Maharashtra Board Class 8 Science Chapter 10 Cell and Cell Organelles Solutions

Cell And Cell Organelles Class 8 Science Chapter 10 Questions And Answers Maharashtra Board

Std 8 Science Chapter 10 Cell And Cell Organelles Question Answer Maharashtra Board

Class 8 Science Chapter 10 Cell And Cell Organelles Question Answer Maharashtra Board

1. Who Am I?

Question a.I am ATP producing factory.
Answer: Mitochondria
In simple words: Mitochondria are known as the powerhouses of the cell because they generate most of the chemical energy needed to power the cell's biochemical reactions, stored in adenosine triphosphate (ATP).

🎯 Exam Tip: Identifying key cellular organelles and their primary functions is crucial for scoring well in cell biology questions.

Question b.I am single-layered but maintain cellular osmotic pressure.
Answer: Vacuole
In simple words: Vacuoles are membrane-bound sacs within the cell that store water, nutrients, and waste, playing a vital role in maintaining turgor pressure and osmotic balance.

🎯 Exam Tip: Understand the structure (single-layered membrane) and function (osmotic pressure regulation) of vacuoles, especially in plant cells.

Question c.I support the cell, but I am not cell wall. I have a body resembling net.
Answer: Endoplasmic reticulum
In simple words: The endoplasmic reticulum is a network of membranes forming sacs and tubules within the cytoplasm, involved in protein and lipid synthesis and providing structural support to the cell.

🎯 Exam Tip: Focus on the structural role and network appearance of the endoplasmic reticulum to differentiate it from the cell wall.

Question d.I am chemical factory of the cell.
Answer: Chloroplasts in case of plant cells can be called chemical factory as they synthesise carbohydrates. Ribosomes also synthesise proteins, so those can also be called chemical factory. Golgi complex is secretory in function, hence it can be also called factory. Mitochondria though mainly referred to as powerhouse of the cell, it is also mentioned as chemical factory by some authors.
In simple words: Several organelles function as 'chemical factories'; chloroplasts synthesize carbohydrates, ribosomes produce proteins, and the Golgi complex processes and packages substances, all performing essential chemical reactions within the cell.

🎯 Exam Tip: Recognize that different organelles contribute to the cell's metabolic activities, making multiple answers possible depending on the specific chemical process.

Question e.Leaves are green because of me.
Answer: Chloroplast.
In simple words: Chloroplasts contain chlorophyll, the green pigment that captures sunlight for photosynthesis, making leaves appear green.

🎯 Exam Tip: Connect the green color of plants directly to chloroplasts and their primary function of photosynthesis.

2. What Would Have Happened? If-..........

Question a.RBCs had mitochondria.
Answer: Mitochondria continuously carry out oxidation and form energy inside the cell. They produce energy-rich compound, ATP. In this process, they utilize carbohydrates, fats and proteins present in the cell. If RBCs has mitochondria, they would have used oxygen for this purpose than carrying it to all the cells of the body. The cells would not have obtained oxygen.
In simple words: If red blood cells (RBCs) had mitochondria, they would consume the oxygen they are meant to transport, leaving less oxygen for other body cells and hindering their primary function.

🎯 Exam Tip: This question tests understanding of RBC specialization for oxygen transport; the absence of mitochondria is key to their efficiency.

Question b.There had been no difference between mitochondria and plastids.
Answer: Mitochondria carry out oxidation of carbohydrates, fats, etc. with the help of enzymes. Plastids are synthesising carbohydrates with the help of solar energy and chlorophyll. Both the cell organelles have their own sets of different enzymes as per their role. If there would have been no difference between mitochondria and plastids, the specific functions would not have been taken place.
In simple words: If mitochondria and plastids were identical, the cell would lose specialized functions like energy production (respiration) by mitochondria and food synthesis (photosynthesis) by plastids, disrupting cellular metabolism.

🎯 Exam Tip: Clearly distinguish the roles of mitochondria (respiration) and plastids (photosynthesis) and their unique enzyme sets; absence of differentiation means loss of specific functions.

Question c.Genes had been absent on the chromosomes.
Answer: Genes are functional segments on the chromosomes which are responsible for transmitting the hereditary information.
In simple words: If genes were absent on chromosomes, hereditary information could not be transmitted, preventing the inheritance of traits from parents to offspring.

🎯 Exam Tip: Emphasize that genes on chromosomes are the fundamental units of heredity; their absence would cease genetic inheritance.

Question d.Plasma membrane had not been selectively permeable.
Answer: Selectively permeable membrane allows some substances to enter the cell, while prevents other unwanted or harmful substances. If plasma membrane would not have been selectively permeable, there would be no control over entry and exit of any substances. The process of osmosis would also be erroneous in such case.
In simple words: Without selective permeability, the plasma membrane would allow all substances, harmful or beneficial, to enter or exit freely, leading to uncontrolled internal conditions and improper cell function, including osmosis.

🎯 Exam Tip: Highlight the plasma membrane's role in regulating cell entry/exit, maintaining internal balance, and facilitating processes like osmosis; its loss would be detrimental.

Question e.Plants lacked anthocyanin.
Answer: If plants lacked anthocyanin, no part of the plant would display purple or blue colour. Anthocyanin attracts the insects for pollination and seed dispersal. These processes will be affected due to lack of anthocyanin. These pigments are also said to be protective in nature for the plant. This protection will not be given to the plant in absence of anthocyanin.
In simple words: Without anthocyanin, plants would lack purple or blue colors, reducing their attractiveness to pollinators and seed dispersers, and losing a natural protective pigment.

🎯 Exam Tip: Focus on the dual role of anthocyanin-pigmentation for attraction (pollination/dispersal) and protection in plants.

3. Who Is Odd Man Among Us? Give Reason.

Question a.Nucleolus, mitochondria, plastids, endoplasmic reticulum
Answer: Nucleolus. (All the others are cell organelles but nucleolus is not a cell organelle present in cytoplasm.)
In simple words: The nucleolus is a structure inside the nucleus, whereas mitochondria, plastids, and endoplasmic reticulum are distinct organelles found in the cytoplasm.

