7th Science Guide Term 2 Lesson 4 Cell Biology

7th Std Science Term 2 Solution in English | Lesson.4 Cell Biology

7th Standard Science Samacheer kalvi guide Term 2 Lesson 4 Cell Biology Book Back Question and answers Tamil Medium. 7th All subject Guide / Book Back answers. 7th Standard Science Text Book Download PDF.

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7th Science Guide Term 2 Lesson 4 Cell Biology

I . Choose the correct answer.

1. Basis unit of life.

1. Cell
2. Protoplasm
3. Cellulose
4. Nucleus

Ans : Cell

2.  I am the outer most layer of an animal cell. Who am I?

1. Cell wall
2. Nucleus
3. Cell membrane
4. Nuclear membrane

Ans : Cell membrane

3. Which part of the cell is called the brain of the cell?

1. Lysosome
2. Ribosome
3. Mitochondria
4. Nucleus

Ans : Nucleus

4. ________ helps in cell division

1. Endoplasmic reticulum
2. Golgi complex
3. Centriole
4. Nucleus

Ans : Centriole

5. Suitable term for the various components of cell is ________

1. Tissue
2. Nucleus
3. Cell
4. Cell organelle

Ans : Cell organelle

II. Fill in the blanks:

1. The jelly like substance present in the cell is called ____________Ans : cytoplasm
2. I convert the Sun’s energy into food for the plant. Who am I? ____________Ans : chloroplast
3. Mature Red blood cell do not contain a ____________.Ans : Nucleus
4. Unicellular organisms can only be seen under a _______________.Ans : Microscope
5. Cytoplasm plus nucleoplasm is equal to _______________.Ans : Protoplasma

III. Match the following:

1. Transporting channel – Nucleus
2. Suicidal bag – Endoplasmic reticulum
3. Control room – Lysosome
4. Power house – Chloroplast
5. Food producer – Mitochondria

Ans : 1 – B, 2 – C, 3 – A, 4 – E, 5 – D

IV. True or False – If false give the correct answer:

1. Animal cells have a cell wall.Ans : False.

Cu. An : Plant cells have a cell wall.

2. Salmonella is a unicellular bacteria.Ans : True
3. Cell membrane is fully permeableAns : False.

Cu. An. : Cell membrane is selectively permeable.

4. Only plant cells have chloroplastsAns : True
5. Human stomach is an organ.Ans : True
6. Ribosomes are small organelles with a membrane.Ans : False

Cu. An. : Ribosomes are small organelles without a membrane.

V. Analogy:

1. Bacteria : microorganism : : mango tree : _________Ans : Macro-organism.
2. Adipose : tissue : : eye : ________Ans : Organ.
3. Cell wall : plant cell : : centriole : ________________Ans : Animal cell.
4. Chloroplast : photosynthesis : : mitochondria : __________Ans : Respiration

VII. Assertion and Reason:

1. Both A and R are true
2. Both A and R are false
3. A is true but R is false.
4. A is false but R is true.

1. Assertion (A) : Tissue is a group of dissimilar cells.

Reason (R) : Muscle is made up of Muscle cell.

Ans : Both A and R are true

2. Assertion (A) : Majority of cells cannot be seen directly with naked eye because.

Reason (R) : Cells are microscopic.

Ans : A is true but R is false.

VII. Very short answer :

1. What are the functions of cell wall in plant cell?

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

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

• Chloroplast uses energy from sunlight to make starch.

3. What are the main things in a nucleus?

• Nuclear envelope
• Nucleolus
• chromatin body.

4. What does cell membrane do?

• It acts as boundary of cell and protects it..

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

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

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

• 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.

VIII. Give Short Answer :

1. Why the cell is very important for us?

• 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.

2. Distinguish between the following pairs

Smooth ER and Rough ER

Smooth ER (Endoplasmic Reticulum)	Rough ER (Endoplasmic Reticulum)
1. It is smooth due to absence of Ribosomes.	It is’rough due to presence of Ribosomes.
2. It helps in transport of steroids and lipids.	It helps in protein synthesis

Cell wall and cell membrane

Cell Wall	Cell Membrane
1. It is seen only in plant cells.	It is seen in plant and animal cells.
2. It is made of cellulose.	It is made of proteins and lipids.

Chloroplast and mitochondria

Chloroplast	Mitochondria
1. It is a organelle seen only in plant cells (green plants)	It is a organelle seen in plant and animal cells.
2. It helps in synthesis and storage of starch.	It is the centre of respiration in a cell and produces energy.

3. Write correct sequence from cell to organism?

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

4. Write a short note on nucleus.

• 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.

5. Classify 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.

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

6. On 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___________.

• 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

X. Long answer type question :

1. Write about any three organelles in detail.

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.

2. In a situation, how to explain, while your friend ask what is this, never seen before ?

• 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.

3. Compare the plant cell and the animal cell and complete the illustration given below.

Common to both

• Nucleus
• Ribosome
• Cytoplasm
• Golgi body
• Endoplasmic
• Mitochondria

Different to both

Animal cell	Plant cell
1. Cell membrane or plasma membrane is the boundary of an animal cell.	Cell wall is an additional layer  on outside of the cell membrane
2. Centrioles or Centrosomes are present only in animal cell and involves in cell division.	Chloroplasts  are present only in plants,  involved in photosynthesis
3. Small Vacuoles are present	Large  Vacuoles are present