AP 9th Class Biology 5th Lesson Important Questions The Fundamental Unit of Life

These AP 9th Class Biology Important Questions 5th Lesson The Fundamental Unit of Life will help students prepare well for the exams.

AP 9th Class Biology 5th Lesson The Fundamental Unit of Life Important Questions

Class 9 Biology Chapter 5 Important Questions – 2 Marks

Question 1.
What is cell theory ?
Answer:
The cell theory explains that …….
a) All the plants and animals are composed of cells and that the cell is the basic unit of life.
b) All cells arise from pre existing cells.

Question 2.
What are multicellular organisms ?
Answer:
The organisms which are formed with more than one cell are called multicellular organisms.
Ex : Plants and animals.

Question 3.
On which aspect the shape and size of cells are related to ?
Answer:
The shape and size of the cells are related to the specific function of the cell that perform.

Question 4.
What is division of labour in multicellular organisms ?
Answer:
Different parts of the human body perform different functions. That is division of labour.

Question 5.
What is plasma membrane ?
Answer:
The plasma membrane is the outermost covering of the cell that separates the contents of the cell from its external environment.

Question 6.
Plasma membrane is also called as selective permeable membrane.
Answer:

1. The plasma membrane allows or permits the entry and exit of some materials in and and out of the cell.
2. It also prevents movement of some other materials.
   So the plasma membrane is also called as selective permeable membrane.

Question 7.
What is diffusion ?
Answer:
The spontaneous movement of a substance from a region of high concentration to a region where its concentration is low. It is called diffusion.

Question 8.
What is osmosis ?
Answer:
The movement of water molecules through such a selectively permeable membrane is called osmosis.

Question 9.
What is hypotonic solution ?
Answer:
If the medium surrounding the cell has a higher water concentration than the cell, meaning that the outside solution is very dilute, the cell gain water by osmosis. Such as solution is called hypotonic solution.

Question 10.
What is Isotonic solution ?
Answer:
If the medium has exactly the same water concentration as the cell, there will be no net movement of water across the cell membrane such a solution is known as Isotonic solution.

Question 11.
What is a hypertonic solution ?
Answer:
If the medium has a lower concentration of water than the cell, meaning that it is a very concentrated solution, the cell will be water by osmosis. Such a solution is known as a hypertonic solution.

Question 12.
Define endocytosis. Give an example.
Answer:
The flexibility of the cell membrane enables the cell to engulf in food and other material from its external environment. Such processes are known as endocytosis.

Question 13.
What is cell wall ?
Answer:
The rigid outer cover present in plant cell in addition to the plasma membrane is called cell wall.

Question 14.
Define the plasmolysis.
Answer:
When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell and from the cell wall.’This phenomenon is known as plasmolysis.

Question 15.
What is Nucleus ?
Answer:
A dark coloured, spherical or oval dot like structure near the centre of each cell is called Nucleus.

Question 16.
Name some cell organelles.
Answer:
Endoplasmic reticulum, Golgi Apparatus, lysosomes, mitochondria and plastids, Nucleus, plasma membrane, cell wall, cytoplasm.

Question 17.
What is biogenesis ?
Answer:
The process of some of the proteins and lipids help in building the cell membrane is called biogenesis.

Question 18.
Define the following.
i) Mitosis
ii) Meiosis
Answer:
i) Mitosis : The process of cell division by which most of the cells are divide for growth is called mitosis.
ii) Meiosis : The process of cell division by which reproductive cell to form gametes is called Meiosis.

Question 19.

i) Identify the diagram
ii) Label the parts a, b
iii) Which letter indicates the Nucleus.
Answer:
The diagram is cells of an onion peel
i) Part a – Cell
ii) Part b – Indicates the Nucleus

Question 20.

i) Identify the figure.
ii) Is it round. If not how is it ?
Answer:
i) It is a nerve cell.
ii) It is not round, It is long and branched.

Question 21.

i) Name the diagram.
ii) Why is it prokaryotic cell ?
Answer:
i) The diagram is prokaryotic cell.
ii) There is no nuclear member over the nucleus so it is prokaryotic cell.