🎯 Exam Tip: Differentiate between structures *within* the nucleus (like the nucleolus) and true cytoplasmic organelles.

Question b.DNA, Ribosomes, Chlorophyll
Answer: Chlorophyll. (DNA and Ribosomes are present in plant as well as in animal cells. Chlorophyll is present only in plant cells.)
In simple words: Chlorophyll is unique to plant cells, while DNA and ribosomes are fundamental components found in both plant and animal cells.

🎯 Exam Tip: Understand which components are universal to most eukaryotic cells (DNA, ribosomes) and which are specific to certain cell types (chlorophyll in plant cells).

4. Give Functions.

Question a.Plasma membrane.
ℹ️ चित्र व्याख्या (Diagram Explanation): प्लाज्मा झिल्ली की संरचना को दर्शाने वाला एक चित्र जिसमें प्रोटीन अणु लिपिड बायलेयर में धंसे हुए हैं और कार्बोहाइड्रेट श्रृंखलाएं बाहरी सतह से जुड़ी हैं। (A diagram illustrating the structure of the plasma membrane, showing protein molecules embedded in a lipid bilayer and carbohydrate chains attached to the outer surface.)
Answer:1. Plasma membrane acts as a selectively permeable membrane. It allows entry of those useful substances which are needed for the cell. It does not allow entry of the harmful and unwanted substances. 2. Plasma membrane keeps the homeostasis in the cell. The cell is kept in steady state even if the external environment changes. 3. Plasma membrane is responsible for processes of endocytosis and exocytosis. 4. The processes of diffusion and osmosis are possible only due to plasma membrane. 5. In animal cells, plasma membrane is the outermost protective covering of the cell.
In simple words: The plasma membrane controls what enters and leaves the cell, maintains internal balance, and facilitates processes like diffusion, osmosis, endocytosis, and exocytosis, also acting as the outer protective layer in animal cells.

🎯 Exam Tip: When describing plasma membrane functions, always include selective permeability, homeostasis, and its role in transport mechanisms (diffusion, osmosis, endocytosis/exocytosis).

Question b.Cytoplasm.
Answer:1. All the cell organelles are spread in the cytoplasm of a cell. 2. The cytoplasm is the medium for many cellular chemical reactions. 3. The cytosol which is the part of cytoplasm other than cell organelles stores many vital substances like amino acids, glucose, vitamins, etc. 4. Cytosol also helps in the cellular movements.
In simple words: Cytoplasm is the jelly-like substance filling the cell, where organelles are suspended, numerous chemical reactions occur, and vital substances are stored, also assisting in cell movement.

🎯 Exam Tip: Remember cytoplasm as the "cellular environment" where organelles reside and metabolic activities take place, distinguishing it from the cytosol.

Question c.Lysosome.
ℹ️ चित्र व्याख्या (Diagram Explanation): लाइसोसोम की आंतरिक संरचना को दर्शाने वाला एक चित्र, जो एक एकल झिल्ली से घिरा है और उसमें एंजाइम कॉम्प्लेक्स मौजूद हैं। यह कोशिका के भीतर अपशिष्ट निपटान और प्रतिरक्षा में महत्वपूर्ण भूमिका निभाता है। (A diagram illustrating the internal structure of a lysosome, which is enclosed by a single membrane and contains enzyme complexes. It plays a crucial role in waste disposal and immunity within the cell.)
Answer:1. Lysosome helps in the destruction of attacking viruses and bacteria and thereby help in the immune response. 2. Lysosomes act as demolition squads. They destroy worn-out cellular organelles and organic debris. This process is called autolysis which All Pagesmeans self-destruction. 3. They are also called suicide bags as in a worn out, damaged or old cell, lysosomes automatically burst. The lytic enzymes present in the lysosome digest their own cells. 4. Lysosomes can digest stored proteins, fats during starvation.
In simple words: Lysosomes are the cell's "recycling centers," breaking down waste, worn-out parts, and foreign invaders using digestive enzymes, and can even trigger self-destruction if the cell is damaged.

🎯 Exam Tip: Key terms for lysosomes include "demolition squads," "suicide bags," and their role in immune response and waste degradation through lytic enzymes.

Question d.Vacuole.
ℹ️ चित्र व्याख्या (Diagram Explanation): एक गोलाकार रिक्तिका को दर्शाने वाला एक चित्र, जो कोशिका के भीतर एक झिल्ली-बद्ध पुटिका होती है। यह कोशिका में पानी, पोषक तत्वों और अपशिष्ट उत्पादों के भंडारण और विनियमन में मदद करती है। (A diagram illustrating a spherical vacuole, which is a membrane-bound vesicle within a cell. It helps in the storage and regulation of water, nutrients, and waste products in the cell.)
Answer:1. Vacuoles maintain the osmotic pressure of the cell. 2. Various metabolic byproducts and end products such as glycogen, proteins, water, etc. are stored in the lysosome. 3. In food vacuole of amoeba, the food is temporarily stored till digestion. In other animal cells, vacuoles can store waste products and food. 4. Vacuoles of plant cells can provide turgidity and rigidity as it contains good amount of cell sap.
In simple words: Vacuoles regulate cell turgor and osmotic pressure, store water, nutrients, and waste, and play a role in food digestion, especially in plant cells where they provide rigidity.

🎯 Exam Tip: Remember the diverse roles of vacuoles in storage, waste removal, and maintaining cell shape, particularly their large size and central position in plant cells for turgidity.

Question e.Nucleus.
ℹ️ चित्र व्याख्या (Diagram Explanation): कोशिका के केंद्रक की संरचना को दर्शाने वाला एक चित्र, जिसमें क्रोमेटिन, केंद्रिका (न्यूक्लियोलस), नाभिकीय छिद्र (न्यूक्लियर पोर) और नाभिकीय झिल्ली (न्यूक्लियर मेम्ब्रेन) स्पष्ट रूप से दिखाए गए हैं। केंद्रक कोशिका की सभी गतिविधियों को नियंत्रित करता है। (A diagram illustrating the structure of the cell nucleus, clearly showing chromatin, nucleolus, nuclear pore, and nuclear membrane. The nucleus controls all cellular activities.)
Answer:1. Nucleus is the controlling centre for the entire cell. 2. It controls all metabolic activities of the cell. 3. The cell division is possible due to the nucleus. 4. The chromosomes present in the nucleus carry the genes. These genes are responsible for the transmission of hereditary characters from parental generation to the next generations.
In simple words: The nucleus is the cell's control center, housing genetic material (chromosomes with genes) that directs all metabolic activities and enables cell division and hereditary transmission.

