NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

These NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

The Fundamental Unit of Life NCERT Solutions for Class 9 Science Chapter 5

Class 9 Science Chapter 5 The Fundamental Unit of Life InText Questions and Answers

Question 1.
Who discovered cells and how?
Answer:
Cells were discovered in 1665 by an English Botanist, Robert Hooke. He used a primitive microscope to observe cells in a cork slice.

Question 2.
Why is the cell called the structural and functional unit of life?
Answer:
Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions. Cells are the building blocks of life. This is the reason why cells are referred to as the basic structural and functional units of life. All cells vary in their shape, size, and activity they perform. In fact, the shape and size of the cell is related to the specific functions they perform.

Question 3.
How do substances like CO2 and water move in and out of the cell? Discuss.
Answer:
The cell membrane is selectively permeable and regulates the movement of substances in and out of the cell.

Movement of CO2:
CO2 is produced during cellular respiration. Therefore, it is present in high concentrations inside the cell. This CO2 must be excreted out of the cell. In the cell’s external environment, the concentration of CO2 is low as compared to that inside the cell. Therefore, according to the principle of diffusion, CO2 moves from a region of higher concentration (inside the cell) towards a region of lower concentration (outside the cell). Similarly, O2 enters the cell by the process of diffusion when the concentration of O2 inside the cell is low as compared to its surroundings.

Movement of water:
Water moves from a region of high concentration to a region of low concentration through the plasma membrane. The plasma membrane acts as a semi-permeable membrane, and this movement of water is known as osmosis.

However, the movement of water across the plasma membrane of the cell is affected by the amount of substance dissolved in water.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 4.
Why is the plasma membrane called a selectively permeable membrane?
Answer:
The cell membrane or the plasma membrane is known as a selectively permeable membrane because it regulates the movement of substances in and out of the cell. This means that the plasma membrane allows the entry of only some substances and prevents the movement of some other materials.

Question 5.
Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

Prokaryotic cell Eukaryotic cell
1. Size: generally small (1-10 μm) 1 pm
1μm = 10-6m
1. Size is generally large (5 – 100 μm).
2. Nuclear region: _________
____________________________
are known as _____________
2. Nuclear region:
Well defined and surrounded by the nuclear membrane.
3. Chromosome: single 3. More than one chromosome.
4. Membrane bound cell org are absent. 4. _________________

Answer:

Prokaryotic cell Eukaryotic cell
1. Size: generally small (1-10 μm) 1 pm
1μm = 10-6m
1. Size is generally large (5 – 100 μm).
2. Nuclear region not surrounded by nuclear membrane, found immersed in cytoplasm and is known as nucleoid. 2. Nuclear region:
Well defined and surrounded by the nuclear membrane.
3. Chromosome: single 3. More than one chromosome.
4. Membrane bound cell org are absent. 4. Membrane bound cell organelles are present.

Question 6.
Can you name the two organelles we have studied that contain their own genetic material?
Answer:
Mitochondria and plastids are the two organelles that contain their own genetic material. Both these organelles have their own DNA and ribosomes.

Question 7.
If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen?
Answer:
Cell is the smallest unit of life, which is capable of all living functions. If the organisation of a cell is destroyed due to some physical or chemical influence, then the ability of the cell to perform all living functions such as respiration, nutrition, excretion, etc. would be affected.

Question 8.
Why are lysosomes known as suicide bags?
Answer:
Lysosomes are membrane-bound vesicular structures that contain powerful digestive enzymes. These enzymes are capable of breaking down any foreign food particle or microbes entering the cell. Sometimes, lysosomes can cause self-destruction of a cell by releasing these digestive enzymes within the cells. Hence, they are also known as ‘suicidal bags’.

