Term 2 · Class 7 Science · Chapter 4

Samacheer Class 7 Science - Cell Biology

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Chapter-wise textbook exercise answers for Cell Biology with validation-aware solutions.

Answers marked verified were checked during generation against the chapter context and source question text.
Sections in this chapter
I. Choose the correct answers: 5III. True or False – If False give the correction answer 6IV. Match the following: 1V. Analogy: 4VI. Choose Use connect alternative from the following : 2VII. Very short answer: 6VII. Give short answer : 5IX. Given long answer: 3X. Higher ordear Thinking question : 1Activity – 1 4Activity – 2 1Activity – 3 1
Your Progress - Chapter 40% complete
1I. Choose the correct answers:5 questions
Q.1Basis unit of life.v
  1. A. Cell
  2. B. Protoplasm
  3. C. Cellulose
  4. D. Nucleus
Solution

(a) Cell

Answer:

(a) Cell

Q.2the outer most layer of an animal cell. Who am I?v
  1. A. Cell wall
  2. B. Nucleus
  3. C. Cell membrane
  4. D. Nuclear membrane
Solution

(c) Cell membrane

Answer:

(c) Cell membrane

Q.3Which part of the cell is called the brain of the cell?v
  1. A. Lysosome
  2. C. Mitochondria
  3. B. Ribosome
  4. D. Nucleus.
Solution

d) Nucleus

Answer:

d) Nucleus

Q.4________ helps in cell division.v
  1. A. Endoplasmic reticulum
  2. B. Golgi complex
  3. C. Centriole
  4. D. Nucleus
Solution

(c) Centriole

Answer:

(c) Centriole

Q.5Suitable term for the various components of cell is _________v
  1. A. Tissue
  2. B. Nucleus
  3. C. Cell
  4. D. Cell organelle
Solution

(d) Cell organelle
Fill in the blanks:
The jelly like substance present in the cell is called _______.
I convert the Sun’s energy into food for the plant. Who am I?_________.
Mature Red blood cell do not contain a ________.
Unicellular organisms can only be seen under a ________.
Cytoplasm plus nucleoplasm is equal to ________.
cytoplasm
chloroplast
Nucleus
Microscope
Protoplasma

Answer:

(d) Cell organelle
Fill in the blanks:
The jelly like substance present in the cell is called _______.
I convert the Sun’s energy into food for the plant. Who am I?_________.
Mature Red blood cell do not contain a ________.
Unicellular organisms can only be seen under a ________.
Cytoplasm plus nucleoplasm is equal to ________.
cytoplasm
chloroplast
Nucleus
Microscope
Protoplasma

2III. True or False – If False give the correction answer6 questions
Q.1Animal cells have a cell wall.v
Solution

False, Plant cells have a cell wall.

Answer:

False, Plant cells have a cell wall.

Q.2Salmonella is a unicellular bacteria.v
Solution

True

Answer:

True

Q.3Cell membrane is fully permeable.v
Solution

False, Cell membrane is selectively permeable.

Answer:

False, Cell membrane is selectively permeable.

Q.4Only plant cells have chloroplasts.v
Solution

True.

Answer:

True.

Q.5Human stomach is an organ.v
Solution

True.

Answer:

True.

Q.6Ribosomes are small organelles with a membrane.v
Solution

False. Ribosomes are small organelles without a membrane.

Answer:

False. Ribosomes are small organelles without a membrane.

3IV. Match the following:1 questions
Q.1Transporting channel – Nucleus Suicidal bag – Endoplasmic reticulum Control room – Lysosome Power house – Chloroplast Food producer – Mitochondriav
Solution

Transporting channel – Endoplasmic reticulum
Suicidal bag – Lysosome
Control room – Nucleus
Power house – Mitochondria
Food producer – Chloroplast

Answer:

Transporting channel – Endoplasmic reticulum
Suicidal bag – Lysosome
Control room – Nucleus
Power house – Mitochondria
Food producer – Chloroplast

4V. Analogy:4 questions
Q.1Bacteria : microorganism :: mango tree :________v
Solution

Macroorganism.

Answer:

Macroorganism.

Q.2Adipose : tissue :: eye :_________v
Solution

Organ

Answer:

Organ

Q.3Cell wall: plant cell:: centriole :_________v
Solution

Animal cell.

