Samacheer Kalvi 7th Science Term 2 Solutions Chapter 4 Pdf
Tamilnadu Board Samacheer Kalvi 7th Science Term 2 Solutions Chapter 4: Tamilnadu State Board Solution Class 7 Science Term 2 Chapter 4 – Cell Biology.
Samacheer Kalvi 7th Science Term 2 Solutions Chapter 4: Overview
Board |
Samacheer Kalvi |
Class |
7 |
Subject |
Science |
Chapter |
4 |
Chapter Name |
Cell Biology |
Samacheer Kalvi 7th Science Term 2 Solutions Chapter 4 Pdf
I.) Choose the correct answer
1.) Basis unit of life.
A) Cell
B) Protoplasm
C) Cellulose
D) Nucleus
Answer : A) Cell
Solution : Cell is called the fundamental unit of life. It perform all the function.
2.) I am the outer most layer of an animal cell. Who am I?
A) Cell wall
B) Nucleus
C) Cell membrane
D) Nuclear membrane
Answer : C) Cell membrane
Solution : The outermost layer of an animal cell is cell membrane. In plants cell wall is the outermost layer of the cell.
3.) Which part of the cell is called the brain of the cell?
A) Lysosome
B) Ribosome
C) Mitochondria
D) Nucleus
Answer : D) Nucleus
Solution : Nucleus of the cell is called the brain of the cell .
4.) ___ helps in cell division
A) Endoplasmic reticulum
B) Golgi complex
C) Centriole
D) Nucleus
Answer : C) Centriole
Solution : Centriole is present in animal cells. Performs cell division.
5.) Suitable term for the various components of cell is__
A) Tissue
B) Nucleus
C) Cell
D) Cell organelle
Answer : D) Cell organelle
Solution : Cell oraganelle term is used for the various components of cell.
II) Fill in the Blanks
The jelly like substance present in the cell is called __cytosol ___
I convert the Sun’s energy into food for the plant. Who am I? _chloroplast _
Mature Red blood cell do not contain a _nucleus_.
Unicellular organisms can only be seen under a _microscope __.
Cytoplasm plus nucleoplasm is equal to_protoplasm__.
III.) True or False – If false give the correct answer
1.) Animal cells have a cell wall.
Answer : False
Correct statement : Animal cells do not have a cell wall.
2.) Salmonella is a unicellular bacteria.
Answer : True
3.) Cell membrane is fully permeable
Answer : False
Correct statement : Cell membrane is selectively permeable membrane.
4.) Only plant cells have chloroplasts.
Answer : True
5.) Human stomach is an organ.
Answer : True
6.) Ribosomes are small organelles with a membrane.
Answer : False
Correct Statement : Ribosomes are small organelles without a membrane.
IV.) Match the following
1. | Transporting channel | Endoplasmic reticulum |
2. | Suicidal bag | Lysosome |
3. | Control room | Nucleus |
4. | Power house | Mitochondria |
5. | Food producer | Chloroplast |
V.) Analogy
1.) Bacteria : microorganism :: mango tree : _macroorganism__
2.) Adipose : tissue :: eye : _organ_
3.) Cell wall : plant cell :: centriole : _animal cell_
4.) Chloroplast : photosynthesis :: mitochondria : _cellular respiration _
VI.) Choose the correct alternative from the following
1.) Assertion (A) : Tissue is a group of dissimilar cells.
Reason (R) : Muscle is made up of Muscle cell.
a). Both A and R are true
b). Both A and R are false
c). A is true but R is false.
d). A is false but R is true.
Answer : d). A is false but R is true.
2.) Assertion (A) : Majority of cells cannot be seen directly with naked eye because.
Reason (R) : Cells are microscopic.
a). Both A and R are true
b). Both A and R are false
c). A is true but R is false.
d). A is false but R is true.
Answer : d). A is false but R is true.
VII.) Very short answer
1.) What are the functions of cell wall in plant cell?
Answer : The functions of cell wall are:
i) To maintain the shape of the plant cell.
ii) Allows the plant to remain rigid and upright even if it grows to great heights.
2.) Which organelle uses energy from sunlight to make starch?
Answer : Chloroplast uses energy from sunlight to make starch.
3.) What are the main things in a nucleus?
Answer : Nucleus is surrounded by a nuclear membrane. One or two nucleolus and the chromatin body are present inside the nucleus.
4.) What does cell membrane do?