Question 9.
Where are proteins synthesized inside the cell?
Answer:
Ribosomes are the site for protein synthesis. Ribosomes are very small structures found either in a free state, suspended in the cytoplasm, or attached to the surface of the endoplasmic reticulum. They are composed of ribonucleic acids and proteins.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Class 9 Science Chapter 5 The Fundamental Unit of Life Textbook Questions and Answers

Question 1.
Make a comparison and write down ways in which plant cells are different from animal cells.
Answer:
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 1

Question 2.
How is a prokaryotic cell different from a eukaryotic cell?
Answer:
Prokaryotic cell :

  1. Most prokaryotic cells are unicellular.
  2. Size of the cell is generally small (0.5-5 μm).
  3. Nuclear region is poorly, defined due to the absence of a nuclear membrane or the cell lacks true nucleus.
  4. It contains a single chromosome.
  5. Nucleolus is absent.
  6. Membrane-bound cell organelles such as plastids, mitochondria, endoplasmic reticulum, Golgi apparatus, etc. are absent.
  7. Cell division occurs only by mitosis.
  8. Prokaryotic cells are found in bacteria and blue-green algae.

Eukaryotic cell:

  1. Most eukaryotic cells are multicellular.
  2. Size of the cell is generally large (50-100 μm).
  3. Nuclear region is well-defined and is surrounded by a nuclear membrane, or true nucleus bound by a nuclear membrane is present in the cell.
  4. It contains more than one chromosome.
  5. Nucleolus is present.
  6. Cell organelles such as mitochondria, plastids, endoplasmic reticulum, Golgi apparatus, lysosomes, etc. are present.
  7. Cell division occurs by mitosis and meiosis.
  8. Eukaryotic cells are found in fungi, plants, and animal cells.

Question 3.
What would happen if the plasma membrane ruptures or breaks down?
Answer:
If the plasma membrane of a cell is ruptured, then the cell will die. The plasma membrane regulates the movement of substances in and out of the cell by diffusion or osmosis. Thus, if the plasma membrane is ruptured, then the cell might leak out its contents.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 4.
What would happen to the life of a cell if there was no Golgi apparatus?
Answer:
If there was no Golgi apparatus in the cell, then most activities performed by the Golgi apparatus will not take place.
(i) Membranes of the Golgi apparatus are often connected to ER membranes. It collects simpler molecules and combines them to make more complex molecules. These are then packaged in small vesicles and are either stored in the cell or sent out as per the requirement. Thus, if the Golgi apparatus is absent in the cell, then the above process of storage, modification, and packaging of products will not be possible.

(ii) The formation of complex sugars from simple sugars will not be possible as this takes place with the help of enzymes present in Golgi bodies.

(iii) The Golgi apparatus es involved in the formation of lysosomes or peroxisomes. Thus, if the Golgi body is absent in a cell, the synthesis of lysosomes or peroxisomes will not be possible in the cell.

Question 5.
Which organelle is known as the powerhouse of the cell? Why?
Answer:
Mitochondria are known as the powerhouse of cells. Mitochondria create energy for the cell, and this process of creating energy for the cell is known as cellular respiration. Most chemical reactions involved in cellular respiration occur in the mitochondria. The energy required for various chemical activities needed for life is released by the mitochondria in the form of ATP (Adenosine triphosphate) molecules. For this reason, mitochondria are known as the powerhouse of cells.

Question 6.
Where do the lipids and proteins constituting the cell membrane get synthesized?
Answer:
Lipids and proteins constituting the cell membrane are synthesized in the endoplasmic reticulum.
SER (Smooth endoplasmic reticulum) helps in the manufacturing of lipids.
RER (Rough endoplasmic reticulum) has particles attached to its surface, called ribosomes. These ribosomes are the site for protein synthesis.

Question 7.
How does an Amoeba obtain its food?
Answer:
Amoebaobtains its food through the process of endocytosis. The flexibility of the cell membrane enables the cell to engulf the solid particles of food and other materials from its external environment.
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 2

Question 8.
What is osmosis?
Answer:
The movement of water molecules from a region of high concentration to a region of low concentration through a selectively permeable membrane is called osmosis. It is a special case of diffusion, where the medium is water.

For example, if the medium surrounding the cell has a higher water concentration than the cell i.e., if the solution is a dilute solution, then the cell will gain water by osmosis.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 9.
Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water.
Now-
(a) Keep cup A empty
(b) Put one teaspoon sugar in cup B
(c) Put one teaspoon salt in cup C
(d) Put one teaspoon sugar in the boiled potato cup D.
Keep these for two hours. Then observe the four potato cups and answer the following:
(i) Explain why water gathers in the hollowed portion of Band C.
(ii) Why is potato A necessary for this experiment?
(iii) Explain why water does not gather in the hollowed out portions of A and D.
Answer:
(i) Water gathers in the hollowed portions of set-up B and C because water enters the potato as a result of osmosis. Since the medium surrounding the cell has a higher water concentration than the cell, the water moves inside by osmosis. Hence, water gathers in the hollowed portions of the potato cup.

