DAV Class 8 Science Chapter 1 Question Answer – The Cell Its Structure and Functions

The DAV Class 8 Science Book Solutions Pdf and DAV Class 8 Science Chapter 1 Question Answer – The Cell Its Structure and Functions are essential study tools for DAV public school students in Class 8.

DAV Class 8 Science Ch 1 Question Answer – The Cell Its Structure and Functions

DAV Class 8 Science Ch 1 Solutions – The Cell Its Structure and Functions

Something To Know

A. Fill in the blanks.

Question 1.
All living organisms are made up of ________ .
Answer:
cells

Question 2.
The ________ provides rigidity and protection to the plant cell.
Answer:
cell wall

Question 3.
All cellular activities are controlled by the ________ .
Answer:
nucleus

Question 4.
The ________ is known as the powerhouse of the cell.
Answer:
mitochondria

Question 5.
________ is a group of cell performing a specific function.
Answer:
tissue

Question 6.
It was ________ who observed cells for the first time.
Answer:
Robert Hooke

B. Match the following:

Column I	Column II
(1) Golgi Complex	(a) Genes
(2) Ribosomes	(b) Cork
(3) Chromosomes	(c) Chloroplasts
(4) Dead cells	(d) Packaging centre
(5) Photosynthesis	(e) Protein synthesis

Answer:

Column I	Column II
(1) Golgi Complex	(d) Packaging centre
(2) Ribosomes	(e) Protein synthesis
(3) Chromosomes	(a) Genes
(4) Dead cells	(b) Cork
(5) Photosynthesis	(c) Chloroplasts

C. Tick (✓) the correct option:

Question 1.
The cell organelle, which acts as a storage bag for a cell, is known as the-
(a) Chloroplast
(b) Mitochondria
(c) Chromoplast
(d) Vacuole
Answer:
(d) Vacuole

Question 2.
Hen’s egg is-
(a) A cell organelle
(b) A tissue
(c) A single cell
(d) An organ
Answer:
(c) A single cell

Question 3.
The nucleus is separated from the cytoplasm by the
(a) Cytoplasm
(b) Nuclear membrane
(c) Cell membrane
(d) Protoplasm
Answer:
(b) Nuclear membrane

Question 4.
Which of the following will not be found in an egg cell, human liver cell and an amoeba?
(a) Ribosomes
(b) Mitochondria
(c) Cell membrane
(d) Cell wall
Answer:
(d) Cell wall

Question 5.
Which of the following represents the correct sequence?
(a) Tissue cell → organ → organ system
(b) Organ → tissue → organ system → cell
(c) Cell → organ → tissue → organ system
(d) Cell → tissue organ → organ system
Answer:
(a) Tissue cell → organ → organ system

Question 6.
Which, amongst the following pairs, can be found only in a plant cell but not in an animal cell?
(a) Cell wall and plastids
(b) Plastids and cilia
(c) Cell wall and cell membrane
(d) Plastids and mitochondria
Answer:
(a) Cell wall and plastids

D. Answer the following questions in brief:

Question 1.
List the main factors that determine the shape of a cell.
Answer:
Location and function of a cell determines its shape.

Question 2.
Distinguish between unicellular and multicellular organisms. Give two examples of each.
Answer:

Unicellular Organisms	Multicellular Organisms
Composed of a single cell.	Composed of more than one cell.
Examples: amoeba, bacteria	Examples: cockroach and monkey

Question 3.
Give reasons for the following:
(a) The cell is called the structural and fundamental unit of life.
Answer:
All organisms are made up of cells. A cell is capable of independent existence. Due to this, cell is called the structural and fundamental unit of life.

(b) Plant cells are more rigid than animal cells.
Answer:
Cell wall is present in plant cell. Due to this, plant cells are more rigid than animal cells.

Question 4.
Which cell organelle is known as the “Powerhouse of the cell”? Why is it so called?
Answer:
Mitochondria are the site of cellular respiration. Energy is produced during this process. Due to this, mitochondria are called the Powerhouse of the cell.

Question 5.
Name the cell organelles responsible for imparting colour to the leaves and fruits of a plant.
Answer:
Chloroplast is responsible for imparting colour to the leaves. Chromoplast is responsible for imparting colour to fruits.

Question 6.
What are cilia and flagella? Write one similarity and one dissimilarity between the two of them.
Answer:
These are small extensions on some cells. These structures help in locomotion in a cell. Cilia are much smaller than flagella.