🎯 Exam Tip: The nucleus's role as the "controlling center" and its containment of genetic information (chromosomes/genes) are fundamental concepts to emphasize.

5. Who Gives Me The Colour? (Select The Correct Option).

Question a.

🎯 Exam Tip: Memorize common plant pigments and the colors they impart; matching questions like this frequently appear in exams.

Project:

Question 1. Prepare model of a cell using different ecofriendly materials.

Question 2. Study osmosis using parchment paper or a similar membrane.

Question 3. Form a friends' group in your class. Give each one role of a cell organelle. Present a skit accordingly.

Class 8 Science Chapter 10 Cell And Cell Organelles Important Questions And Answers

Rewrite The Sentences After Filling The Blanks:

Question 1.Cell wall is mainly composed of carbohydrates like ........... and ...........
Answer: Cell wall is mainly composed of carbohydrates like cellulose and pectin.
In simple words: The cell wall, providing structural support to plant cells, is primarily made up of complex carbohydrates called cellulose and pectin.

🎯 Exam Tip: Remember the main components of the plant cell wall, cellulose and pectin, as they are fundamental to its structure.

Question 2.Plasma membrane is said to be a .................... membrane as it allows some substances to enter the cell, while prevents other substances.
Answer: Plasma membrane is said to be a selectively. permeable membrane as it allows some substances to enter the cell, while prevents other substances.
In simple words: The plasma membrane controls what goes in and out of the cell, allowing only specific substances to pass through, hence it is called a selectively permeable membrane.

🎯 Exam Tip: The term "selectively permeable" is crucial for describing the plasma membrane's function; ensure its accurate spelling and understanding.

Question 3.Homeostasis is maintained in the cell by ....................
Answer: Homeostasis is maintained in the cell by plasma membrane.
In simple words: The plasma membrane plays a critical role in maintaining homeostasis, which is the stable internal environment necessary for a cell to function properly.

🎯 Exam Tip: Link the plasma membrane's regulatory function directly to the concept of cellular homeostasis.

Question 4.An ............... is a specialized subunit having specific function within the cell.
Answer: An organelle is a specialized subunit having specific function within the cell.
In simple words: An organelle is a small, specialized structure within a cell that performs a specific job, contributing to the cell's overall function.

🎯 Exam Tip: Understand the definition of an organelle as a specialized compartment with a distinct function within the cell.

Question 5................. has ribosome granules on its outer surface.
Answer: Rough ER has ribosome granules on its outer surface.
In simple words: The Rough Endoplasmic Reticulum (RER) is characterized by ribosomes attached to its surface, giving it a "rough" appearance and enabling protein synthesis.

🎯 Exam Tip: Differentiate Rough ER from Smooth ER by the presence of ribosomes on its surface, which is key to its protein synthesis function.

Question 6.During starvation, .................... digest stored proteins, fats.
Answer: During starvation, lysosomes digest stored proteins, fats.
In simple words: When the cell lacks nutrients during starvation, lysosomes break down stored proteins and fats to provide energy.

🎯 Exam Tip: Recognize lysosomes' role in cellular "digestion" and nutrient recycling, especially under conditions like starvation.

Question 7................. is the secretory organ of the cell.
Answer: Golgi complex is the secretory organ of the cell.
In simple words: The Golgi complex modifies, sorts, and packages proteins and lipids, preparing them for secretion or delivery to other organelles, acting as the cell's secretory hub.

🎯 Exam Tip: The Golgi complex's primary role in processing, packaging, and secretion is a key function to remember.

Question 8................. compound ATP is produced in the mitochondria.
Answer: Energy-rich compound ATP is produced in the mitochondria.
In simple words: Mitochondria are responsible for generating ATP, a molecule rich in energy that powers most cellular processes.

🎯 Exam Tip: ATP (Adenosine Triphosphate) is the universal energy currency of the cell, and its production is a defining function of mitochondria.

Given Below Are Incorrect Statements. Rewrite Them After Correcting Them:

Question 1.In mitochondria, the inner membrane is porous and the outer membrane is deeply folded.
Answer: In mitochondria, the outer membrane is porous and the inner membrane is deeply folded.
In simple words: The statement is incorrect; in mitochondria, the outer membrane is actually porous, while the inner membrane is extensively folded into cristae to increase surface area for energy production.

🎯 Exam Tip: Pay close attention to the structural details of mitochondria; the folding of the inner membrane (cristae) is a critical feature for its function.

Question 2.Vacuole is bound by double membrane.
Answer: Vacuole is bound by single membrane.
In simple words: Contrary to the statement, vacuoles are enclosed by a single membrane, not a double one.

🎯 Exam Tip: Remember that vacuoles are single-membrane bound organelles; double membranes are characteristic of mitochondria and chloroplasts.

Question 3.If fruit pieces are kept in thick saturated sugar solution, the water from fruit pieces enter the sugar solution resulting into their swelling.
Answer: If fruit pieces are kept in a thick saturated sugar solution, the water from fruit pieces enter the sugar solution resulting into their shrinking.
In simple words: When fruit is placed in a concentrated sugar solution, water moves out of the fruit into the solution due to osmosis, causing the fruit to shrink, not swell.

🎯 Exam Tip: Understand the principles of osmosis; water moves from a region of higher water concentration (inside fruit) to lower water concentration (sugar solution), causing shrinking in hypertonic solutions.

Question 4.Raisins kept in water shrink after an hour.
Answer: Raisins kept in water swell after an hour.
In simple words: Raisins, when soaked in water, absorb water through osmosis because their internal solute concentration is higher, causing them to swell.