(ii) Potato A in the experiment acts as a control set-up. No water gathers in the hollowed portions of potato A.

(iii) Water does not gather in the hollowed portions of potato A because potato cup A is empty. It is a control setup in the experiment.

Water is not able to enter potato D because the potato used here is boiled. Boiling denatures the. proteins present in the cell membrane and thus, disrupts the cell membrane. For osmosis, a semi-permeable membrane is required, which is disrupted in this case. Therefore, osmosis will not occur. Hence, water does not enter the boiled potato cup.

Class 9 Science Chapter 5 The Fundamental Unit of Life Additional Important Questions and Answers

Multiple Choice Questions
Choose the correct option:

Question 1.
Which of the following can be made into crystal?
(a) A Bacterium
(b) An Amoeba
(c) A Virus
(d) A Sperm
Answer:
(c) A Virus

Question 2.
A cell will swell up if
(a) The concentration of water molecules in the cell is higher than the concentration of water molecules in surrounding medium
(b) The concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell
(c) The concentration of water molecules is same in the cell and in the surrounding medium
(d) Concentration of water molecules does not matter
Answer:
(b) The concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell

Question 3.
Chromosomes are made up of
(a) DNA
(b) protein
(c) DNA and protein
(d) RNA
Answer:
(c) DNA and protein

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 4.
Which of these options are not a function of Ribosomes?
(i) It helps in manufacture of protein molecules
(ii) It helps in manufacture of enzymes
(iii) It helps in manufacture of hormones
(iv) It helps in manufacture of starch mol¬ecules
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (iv) and (i)
Answer:
(c) (iii) and (iv)

Question 5.
Which of these is not related to endoplasmic reticulum?
(a) It behaves as transport channel for proteins between nucleus and cytoplasm
(b) It transports materials between various regions in cytoplasm
(c) It can be the site of energy generation
(d) It can be the site for some biochemical activities of the cell
Answer:
(c) It can be the site of energy generation

Question 6.
Following are a few definitions of osmosis Read carefully and select the correct definition
(a) Movement of water molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane
(b) Movement of solvent molecules from its higher concentration to lower concentration
(c) Movement of solvent molecules from higher concentration to lower concentration of solution through a permeable membrane
(d) Movement of solute molecules from lower concentration to higher concentration of solution through a semipermeable membrane
Answer:
(a) Movement of water molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane

Question 7.
Plasmolysis in a plant cell is defined as
(a) break down (lysis ) of plasma membrane in hypotonic medium
(b) shrinkage of cytoplasm in hypertonic medium
(c) shrinkage of nucleoplasm
(d) none of them
Answer:
(b) shrinkage of cytoplasm in hypertonic medium

Question 8.
Which of the following are covered by a single membrane?
(a) Mitochondria
(b) Vacuole
(c) Lysosome
(d) Plastid
Answer:
(b) Vacuole

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 9.
Find out the false sentences
(a) Golgi apparatus is involved with the formation of lysosomes
(b) Nucleus, mitochondria and plastid have DNA; hence they are able to make their own structural proteins
(c) Mitochondria is said to be the powerhouse of the cell as ATP is generated in them.
(d) Cytoplasm is called as protoplasm
Answer:
(a) Golgi apparatus is involved with the formation of lysosomes

Question 10.
Find out the correct sentence
(a) Enzymes packed in Lysosomes are made through RER (rough endoplasmic reticulum)
(b) Rough endoplasmic reticulum and
smooth endoplasmic reticulum produce lipid and protein respectively
(c) Endoplasmic reticulum is related with the destruction of plasma membrane
(d) Nucleoid is present inside the nucleoplasm of eukaryotic nucleus
Answer:
(a) Enzymes packed in Lysosomes are made through RER (rough endoplasmic reticulum)