Question 7.
If onion peel cells and cheek cells are observed through a microscope, state the two major differences that the observer is likely to see.
Answer:

Onion peel cells	Cheek cells
Cells are arranged in rows.	Cells randomly arranged.
Cell wall is present.	Cell wall is absent.

Question 8.
Classify the following into cells, tissue and organ: skin, fat cell, RBC, blood, ear, muscle.
Answer:

Cell	Tissue	Organ
Fat cell, RBCs	Blood, muscle	Skin, ear

E. Answer the following questions:

Question 1.
“All cells in an organism do not have the same shape.” Justify the above statement by drawing at least three different types found in human beings.
Answer:

These figures show that liver cell is irregular in shape, fat cell is spherical and muscle cell is spindle-shaped. This shows that all cells in an organism do not have the same shape.

Question 2.
Where, and how, are chromosomes formed? State their significance.
Answer:
Chromosomes are formed in the nucleus during cell division. When the cell is ready to divide, the chromatin (in nucleus) condenses to form thicker, thread-like chromosomes. Chromosomes are responsible for inheritance of characters from one generation to the next generation.

Question 3.
With the help of well labelled diagrams, highlight three differences between plant cell and animal cell.
Answer:

Plant cell	Animal cell
Cell wall is present.	Cell wall is absent.
Chloroplast is present.	Chloroplast is absent.
Vacuole is very large.	Vacuoles are small.

Question 4.
Write the functions performed by the following cell organelles,
(a) Endoplasmic Reticulum
(b) Golgi Complex
(d) Nucleus
(d) Chromoplasts
(e) Vacuoles
(f) Mitochondria
Answer:
(a) Transport of substance
(b) Packaging of substances
(c) Controlling the functions of a cell
(d) Imparting colour to flowers and fruits
(e) Storage
(f) Respiration

Question 5.
The cell membrane is a veiy important component of a cell. How is damage to the cell membrane likely to impact the functions of the cell?
Answer:
When the cell membrane gets damaged, it exposes the cell’s contents to external environment. This results in stoppage of all functions of the cell, and eventually to cell death.

Question 6.
Define the lerm ‘cell’ , for plants/animals. Name the different organelles that make a cell. Explain why none of these is called the structural and functional unit of life?
Answer:
Cell is the fundamental and structural unit of life. Different cell organelles in a plant cell are; nucleus, Golgi complex, mitochondria, chloroplast, endoplasmic reticulum, lysosome, vacuole, and ribosome. None of the cell organelles is capable of independent existence. So, they are not called the structural and functional unit of life.

Value Based Questions

The biology teacher started her lesson on the structure and functions of the animal/ plant cells by talking about a cricket team. She told her students that a team wins its matches only when all its members Vork as a team’ and do their assigned roles in an efficient, sincere and responsible way. She then went on to say that the animal/plant cells also work properly as their different parts work as a ‘team’ and do their specific functions. She advised her students to imbibe the ‘team spirit’ and do their specific functions as responsible members of any ‘team’ they may be a part of.

Question 1.
Name two of the values that the teacher spoke of in her class.
Answer:
Team spirit, and sticking to your role.

Question 2.
Have a group discussion in which students suggest how, ‘working as a team’ can improve the ‘overall working; of a home or a school.
Answer:
Do it yourself.

Question 3.
Have a ‘play’ in the class in which a group of students give themselves names corresponding to the different cell organelles of a plant/animal cell. Each ‘name’ has to then explain her/his role in the working of the cell.
Answer:
Do it yourself.

Something To Do

Question 1.
Hydrilla is an aquatic plant that can be seen in lakes and ponds. It has small, thin leaves. Take a Hydrilla leaf and place it on a glass slide. Observe it under a microscope.
Note your observations.

Question 2.
Divide the class into four groups of students.
Each group will prepare a short report on the topics/questions given below. Two students from each group may then present the report to the whole class.
(a) When were cells discovered? Were they discovered before or after the invention of the compound microscope?
Answer:
Cells were discovered in 1665; much before the invention of the compound microscope.

(b) Does the size and number of cells depend upon the size of the organism?
Answer:
Size of cells does not depend on the size of the organism. But number of cells depends on the size of an organism. Number of cells in an elephant would be much higher than that in a mouse.

