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

AP State Board new syllabus AP Board Solutions Class 9 Biology 5th Lesson The Fundamental Unit of Life Questions and Answers.

Biology 9th Class 5th Lesson Questions and Answers The Fundamental Unit of Life

9th Class Biology 5th Lesson The Fundamental Unit of Life Questions and Answers (Exercise)

Question 1.
Make a comparison and write down ways in which plant cells are different from animal cells.
Answer:
Differences between a plant ceil and an animal cell.

Plant cell	Animal cell
1) Plant cells have cell wall.	1) Animal cells don’t have a cell wall
2) They contain chloroplast.	2) They don’t have ehloroplasts.
3) They do not have centriole.	3) Centriole is present in them.
4) Vacuole is large and present in centre of the cell.	4) Vacuole is small.
5) Nucleus is present in the side of the plant cell.	5) Nucleus is present in the centre of the animal cell.

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

Prokaryotic cell	Eukaryotic cell
1) Size : Generally small (1 -10μm) 1μm pm = 10-6 m	1) Size : Generally large (5 -100 pm)
2) Nuclear region is poorly defined due to absence of a nuclear membrane and known as nucleoid.	2) Nuclear region is well defined and surrounded by a nuclear membrane
3) There is a single chromosome.	3) There are more than one chromosomes.
4) Membrane bound cell organelles absent.	4) Membrane bound cell organelles present.

Question 3.
What would happen if the plasma membrane ruptures or breaks down?
Answer:
If plasma membrane ruptures or breaks down then molecules of some substances will freely move in and out.

Question 4.
What would happen to the life of a cell if there was no Golgi apparatus ?
Answer:
If there were no Golgi bodies, packaging and dispatching of materials synthesised by the cell will be stocked.

Question 5.
Which organelle is known as the powerhouse of the cell ? Why?
Answer:
Mitochondria is known as the ‘Power House’ of the cell because it stores the energy in the form of ATP, it releases the energy to the cell whenever it requires to perform different activities of life.

Question 6.
Where do the lipids and proteins constituting the cell membrane get synthesised?
Answer:
Lipids and proteins constituting the cell membrane synthesized in Endoplasmic Reticulum.

Question 7.
How does Amoeba obtain its food ?
Answer:

• Through the process of endocytosis, an amoeba obtains its food.
• As its cell membrane is flexible enough, food particles are engulfed, forming a food vacuole girdling it, which is assisted by the pseudopodia.
• Amoeba secretes digestive enzymes to bring about digestion of the engulfed partide once the food is trapped.

Question 8.
What is osmosis ?
Answer:
The process of movement of water molecule from a region of higher concentration to a region of lower concentration through a semipermeable ’membranes is known as Osmosis.

Question 9.
Carry out the following osmosis experiment.
Take four peeled potato halves and scoops each one out to piake 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 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 B and 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 accumulates in the hollowed portions of B and C as a difference in the water concentration is observed. There by endosmosis occurs as the cells acts as semi- permeable membrane.

ii) Potato A is essential in this experiment as it is significant to compare different scenarios seen in potato cups B, C and D. A in this experiment clearly shows that the potato cavity on its own cannot bring about water movement.

iii) Cup in A does not show any change in the water flow concentration for osmosis to occur which requires concentration to be higher than the other. Cells in cup D are dead, thus there is no existence of a semipermeable membrane for water flow. Consequently osmosis does not occur.

Question 16.
Which type of cell division is required for growth and repair of body and which type is involved in the formation of gametes ?
Answer:
There are two ways in which a ceH divides :

• Mitosis
• Meiosis

Mitosis is the type of cell division that is involved in the growth and repair of the body, whereas meiosis is a type of cell division which results in the formation of gametes.

9th Class Biology 5th Lesson Questions and Answers (InText)

Page No. 6

Question 1.
Who discovered cells and how ?
Answer:

• Robert Hooke discovered cells in 1665.
• While examining thin slice of cork through a self designed microscope.
• He saw that cork resemble the structure of a honey comb comprises many little compartments.
• These small boxes are called cells.

Question 2.
Why is the cell called the structural and functional unit of life?
Answer:

• Cells form the structure of an entity. . .
• A group of cells form a tissue, further an organ and ultimately an organ system.
• They perform fundamental functions and life processes such as respiration, digest­ing, excretion etc., in the unicellular and multicellular organisms. They perform all the activities independently.
• Hence cells are referred to as structural and fundamental units of life.

Page No. 10.

Question 1.
How do substances like CO₂ and water move in and out of the cell ? Discuss.
Answer:
a) CO₂ moves by diffusion.