Question 11.
Which cell organelle plays a crucial role in detoxifying many poisons and drugs in a cell?
(a) Golgi apparatus
(b) Lysosomes
(c) Smooth endoplasmic reticulum
(d) Vacuoles
Answer:
(c) Smooth endoplasmic reticulum

Question 12.
The proteins and lipids, essential for building the cell membrane, are manufactured by
(a) rough endoplasmic reticulum
(b) golgi apparatus
(c) plasma membrane
(d) mitochondria
Answer:
(a) rough endoplasmic reticulum

Question 13.
The undefined nuclear region of prokaryotes are also known as
(a) nucleus
(b) nucleolus
(c) nucleic acid
(d) nucleoid
Answer:
(d) nucleoid

Question 14.
The cell organelle involved in forming complex sugars from simple sugars are
(a) endoplasmic reticulum
(b) ribosomes
(c) plastids
(d) golgi apparatus
Answer:
(d) golgi apparatus

Question 15.
Which out of the following is not a function of vacuole?
(a) Storage
(b) Providing turgidity and rigidity to the cell
(c) Waste excretion
(d) Locomotion
Answer:
(d) Locomotion

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 16.
Amoeba acquires its food through a process, termed
(a) exocytosis
(b) endocytosis
(c) plasmolysis
(d) exocytosis and endocytosis both
Answer:
(b) endocytosis

Question 17.
Cell wall of which one of these is not made up of cellulose?
(a) Bacteria
(b) Hydrilla
(c) Mango tree
(d) Cactus
Answer:
(a) Bacteria

Question 18.
Silver nitrate solution is used to study
(a) endoplasmic reticulum
(b) golgi apparatus
(c) nucleus
(d) mitochondria
Answer:
(b) golgi apparatus

Question 19.
Organelle other than nucleus, containing DNA is
(a) endoplasmic reticulum
(b) golgi apparatus
(c) mitochondria
(d) lysosome
Answer:
(c) mitochondria

Question 20.
Kitchen of the cell is
(a) mitochondria
(b) endoplasmic reticulum
(c) chloroplast
(d) golgi apparatus
Answer:
(c) chloroplast

Very Short Answer Questions

Question 1.
Define a cell.
Answer:
Cell is the fundamental structural and functional unit of life.

Question 2.
Which is the outermost boundary of a plant cell?
Answer:
The cell wall is the outermost boundary of a plant cell.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 3.
Which is the outermost boundary of an animal cell?
Answer:
Cell (Plasma) membrane is the outermost boundary of an animal cell.

Question 4.
Why do you use glycerine when preparing the temporary mount of a cell?
Answer:
Glycerine is used to prevent the dehydration of cells.

Question 5.
Name the cell organelles found in a green plant cell but not in an animal cell.
Answer:
Chloroplast containing chlorophyll that imparts the green colour to a plant cell.

Question 6.
How is cell wall different from cell membrane?
Answer:
Cell wall found in plant cell, made up of cellulose is dead but cell membrane found in both plant and animal cell, made up of protein and phospholipids is living.

Question 7.
How will you identify the nucleus in the plant cell?
Answer:
Nucleus is the dark pink stained small round body found at the periphery or the cell in a safranin stained cells.

Question 8.
How do you identify the cytoplasm in an animal cell?
Answer:
Cytoplasm is the light blue stained surface in between nucleus and cell membrane, in a cell stained with methylene blue or light pink in a cell stained with safranin.

Question 9.
Why are cells in onion peel rectangular but check cells are irregular in shape?
Answer:
Onion peel cells have rigid cell wall that imparts them a specific shape but cell membrane being flexible and elastic fails to provide it a definite shape.

Question 10.
Why a student needs to stain the cells when preparing temporary mount?
Answer:
A student needs to stain the cells when preparing temporary mount to develop a contrast in its different parts.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 11.
Which adjustment will you use in microscope to focus the image of the specimen?
Answer:
To focus the image of the specimen, the coarse adjustment is used by the student.

Question 12.
Which are the two main functions of a microscope?
Answer:
A microscope both resolves and magnifies the image of the specimen.

