In this page, we are providing Cell Structure and Functions Class 8 Extra Questions and Answers Science Chapter 8 pdf download. NCERT Extra Questions for Class 8 Science Chapter 8 Cell Structure and Functions with Answers will help to score more marks in your CBSE Board Exams.
Class 8 Science Chapter 8 Extra Questions and Answers Cell Structure and Functions
Extra Questions for Class 8 Science Chapter 8 Cell Structure and Functions with Answers Solutions
Cell Structure and Functions Class 8 Extra Questions Very Short Answer Type
Question 1.
What is the basic, functional and structural unit of life?
Answer:
Cell
Question 2.
Which cell does not have nucleus?
Answer:
Red blood cell
Question 3.
What is the name of the organism which can be seen only with the help of microscope?
Answer:
Microorganisms
Question 4.
What are the organisms which are composed of many cells packed together called?
Answer:
Multicellular organisms
Question 5.
What is the name of the power house of the cell?
Answer:
Mitochondria
Question 6.
Name one example of prokaryotic cell.
Answer:
Blue-green algae
Question 7.
Amoeba and Paramecium belong to which category of organisms?
Answer:
Unicellular
Question 8.
Which instrument is used to observe cells?
Answer:
Micrbscope
Question 9.
Why we do not sense any pain when we cut nails and hair?
Answer:
Nails and hair are made up of dead cells.
Question 10.
What is the name of living substance present in cell?
Answer:
Protoplasm
Question 11.
What is the other name of cell membrane?
Answer:
Plasma membrane
Question 12.
What is the name of thread-like structure present in nucleoplasm?
Answer:
Chromatin
Question 13.
What is the name of cell which has a well-defined nucleus?
Answer:
Eukaryotic cell
Question 14.
Name the two types of cell.
Answer:
Prokaryotic cells and eukaryotic cells.
Cell Structure and Functions Class 8 Extra Questions Short Answer Type
Question 1.
What is the function of cell wall?
Answer:
Cell wall is a tough, rigid layer that surrounds some types of cells (plants and some bacterial cells). The major function of the cell wall is to provide rigidity, tensile strength, structural support, protection against mechanical stress and infection.
Question 2.
Name the parts of the nucleus and state its function.
Answer:
Nucleus consists of three main parts nuclear membrane, nucleoplasm and nucleolus. Nucleus plays an important role during cell division. It also controls the activities of the cell.
Question 3.
What is an organ?
Answer:
The structure that contains more than one type of tissues and is visible to the naked eyes are called organs.
Question 4.
What do you mean by unicellular and multicellular organisms?
Answer:
Organisms which consists of only one cell are called unicellular organisms while the organisms made up of more than one cell are called multicellular organisms.
Question 5.
Give a brief description of nucleus.
Answer:
Nucleus is a dense round body found in the centre of an animal cell and mostly on the periphery of the plant cell. The nucleus controls all the activities in a cell.
Question 6.
Name the following:
(i) Controls the function of a cell.
(ii) Selectively allows things to get in and out of the cell.
(iii) Transfer characters from parents to offsprings.
Answer:
(i) Nucleus
(ii) Cell membrane
(iii) Genes
Question 7.
What is nucleolus?
Answer:
A spherical body present at the centre of the nucleus is called the nucleolus.
Question 8.
What is endoplasmic reticulum?
Answer:
It is the system of complex folded network of membranous tubes which connects nuclear membrane with the plasma membrane. They allow movement of substances within the cell.
Question 9.
What are cell organelles?
Answer:
The tiny components present in the cytoplasm are called cell organelles.
Question 10.
What is cell membrane?
Answer:
The thin and delicate membrane surrounding the cell cytoplasm is called cell membrane.
Cell Structure and Functions Class 8 Extra Questions Long Answer Type
Question 1.