🎯 Exam Tip: This is a common example of osmosis. Raisins swelling in water demonstrates water moving into a hypertonic object (raisin) from a hypotonic environment (water).

Question 5.Lysosome produces vacuoles and secretory vesicles.
Answer: Golgi complex produces vacuoles and secretory vesicles.
In simple words: Lysosomes are involved in waste breakdown, while it is the Golgi complex that forms and packages vacuoles and secretory vesicles.

🎯 Exam Tip: Correctly associate the Golgi complex with the formation of secretory vesicles and vacuoles, as it's the organelle responsible for packaging and transport.

Who Gives Me The Colour? (Select The Correct Option)

Question 1.

🎯 Exam Tip: For matching questions, identify the most distinctive function or characteristic of each item to ensure accurate pairing.

Find The Odd One Out By Giving Suitable Reasons:

Question 1.Demolition squads, Suicide Bags, Immune system, Powerhouse of the cell.
Answer: A powerhouse of the cell. (All the others are descriptions of the lysosomes.)
In simple words: "Powerhouse of the cell" refers to mitochondria, while "demolition squads," "suicide bags," and "immune system" are all functions or names associated with lysosomes.

🎯 Exam Tip: When finding the odd one out, group terms with similar meanings or associations and identify the term that does not fit the common category.

Question 2.Lignin, Suberin, Cutin, Iodine
Answer: Iodine. (All the others are polymers present in the cell wall.)
In simple words: Lignin, suberin, and cutin are structural polymers found in plant cell walls, whereas iodine is a chemical element used as a stain and is not a cell wall component.

🎯 Exam Tip: Distinguish between structural components of cells and chemical reagents used in biological studies to correctly identify the odd one out.

Question 3.Nucleolus, Genes, Chromosomes, Ribosomes
Answer: Ribosomes. (All the others are inclusions in the nucleus.)
In simple words: The nucleolus, genes, and chromosomes are all found within the nucleus, while ribosomes are primarily located in the cytoplasm or attached to the endoplasmic reticulum.

🎯 Exam Tip: Clearly know the location of various cellular components; ribosomes are cytoplasmic, while nucleolus, genes, and chromosomes are nuclear.

Write Definitions/Give Meanings:

Question 1. Homeostasis: The tendency of the cell to keep the cellular environment constant in spite of changes in the outer- environment is called homeostasis.
In simple words: Homeostasis is a cell's ability to maintain stable internal conditions despite external changes, ensuring proper functioning.

🎯 Exam Tip: Define homeostasis as maintaining a stable internal environment; it's a fundamental concept in biology.

Question 2. Endocytosis: To take in the food or any other substance from outer environment into the cell is called endocytosis.
In simple words: Endocytosis is the process where a cell engulfs substances from its external environment by enclosing them in a part of its cell membrane, forming a vesicle.

🎯 Exam Tip: Clearly state that endocytosis is the *uptake* of substances into the cell, often involving vesicle formation.

Question 3. Exocytosis: To give out the unwanted substances from the cell to the outer « environment is called exocytosis.
In simple words: Exocytosis is the process by which cells release substances, like waste or secretions, from their interior to the outside environment, usually via vesicles fusing with the plasma membrane.

🎯 Exam Tip: Define exocytosis as the *release* of substances *out* of the cell, contrasting it with endocytosis.

Question 4. Diffusion: The movement of the molecules from region of higher concentration to the region of lower concentration is called diffusion.
In simple words: Diffusion is the passive movement of particles from an area where they are highly concentrated to an area where they are less concentrated, until equilibrium is reached.

🎯 Exam Tip: Emphasize that diffusion involves movement down a concentration gradient, from high to low concentration.

Question 5. Osmosis: The movement of solute from low concentration to high concentration and the movement of solvent from high concentration to the region of low concentration across semipermeable membrane is called osmosis.
In simple words: Osmosis is the specific diffusion of water (solvent) across a semipermeable membrane from an area of high water concentration (low solute) to an area of low water concentration (high solute).

🎯 Exam Tip: Highlight the key aspects of osmosis: it's about water movement, involves a semipermeable membrane, and follows a concentration gradient of water.

Question 6. Plasmolysis: When the cell is kept ?! in hypertonic medium, the water exits through the process of exosmosis causing shrinkage of the cytoplasm, this is known as plasmolysis.
In simple words: Plasmolysis is the shrinking of the cytoplasm away from the cell wall when a plant cell is placed in a hypertonic solution, causing water to leave the cell.

🎯 Exam Tip: Connect plasmolysis to hypertonic solutions and the resulting water loss from the cell, leading to cytoplasmic shrinkage.

Question 7. Isotonic solution: When the concentration of the cell and that of the medium in which the cell is kept is same, then such solution is called isotonic solution.
In simple words: An isotonic solution has the same solute concentration as the cell, meaning there is no net movement of water across the cell membrane.

🎯 Exam Tip: For isotonic solutions, emphasize that concentrations are equal, leading to no net water movement and stable cell volume.

Question 8. Hypotonic solution: When the concentration of the water in the cell is less than that of the concentration of the water in the surrounding medium in which the cell is kept, then such solution is called hypotonic solution.
In simple words: A hypotonic solution has a lower solute concentration (and thus higher water concentration) than the cell, causing water to move into the cell.

🎯 Exam Tip: In hypotonic solutions, remember water enters the cell, potentially causing it to swell or burst (in animal cells).

Question 9. Hypertonic solution: When the concentration of the water in the cell is more than that of the concentration of water in the surrounding medium then such solution is called hypertonic solution.
In simple words: A hypertonic solution has a higher solute concentration (and thus lower water concentration) than the cell, causing water to move out of the cell.

🎯 Exam Tip: In hypertonic solutions, water leaves the cell, leading to shrinkage or plasmolysis (in plant cells).

Distinguish Between The Following:

Question 1. Prokaryotic and eukaryotic cell:
Answer:

🎯 Exam Tip: Focus on the presence/absence of a true nucleus and membrane-bound organelles, and cell size, as primary distinctions between prokaryotic and eukaryotic cells.