Question 13.
When you will observe less number of magnified and resolved cells of a temporary mount underflow power or high power?
Answer:
Under the high power of 40X or 45X

Question 14.
Which is the longest body cell?
Answer:
A neuron is the longest body cell.

Question 15.
Which cell in the human body has the finest cell membrane?
Answer:
Red blood cells in. the blood have the finest cell membrane.

Question 16.
Which cell in a plant is living but non-nucleated?
Answer:
Sieve cells present in the phloem are living but non-nucleated.

Question 17.
Name the largest and the smallest living cell.
Answer:
An ostrich egg is the largest living cell while the PPLO, (Pleuro pneumonia like organism) a mycoplasm is the smallest living cell.

Question 18.
In which cells the vacuoles are small and not much prominent?
Answer:
An animal cell.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 19.
Which cell organelle is found both in prokaryotic and eukaryotic cells?
Answer:
Ribosome

Question 20.
What are mesosomes?
Answer:
These are imaginations of plasma membrane found in prokaryotic cells. They are secretory in function and the site of cellular respiration.

Short Answer Questions

Question 1.
State the contribution of Anton Von Leuween Hooke in developments that have taken place in field of cell biology.
Answer:
Anton vop Leeuwen Hooke has observed the first living cell of unicellular organisms in a drop of pond water under his self built simple microscope. He is also considered as the pioneer of the simple microscope.

Question 2.
Do all organisms have similar type of cells?
Answer:
No, all organisms do not have similar type of cells because the shape and size of the cell depends upon the function, a cell needs to perform. Therefore, some cells are oval, some are motile with cilia or flagella and some are long like muscle fibres or neuron.

Question 3.
What are cell organelles? Give examples.
Answer:
Cell organelles are granule like structures found immersed in cell cytoplasm. Each cell organelle has a specific function to perform such as mitochondria is the seat of respiration and chloroplasts are the seat of photosynthesis in green plant cells.

Question 4.
Define the following terms: Protoplasm, Cytoplasm and Nucleoplasm.
Answer:
Protoplasm includes all the living material found in a cell invested by thin cell membrane. It is comprised of the nucleus and cytoplasm.

Cytoplasm is the jelly like substance containing call organelles that is present in between the nucleus and cell membrane. The cytoplasm close to nucleus is in sol state while the cytoplasm close to cell membrane in gel state.

Nucleoplasm is the jelly like substance that is presentin the nucleus of a cell. The network of fibre like structure called chromatin material is found immersed r it along with different types of RNA.

Question 5.
State the major postulates of cell theory.
Answer:
The major postulates of cell theory proposed by Schwan and Schleiden are:

  • Cell is the fundamental structural unit of all living organisms.
  • Cell is the fundamental functional unit of all living organisms.
  • Every cell arises from the pre-existing cell.
  • Cell is the carrier of genetic information from one generation to the next generation.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 6.
Differentiate in the followings:
(i) Cell wall and cell membrane
(ii) DNA and RNA
Answer:
(i)

Cell Wall Cell membrane
1. It is found only in plant cells. 1. It is found both in plant and animal cells.
2. It is a dead structure made of cellulose. 2. It is a living structure made of proteins and phospholipids.
3. It is permeable. 3. It is selectively permeable.

(ii)

DNA RNA
1. It is a double helical structure. 1. It is a single helical structure.
2. It is capable of self replication and is semiconservative in nature. 2. It is not capable of self replication but is formed by DNA.
3. It contains deoxyribose sugar. 3. It contains ribose sugar.
4. It is the carrier of genetic information in a cell. 4. In a cell, it regulates the protein synthesis.

Question 7.
What are genes? State their functions.
Answer:
Genes are the segments of DNA arranged in a linear order in a chromosome.

Genes are the units of hereditary characteristics as when transferred from one generation to the next generation, they carry the codes of different characters with Item.

Question 8.
Give examples of non-membranous single-membranous and double membranous cell organelles.
Answer:
Non-membranous cell organelles—Ribosome and nucleolus.
Single membranous organelles—Lysosome and vacuole
Double membranous organelles—Mitochondria and chloroplast

Question 9.
Which are the three functional regions of a cell?
Answer:
The three functional regions of a cell include:

  • Nucleus, it acts as the control centre of all cellular activities.
  • Cytopiasirvjelly like substance with cell organelles carrying out different cellular activities.
  • Plasma membrane, active in regulation of the transport of different substances across it.