(c) List the functions of cell organelles and also mention the organ/organ system, that the organelle is similar to, in the human body.
Answer:

Cell organelle	Function	Similar organ
Nucleus	Controls the functions of a cell.	Brain
Endoplasmic reticulum	Transport of substances.	Circulatory system
Lysosome	Digestion	Digestive system
Golgi complex	Packaging	Liver
Cell membrane	Protection, boundary	Skin

(d) List the advantages of having a cell wall as the outermost boundary in cells.
Answer:
Cell wall gives following advantages to cell:

• Gives extra protection to cell.
• Makes the cell more rigid.
• Prevents excess expansion of cell in case of osmosis of too much water into the cell.

Question 3.
Complete the crossword puzzle given below.

Across →	Down ↓
3. Storage structures of a cell.	1. Help Paramecium in locomotion.
5. Regulates the entry and exit of materials in and out of the cell.	2. Structure that helps in protein synthesis.
7. Impart colour to flowers and fruits.	4. Help plant cells in converting solar energy into usable form.
8. Provides shape and rigidity to a plant cell.	6. Control centre of the cell.
10. Powerhouse of the cell.	9. Responsible for transferring traits from one generation to next.

Answer:

Across →	Down ↓
3: Vacuoles	1: Cilia
5: Cell Membrane	2: Ribosome
7: Chromoplast	4: Chloroplasts
8: Cell wall,	6: Nucleus
10: Mitochondria	9: Gene

DAV Class 8 Science Chapter 1 Solutions – The Cell Its Structure and Functions Important Questions and Answers

I. Fill in the blanks:

1. ________ was the first scientist to observe cells.
Answer:
Robert Hooke

2. Cell wall is ________ in amoeba.
Answer:
Absent

3. Cell membrane is ________ in a plant cell.
Answer:
Present

4. Chloroplast imparts ________ colour to a plant part.
Answer:
Green

5. Materials are stored in ________ in a cell.
Answer:
Golgi complex

II. Tick (✓) the correct answer:

Question 1.
Which of these is the smallest cell?
(a) RBC
(b) Neuron
(c) Mycoplasma
(d) Egg
Answer:
(c) Mycoplasma (✓)

Question 2.
What is the name of the protoplasm which is present in the nucleus?
(a) Cytoplasm
(b) Nucleoplasm
(c) Life fluid
(d) Nuclear fluid
Answer:
(b) Nucleoplasm (✓)

Question 3.
Which of these cell organelles is also known as powerhouse of the cell?
(a) Golgi complex
(b) Endoplasmic reticulum
(c) Mitochondria
(d) Chloroplast
Answer:
(c) Mitochondria (✓)

Question 4.
Which of these is the site for photosynthesis?
(a) Golgi complex
(b) Endoplasmic reticulum
(c) Mitochondria
(d) Chloroplast
Answer:
(d) Chloroplast (✓)

Question 5.
What is the function of ribosome?
(a) Cellular respiration
(b) Protein synthesis
(c) Lipid synthesis
(d) Cell division
Answer:
(b) Protein synthesis (✓)

III. Answer the following questions:

Question 1.
Define cell.
Answer:
The basic structural and functional unit of living organisms is called cell.

Question 2.
What is a unicellular organism?
Answer:
Some organisms are composed of a single cell. These are called unicellular organisms.

Question 3.
What is a multicellular organism?
Answer:
Some organisms are composed of more than one cell. These are called multicellular organisms.

Question 4.
Write a brief note on cell membrane.
Answer:
All living cells are bound by a thin membrane called plasma membrane or cell membrane. The cell membrane provides protection to the contents of the cell and controls the entry and exit of various substances as per a cell’s requirement.

Question 5.
Mitochondria are also known as powerhouse of the cell. Why?
Answer:
Cellular respiration takes place in mitochondria and energy is generated. Due to this, mitochondria are also called the powerhouse of the cell.

Question 6.
What do you understand by cellular level of organization?
Answer:
This level of organization is found in unicellular and in some simple multicellular organisms. In such organisms, a single cell is responsible for all life functions.

IV. Projects:

Question 1.
Ask your teacher to show slides of animal cell and plant cell. Make a note of various cell organelles which can be seen through a compound microscope.
Answer:
Do it yourself.

Question 2.
Take wool of different colours, some beads and a chart paper. Make a model of animal cell with these materials.
Answer:
Do it yourself.