Answer : Cell membrane is a selectively permeable membrane which allows certain substances to pass in and out of the cell through it .
5.) Why lysosomes are known as scavengers of the cell?
Answer : Lysosomes are the main digestive compartments of the cell. They lyse a cell, 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?
Answer : Yes, I agree. Because viruses are not made out of cell. They remain inactive when present outside host body and gets activated in host body. They do not grow and cannot make their own energy.
VIII.) Give short Answer
1.) Why the cell is very important for us?
Answer : Cells are the basic structural and functional units of all living organisms. Cell perform all the functions such as production, digestion, respiratory etc which is vital for living organisms therefore cell is very important for us.
2.) Distinguish between the following pairs
Smooth ER and Rough ER
Answer :
Smooth ER | Rough ER |
Smooth endoplasmic reticulum is a network
of tubular sacs without ribosomes on the membrane. They play a role in the synthesis of lipids, steroids and also transport them within the cell |
Rough endoplasmic reticulum are rough due
to the ribosomes attached to the membrane. which helps in the synthesis of protein.
|
Cell wall and cell membrane
Answer :
Cell wall | Cell membrane |
Cell wall is a rigid outer layer made up of cellulose which is present only in plants.
Provide mechanical strength to the plant. |
Cell membrane is outer layer made up of glycolipid which is present in both animal and plant cell.
It is selectively permeable to certain substances. |
Chloroplast and mitochondria
Answer :
Chloroplast | Mitochondria |
Chloroplasts are the only cell organelles that
can produce food from the sun energy. Only plants with chloroplast are able to do photosynthesis because they contain the very important green pigment, chlorophyll. |
Mitochondrian is an oval or rod shaped
double membrane bounded organelle. Aerobic respiratory reactions take place with in the mitochondrion to release energy. So it is known as “the Power House” of the cell. |
3.) Write correct sequence from cell to organism?
Answer : Cell → Tissue → Organ → Organ system → Organism
4.) Write a short note on nucleus.
Answer : Nucleus is present inside the cytoplasm. The nucleus is surrounded by a nuclear membrane . One or two nucleolus and the chromatin body are present inside the nucleus. The nucleus is responsible for the transfer of character from one generation to another. It controls all the processes and called the brain of the cell.
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.
Answer :
Cell | Tissue | Organ |
Neuron | xylem | Lungs |
RBC | adipose | Brain |
WBC | muscle | Leaf |
Ovum | squamous | Hand |
phloem | Heart | |
Cartilage |
IX.) Give long answer
1.) Write about any three organelles in detail.
Answer : Centrioles
They are generally found close to the nucleus and are made up of tube-like structures. Centrioles or centrosomes are present only in animal cells and absent in plant cells. They help in the separation of chromosomes during cell division.
Lysosome
Lysosomes are very small to view using a light microscope. They are the main digestive compartments of the cell. They destroy and dissolve the cells. As they lyse a cell they are called “suicidal bag’’.
Golgi Complex
Membrane-bounded sacs are stacked on top of one another with associated secretory vesicles. They are collectively known as golgi complex. Functions of golgi complex are the production of secretory substances, packaging and secretion. This is the secret behind the change in the colour and taste of fruits.
2.) In a situation, how to explain, while your friend ask what is this, never seen before?
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 mitochondria ,Golgi apparatus, Ribosomes, etc.. It has centrioles which are not seen in plant cells. Nucleus is the controlling centre of the cell.
Cell organelles
Endoplasmic Reticulum : It is a membranous net work in cytoplasm. Two types of ER : Rough and Smooth ER . Rough ER is rough due to the presence of ribosomes. It helps in the synthesis of protein.
Mitochondrian – It is the powerhouse of the cell. It is responsible for cellular respiration which releases the energy from the food.
Centriole : It is a pair of minute cylindrical structure. It is involved in the process of cell division.
Golgi apparatus : It is a complex of vesicles and folded membranes. It is involved in secretion and intracellular transport.
Lysosome : Lysosomes are very small. They are main digestive compartments of the cell. A lysosome is called the suicidal bag.
3.) Compare the plant cell and the animal cell and complete the illustration given below
Answer :
Animal cell | Plant cell |
Cell membrane | Cell wall |
Centrioles | Chloroplast |
Mostly round cells | Mostly rectangular cells |
X.) Higher order thinking question
Virus is called Acellular. Why?
Answer : Virus is called Acellular because it do not have cell wall , cell membrane, cytoplasm and cell organelle.