Question 10.
State the functions of the following organelles :
Mitochondria, chloroplasts, lysosomes, golgi apparatus, ribosome, S.E.R.
Answer:
Mitochondria: They are the seat of cellular respiration and generation of energy in form of ATP and hence, also called as the powerhouse of cell.

Chloroplasts: They are the seat of photosynthesis in cells of green plant parts hence, also called as the kitchen of a green plant cell.

Lysosomes: These are single membranous vacuole like structures that are filled with hydrolytic enzymes and hence, responsible for intracellular digestion.

Golgi apparatus: These are the stacks of cisternae responsible for the formation of primary lysosomes, secretion and excretion from the cell.

Ribosomes: These are non-membranous granule like structures which are the seat of protein synthesis and hence, also called as the protein factories of a cell.

S.E.R.: These are endoplasmic reticulum that are devoid of ribosome on their surface. They are known to take active part in the steroid synthesis in a cell.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 11.
What happens when a R.B.C and a plant cell is immersed in distilled water? Why?
Answer:
In both RBC and plant cell the endosmosis takes place. The distilled water act as hypotonic solution and the cell cytoplasm act as hypertonic solution.

The plant cell swells with incoming of water and become turgid but the RBC burst open with incoming water as cell membrane alone being flexible and elastic fail to bear the pressure exerted by the incoming water.

Question 12.
What do you expect to happen if a student immerses
(i) few grapes in concentrated sugar solution? Why?
(ii) few raisins in distilled water.
Answer:
(i) The grapes will undergo plasmolysis, shrink and take the form of raisins. The outside solution is hypertonic as compared to inside solution in grapes hence the exosmosis will occur leading to the loss of water from inside of the grapes to the outside.

(ii) Raisins immersed in distilled water would swell because of imbibitions of water and endosmosis.

Question 13.
What are centrosomes? State their fucntions.
Answer:
These are special structures found close to nucleus in an animal cell. They consist of two granules like structures, one large and other small called centriole.

They play an important role during cell division in spindle formation and lower animals in the development of the locomotory organs such as cilia aa flagella.

Question 14.
What are prokaryotic and eukaryotic cells? Give two examples.
Answer:
Procaryotic cells: These are cells without a well defined nucleus and membrane bound cell organelles e.g. bacteria, mycoplasm, blue green algae, etc.

Eucaryotic cells: These are cells with a well defined nucleus and membrane bound cell organelles e.g. cells in higher plants and animals like human cells, etc.

Question 15.
How is diffusion different from osmosis?
Answer:
Diffusion involves the free movement of substances i.e. both solute and solvent from higher concentration to the low concentration.

Osmosis involves the movement of solvents like water from region of hypotonic solution into hypertonic solution across a semi-permeable membrane.

In both diffusion and osmosis , the movement continues until a state of equilibrium is achieved in two adjoining systems.

Long Answer Questions

Question 1.
Draw the diagram of some cells in human body showing the diversity of shape of cells.
Answer:
In body different cells perform different functions, therefore they posses different shape to make their work easier.
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 3

Question 2.
Draw a labelled diagram of a compound simple microscope and state the notions of its different parts.
Answer:
A compound microscope is an optical:
device that is used to see minute things such as cells or microorganisms that are invisible to naked eyes. The main parts of a compound microscope includes the followings:

Reflector: A concave mirror that focuses the light on the specimen in slide for the vision.
Condenser: It condenses the beam of light on its way to the specimen.
Specimen stage: It’s a platform with a hole where the specimen on the slide is kept for viewing through eyepiece.
Objective piece: It consists of a biconvex lens of small focal length. It comes closer to the specimen to form its image.
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 4
Eyepiece: It also consists of a biconvex lens but of large focal length. The specimen is observed by keeping the eyes slightly above it.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 3.
What are the different types of plastids found in a plant cell?
Answer:
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 5
Leucoplasts are plastids without any pigment. They help in storage of food.
Amyloplasts are leucoplasts which stores starch.
Aleuroplasts are leucoplasts which stores proteins.
Elaioplasts are leucoplasts which stores fats and oils.
Chromoplasts are plastids with a pigment that impart them a specific colour.
Chloroplasts bear chlorophyll as pigment and are green in colour.
Phaeoplasts bear fucoxanthin and xanthophylls as pigment arid are brown in colour.
Rhodoplasts bear phycoerythrin as pigment and are red in colour.