Answer:

Animal cell.

Q.4Chloroplast: photosynthesis :: mitochondria :________v
Solution

Respiration.

Answer:

Respiration.

5VI. Choose Use connect alternative from the following :2 questions
Q.1Assertion (A) : Tissue is a group of dissimilar cells. Reason (R) : Muscle is made up of Muscle cell.v
  1. A. Both A and R are true
  2. B. Both A and R are false
  3. C. A is true but R is false
  4. D. A is false but R is true
Solution

(a) Both A and R are true

Answer:

(a) Both A and R are true

Q.2Assertion (A) :Majority of cells cannot be seen directly with naked eye because. Reason (R) :Cells are microscopic.v
  1. A. Both A and R are true
  2. B. Both A and R are false
  3. C. A is true but R is false.
  4. D. A is false but R is true.
Solution

(a) Both A and R are true

Answer:

(a) Both A and R are true

6VII. Very short answer:6 questions
Q.1What are the functions of cell wall in plant cell?v
Solution

Protection, maintains shape of cell and acts as protective framework.

Answer:

Protection, maintains shape of cell and acts as protective framework.

Q.2Which organelle uses energy from sunlight to make starch?v
Solution

Chloroplast uses energy from sunlight to make starch.

Answer:

Chloroplast uses energy from sunlight to make starch.

Q.3What are the main things in a nucleus?v
Solution

Nuclear envelope, Nucleolus, chromatin body.

Answer:

Nuclear envelope, Nucleolus, chromatin body.

Q.4What does cell membrane do?v
Solution

It acts as boundary of cell and protects it.

Answer:

It acts as boundary of cell and protects it.

Q.5Why lysosomes are known as scavengers of the cell?v
Solution

The lysosomes are the main digestive compartments of a cell and digest damaged cell parts. Hence they are called scavengers of the cell.

Answer:

The lysosomes are the main digestive compartments of a cell and digest damaged cell parts. Hence they are called scavengers of the cell.

Q.6Teacher said “A virus is not an organism” Do you agree with this statement or not? Explain Why?v
Solution

True I agree with the statement. A virus acts as a living organism within the body of a host and behaves like a non-living thing outside. It lacks cell wall, cell membrane, cytoplasm and organelles. Hence it is not a organism.

Answer:

True I agree with the statement. A virus acts as a living organism within the body of a host and behaves like a non-living thing outside. It lacks cell wall, cell membrane, cytoplasm and organelles. Hence it is not a organism.

7VII. Give short answer :5 questions
Q.1Why the cell is very important for us?v
Solution

Cell is the basic structural and functions unit of life.
It is the building unit of living organism.
A group of cells form a tissue which forms the organ and organ systems.
This helps a living organism to do its functions. Hence cell is very important for us.
Distinguish between the following pairs
Smooth ER and Rough ER
Cell wall and cell membrane
Chloroplast and mitochondria
Smooth ER (Endoplasmic Reticulum)
It is smooth due to absence of Ribosomes.
It helps in transport of steroids and lipids.
Rough ER (Endoplasmic Reticulum)
It is’rough due to presence of Ribosomes.
It helps in protein synthesis
Cell wall
It is seen only in plant cells.
It is made of cellulose.
Cell membrane
It is seen in plant and animal cells.
It is made of proteins and lipids.
Chloroplast
It is a organelle seen only in plant cells (green plants)
It helps in synthesis and storage of starch.
Mitochondria
It is a organelle seen in plant and animal cells.
It is the centre of respiration in a cell and produces energy.

Answer:

Cell is the basic structural and functions unit of life.
It is the building unit of living organism.
A group of cells form a tissue which forms the organ and organ systems.
This helps a living organism to do its functions. Hence cell is very important for us.
Distinguish between the following pairs
Smooth ER and Rough ER
Cell wall and cell membrane
Chloroplast and mitochondria
Smooth ER (Endoplasmic Reticulum)
It is smooth due to absence of Ribosomes.
It helps in transport of steroids and lipids.
Rough ER (Endoplasmic Reticulum)
It is’rough due to presence of Ribosomes.
It helps in protein synthesis
Cell wall
It is seen only in plant cells.
It is made of cellulose.
Cell membrane
It is seen in plant and animal cells.
It is made of proteins and lipids.
Chloroplast
It is a organelle seen only in plant cells (green plants)
It helps in synthesis and storage of starch.
Mitochondria
It is a organelle seen in plant and animal cells.
It is the centre of respiration in a cell and produces energy.