Question 2. Plant cell and animal cell
Answer:

🎯 Exam Tip: Key differentiators include the presence of a cell wall, the size and location of vacuoles, and the presence of plastids (plant) versus lysosomes (animal).

Answer The Following Questions In One Sentence:

Question 1. What are the components of plasma membrane?
Answer: In plasma membrane, protein molecules are embedded in two layers of phospholipids.
In simple words: The plasma membrane is composed of a double layer of phospholipids with protein molecules embedded within it.

🎯 Exam Tip: Remember the fluid mosaic model describing the plasma membrane structure for potential diagram questions.

Question 2. Which part of the cell maintains the homeostasis?
Answer: Plasma membrane of the cell maintains the homeostasis.
In simple words: The plasma membrane is responsible for maintaining homeostasis by regulating what enters and leaves the cell.

🎯 Exam Tip: Understanding the selectively permeable nature of the plasma membrane is key to explaining homeostasis.

Question 3. What are genes?
Answer: Genes are the functional segments on the chromosomes that carry hereditary information from the parental generation to the offspring.
In simple words: Genes are sections of DNA on chromosomes that carry instructions for inherited traits, passing them from parents to children.

🎯 Exam Tip: Connect genes to chromosomes and heredity; this is a fundamental concept in biology.

Question 4. What is meant by rough ER?
Answer: The endoplasmic reticulum that has ribosomes on its outer membrane is called rough ER.
In simple words: Rough ER is a type of endoplasmic reticulum that appears "rough" because it has ribosomes attached to its surface, which are involved in protein synthesis.

🎯 Exam Tip: Differentiate rough ER from smooth ER by the presence of ribosomes and their primary functions.

Question 5. Write the examples of plant pigments.
Answer: Chlorophyll, Carotene, Xanthophyll, Anthocyanin, Betalains and Lycopene are some of the plant pigments.
In simple words: Plant pigments include chlorophyll (for green), carotene (orange), xanthophyll (yellow), anthocyanin (purple/blue), betalains (red/yellow), and lycopene (red), giving plants their various colors.

🎯 Exam Tip: Memorize at least 3-4 common plant pigments and their associated colors.

Question 6. What are the inclusions in the stroma of chloroplasts?
Answer: Enzymes, DNA, ribosomes and carbohydrates that are necessary for photosynthesis are present in the stroma of the chloroplasts.
In simple words: The stroma of chloroplasts contains enzymes, DNA, ribosomes, and carbohydrates, all essential for the process of photosynthesis.

🎯 Exam Tip: Recognize that chloroplasts, like mitochondria, have their own DNA and ribosomes, indicating their semi-autonomous nature.

Question 7. Which staining technique was developed by Camilio Golgi? Where was this technique used?
Answer: Camilio Golgi developed the staining technique called 'Black reaction' which was used in the study of nervous system.
In simple words: Camilio Golgi developed the "Black Reaction" staining method, which was used to visualize cells within the nervous system.

🎯 Exam Tip: Connect Camilio Golgi with his specific staining technique and its application in neuroscience.

Question 8. What type of work is done by National Centre for Cell Science?
Answer: National Centre for Cell Science - NCCS is involved in research in cytology and research about cancer treatment and it also provides services for National Animal cell repository.
In simple words: The National Centre for Cell Science (NCCS) conducts research in cytology and cancer treatment, and also maintains a national repository for animal cells.

🎯 Exam Tip: Know the primary functions of key scientific institutions when asked, focusing on their specific contributions.

Question 9. Ripe tomatoes appear red.
Answer: When green tomatoes become ripe they lose chlorophyll and develop red pigment in them called lycopene. Therefore, ripe tomatoes appear red.
In simple words: As tomatoes ripen, their green chlorophyll breaks down and a red pigment called lycopene is produced, making them appear red.

🎯 Exam Tip: This question highlights the role of pigments in fruits; understand the transition from chlorophyll to other pigments.

Give Scientific Reasons:

Question 1. Raisins swell after keeping in plain water.
Answer: When raisins are placed in plain water, there is action of endosmosis. The outer skin of raisins acts like selectively permeable membrane. Since the concentration of water inside the raisin is lesser than the concentration of water in the outer medium, water enters in the raisin. This causes raisins to swell after keeping them in plain water.
In simple words: Raisins swell in plain water due to endosmosis, as water moves from the higher concentration outside the raisin (plain water) into the lower concentration inside the raisin through its selectively permeable skin.

🎯 Exam Tip: This is a classic example of osmosis. Ensure you understand the concepts of selectively permeable membrane, water concentration gradient, and endosmosis.

Question 2. The fruit pieces kept in sugar syrup show shrinking.
Answer: There is more concentration of water in the fruit pieces as compared to the concentration of water in the sugar syrup. Therefore, water is lost out by exosmosis. The membranes of the fruit pieces act as selectively permeable membranes. Thus the process of plasmolysis occurs resulting into shrinking of the fruit pieces.
In simple words: Fruit pieces shrink in sugar syrup because exosmosis occurs; water moves from the fruit (higher water concentration) to the concentrated sugar syrup (lower water concentration), causing the fruit cells to lose water and shrink.

🎯 Exam Tip: This demonstrates exosmosis and plasmolysis. Contrast it with the raisin example to solidify understanding of water movement across membranes.

Question 3. The nucleus of the sieve tubes of the plant phloem is lost.
Answer: The sieve tubes of the plant phloem conduct the food in plants. To make this transport easier, the nucleus of the sieve tubes of the plant phloem is lost,
In simple words: Sieve tube cells in plant phloem lose their nucleus to create more space, allowing for more efficient and unobstructed transport of food (sugars) throughout the plant.

🎯 Exam Tip: Relate structural modifications of cells (like loss of nucleus) to their specialized functions (like transport efficiency in phloem).

Question 4. Plant cells have less mitochondria than those of animal cells.
Answer: Mitochondria are the cell organelles which are called powerhouse of the cell. They produce energy in the form of ATP. Animals are motile and need more energy for walking, running and moving. Plants are stationary. They do not need energy to greater extent. Therefore, they have lesser number of mitochondria.
In simple words: Plant cells have fewer mitochondria than animal cells because plants are stationary and require less energy for movement, while animals are motile and need more ATP for their active lifestyles.