Question 22.

Name the figure.
Answer:
Mitochondria

Question 23.
What happens if there is no cell ?
Answer:

1. As the cell is the basic structure of the life, so one cannot survive without a cell.
2. If there is no cell, there is no life.

Question 24.
Do you say that all cells are alike in shape, size; otherwise mention some shapes of cells.
Answer:

1. No, All cells are not alike in shape, size.
2. Some cells are round, circular, long and branched, spindle shaped.

Question 25.
Bindu said that every cell arise from pre – existing cells. Do you agree with this statement ? Support your answer.
Answer:
Yes. Bindu’s statement is correct only. I agree with that as per the cell theory proposed Schleidan & Schwanan Virchow “All cells arise from pre – existing cells”.

Question 26.
Bacteria do not have chloroplast but some bacteria are photo autotrophic in nature and perform photosynthesis. Which part of bacterial cell performs this ?
Answer:
In most photosynthetic bacteria, pigments and enzymes involved in photosynthesis are found in infoldings of plasma membrane that extend into the cytoplasm.

Question 27.
Why is the Golgi Apparatus called the secretary organelles of the cell ?
Answer:
This is because it packages material synthesized in the ER and dispatches it to intracellular and extra cellular targets.

The Fundamental Unit of Life Class 9 Important Questions – 3 Marks

Question 1.
How can you say the cell is the fundamental unit of cell ? Or a building unit of cell?
Answer:
Yes, cell is a building unit of an organism. The body of an organism is made up of various organ systems like digestive system, reproductive system etc., The organ systems are made up of various organs which in turn are made up of tissues. A tissue is a group of cells performing the same function. Hence a cell is the basic building unit or fundamental unit of an organism.
It can be represented as ……….
Cell → Tissue → Organ → Organ system – organism

Question 2.
Why does the skin of your finger shrink when you wash clothes for a long time ?
Answer:

1. Soap solution is a hypertonic solution.
2. It is more concentrated than the cells of our skin.
3. As we know when a cell is immersed in a hypertonic solution, water leaves the cell by the processes exosmosis resulting in shrinkage of the cell.
4. ln the same way, while washing clothes for a long time, exosmosis occurs in the skin celfs resulting in the shrinkage of skin cells of our fingers.

Question 3.
How are chromatin, chromatid and chromosomes related to each other ?
Answer:

1. Chromatin occurs as diffuse network of fine filaments in non – dividing Nucleus.
2. At the time of cell division, chromatin material becomes condensed into rod – like structures called chromosomes.
3. Each chromosome has a centromere and two arms called chromatid.

Question 4.
Why do plant cells possess large sized vacuole ?
Answer:

1. In mature plant cells, a large central vacuole occupying most of the cell space is present.
2. It is because in the plant cells, vacuole does not only store food material and waste products, rather it also contains cell sap.
3. The cell sap helps to keep the cell turgid and provides rigidity and support to it.
4. Vacuole also helps in maintaining water balance of the cell.
5. Thus plant cell possess large sized vacuole.

Question 5.
Which kind of plastid more common in ……………….
a) Roots of the plant
b) Leaves of the plant
c) Flowers and fruits
Answer:
a) Leucoplasts are more common in non – photosynthetic organs such as roots of the plant.
b) Chloroplasts are more common in green photosynthetic organs such as leaves of the plant.
c) Chromoplasts are more common in colourful parts such as flowers and fruits.

Question 6.
Which cell organelle controls most of the activities of the cell ?
Answer:

1. Nucleus controls the most of the activities of the cell such as cellular metabolism, reproduction etc due to the presence of DNA which contains all the information- required the cell.
2. DNA directs the synthesis of RNA, which in turn directs the synthesis of proteins and enzymes required for various cellular activities.

Question 7.
Why are lysosomes are called suicidal bags of the cells ?
Answer:

1. Lysosomes are called suicidal bags of the cells because they are a kind of waste disposal system of cell.
2. This is due to the presence of powerful digestive enzymes which are capable of break down all organic material.
3. Lysosomes help to keep the cell clean by digesting any foreign material such as bacteria, food particles etc, as well as worn – out cell organelles.

