelles. 

Hence, the correct answer is option (d).

Page No 42:

Question 20:

Cheek cells do not have _______
(a) cell membrane 
(b) nucleus
(c) golgi apparatus
(d) plastids

Answer:

Plastids are not present in cheek cells. A cheek cell is an animal cell that has all cell organelles such as mitochondria, golgi apparatus, vacuole, lysosome, etc. Plastids are present in plant cells. 

Hence, the correct answer is option (d).

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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:

Prokaryotes are unicellular organisms that lack a true nucleus and other cell organelles. For example- bacteria and blue-green algae.

Hence, the correct answer is option (d).

Page No 42:

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:

Eukaryotic cells have a nuclear membrane and a well-defined nucleus. They have cell organelles like mitochondria, golgi apparatus, endoplasmic reticulum, vacuole, lysosome, etc. For example- plant cell and animal cell.

Hence, the correct answer is option (b).



Page No 43:

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:

Cells present in tissue have similar structures that are organized and work together to perform specific functions. Each organ is made up of smaller parts called tissues.

Hence, the correct answer is option (c).

Page No 43:

Question 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:

A-Pseudopodia, B-Photosynthesis, C-Muscle cell, D-Branched.  Pseudopodia in Amoeba is a locomotory organ that helps in the movement and capturing of food. Plastids in plant cells help in the process of photosynthesis. They are of different colors and green-colored plastids are called chloroplast that contains chlorophyll. Muscle cells are spindle-shaped cells that help in muscles contraction. Nerve cells or neurons are branched cells that tends to receive and transfer messages and helps in the control and coordination of the working of different parts.

Hence, the correct answer is option (b).

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Question 25:

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

Answer:

Chloroplasts are green coloured plastid that contains a green coloured pigment called chlorophyll. This pigment is responsible for the green colour in leaves that is responsible for the process of photosynthesis.

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Question 26:

The instrument used to observe cells is ________.

Answer:

The microscope is an instrument that is used to observe cells. Cells are the smallest structural and functional units of life that cannot be seen by naked eyes. 

The instrument used to observe cells is the microscope.

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Question 27:

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

Answer:

Nerve cells are not present in nails and hair. They are dead cells. This is the reason that we don't feel any pain when we clip our nails or cut our hair.

Page No 43:

Question 28:

In a cell, where are the genes located?

Answer:

Genes are located in thread-like structures called chromosomes. Chromosomes are located in the nucleus. Genes help in the inheritance of characters from parents to the offspring.

Page No 43:

Question 29:

Amoeba and Paramecium belong to which category of organisms?

Answer:

Amoeba and Paramecium are unicellular, eukaryotic organisms. Such organisms are made of single-cell but have a well-defined nucleus as well as cell organelles.



Page No 44:

Question 30:

What are the functions of cell wall in plant cells?

Answer:

The cell wall is an outer thick layer in plant cells. This layer surrounds the cell membrane of the plant's cell and provides protection to the cell as plants are immobile. The plant cell wall provides shape to the cell and maintains cell turgidity.

Page No 44:

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:

Single-celled organisms are called unicellular organisms. They perform all the necessary functions like digestion, respiration, excretion, and reproduction that multicellular organisms perform. So, the corrected statement will be:
"Unicellular as well as multicellular organisms both respire"

Page No 44:

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- (iii) Chloroplast is the site for photosynthesis as they contain a green colour pigment called chlorophyll that gives green colour to the leaves.
B- (iv) Cell membrane is also called plasma membrane that controls the movement of materials inward and outward of the cell. Thus it is also known as semi-permeable membrane.
C- (ii) Nucleus is called the control centre of the cell as it plays an essential role in controlling all the activities of the cell.
D- (i) Chromosome are thread-like structures present in the nucleus and carries genes that are responsible for the inheritance of characters from parents to the offsprings.

A-(iii)  ; B-(iv)  ; C-(ii)  ; D-(i)  

Page No 44:

Question 33:

Observe the following diagram given as in the figure.



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. The given figure represents an animal cell. As plant cells contain large vacuoles, chloroplast, and cell walls.   Animal cells have small vacuoles, lack chloroplast, and cell walls. 
B. Animal cell is a eukaryotic cell as they have a well-defined defined nucleus and membrane-bound cell organelles. 



Page No 45:

Question 34:

Label the parts A to E as given in the given figure.




 

Answer:



A. Cell wall. It is the outer-thick layer of the plant cell that provides protection to the cell from variation in temperature, high wind speed, atmospheric moisture, etc.
B. Cell membrane. It is also called plasma membrane and it allows the movement of materials inwards or outwards of the cell.
C. Nucleus. It is also called the control center of the cell as it helps in controlling all the cellular activities of the cells.
D. Cytoplasm. It is a jelly-like fluid that is present between the cell membrane and the nucleus. All the cell organelles like mitochondria, golgi apparatus, nucleus, cell membrane, cell wall, vacuoles, etc. float in the cytoplasm.
E. Vacuole. They are storage cells organelles. They are large in plant cells and small in animal cells. 

Page No 45:

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

Cell   Tissue Organ
     
     
     

Answer:

Cell   Tissue Organ
RBC Blood Blood vessels
WBC Muscle Brain
Nerve cell - Heart
- - Hand

Page No 45:

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. It is also called the control center of the cell as it controls all cellular activities of the cell. 
B.Cell membrane or plasma membrane. It allows the movement of selective materials inwards and outward of the cell.
C. Genes. They are present on the chromosomes, which helps in the inheritance of characters from parents to the offspring.



Page No 46:

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

Page No 46:

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:

All cell organelles have a specific structure and perform particular functions in the cell but are not called structural and functional units of living organisms because they are only able to perform their functions when are present in the cell. They are not able to perform functions outside the cell.

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Question 39:

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

Answer:

Plants cell have an extra thick outer layer called cell walls. This extra layer surrounds the cell membrane of the plant cell and provides protection to the cell. The cell wall protects the plant cell from variation in temperature, high wind speed, atmospheric moisture, etc. It also provides shape and maintains the turgidity of the cell.

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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:

No, the size of the cells of an organism has no relation with the size of its body. The size of the cell depends upon the function it performs. The nerve cells of an elephant and a rat are the same because they have a similar function of sending and receiving messages to and from the outer environment.



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