CBSE Class 9 Biology Fundamental Unit Of Life Worksheet Set B

1. Fill in the blanks:-

(a) New cells are formed from pre-existing cells.

(b) Movement of water molecules from their higher concentration to their lower concentration through a semi- permeable membrane is called Osmosis.

(c) The functional components of cell are plasma membrane, cytoplasm & nucleus.

(d) Protoplasm has two parts- cytoplasm & nucleoplasm.

(e) Nucleus, mitochondria & plastids have their own DNA & ribosomes.

(f) The shrinkage or contraction of the contents of the cell away from the cell wall is known as plasmolysis.

(g) The process by which Amoeba can engulf a food particle is endocytosis.

(h) Biogenesis is the manufacture of lipids required for making cell membrane.

(i) A cell that lacks nuclear membrane is called a prokaryotic cell & the nuclear region is called nucleoid.

(j) Movement of materials in & out of the cell takes place by diffusion & osmosis.

2. What is the advantage of multicellularity over unicellularity?
Answer : Division of labour.

3. What are the chromosomes made up of?
Answer : DNA & proteins

4. A cell placed in a solution swells up. What kind of solution is it? Why does it happen?
Answer : It is a hypotonic sol ution & water enters the cell by endosmosis causing the cell to swell up.

5. Why are lysosomes known as “suicidal bags”?
Answer : They secrete powerful digestive enzymes to digest the worn out and damaged cell organelles as well as the cell itself when it loses its functional ability

6.Why is the nucleus so significant in a cell?
Answer : Nucleus has the following important functions-
(i) It controls all cell activities
(ii) It contains hereditary material that transmits hereditary information from one generation to the next
(iii) It helps in cell division

7. Differentiate between plant & animal cells.

8. Draw neat & labeled diagrams of the following:-

(i) Typical plant cell

(ii) Typical animal cell

(iii) Prokaryotic cell

9. Give the major functions of the following cell organelles-

(a) Endoplasmic reticulum-
RER- Synthesis of proteins as it has ribosomes attached to it
SER- Synthesis of lipids required for making cell membrane

(b) Golgi apparatus-
Storage & packaging of various products.
(c) Mitochondria-
Production of ATP(Adenosine Triphosphate) which is a source of energy.

(d) Ribosomes-
Protein synthesis

(e) Golgi Apparatus-
Storage & packaging of various products.

(f) Lysosomes-
Digestion of worn out & damaged organelles

Exam Questions NCERT Class 9 Science Chapter 5 The Fundamental Unit of Life

Question. Give difference between organs and organelles.
Answer : Organs :
They are found in multicellular organisms.
They are large sized.
They may be external or internal to the body of organisms.
Organelles : 
1. They are found in all eukaryotic cells.
2. They are very small sized.
3. They are mostly internal.

Question. Give difference between Chloroplasts and Chromoplasts.
Answer : Chloroplasts :
(i) They are green plastids.
(ii) They contain chlorophylls and carotenoids.
(iii) Lamellae are present.
(iv) Chloroplasts are sites of photosynthesis.
Chromoplasts :
(i) They are non-green coloured plastids.
(ii) Chlorophylls are absent.
(iii) Lamellae are absent.
(iv) They add colour to the organs for attracting animals to perform pollination and fruit dispersal.

Question. How do lysosomes perform their function?
Answer : Functions of lysosomes :
(i) Extracellular digestion : Sometimes lysosome enzymes are released outside the cell to break down extracellular material.
(ii) Destruction of foreign material : Lysosome also destroys any foreign material which enters inside the cell such as bacteria.
(iii) Cellular digestion : Enzymes are released in damaged cells, ageing cells or dead cells. These enzymes digest their own cell.
Lysosomes contain about 40 hydrolytic enzymes.
Lysosomes burst and their enzymes digest their own cell when the cell gets damaged. So, lysosomes are called ‘suicide bags’.
Foreign materials entering the cell, such as bacteria or food, as well as dead old organelles in the lysosomes break up into small pieces.