🎯 Exam Tip: Connect the energy requirements of an organism (motility vs. stationary) to the abundance of mitochondria in their cells.

Question 5. Vacuoles do not have any typical size or shape.
Answer: Vacuoles change their shape and size as per the need of the cell. Thus they do not have any fixed shape or size.
In simple words: Vacuoles can vary in size and shape because they adapt to the cell's changing needs, such as storage, waste removal, or maintaining turgor pressure.

🎯 Exam Tip: Emphasize the dynamic nature of vacuoles and their roles beyond just storage.

Question 6. Ripe tomatoes appear red.
Answer: When green tomatoes become ripe they lose chlorophyll and develop red pigment in them called lycopene. Therefore, ripe tomatoes appear red.
In simple words: Ripe tomatoes turn red because the green chlorophyll degrades, and a red pigment called lycopene is synthesized, giving them their characteristic color.

🎯 Exam Tip: This question is a repeat from "Answer the following questions in one sentence". Ensure the explanation is consistent and clear.

Give Functions:

Question 1. Endoplasmic reticulum.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एंडोप्लाज्मिक रेटिकुलम की संरचना को दर्शाता है, जिसमें न्यूक्लियस के पास राइबोसोम और ट्यूब जैसी संरचनाएं दिखाई गई हैं. यह कोशिका के भीतर पदार्थों के परिवहन और संश्लेषण में महत्वपूर्ण भूमिका निभाता है, न्यूक्लियस से जुड़ा हुआ और राइबोसोम के साथ या बिना हो सकता है.
Answer:
1. Endoplasmic reticulum or ER is the supporting framework of the cell.
2. The ribosomes attached to the membrane of the ER synthesize proteins. These proteins are conducted by ER.
3. The detoxification process is done by ER. The toxins that enter the cell through food, air and water are removed out by making them water soluble.
In simple words: The endoplasmic reticulum acts as a cell's internal transport system, synthesizes and processes proteins (with ribosomes on rough ER), and detoxifies harmful substances, essentially providing structural support and facilitating substance movement.

🎯 Exam Tip: Remember to distinguish between Rough ER (protein synthesis and transport) and Smooth ER (lipid synthesis and detoxification).

Question 2. Golgi complex.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र गॉल्जी कॉम्प्लेक्स की संरचना को दर्शाता है, जिसमें सिस्टर्न, सिस्टर्न के चेहरे (सिस फेस), फ्यूजिंग वेसिकल्स, लुमेन, और नए व स्रावी वेसिकल्स शामिल हैं. यह प्रोटीन और लिपिड को संशोधित करने, छांटने और पैक करने में महत्वपूर्ण है.
Answer:
1. Different secretions are prepared in the Golgi complex. Hence it is called the secretory organ of the cell.
2. The secretions are modified and sorted out as per their functions. They are further packed.
3. The enzymes, mucus, proteins, pigments, etc. are sorted and then dispatched to various target regions like plasma membrane, lysosome, etc.
4. Golgi complex also produces vacuoles and secretory vesicles.
5. Formation of cell wall, plasma membrane and lysosomes is aided by Golgi complex.
In simple words: The Golgi complex modifies, sorts, and packages proteins and lipids into vesicles, acting as the cell's "post office" to deliver these substances to their correct destinations, and also helps in forming cell walls and lysosomes.

🎯 Exam Tip: Highlight the three main functions of the Golgi complex: modification, sorting, and packaging of cellular products.

Question 3. Plastids.
Answer:
1. Chloroplasts contain chlorophyll. They carry out the process of photosynthesis. They convert solar energy to chemical energy in the form of food.
2. Chromoplasts with different pigments can impart different colours to flowers and fruits.
3. Leucoplasts are responsible for the synthesis and storage of food like starch, oils and proteins.
In simple words: Plastids are responsible for various functions in plant cells: chloroplasts perform photosynthesis, chromoplasts provide color to flowers and fruits, and leucoplasts synthesize and store food substances like starch, oils, and proteins.

🎯 Exam Tip: Differentiate between the three main types of plastids-chloroplasts, chromoplasts, and leucoplasts-and their distinct functions.

Answer The Following Questions:

Question 1. How does endosmosis and exosmosis occur in the cell?
Answer:
1. When the water concentration inside the cell is less as compared to the medium in which it is present, then the endosmosis takes place. This makes the water to enter inside the cell.
2. When water concentration inside the cell is more than the water concentration in the medium in which it is present, then the water comes out of the cell. This is called exosmosis.
3. Since the cell membrane acts as a semipermeable membrane, the processes of endosmosis and exosmosis takes place in the cell.
In simple words: Endosmosis occurs when water moves into a cell from a region of higher external water concentration, causing the cell to swell; exosmosis occurs when water moves out of a cell to a region of lower external water concentration, causing the cell to shrink. Both processes rely on the cell membrane's selective permeability.

🎯 Exam Tip: Clearly define endosmosis and exosmosis, explaining the direction of water movement relative to concentration gradients and the role of the semipermeable membrane.

Question 2. What is cytoplasm? What are the constituents of cytoplasm?
Answer:
1. The jelly like material present between the cell membrane and nucleus is called cytoplasm.
2. Cytoplasm without cell organelles is called cytosol.
3. All the cell organelles are spread in the cytoplasm.
4. Cytosol stores many vital constituents such as amino acids, glucose, vitamins, etc.
5. The cytoplasm of animal cells is dense and granular while that of plant cells is thin and peripheral. It is pushed to sides due to large central vacuole.
In simple words: Cytoplasm is the jelly-like substance filling the cell, between the cell membrane and the nucleus. It consists of cytosol (the fluid part) and all the cell organelles suspended within it, storing essential substances and facilitating cellular processes.

🎯 Exam Tip: Remember that cytoplasm includes both the cytosol (liquid portion) and the organelles, and its consistency can vary between plant and animal cells due to vacuole size.