Question 8.
How is a bacterial cells different from an onion peel cell ?
Answer:

1. A bacterial cell is a prokaryotic cell which contains a poorly defined region called nucleoid.
2. All the membrane bound cell organelles are absent in a bacterial cell.
3. An onion peel cell is a Eukaryotic plant cell which contains a well defined nucleus and all the membrane – bound cell organelles such as mitochondria, ER etc.,

Question 9.
Write the name of different plant parts in which chromoplast, chloroplast and Leucopast are present ?
Answer:

1. Chromoplasts are present in flowers, fruits and other colourful parts of the plant.
2. Chloroplasts are present in green coloured parts eg. Leaves of the plant.
3. Leucoplasts are present in non – photosynthetic and storage organs of the plant.
   Ex : Seeds, fruits, tubers, roots etc.

Question 10.
If you are provided with some vegetables to cook. You generally add salt into the vegetables during cooking process after adding salt, vegetables release water. What mechanism is responsible for this ?
Answer:

• The mechanism responsible for this process is exosmosis.
• Addition of salt during cooking makes the surrounding medium hypertonic i.e., the surrounding medium has lower water concentration than the cells of vegetables.
• As we know when a cell is immersed in a hypertonic solution water leaves the cell by the process of exosmosis resulting in its shrinkage. Therefore vegetables release water afer adding salt during cooking process.

Question 11.
A person takes concentrated solution of salt, after some time, he starts vomiting. What is the phenomenon responsible for such situation ? Explain.
Answer:

• The phenomenon responsible for such situation is exosmosis.
• Concentrated solution of salt is hypertonic to the cells of our body i.e., concentration of water molecules in it is lesser than the concentration of water molecules in the cells of our body. ,
• When a person drinks concentrated salt solution, water comes out of the cells of the alimentary canal by the process of exosmosis causing a loss of water in the cells.
  This results in dehydration, diarrhea and vomiting.

Question 12.
Differentiate between diffusion and osmosis.
Answer:

Diffusion	Osmosis
1) It occurs in any medium.	1) It occurs in liquid medium only.
2) Diffusing molecules may be solid, liquid or gaseous solutes.	2) It involves movement of solvent molecules only.
3) Semi permeable membrane is not required.	3) Semi permeable membrane is required.

Question 13.
Differentiate between Rough endoplasmic reticulum and smooth endoplasmic reticulum.
Answer:

Rough endoplasmic reticulum	Smooth endoplasmic reticulum
1) They have ribosomes attached on their surfaces.	1) They do not have ribosomes attached on their surfaces.
2) RER manufactures proteins and transports them to various places.	2) SER helps in manufacturing lipids and transports them to various places.

Question 14.
Write the differences between a plasma membrane and a cell wall ?
Answer:

Plasma membrane	Cell wall
1) It holds cellular contents and controls passage of materials in and out of cell.	1) It gives protection, strength and rigidity to the cell.
2) It is semipermeable in nature and allows entry of selected molecules into the cell.	2) It is completely permeable in nature.
3) It is not elastic.	3) It is elastic and controls the cells turgidity preventing its bursting.

Question 15.

i) Identify the diagram given in the picture.
ii) Mention the function of mitochondria.
iii) Why is it called power house of the cell ?
Answer:
i) The given diagram is Mitochondria.
ii) Mitochondria is responsible for cellular response.
iii) Mitochondria stores the energy and it releases whenever the cell requires energy.
So it is called power house of the cell.

Question 16.

i) Label the parts of a, b, c.
ii) What are the functions of Rough Endoplasmic Reticulum ?
iii) What are the functions of smooth Endoplasmic Reticulum ?
iv) What is the function of Ribosomes ?
Answer:
i) Part a = Rough Endoplasmic Reticulum
Part b = Ribosomes
Part c = Smooth Endoplasmic Reticulum

ii) Functions of Rough Endoplasmic Reticulum
a) They helps in synthesise of proteins.

iii) Functions of smooth Endoplasmic Reticulum.
a) They helps in the manufacture of molecules, or lipids important for cell function.

iv) Functions of Ribosomes : a) Ribosome helps in synthesize of proteins.

