DAV Class 8 Science Solution Chapter 1 The Cell – Its Structure and Functions
DAV School Books Class 8 Science Solution Chapter 1 The Cell – Its Structure and Functions all Question Answer. DAV Class 8 1st Chapter The Cell – Its Structure and Functions full Chapter explanation by expert teacher.
DAV School Books Class 8 Science Solution Chapter 1 The Cell – Its Structure and Functions
A.) Fill in the blanks.
1. All living organisms are made up of ___________.
2. The ___________ provides rigidity and protection to the plant cell.
3. All cellular activities are controlled by the ___________.
4. The ___________ is known as the powerhouse of the cell.
5. ___________ is a group of cells performing a specific function.
6. It was ___________ who observed cells for the first time.
Answer: (1) cells (2) cell wall (3) nucleus (4) mitochondria (5) tissue (6) Robert Hooke
B.) Match the following.
1. Golgi complex | a. Genes |
2. Ribosomes | b. Cork |
3. Chromosomes | c. Choloroplasts |
4. Dead cells | d. Packaging centre |
5. Photosynthesis | e. Protein synthesis |
Answer: (1) d, (2) e, (3) a, (4) b, (5) c
C.) Tick the correct option.
1.) The cell organelle, which acts as a storage bag for a cell, is known as the-
Answer: vacuole
2.) Hen’s egg is-
Answer: a single cell
3.) The nucleus is separated from the cytoplasm by the-
Answer: nuclear membrane
4.) Which of the following will not be found in an egg cell, human liver cell and an Amoeba?
Answer: cell wall
5.) Which of the following represents the correct sequence?
Answer: cell → tissue → organ → organ system
6.) Which, amongst the following pairs, can be found only in a plant cell but not in an animal cell?
Answer: cell wall and plastids
D.) Answer the following questions in brief.
1.) List the (main) factors that determine the shape of a cell.
The three essential components that determine the size and shape of cells are
- the cytoskeleton,
- the volume of water inside the cell, and
- the condition of the cell membrane.
2.) Distinguish between unicellular and multicellular organisms. Give two examples of each.
Multicellular Organism |
Unicellular Organism |
Composed of more than one cell | Composed of a single cell |
Complex body structure | Simple body structure |
Different organelles perform specific functions | A single cell performs all the activiies |
3.) Give reasons for the following:
(a) The cell is called the structural and functional unit of life.
Answer: A cell performs important functions such as respiration and excretion, also produces energy in the form of ATP. All living things are composed of cells and in fact it is the smallest component of any organism. Thus it is known as the functional and structural unit of life
(b) Plant cells are more rigid than the animal cells.
Answer:In plant cells they have a protective outer layer that is made of cellulose. This cell wall provides rigidity and protection to plant cells. Cell walls made of cellulose are absent in animals.
4.) Which cell organelle is known as the ‘Powerhouse of the cell? Why is it so called?
Answer: The mitochondria are the “powerhouse” of the cell.
The mitochondria are where cellular respiration takes place. Energy is produced in the form of ATP during this process. The cell and other parts of the body uses this ATP or form of energy to perform functions. Thus, mitochondria is known as the powerhouse of the cell since it provides energy for all other important functions.
5.) Name the cell organelles responsible for imparting colour to the leaves and fruits of a plant.
Answer: Chloroplasts are responsible for the colour of the leaves. Chromoplast activity is responsible for the colour of fruits.
6.) What are cilia and flagella? Write one similarity and one dissimilarity between the two of them.
Both Cilia and flagella are locomotive organelles found in unicellular organisms.
Cilia are short in length and hair like protrusions from the cell surface. The motile cilia move is a sweeping motion to facilitate location for the organism. Flagellas are lesser in number within an organism and are longer but less thicker than cilias.
Both are useful for locomotion but however differ in shape and size.
7.) If onion peel cells and cheek cells are observed through a microscope, state the two major differences that the observer is likely to find.
Onion cells are roughly rectangular in shape, whereas cheek cells have an amorphous polygonal shape.Onion cells (plant cells) have cell walls, whereas cheek cells (animal cells) do not since they are animal cells.
8.) Classify the following into cells, tissue and organ.
skin, fat cell, RBC, blood, ear, muscle.
CELL | TISSUE | ORGAN |
Fat cell, RBC | Blood and Muscle | Skin, ear |
E.) Answer the following questions.
1.) “All cells in an organism do not have the same shape.”
Justify the above statement by drawing at least three different cell types found in human beings.
The above diagram shows how muscle cells are spindle like in shape, a nerve cell is elongated and has branch like endings. The liver cell has an indefinite shape. The variety of shape and size of different cells exists within an individual organism.
2.) Where, and how, are chromosomes formed? State their significance.
The chromosomes are formed within the nucleoplasm of the nucleus. The nucleoplasm contains networks of thin thread-like structures known as the chromatin threads. These threads condense into thicker strands and form chromosomes.
Chromosomes are responsible for carrying genetic information from one generation to the other.
3.) With the help of well labelled diagrams, highlight three differences between a plant cell and an animal cell
Plant Cell |
Animal cell |
Cell wall is present in plant cells made up of cellulose | Cell wall is absent even though it has a cell membrane. |
Plastids are present in plant cells | Plastids are absent |
Vacuoles are usually very large for storing food and minerals | Vacuoles are small because there is no need for food storage. |
4.) Write the functions performed by the following cell organelles.
a).endoplasmic reticulum is a network of membranes found in the cell. It offers pathways for the movement of materials inside a cell. It is of two types the rough and smooth endoplasmic reticulum.
(b) Golgi Complex: These sac-like structures occur one on top of the other. They help in the process of packaging the materials that the cell produces including protein and lipids
(c) The nucleus, a specialised cell structure enclosed within the nuclear membrane and in charge of regulating all cellular activities.It is also responsible for carrying chromosomes.
d) Chromoplasts are plastids that are in charge of giving the various plant parts their other colours, besides green.
e)Vacuoles are seen as empty spaces in the cytoplasm in cells. They are usually found to be larger in plant cells and are used to store excess food , water and minerals.
f) Mitochondria is an important organelle and are either spherical or rod-shaped. They perform the task of cellular respiration and the production of energy in the form of ADP that is utilised by the cell and body for different processes.
5.) The cell membrane is a very important component of a cell. How is damage to the cell membrane likely to impact the functions of the cell?
The cell’s contents are exposed to the outside environment when the cell membrane is compromised. This causes the cell to stop performing all of its functions, which ultimately leads to cell death.
6.) Define the term ‘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.
The fundamental structural, functional, and biological unit of all recognised organisms is the cell. Cells are frequently referred to as the “building blocks of life” because they are the smallest unit of life.A cell is made up of the nucleus, Golgi complex, mitochondria, chloroplasts, endoplasmic reticulum, lysosomes, vacuoles, and ribosomes, among other organelles.Together, these cell organelles carry out the various tasks required by the cell. These cannot all exist independently of one another. This means that they are not referred to as the structural and functional unit of life.