Question 3. Describe the structure of the nucleus in the cell.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक कोशिका के केंद्रक की संरचना को दर्शाता है, जिसमें क्रोमेटिन, न्यूक्लियोलस, न्यूक्लियर पोर, और न्यूक्लियर मेम्ब्रेन शामिल हैं. यह कोशिका के आनुवंशिक सामग्री को धारण करता है और कोशिका की गतिविधियों को नियंत्रित करता है.
Answer:
1. Nucleus is the most important part of the eukaryotic cell.
2. Inside the nucleus there is round darkly stained nucleolus.
3. The nucleus is covered over by double membrane which is porous.
4. The nuclear pores allow the transport of different substances in and out of the nucleus to cytoplasm.
5. Inside the nucleus is the chromatin network which contains chromosomes. Chromatin fibres are thin which condense to form chromosomes. The chromosomes become clear and distinct at the time of cell division.
6. In every cell there are specific number of chromosomes. Chromosomes contain genes which are bearers of hereditary characters.
In simple words: The nucleus, the cell's control center, is enclosed by a porous double membrane and contains a nucleolus and a chromatin network that condenses into chromosomes. These chromosomes carry genes, which are responsible for transmitting hereditary information.

🎯 Exam Tip: Focus on the key components of the nucleus: nuclear envelope, nucleolus, chromatin/chromosomes, and nuclear pores, and their respective functions in genetic control and transport.

Question 4. Why is endoplasmic reticulum compared with the pipelines?
Answer:
1. The endoplasmic reticulum works as pipelines to carry different substances in the cell.
2. It is a net like structure consisting of interconnected small tubes and sheets filled with fluid.
3. On the inner side the E.R. is connected to nucleus while at the outer side it is in contact with plasma membrane. Therefore, it works like a pipeline.
In simple words: The endoplasmic reticulum is compared to pipelines because it forms a vast, interconnected network of tubules and sacs throughout the cytoplasm, acting as a transport system to move various substances within the cell, much like pipes carry fluids.

🎯 Exam Tip: The analogy of "pipelines" effectively illustrates the ER's primary function in intracellular transport and its extensive network.

Question 5. Write an account of the different structures seen in Golgi complex.
Answer:
1. Golgi complex is made up of 5-8 hollow and flat sacs called cisternae.
2. These are placed parallel to each other and are filled with different enzymes.
3. Golgi complex has two faces called forming face and maturation face.
4. The proteins packed in vesicles and coming from ER reach Golgi complex through cytoplasm.
5. They fuse with the formation face of the Golgi membranes for emptying their contents in the cisternae.
6. When these contents pass through the cisternae, they are chemically modified with the help of enzymes and are again packed in the vesicles.
7. These vesicles come out of Golgi ' complex at the maturation face.
In simple words: The Golgi complex is structured from 5-8 flattened, enzyme-filled sacs called cisternae, arranged parallel to each other. It has a forming face where vesicles from the ER merge, and a maturation face where modified and packaged substances, now in new vesicles, depart.

🎯 Exam Tip: Describe the key structural components (cisternae, forming face, maturation face) and how they facilitate the processing and packaging of cellular products.

Question 6. How is energy produced in the mitochondria? How the structures of mitochondria help in this process?
Answer:
1. Around every mitochondrion there is a double membrane.
2. The outer membrane of these is porous while the inner membrane is deeply folded.
3. These folds or 'cristae' enclose the matrix filled with proteinaceous gel containing ribosomes, phosphate granules and DNA. Protein synthesis takes place in this matrix.
4. Mitochondria carry out oxidation of carbohydrates and fats in the cell. This produces energy in the form of ATP, s i.e. Adenosine Tri Phosphate
In simple words: Mitochondria produce energy (ATP) by oxidizing carbohydrates and fats. Their inner membrane is deeply folded into cristae, which increases the surface area for energy-producing reactions, while the matrix contains enzymes, ribosomes, and DNA essential for these processes.

🎯 Exam Tip: Focus on the inner membrane's folds (cristae) and the matrix as crucial structural features that maximize efficiency in ATP production.

Question 7. What is the benefit of foldings of inner membrane in mitochondria?
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र माइटोकॉन्ड्रिया की आंतरिक संरचना को दर्शाता है, जिसमें बाहरी और भीतरी मेम्ब्रेन, क्रिस्टी (भीतरी मेम्ब्रेन के फोल्ड), और मैट्रिक्स शामिल हैं. क्रिस्टी ऊर्जा उत्पादन की प्रक्रियाओं के लिए सतह क्षेत्र को बढ़ाती है.
Answer: The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. The numerous imaginations of the membrane are called cristae. This folded inner membrane increases the area which is about 5 times more than that the outer membrane due to cristae. Cristae membranes have small round protein complexes known as Fx particles. In these particles the process of energy production goes on.
In simple words: The inner mitochondrial membrane is highly folded into cristae, significantly increasing its surface area (up to 5 times). This larger surface provides more space for the numerous protein complexes (Fx particles) where the vital chemical reactions of cellular respiration and ATP production occur.

🎯 Exam Tip: The main benefit of cristae is the increased surface area, which directly enhances the efficiency of ATP synthesis by accommodating more enzyme complexes.

Research:

Question 1. Keep 4 - 5 raisins in water and observe after an hour. Afterward, keep the same raisins in sugar solution and observe after an hour. Note down the observations and discuss in the classroom.
Answer: When raisins are kept in water its outer skin acts as a semi-permeable membrane. The water content inside the raisin is lesser as compared to the water content in the outside medium. Therefore the water enters in the raisins due to process of endosmosis. Thus if raisins kept in plain water are observed after one hour, they are seen to be swollen.
On the other hand, if raisins are kept in sugar solution, they show plasmolysis and they shrink. The sugar solution acts as hypertonic medium. Water content in the raisin is higher than that present in the sugary solution. Thus water exists from raisins and its content thus shrinks.
In simple words: Raisins swell in plain water due to endosmosis, as water moves into them. Conversely, when these swollen raisins are placed in sugar solution, they shrink due to exosmosis (plasmolysis) as water leaves the raisins and moves into the concentrated sugar solution.