Question 17.

i) Name the part a.
ii) Who described it first ?
iii)What is the function of Golgi complex ?
Answer:
i) Name of the part a = Golgi Apparatus
ii) Cabrillo Golgi discovered it first.
iii) Function of Golgi complex.
a) The Golgi apparatus fucntions include the storage, modification and packaging of products in vesicles.
b) It also involved in the formation of lysosomes.

Important Questions on The Fundamental Unit of Life Class 9 – 5 Marks

Question 1.
In brief state what happens when ….
a) dry raisins are left for some time in pure water and later transferred to sugar solution ?
b) a red blood cell is kept in concentrated saline solution ?
c) the plasma membrane of a cell breaks down ?
d) Rheo leaves are boiled in water first and then a drop of sugar syrup is put on it ?
e) Golgi apparatus is removed from the cell ?
Answer:
a) The apricots swell due to osmosis initially and when transferred to sugar solution shring again due to exosmosis.

b) RBCs shrink due to exosmosis.

c) It would help lead to scattering of cell organelles and there will be no functioning of the organs.

d) There will be no change in cell shape or size because the cells are dead due to boiling.

e) Function of Golgi apparatus is packing, storing and transfer of protein. It would affect the functioning of cell.

Question 2.
If cells of onion peel and RBQ are separately kept in hypotonic solution, what will happen to each of them ? Explain the reason for your answer.
Answer:
a) Both the cells will swell up.

b) RBC will burst easily while cells of onion peel will resist the bursting to some extent. Because
i) When kept in a hypotonic solution, the onion cells will become turgid because the water will enter the cell due to osmosis. But the cell wall present outside the cell provide it’s rigidity and does not let any harm to occur.
ii) Where as in RBC the movement of water inside the cell due to osmosis will lead to bursting of the cell because it does not have a rigid cell wall.
Therefore RBC will burst easily while onion cell peels will resist it to some extent.

Question 3.
How does Amoeba obtains its food ?
Answer:

1. Amoeba obtains its food by the process of endocytosis.
2. Endocytosis refers to the invagination of a small region of the plasma membrane to engulf the food particle and ultimately forming an intrecellular membrane-bound vesicle.
3. Depending upon the type of food material, endocytosis may be i) Phagocytosis ii) Pinocytosis
4. Phagocytosis is a common method of feeding in some protozoans, eg. Amoeba. In this method, a part of plasma membrane invaginates in the region of solid food particles and engulf it.
5. The membrane enclosed vesicle called phagosome containing the food particle detaches from the plasma membrane into the cytoplasm, where it’s contents are digested by lysosomal engymes.

Question 4.
What are the consequences of the following conditions ?
a) A cell containing high water concentration than the surroudings medium.
b) A cell having low water concentration than the surrounding medium.
c) A cell having equal water concentration to its surrounding medium.
Answer:
a) A cell having high water concentration than the surrounding medium will lose water due to exosmosis. The cell will ultimately shrink.

b) A cell having low water concentration than the surrounding medium will gain water due to endosmosis and the cell will ultimately swell up.

c) A cell having equal water concentration to its surrounding medium will remain in its original state as there is no net movement of water into or out of the cell.

Question 5.
Illustrate only a plant cell as seen under electron microscope. How is it different from animal cell ?
Answer:

Differences between a plant cell and animal cells :

Plant cell	Animal cell
1) Cell wall is present.	1) Cell wall is absent.
2) A large central vacuole is present.	2) Many small vacuoles are present.
3) Nucleus is peripheral in position	3) Nudes is centrally placed.
4) Golgi aparatus is present in the form of freely distributed units called dictyosomes.	4) Single Golgi apparatus is present generally near the nuclear envelope.
5) Centrioles are absent.	5) Centrioles are present.
6) Plastids are present.	6) Plastids are absent.
7) Mitochondria are comparatively fewer in number.	7) Mitochondria are numerous.
8) Lysosomes are rarely present.	8) Typical lysosomes are present.
9) Reserve food material is mainly starch.	9) Reserve food material is mainly glycogen.