Question 4.
Draw a labelled diagram of an animal cell showing different cell organelles.
Answer:
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 6

Question 5.
How will you prepare the temporary mount of onion peel for its observation in the microscope.
Answer:
To prepare the temporary mount of an onion peel, a student is expected follow the following steps:

  • Take a small piece from an onion bulb.
  • With the help of set of forceps peel off the epidermis (skin) from the concave side.
  • Put it in a petridish or watch glass having some water.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 7

  • Transfer the peel to another watch glass containing some stain or iodine.
  • Wait for 2-3 minutes to allow the peel to imbibe the stain.
  • Wash the peel using brush and then transfer it in the centre of a slide on top of a drop or two of glycerine.
  • Carefully plate a coverslip to avoid any air bubble.
  • Put the slide on the stage and observe.
  • Record your observations with a labelled diagram.

NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life

Question 6.
Draw a labelled diagram of a typical plant cell showing different cell organelles.
Answer:
NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit of Life 8

Question 7.
Write the different parts of a cell observed under microscope with their functions.
Answer:
Different parts seen under the microscope include the followings:
(1) Plasma membrane: It is living and outermost covering of the animal cell. In plant cell it is covered by cell wall.
Functions: It regulates the movement of molecules in and out of the cell and protects the inner parts of the cell.

(2) Nucleus: It is surrounded by a double layered nuclear membrane, embedded in the cytoplasm. It is placed centrally in the animal cell. Nucleolus and chromation material are is the other component of nucleus.

Functions:
(i) It contains nucleic acid, RNA and DNA.
(ii) DNA stores the hereditary informations. Segments of DNA are called genes.
(iii) RNA rules over the activities, taking place in cytoplasm and in synthesis of ribosomes.

(3) Cytoplasm: It is a viscous, translucent part of cell inner to plasma membrane. It contains 90% of water, organic and inorganic molecules in it. All cell organelles are embedded in it. Nucleus and cytoplasm together consitute protoplasm.

(4) Cell organelles:
(a) Endoplasmic Reticulum (E.R.): It is an extensive network of membrane bound tubes and sheets that run through the cytoplasm. These are of two types (i) Rough Endopolasmic Reticulum (RER)—It is termed so because it has ribosomes attached on its furface which gives it a rough appearance. (2) Smooth Endoplasmic Reticulum (SER), they are devoid of ribosomes.

Functions: (i) RER—systesized proteins. SER—Secretes organic molecules called lipids.
(ii) It provides mechanical strength to the cell.

(b) Ribosomes—Grannular bodies attached to RER, help in the synthesis of proteins.

(c) Mitrochondria: They are known as the powerhouse of the cell as they store energy in the form of ATR They are double membrane structures. Their inner membrane is deeply folded. These folds create large surface area for chemical reaction. They have their own DNA and ribosomes.

(d) Lysosomes—Digestive enzymes containing sac like structure, help in digestion of un-wanted material and part of worn out cell organelles. During breakdown of cell structure i.e. when the cell gets damaged, lysosomes may burst and the enzymes eat up their own cell hence, known as suicide bags.

(e) Golgi Apparatus: Consists of a set of smooth flattened sack like structures stacked together usually placed one above the other near the nucleus.
It is termed as dictyosomes if present in plant cell.
Function: Responsible for all types of cell secretion and excretion.

(f) Plastide: Tey are found in plant cell only. They are of three types based on the pigments present in them. The most important is chloroplast which contain green pigment essential for photosynthesis. Chromoplast—Contain pigments of different colurs in different fruits and flowers. Leucoplast contain colouless pigments, responsible for storange of food.

(g) Vacuoles: These are found in plant cell as well as in animal cells. In plant cell, they are very large and occupies maximum space whereas in animal cell these are minute and large in numbers.

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