🎯 Exam Tip: This experiment is a practical demonstration of osmosis. Understand the concepts of hypotonic (plain water), hypertonic (sugar solution), endosmosis, and exosmosis.

Question 2. Wooden doors fit very tightly in rainy season. Why does it happen?
Answer: During rainy season there is more humidity in air. The doors get soaked in rain water. Though wood is non-living, it has the ability to absorb water. As the moisture is more in the surrounding area, it enters the wood. This is a type of endosmosis. It causes the doors to swell. The swollen doors then fit very tightly.
In simple words: Wooden doors swell and fit tightly in the rainy season because the wood, although non-living, absorbs moisture from the humid air through a process similar to endosmosis, causing the wood fibers to expand.

🎯 Exam Tip: Connect the concept of water absorption (imbibition, a type of diffusion) by materials like wood to environmental conditions (humidity) and observable effects.

Diagram Based Questions:

Question 1. Structure of the cell:
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक पादप कोशिका (बाईं ओर) और एक जंतु कोशिका (दाईं ओर) की संरचनाओं को दर्शाता है. पादप कोशिका में एक कोशिका भित्ति और बड़ी केंद्रीय रिक्तिका होती है, जबकि जंतु कोशिका में कोशिका भित्ति नहीं होती और रिक्तिकाएँ छोटी या अनुपस्थित होती हैं, जिसमें विभिन्न कोशिकांग जैसे माइटोकॉन्ड्रिया, केंद्रक, कोशिका झिल्ली, एंडोप्लाज्मिक रेटिकुलम, गोल्जी कॉम्प्लेक्स, न्यूक्लियोलस, साइटोप्लाज्म, क्लोरोप्लास्ट और पिनोसाइटिक वेसिकल प्रदर्शित हैं.
Answer:

🎯 Exam Tip: Be able to confidently list and differentiate the unique and common organelles between plant and animal cells, especially the cell wall, plastids, and lysosomes.

Question 2. Sketch the diagrams to show how osmosis occurs in plant cell if kept separately in isotonic, hypotonic and hypertonic medium.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दर्शाता है कि पादप कोशिकाएं समपरासरी (आइसोटोनिक), अल्पपरासारी (हाइपोटोनिक) और अतिपरासारी (हाइपरटोनिक) माध्यमों में परासरण की प्रक्रिया से कैसे प्रभावित होती हैं. अल्पपरासारी घोल में कोशिका स्फीत हो जाती है, समपरासरी घोल में सामान्य रहती है, जबकि अतिपरासारी घोल में जीवद्रव्य संकुचित हो जाता है.
Answer:

\[ \text{Diagram showing osmosis in plant cell: Isotonic, Hypotonic, Hypertonic solutions} \]
In simple words: In a hypotonic solution, a plant cell swells (turgid) as water enters; in an isotonic solution, it remains normal; and in a hypertonic solution, it loses water and the protoplast shrinks (plasmolysis).

🎯 Exam Tip: Practice drawing and labeling these diagrams to illustrate the effect of different osmotic solutions on plant cells, clearly showing water movement and cell state (turgid, flaccid, plasmolysed).

Question 3. Sketch the diagrams to show how osmosis occurs in animal cell if kept separately in isotonic, hypotonic and hypertonic medium
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दर्शाता है कि जंतु कोशिकाएं समपरासरी (आइसोटोनिक), अल्पपरासारी (हाइपोटोनिक) और अतिपरासारी (हाइपरटोनिक) माध्यमों में परासरण की प्रक्रिया से कैसे प्रभावित होती हैं. अल्पपरासारी घोल में कोशिका फूलकर फट सकती है, समपरासरी घोल में सामान्य रहती है, जबकि अतिपरासारी घोल में कोशिका संकुचित हो जाती है.
Answer:

\[ \text{Diagram showing osmosis in animal cell: Isotonic, Hypotonic, Hypertonic solutions} \]
In simple words: In a hypotonic solution, an animal cell swells and can burst (hemolysis); in an isotonic solution, it maintains its normal shape; and in a hypertonic solution, it shrinks and becomes crenated as it loses water.

🎯 Exam Tip: Understand the differences in how plant and animal cells react to osmotic solutions due to the presence/absence of a cell wall. Animal cells are more vulnerable to lysis in hypotonic solutions.

Activity-Based Questions:

Question 1. Experiment Activity - Take a drop of water on a clean glass slide. Using an ice-cream spoon, gently scrap the inner surface of your cheek. With a needle, transfer a little material from spoon to the water drop on the slide and spread it evenly. Put a drop of methylene blue stain on the smear. Put a cover slip and observe under microscope. Did you observe the cells with blue nucleus?
Answer: Students should do this activity at school laboratory. There are squamous epithelial cells in the inner side of the cheek. When stained with methylene blue the nucleus takes up dark stain and can be seen clearly.
In simple words: When observing human cheek cells under a microscope after staining with methylene blue, students will see squamous epithelial cells, and their nuclei will appear clearly stained in blue due to the dye's affinity for nuclear material.

🎯 Exam Tip: This experiment demonstrates how to prepare and observe animal cells, highlighting the role of staining in visualizing cell structures like the nucleus.

Question 2. Experiment Activity - Take out a thin peel of Rheo or Croton leaf and observe the chromoplasts under the compound microscope.
Answer: Students are expected to do the observations in the school laboratory.
In simple words: Students are expected to perform this experiment in a lab to observe chromoplasts in Rheo or Croton leaf peels under a microscope, which are responsible for the colorful pigments in plant parts.

🎯 Exam Tip: This activity focuses on observing specific plant organelles (chromoplasts) and understanding their role in plant coloration.

Question 3. Can you recall? Observe the cells of onion peel under the microscope. Have you seen the fully turgid, rectangular cells of onion peelings?
Answer: Students are expected to do the observations in the school laboratory.
In simple words: Students should observe onion peel cells under a microscope to identify their characteristic rectangular shape and note their turgid state, which is maintained by the cell wall and vacuole.

🎯 Exam Tip: This activity reinforces the understanding of plant cell structure, specifically the cell wall's role in maintaining shape and turgidity.

8th Std Science Questions And Answers:

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