Question 6.
Draw a neat labelled diagram of an animal cell.
Answer:

Question 7.
Draw a well labelled diagram of an Eukaryotic nucleus. How Is it different from nucleoid?
Answer:

Differences between a plant cell and animal cells :

Nucleus	Nucleoid
1) It is in larger size.	1) It is smaller in size.
2) It is bounded by double membrane.	2) It is not bounded by any membrane.
3) It contains Nucleolus.	3) It does not contain Nucleolus
4) It contains DNA associated with histone proteins.	4) It contains naked DNA ie., DNA is not associated with histone proteins.
5) It is present in eukaryotic cells.	5) It is present in prokaryotic cells.
6) Plastids are present	6) Plastids are absent.

Question 8.
i) What is cell division ? Write about types of cell divisions.
ii) Write the differences between mitosis & meiosis through a diagram.
Answer:
i) Cell division : The process by which new cells are made is called cell division.

ii) Types of cell divisions : There are two types of cell division : a) Mitosis b) Meiosis
a) Mitosis : Mitosis is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division.
b) Meiosis : Meiosis is a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes.

iii) Differences between mitosis or meiosis are :

Mitosis	Meiosis
1) This takes place in somatic cells.	1) This takes place in reproductive cells.
2) Completed in one stage.	2) Completed in two stages.
3) It produces two daughter cells.	3) It produces four daughter cells.
4) The daughter cells have the same number of choromosomes as mother cell.	4) The daughter cells have half the number of chromosomes than that of the mother cells.

Question 9.
Write the differences between Cytoplasm and Nucleoplasm.
Answer:
Differences between Cytoplasm anjd Nucleoplasm.

Cytoplasm	Nucleoplasm
i) Cytoplasm is the protoplasm which lies outside the nucleus.	i) It is the part of protoplasm that lies inside the nucleus.
ii) It is semi-fluid jelly like substance.	if) It is transparent.
iii) It contains various inorganic subst­ances forming clear true solution as well as organic substances lipids, proteins and carbohydrates.	iii) It contains chromatin material.
iv) It contains various organelles and inclusions.	iv) ft is a colloidal substance having similar composition to cytoplasm but contains more of nucleotides.

Extra Questions on The Fundamental Unit of Life Class 9 – 4 Marks

Question 1.
Read the paragraph and answer the following questions :

Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose, cellulose is a complex substance and provides structural strength to plants. 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.

a) Name the outer cover which the cell have in addition to plasma membrane.
Answer:
Cell wall is the rigid outer cover in addition to the plasma membrane.

b) What is cell wall made up of ?
Answer:
Cell wall is made up of cellulose.

c) What is the function of cell wall ?
Answer:
It provides structural strength to plants.

d) Is there cell wall present in the animal cell ?
Answer:
No, the cell wall is not present in the animal cell.

e) 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 called plasmolysis.

Question 2.
Read the paragraph and answer the following questions :

Plastids are present only in plant cells. There are two types of plastids – chromoplasts (coloured plastids) and leucoplasts (white or colourless plastids). Chromo plasts containing the pigment chlorophyll are known as chloroplasts. Chloroplasts are important for photosynthesis in plants. Chloroplasts also contain various yellow or orange pigments in addition to chlorophyll. Leucoplasts are primarily organelles in which materials such as starch, oils and protein granules are stored.

a) Name the type of plastids in which photosynthesis process takes place.
Answer:
Chioroplasts are the plastids in which photosynthesis process takes place.

b) Fruits and flowers have colour due to the presence of plastids.
Answer:
Chromoplasts.

c) What is the similarity between mitochondria and plastids ?
Answer:
Like the mitochondria, plastids also have their own DNA and Ribosomes.

d) What is the function of leucoplasts ?
Answer:
Leucoplasts store the materials such as starch, oils, and protein granules.