Question. Describe an activity to demonstrate endosmosis and exosmosis. Draw a diagram also.
Answer : 1. Endosmosis : The movement of water in the cell or a body through a semipermeable membrane is called endosmosis. It can be demonstrated as follows :
(i) Take some raisins with stalks and put them in plain water in a beaker.
(ii) Observation : Raisins absorb water and swell. Raisins have high concentration of sugar than surrounding plain water. Because of this, water from the outside passing through
semipermeable membrane enters into the cell. This is endosmosis.

Question. How does a living cell perform basic functions?
Answer : A living cell perform basic functions by division of labour among specific components within it is known as cell organelles.

Question. What could happen if nucleus is removed from the cell?
Answer : If nucleus is removed from a cell, the protoplasm will ultimately dry up and the cell will die because the nucleus controls all the metabolic activities of a cell.

Question. Name the organelles present in liver of animals which detoxifies many poisons and drugs.
Answer : In the liver of animal cells, smooth endoplasmic reticulum helps in detoxifying many poisons and drugs.

Question. How are new cells reproduced?
Answer : Cells multiply by dividing themselves again and again. Cells divide to produce cells of their own kind.

Question. Give example of working of chromoplasts.
Answer : Spinach looks green due to the presence of chloroplasts, papaya is yellow and edible part of watermelon is red due to the presence of chromoplasts.

Question. What is plasmolysis?
Answer : When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.

Question. What would happen to the life of a cell if there was no Golgi apparatus?
Answer : Golgi apparatus plays an important fusion of storage, modification and packaging of the products in vesicles. If there were no Golgi bodies, packaging and dispatching of materials synthesised by the cell will be stopped.

Question. What is the function of vacuoles?
Answer : Vacuoles are the storage sacs for solid or liquid content. In plant cells, it provides turgidity and rigidity to the cell. In single-celled organisms, vacuoles store food, e.g. amoeba.

Question. What is the function of DNA?
Answer : They are responsible for storing and transmitting hereditary information from one generation to another. They contain the information necessary for constructing and organizing cells.

Question. List two similarities between mitochondria and plastids.
Answer : Plastids are similar to mitochondria in external structure. Like the mitochondria, plastids also have their own DNA and ribosome.

Question. Where are genes located in the cell?
Answer : Genes are located in the chromosomes in the nucleus of the cell.

Question. Why does mitochondria have largely folded inner membrane?
Answer : Mitochondria have largely folded inner membrane which provides the increased surface area for ATPgenerating chemical reactions. Mitochondria is the site for cellular respiration and provides energy to the cell.

Question. Name the autonomous organelles in the cell.
Answer : Chloroplast and mitochondria are the autonomous organelles in the cells.

Question. What is the energy currency of the cell?
Answer : ATP—Adenosine Triphosphate.

Question. Name the cell organelle that helps in packaging?
Answer : Golgi apparatus.

Question. What is cell wall?
Answer : Cell wall is the rigid outer covering of plasma membrane in plant cells.

Question. What would happen if the plasma membrane breaks down?
Answer : If plasma membrane breaks down then molecules of some substances will freely move in and out.

Question. Where are proteins synthesized inside the cell?
Answer : The proteins are synthesised in the ribosomes, known as protein factories too.

Question. Who discovered cells in living organisms? Give an example of unicellular organism.
Answer : Leeuwenhoek (1674) was the first to observe the free living cells in pond water. Example of unicellular organisms : Amoeba, Chlamydomonas, Paramoecium, Bacteria, etc.

Question. What is the function of plastids?
Answer : Plastids are present only in plant cells. There are two types of plastids chromoplasts (coloured plastids) and leucoplasts (white or colourless). Chromoplast : Consists of coloured pigments andgiven different colours to flowers, fruits and leaves. The green colour pigment present in leaf is called chlorophyll which helps in the photosynthesis and a plastid with chlorophyll is called chloroplast. Leucoplast : It stores starch, oil and protein granules in it.

Question. Where do lipids and proteins get synthesized?
Answer : Lipids get synthesized in the smooth endoplasmic reticulum and proteins get synthesised in the ribosome and rough endoplasmic reticulum.

Question. Write a function of cell membrane.
Answer : Its major function is to hold cellular contents and control passage of materials in and out of the cell.