• The cellular waste accumulates in high concentration in the cell, whereas the . ‘ concentration of CO₂ in the external surrounds is comparatively lower.
• This difference in the concentration level inside and out side of the cell causes the CO₂ to diffuse from a region of higher (within the cell) to a lower concentration.

b)

• Water diffuses by osmosis through the cell membrane.
• It moves from a region of higher concentration to a lower concentrated region through a selectively permeable membrane until equilibrium is reached.

Question 2.
Why is the plasma membrane called a selectively permeable membrane ?
Answer:

• The plasma membrane allows or permits the entry and exit of some materials in and out of the cell.
• It also prevents the movement of some other materials. Hence plasma membrane is called a selectively permeable membrane.

Page No. 14.

Question 1.
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 pm) lpm=l0″6m	1) Size : Generally large (5-100 pm)
2) Nuclear region : ……….. and  known as ………	2) Nuclear region : well defined and surrounded by a nuclear membrane.
3) Chromosome: single	3) More than one chromosome.
4) Membrane bound cell organelles are absent	4) ……………………………. …………………………….

Answer:
2) Nuclear region : Poorly defined and due to absence of nuclear membrane is called Nucleoid.
4) Membrane bound cell organelles are present.

Question 1.
Can you name the two organelles we have studied that contain their own genetic material?
Answer:
Mitochondria and Plastids have their own DNA and ribosomes.

Question 2.
If the organisation of a cell is destroyed due to some physical or chemical influence, What will happen ?
Answer:
If the organisation of a cell is destroyed due to some physical or chemical influence, the cell will not be able to perform the basic functions.

Question 3.
Why are lysosomes known as suicide bags ?
Answer:

• When foreign materials entering the cell, such as bacteria, or food as well as old organelles end up in lysosomes, which break complex substances into simpler
  sub-stances as they contain digestive juices.
• When the cell gets damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are also called as suicide bags of cell.

Question 4.
Where are proteins synthesised inside the cell ?
Answer:
Endoplasmic reticulum synthesise proteins inside the cell.

Page No. 4

Question 1.
Can we find out names of some more unicellular organisms.
Answer:
Yes. Euglena, Vorticella

Question 2.
Every multi-cellular organism has come from single cell. How ?
Answer:
Yes. According to the cell theory, all cells arise from pre-existing cells, that means every cell divides and form new cells.

Page No. 6

Question 3.
How does a living cell perform these basic functions?
Answer:
Living cell performs these basic functions as it comprises many cell organelles in it. Each kind of cell organells perform a special function. Because of these organelles cell performs all functions. So cell is called a basic unit and functional unit of life.

Question 4.
How is a cell organised ?
Answer:
Cell is made up of some special components called organelles.

Question 5.
How does the movement of substances take place into the cell? How do substances move out of the cell ?
Answer:
The movement of substances take place in by a process called diffusion. Substances move out of cell by a process called diffusion.

Page No. 8

Question 6.
What will happen if we put an animal cell or plant cell into a solution of sugar or salt in water?
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 will gain the water by osmosis. The cell is likely to ‘swell up’.
• If the medium has exactly the same water concentration as the cell, there will be no net movement of water across the cell membrane. The cell will stay the “same size”.
• If the medium has a lower concentration of water than the cell, meaning that it is a very concentrated solution, the cell will lose water by osmosis. Then the cell will “shrink”.

Page No. 10

Question 7.
Remember the temporary mount of onion peel we prepared we had put iodine solution on the peel. Why ?
Answer:
To get the parts cleary visible.

Question 8.
What would we see if we tried observing the peel without putting the iodine solution?
Answer:
We will be unable to get clear vision of the parts.

Question 9.
Further, when we put iodine solution on the peel, did each cell get evenly coloured?
Answer:
No, some parts of the peel only get coloured.

9th Class Biology Chapter 5 Questions and Answers (Lab Activities)

(Page No. 2)

Question 1.
How do you observe cells in onion peel under microscope ? Write your observations.
Answer:
Aim : To observe a cell in the onion peel:
Things required: Onion bulb, onion peel, watch – glass, water, slide, camel hair brush, safranin, coverslip, needle, forceps microscope.

Procedure:

• I took a onion peel from a onion bulb with the help of a forceps.
• Immediately I put it in a watch glass containing water to keep it wet.
• Now I took a glass slide and I put a drop of water on it.
• I transferred a small piece of the feet from the watch glass to the slide perfectly flat with the help of a camel hair brush.
• I put a safranin solution on the peel followed by a coverslip by avoiding air bubbles.
• And I observed the slide under low power followed by high powers of a compound
  microscope.

