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Class IX Science NCERT solutions of chapter 5- Fundamental Unit of Life(Biology)
The class 9 science NCERT solutions of chapter 5- Fundamental Unit of Life are the answers of your science text book NCERT prescribed by CBSE.The class 9 science NCERT solutions of chapter 5- Fundamental Unit of Life are solutions of chapter -5 of Biology section of class 9 science NCERT text book which is a fundamental chapter to clear the concept of Biology. Chapter 5- Fundamental Unit of Life(Biology) is the part of the NCERT science textbook of class 9. The chapter -fundamental Unit of life(Biology) is the initiation for the students who want to become doctors or are interested to join other courses in the medical field. Here you can study the NCERT solutions of chapter -5 fundamental Unit of Life is crafted for the students of 9 class. All the questions are solved by an expert teacher of science.
You can study here all the answers of the questions which are given in the CBSE textbook of class 9 science NCERT chapter 5-Fundamental Unit of Life. Here are solutions of the back exercise of chapter 5-Fundamental Unit of Life and the questions mentioned within the pages of chapter 5 are explained by a CBSE science teacher by a scientific method so we hope every student who go through these NCERT solutions of chapter 5- Fundamental Unit of Life will definitely clear the concepts of the chapter fundamental unit of life.
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Class IX Science NCERT solutions of chapter 5- Fundamental Unit of Life(Biology)
Download PDF-Class IX Science NCERT solutions of chapter 5- Fundamental Unit of Life(Biology)
PDF-Class IX Science NCERT solutions of chapter 5
Q1-Who discovered cells, and how?
Ans-Robert Hooke discovered cells. He examined a slice of cork and found its structure resembled the structure of honeycomb which is made of separate units. He studied it through a self-designed microscope and called these separate unit cells.
Q2-Why is the cell called the structural and functional unit of life?
Ans-Cells are basic building blocks of the body of all living organisms, some of the organisms are unicellular and some of them are multicellular. All body parts are made of different cells. A body part is made of similar kind of cells have the same function. A cell has organelles to perform a particular type of function. The function of a body part depends on the cells it is made up of, it is that’s why the cell is a structural and functional unit of life.
Q3-How do substances like CO2 and water move in and out of the cell? Discuss.
Ans- Due to the process of respiration following reaction occurs inside the cell
C6H12O6 + O2 = CO2 + H2O + energy(ATP)
The concentration of CO2 becomes more inside the cell in comparison of the surrounding of the cell and thus CO2 moves from inside to outside of the cell due to the process of diffusion and because the concentration of O2 is greater outside of the cell comparison to inside of cell it moves from outside to inside of the cells through the process of diffusion. The plasma membrane of the cell is a permeable membrane, the water transports from high concentration to low concentration through the plasma membrane by the process of osmosis.
Q4.Why is the plasma membrane called a selectively permeable membrane?
Ans. The plasma membrane is called the semi-permeable membrane because it allows entering a few selected substances inside and outside of the cell through the process of diffusion and osmosis depending on the concentration of materials in the regions.
Q5-Fill up the gaps in the following table illustrating the differences between prokaryotic and eukaryotic cells.
| Prokaryotic cell | Eukaryotic cell | ||
| 1 | Size: generally small (1 to 10μm) 1 μm = 10-6m | 1 | Size:generally large(5-100μm) |
| 2 | Nuclear region: …………………………………………………………. And is 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 | ………………………………………. |
Ans-
| Prokaryotic cell | Eukaryotic cell | ||
| 1 | Size: generally small (1 to 10μm) 1 μm = 10-6m | 1 | Size:generally large(5-100μm) |
| 2 | Nuclear region: Poorly defined because of the absence of a nuclear membrane and is known as the nucleoid. | 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 | Membrane-bound cell organelles are present such as mitochondria, plastics, etc are present. |
Q6-Can you name the two organelles we have studied that contain their own genetic material?
Ans- Mitochondria and plastids are the two organelles that contain their own genetic material(DNA and ribosomes).
Q7- If the organization of a cell is destroyed due to some physical or chemical influence, what will happen?
Ans-If the organization of a cell is destroyed due to some physical or chemical influence then the cell will not be able to perform its basic functions like respiration, excretion, and absorption of nutrition and as a result of this our body part will not work and even it may result to death.
Q8-Why are lysosomes are known as a suicidal bag?
Ans- Lysosomes are membrane-bound vascular structures.Lysosomes release powerful digestive enzymes, it breakdown any food particles entering into it. Sometimes, lysosomes can cause self-destruction of any cell by the release of such enzymes within the cells, Hence these are also known as ‘suicidal bags’.
Q9-Where are protein synthesized inside the cell?