Q.3Write correct sequence from cell to organism?v
Solution

Cell —> Tissue —> Organ —> Organ system —> Organism.

Answer:

Cell —> Tissue —> Organ —> Organ system —> Organism.

Q.4Write a short note on nucleus.v
Solution

Nucleus is seen in the cytoplasm of plant and Animal cells.
It is surrounded by nuclear envelope.
It has one or two nucleoli and chromatin body.
The chromatin body stores genetic information.
Functions of Nucleus:
It controls all the processes and chemical reactions that take place inside the cell.
Inheritance of character from one generation to another.

Answer:

Nucleus is seen in the cytoplasm of plant and Animal cells.
It is surrounded by nuclear envelope.
It has one or two nucleoli and chromatin body.
The chromatin body stores genetic information.
Functions of Nucleus:
It controls all the processes and chemical reactions that take place inside the cell.
Inheritance of character from one generation to another.

Q.5Classify the following terms into cells, tissues, organs and write in the tabular column given below: Neuron, Lungs, Xylem, brain, adipose, Leaf, RBC, WBC, hand, muscle, heart, ovum, squamous, phloem, cartilage.v
Solution

Cell
Tissue
Organ
Neuron
Xylem
Lungs
RBC
Adipose
Brain
WBC
Muscle
Leaf
Ovum
Squamous
Hand
Phloem
Heart
Cartilage

Answer:

Cell
Tissue
Organ
Neuron
Xylem
Lungs
RBC
Adipose
Brain
WBC
Muscle
Leaf
Ovum
Squamous
Hand
Phloem
Heart
Cartilage

Q.6On the lines given below, write about what you have learned from the activities done in this lesson. Let me tell you about some of the important things I’ve learned about cells. First, I’ll start with… . First, I’ll start with___________________________.v
Solution

Cell is the basic unit of an organisms.
Based on number of cells organisms can be classified as unicellular and multicellular organisms.
The cells form tissues, Tissues form organs, Organ system help an organism to function.
The cell wall is seen only in plant cells.
Cell membrane is seen only in plant cells.
Cell membrane is seen in all cells.
The organelles of the cell like chloroplast, Mitochondria, Ribosomes, Endoplasmic Reticulum, Golgi bodies etc help to perform cell functions.
Nucleus is the controlling centre of a cell.

Answer:

Cell is the basic unit of an organisms.
Based on number of cells organisms can be classified as unicellular and multicellular organisms.
The cells form tissues, Tissues form organs, Organ system help an organism to function.
The cell wall is seen only in plant cells.
Cell membrane is seen only in plant cells.
Cell membrane is seen in all cells.
The organelles of the cell like chloroplast, Mitochondria, Ribosomes, Endoplasmic Reticulum, Golgi bodies etc help to perform cell functions.
Nucleus is the controlling centre of a cell.

8IX. Given long answer:3 questions
Q.1Write about any three organelles in detail.v
Solution

The three organelles are as follows
Chloroplasts:
They are green organelles seen in plant cells only.
They can prepare food using sun is energy and photosynthesize since they contain the pigment chlorophyll.
They absorb the radiant energy of the sun and convert it to chemical energy to be used by plants and animals.
Golgi Complex:
They are cell organelles which consist of membrane bound sacs stacked on top of one another and have associated secretory vesicles.
Golgi complex helps in production of secretory substances, packaging and secretion.
Mitochondria:
It is a oral double membrane bounded organelle.
Aerobic respiration occurs in mitochondria and energy is released. Hence mitochondria is called as power house of the cell
The energy produced is used for metabolic activities of the cell.

Answer:

The three organelles are as follows
Chloroplasts:
They are green organelles seen in plant cells only.
They can prepare food using sun is energy and photosynthesize since they contain the pigment chlorophyll.
They absorb the radiant energy of the sun and convert it to chemical energy to be used by plants and animals.
Golgi Complex:
They are cell organelles which consist of membrane bound sacs stacked on top of one another and have associated secretory vesicles.
Golgi complex helps in production of secretory substances, packaging and secretion.
Mitochondria:
It is a oral double membrane bounded organelle.
Aerobic respiration occurs in mitochondria and energy is released. Hence mitochondria is called as power house of the cell
The energy produced is used for metabolic activities of the cell.