Observation : I observed a small room like structure in the onion peel.
Inference : The small room like structures are called “cell”

(Page No. 4)

Question 2.
We can try preparing temporary mounts of leaf peels, tip of roots of onion or even peels of onions of different sizes.
After performing the above activity, let us see what the answers to the following questions would be:
a) Do all cells look allke in terms of shape and size?
b) Do all cells look alike in structure?
c) Could we find differences among cells from different parts of a plant body?
d) What similarities could we find?
Answer:
Aim : To prepare the temporary mounts of leaf peels.
Things required : Microscope, different types of leaves, root tips of onion, different sizes of onions, slide, cover slip, safranin, blade.
Procedure :

• I took some onions, Raheo leaf and took a peel from them with help of a blade, or a forceps.
• I put them in a watch – glass containing water.
• I transferred them to the slide containing a drop of water and I added some safranin solution them.
• I put a cover slip on the slide without bubbles. My temporary mounts are ready and I observed under a microscope.

Observation : I observed different sizes and shapes of cells.
Inference : The cells are of different sizes and shapes.

Activity Based Questions :

1. Do all cells look alike in terms of shape and size ?
Answer: No, All cells do not look alike in terms of shape and size.

2. Do all cells fook alike in structure ?
Answer: No, All cells do not look alike in structure.

3. Could we find differences among cells from different parts of plant body ?
Answer: Yes, we find differences among cells from different parts of the plant body.

4. What similarities could we find ?
Answer: We get similarities in the parts of the plant body.

(Page No. 8)

Question 3.
Write an experiement with an egg to prove osmosis.
Answer:
Aim : To know the process of osmosis.
Things required : Egg, Dilute HCl, pure water, salt
Procedure :

• I took an egg and removed the shell of the egg by dissolving it in dilute hydrochloric acid.
• A thin outer skin encloses the egg is left over.
• I put the egg in pure water in a beaker and observed.
• I placed a similar deshelled egg in a concentrated salt solution and I observed for 5 minutes.

Observation :
a) The egg swells because water passes into it by osmosis.
b) The egg shrinked, water passes out of the egg solution into the salt solution because the salt solution is more concentrated.
Inference : Exosmosis and endosmosis occured in both conditions.

(Page No. 8)

Question 4.
Write an activity to prove osmosis with dried raisins or apricots.
Answer:
Aim : To observe the process of osmosis in Raisins.
Things required : Dried Raisins/Apricots, water, sugar/salt solution, bowls.

Procedure :

• I took some dried raisins or apricots and put in plain water in a bowl and observed.
• I took some dried raisins and put in a bowl contained concentrated solution of sugar or salt.

Observation :
a) Each raisins gained water and swelled up when placed in water.
b) When I placed them in the concentrated solution, it loses water, consequently shrinks.
Inference : In the plant cells also osmosis occur (Endosmosis & Exosmosis)

(Page No. 10)

Question 5.
Find out about electron microscopes from resources in the school library or through the internet. Discuss it with your teacher.
Answer:
1) An electron microscope is a microscope that uses of beam of electrons as a source of illumination.

2) They use electron optics that are analogous to the glass lenses of an optical light microscope. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light, electron microscopes have a higher resolution of about 0.1 mn, which compares to about 200 nm for light microscopes. These are expensive to build and maintain.

Question 6.
How do you prove that only living cells and not dead cells are able to absorb water by osmosis ?
Answer:
Aim : To observe plasmolysis
Things required : Rheo leaf; water, microscope, strong solution of sugar or salt.

Procedure :

• I mounted the peel of a Rheo leaf in water on a slide and examined under the high power of a microscope.
• I found some small green granules called chloroplasts which contain green substance called chlorophyll.
• I put a drop of strong solution of sugar or salt on the mounted leaf on the slide. I observed under a microscope after one minute.

Observation : I observed that sugar solution entered into the cells and swells up through osmosis.

B)

• Now I placed some Rheo leaves in boiling water for a few minutes.
• This killed the cells.
• Then mounted one leaf on a slide and observed it under a microscope.
• After that I put a drop of strong sugar solution on the mounted leaf on the slide and I observed.
• No, plasmolysis not occured.

Inference : It appears that only living cells, and not dead cells, are able to absorb water by osmosis.

(Page No. 10)

Question 7.
How do you observe human cheek cells in your science laboratory? Draw your observations.
Answer:
Aim : To observe the nucleus in a cheek cell.
Things required : Slide, Microscope, Ice cream spoon, water, Brush, Cover slip ; Methylene Blue solution.

Procedure :

• By using an ice – cream spoon gently I scraped the inside surface of the cheek and put it on the glass slide and spreaded it evenly.
• To stain its I put a drop of methylene blue solution on it.
• I observed it under microscope.

Observation : I observed a darkly coloured, spherical or oval, dot like structure near the centre of each cell.
Inference : This structure is called Nucleus.