Ans- Ribosomes are the sites for protein synthesis. Ribosomes are very small in structures found either in free states suspended in the cytoplasm or attached to the surface of the endoplasmic reticulum. These are composed of ribonucleic acid and protein.
Q10-Make a comparison and write down ways in which plant cells are different from animal cells.
Ans-
| Animal Cell | Plant Cell |
| Chloroplast is absent | Plant Cells have chloroplast to synthesize the food |
| The cell wall is absent | The cell wall is present |
| The shape of the animal is of round shape | Distinct edges, some of them are rectangular and some of the plant cells are of squared shape |
| The nucleus lies at the center of the cell | The nucleus is located at one side of the cell |
| Lysosomes is present | Lysosomes is rarely present |
| Vacuoles are small and more compared with plant cell | Vacuoles are large in size and located around the center of the cell |
Q11.How is a prokaryotic cell different from a eukaryotic cell?
Ans-Prokaryotic cell – Most prokaryotic cells are unicellular. The size of the cell is generally small(0.5 – 5μm). The nuclear region is poorly defined due to the absence of the nuclear membrane. It contains a single chromosome. The nucleolus is absent. Cell organelles like the Golgi apparatus, endoplasmic reticulum, plastids, mitochondria, etc are absent. Cell division occurs by mitosis. A prokaryotic cell is found in bacteria and blue-green algae.
Eukaryotic cell- Most eukaryotic cells are multicellular. The size of the cell is generally large (50 – 100 μm). The nuclear region is well defined and is surrounded by a nuclear membrane. It contains more than one chromosome. The nucleolus is present. Cell organelles like the Golgi apparatus, endoplasmic reticulum, plastids, mitochondria, etc are present. Cell division occurs by mitosis and meiosis. The eukaryotic cell is found in fungi, plants, and animal cells.
Q12-What would happen if plasma membrane ruptures or break down?
Ans-If the plasma membrane of the cell is ruptured, then the cell will die because the plasma membrane regulates the movements of substances in and out of the cell through the plasma membrane by the process of diffusion and osmosis. Thus if the plasma membrane ruptured, then the cell will leak out its contents.
Q13-What would happen to the life of a cell if there was no Golgi apparatus?
Ans-If there was no Golgi apparatus in the cell then activities performed by the Golgi apparatus will not take place.
(i)-The membrane of the Golgi apparatus is often connected to the ER membrane. It collects simple molecules and combines them to make a more complex molecule. These are then packaged in small vesicles and 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 sugar from simple sugar will not be possible as this takes place with the help of enzymes present in the Golgi apparatus.
(iii)-The Golgi apparatus is involved in the formation of lysosomes or peroxisomes. Thus if the Golgi apparatus is absent then the synthesis of lysosomes or peroxisomes will not be possible in the cell.
Q14- Which cell organelles is known as the powerhouse of the cell? why?
Ans- Mitochondria is known as the powerhouse of the cell because it releases energy which is required for all chemical reaction occurs in our body. It releases energy as a result of cellular respiration inside the cell in the form of ATP(Adenosine triphosphate).
Q15- Where do the lipids and protein constituting the cell membrane get synthesized?
Ans-Lipids and protein 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 is known as ribosomes. These ribosomes are the site for protein synthesis.
Q16-How does an Amoeba obtain its food?
Ans-Amoeba obtains its food through the process of endocytosis. The flexibility of the cell enables the cell to engulf solid food particles and other material from its external environment. After the food is taken by amoeba instantly, a vacuole is created inside it with the help of pseudopodia then the food is passed through the process of digestion, absorption, assimilation, and egestion.
Q17-What is osmosis?
Ans- The flow of liquid from higher concentration to lower concentration through a permeable membrane is known as osmosis. As an example, of the concentration of water outside of the cell is more in comparison to the concentration of water inside of the cell then the flow of water will be from outside to the inside of the cell.
Q18- Carry out 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 potatoes cup and answer the following :
(i)Explain why water gathers in the hollowed portion of B and C.
(ii)Why is a potato necessary for this experiment?
(iii)Explain why water does not gather in the hollowed-out portion of A and B.
Experimental setup
(i)Water gathers in the hollowed portion 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 the process of osmosis. Hence water gathers in the hollowed portion of the cup.
(ii)Potato A in the experiment acts as a control set-up. No water gathers in the hollowed portion of potato A.
(iii)Water does not gather in the hollowed portion of potato A because potato cup A is empty. It is a control set-up in the experiment. Water is not able to enter potato D because potato D here is boiled. Boiling disrupts the cell membrane. For osmosis semi-permeable membrane is required, which is disrupted in this case. Therefore osmosis will not occur and water will not enter the boiled potato.
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