Q.2In a situation, how to explain, while your friend ask what is this, never seen before ? Cell Biology 7th Standard Samacheer Kalvi Term 2 Chapter 4v
Solution

This is a animal cell.
It is the basic unit of an animal body.
Animal cell is covered by a cell membrane and lacks cell wall.
It has organelles like mitochondia, Golgi apparatus, Ribosomes, etc..
It differs from plant cells since it lacks chloroplast.
It has centrioles which are not seen in plant cells.
Nucleus is the controlling centre of the cell.

Answer:

This is a animal cell.
It is the basic unit of an animal body.
Animal cell is covered by a cell membrane and lacks cell wall.
It has organelles like mitochondia, Golgi apparatus, Ribosomes, etc..
It differs from plant cells since it lacks chloroplast.
It has centrioles which are not seen in plant cells.
Nucleus is the controlling centre of the cell.

Q.3Compare the plant cell and the animal cell and complete the illustration given belowv
Solution

7th Science Cell Biology Samacheer Kalvi Term 2 Chapter 4

Answer:

7th Science Cell Biology Samacheer Kalvi Term 2 Chapter 4

9X. Higher ordear Thinking question :1 questions
Q.G1Virus is called Acellular. Why?v
Solution

Virus is made up of a outer protein coat and a nucleic acid.
It lacks cell wall, cell membrane, organelles and cytoplasm.
Therefore a virus is described as a cellular.

Answer:

Virus is made up of a outer protein coat and a nucleic acid.
It lacks cell wall, cell membrane, organelles and cytoplasm.
Therefore a virus is described as a cellular.

10Activity – 14 questions
Q.1Do you remember the lesson studied in previous class, how will you find whether an object is living or non – living? Write it down. An object is living or non-living?v
Solution

Living things: Living things use energy. They move or change shape.
Eg: Humans, insects, plants, animals etc.
Non-living things:
Do not move by themselves, grow or reproduce.
Eg: Rocks, car, pencils etc.

Answer:

Living things: Living things use energy. They move or change shape.
Eg: Humans, insects, plants, animals etc.
Non-living things:
Do not move by themselves, grow or reproduce.
Eg: Rocks, car, pencils etc.

Q.2Form a team and work together to write down some of the functions of life, which you can remember.v
Solution

Reproduction, response to stimuli, Growth, movement, excretion

Answer:

Reproduction, response to stimuli, Growth, movement, excretion

Q.3Do you think that an individual cell is living? Explain your answer.v
Solution

Cells are living things. Cells are found in plants, animals and Bactria.

Answer:

Cells are living things. Cells are found in plants, animals and Bactria.

Q.4Write about various organelles of a cell which you know.v
Solution

Vacuole, lysosome, endoplasmic reticulum, Golgi appartus, mitochondria, chloroplast.

Answer:

Vacuole, lysosome, endoplasmic reticulum, Golgi appartus, mitochondria, chloroplast.

11Activity – 21 questions
Q.G2Find out major organs that are part of the circulatory system of a human body and list out their functions.v
Solution

Organs
Heart (Cardiovascular)
Lungs (Pulmonary)
Blood vessels – Arteries
Blood vessels – Veins
Functions
Pumps oxygenated and deoxygenated blood on different sides.
In oxygen from incoming air enters the blood and carbon-di-oxide, a waste gas from the metabolism, leaves the blood.
Carry blood away from the heart.
Carry blood back to the heart.

Answer:

Organs
Heart (Cardiovascular)
Lungs (Pulmonary)
Blood vessels – Arteries
Blood vessels – Veins
Functions
Pumps oxygenated and deoxygenated blood on different sides.
In oxygen from incoming air enters the blood and carbon-di-oxide, a waste gas from the metabolism, leaves the blood.
Carry blood away from the heart.
Carry blood back to the heart.

12Activity – 31 questions
Q.G3Study the pictures given and write the differences between cells that you observe in the given tablev
Solution

Samacheer Kalvi 7th Biology Guide Term 2 Chapter 4 Cell Biology

Answer:

Samacheer Kalvi 7th Biology Guide Term 2 Chapter 4 Cell Biology