Differentiate between
(a) Cell wall and cell membrane
(b) Leucoplast and chloroplast
(c) Vacuole in a plant cell and an animal cell
(d) A tissue and an organ
Answer:
(a) Cell wall and cell membrane
| Cell wall | Cell membrane |
| (i) It is present in only plant cells. | (i) It is present in both plant and animal cells. |
| (ii) It is rigid, thick structure. | (ii) It is delicate, thin structure. |
| (iii) It is completely permeable to ordinary molecules. | (iii) It is selectively permeable to molecules. |
| (iv) It is metabolically inactive and nonliving. | (iv) It is metabolically active and living. |
(b) Leucoplast and chloroplast
| Leucoplast | Chloroplast |
| (i) It is colourless plastid. | (i) It is green plastid. |
| (ii) It is found in underground parts of plants like, roots, and underground modified stems. | (ii) It is found in green parts of plants like leaves, stem and sepals. |
| (iii) It help in storage of food. | (iii) It helps in photosynthesis. |
(c) Vacuole in a plant cell and an animal cell
| Vacuoles in plants | Vacuoles in animals |
| (i) Plant cell vacuoles are large in size. | (i) Animal cell vacuoles are smaller in size. |
| (ii) Usually a large central vacuole is found. | (ii) Many vacuoles are found. |
| (iii) It is usually permanent structure. | (iii) It is mostly temporary structure. |
(d) A tissue and an organ
| Tissue | Organ |
|
It is made of similar cells. |
It is made of similar tissues. Example: Heart, lung, stomach, etc. |
Question 2.
What are the main functional regions of a cell? Explain.
Answer:
Main functional regions of a cell are:
- Plasma membrane: This is the membrane which makes the outer boundary of the cells. It is very thin, delicate and selectively permeable.
- Cytoplasm: Cytoplasm is viscous, transparent jelly-like substance of the cell. It contains cell organelles.
- Nucleus: Nucleus controls the working of the cell. It is a dense oval body lying in the protoplasm of the cell.
Question3.
Define cell membrane and state its functions.
Answer:
Cell membrane or plasma membrane is a thin, delicate membrane surrounding the cytoplasm.
Following are the functions of cell membrane:
- It separates the cells from one another and also separates the cells from the surrounding medium.
- It gives a definite shape to the cell.
- Being porous, it allows the movement of substances from both inside and outside the cells.
- Its porous structure helps in regulating the movement of materials through the cells.
Question 4.
Define nucleus and state its major parts.
Answer:
Nucleus is a dense round body found in the centre of an animal cell and mostly on the periphery of the plant cell. The nucleus controls all the activities in the cell like digesting movement of substances within the cell. Nucleus also controls the process of cell division. This is the reason nucleus is also known as the ‘brain of the cell’.
Nucleus consists of four major parts. They are:
- Nuclear membrane
- Nucleoplasm
- Nucleolus
- Chromatin
Cell Structure and Functions Class 8 Extra Questions HOTS
Question 1.
Which organism is more efficient in its functioning unicellular or multicellular? Why?
Answer:
Multicellular organisms are more efficient in its functioning because labour is divided among the cells and have great capacity to survive than unicellular organisms.
Question 2.
What would happen if animals have cell wall?
Answer:
All parts of the animal would become rigid which will make their movement of limbs and body parts difficult.
Question 3.
Cells consist of many organelles, yet we do not call any of these organelles as structural and functional unit of living organisms. Explain.
Answer:
Organelles cannot function outside the cell as an independent unit. They can perform their functions only when they are within the living cells.
Question 4.
Why plant cells need cell walls?
Answer:
As plants cannot move, they need protection against variations in temperature, high wind speed, atmospheric moisture, etc.
Cell Structure and Functions Class 8 Extra Questions Value Based (VBQs)
Question 1.
In a cell, every cell organelle perform its own function. They coordinate the functions of cell.
(a) Can a cell work if any of its organelle stops working?
(b) What does a cell represent in a real life?
(c) What values do we get from the above paragraph?
Answer:
(a) Cell would not work if any of its organelle stops working.
(b) Cell represent our society where various people do their work to maintain it.
(c) We should perform our duty regularly and honestly for the betterment of the whole world.
Question 2.
Shyam being very inquisitive, didn’t listen to the teacher’s instruction properly. He took the thin layer of onion peel with a drop of water on the glass slide. He placed the coverslip on it and start observing the slide under a microscope. But he was unable to see the cells of onion peel properly.
(a) What do you think he might have forgotten?
(b) What is the function of a dye?
(c) What values do you get from the above incidence?
Answer:
(a) He might have forgotten using dye.
(b) Dye stains the cell and its component and make them visible.
(c) We must always follow teacher’s instruction. In laboratory we must not hurry and keep patience.