Cell (Fundamental Unit Of Life) - MCQ Test (24-05-2017) - Class 9 MCQ

Answer:
The onion peel is obtained from the fleshy and succulent onion leaf. Here is a detailed explanation of why this is the correct answer:
Onion Peel:
- The onion peel refers to the dry outer covering of the onion.
- It is the protective layer that surrounds the fleshy layers of the onion bulb.
Options:
A: Dry outer cover of onion
- This option correctly describes the onion peel.
B: Fleshy and succulent onion leaf
- This option is the correct answer.
- The fleshy and succulent onion leaf is the source of the onion peel.
C: Roots of onion plant
- This option is incorrect.
- The roots of the onion plant do not provide the onion peel.
D: All of these
- This option is incorrect.
- Only option B, the fleshy and succulent onion leaf, provides the onion peel.
In conclusion, the correct answer is option B: Fleshy and succulent onion leaf. This is because the onion peel is obtained from the dry outer cover of the onion, which is the fleshy and succulent onion leaf.

Key Points:
- An animal cell differs from a plant cell in terms of the presence or absence of certain structures and organelles.
- The main difference between animal and plant cells is the presence of a cell wall in plant cells and its absence in animal cells.
- Plant cells have a rigid cell wall made of cellulose, while animal cells do not have a cell wall.
- The cell wall provides structural support and protection to plant cells.
- Animal cells have a flexible and permeable cell membrane that regulates the movement of substances in and out of the cell.
- Plant cells also have a cell membrane, but it is located just beneath the cell wall.
- Both animal and plant cells have endoplasmic reticulum (ER), which is involved in the synthesis, folding, and transport of proteins.
- Ribosomes are present in both animal and plant cells and are responsible for protein synthesis.
- Therefore, the correct answer is B: Cell wall. Plant cells have a cell wall, while animal cells do not.

Animal cell is limited by the plasma membrane.
The plasma membrane is a selectively permeable barrier that encloses the contents of the animal cell. It separates the cell's internal environment from the external environment and regulates the movement of substances in and out of the cell. Here are the reasons why the animal cell is limited by the plasma membrane:
- Regulation of nutrient intake: The plasma membrane controls the intake of nutrients into the cell. It allows the passage of essential molecules such as glucose, amino acids, and ions, while preventing the entry of harmful substances.
- Excretion of waste products: The plasma membrane also plays a crucial role in removing waste products from the cell. It allows the excretion of metabolic waste such as carbon dioxide and urea, ensuring the cell's internal environment remains clean.
- Maintenance of cellular homeostasis: The plasma membrane helps maintain the cell's internal conditions, such as pH and ion concentrations. It regulates the movement of ions across the membrane, ensuring a balance is maintained.
- Cell signaling: The plasma membrane contains various receptors and proteins that allow the cell to receive signals from its surroundings. These signals can trigger specific cellular responses, enabling communication with other cells and coordinating physiological processes.
- Protection and support: The plasma membrane provides physical protection to the cell by enclosing the delicate organelles and structures within. It also helps maintain the cell's shape and provides support.
In conclusion, the animal cell is limited by the plasma membrane because it regulates nutrient intake, excretes waste products, maintains cellular homeostasis, facilitates cell signaling, and provides protection and support to the cell.

Double membrane is absent in:
- Lysosome
Explanation:
- The double membrane is a characteristic feature of certain organelles in eukaryotic cells.
- It consists of two lipid bilayers that enclose the organelle and provide a barrier between the internal and external environments.
- However, not all organelles possess a double membrane.
- Among the given options, the organelle that does not have a double membrane is the lysosome.
- Lysosomes are single-membrane-bound organelles involved in the digestion and recycling of cellular waste materials.
- They contain hydrolytic enzymes that break down macromolecules.
- Unlike mitochondria, chloroplasts, and the nucleus, which all have double membranes, lysosomes have only a single membrane.
- The absence of a double membrane in lysosomes allows for direct interaction between the enzymes inside the organelle and the cytoplasm.
- This interaction is essential for the lysosome's function in cellular waste management.

The process of converting radiant energy from sunlight into chemical energy and storing it is known as photosynthesis. This process occurs in the chloroplasts of plant cells and involves several steps. Here is a detailed explanation of how sunlight energy is converted into chemical energy and stored as ATP:
1. Light Absorption:
- Sunlight is composed of different wavelengths, including visible light.
- Pigments called chlorophylls, located in the chloroplasts, absorb the light energy.
2. Light-dependent Reactions:
- The absorbed light energy is used to power a series of reactions in the thylakoid membrane of the chloroplast.
- These reactions involve the splitting of water molecules, releasing oxygen and generating energy in the form of ATP.
- ATP (adenosine triphosphate) is a molecule that stores and transports chemical energy within cells.
3. Calvin Cycle (Light-independent Reactions):
- ATP and another molecule called NADPH, which is also generated in the light-dependent reactions, are used in the Calvin cycle.
- The Calvin cycle takes place in the stroma of the chloroplast.
- Carbon dioxide from the atmosphere is combined with the ATP and NADPH to produce glucose (a simple sugar) and other organic compounds.
- Glucose is a form of chemical energy that can be stored and used by plants for growth and metabolism.
4. Energy Storage:
- The glucose produced in the Calvin cycle can be stored as starch or converted into other forms, such as cellulose or sucrose.
- Starch is a polysaccharide that serves as a storage molecule in plant cells.
- When energy is needed, the stored glucose can be broken down through cellular respiration to release ATP for various cellular processes.
In summary, the energy from sunlight is converted into chemical energy (ATP) through the process of photosynthesis. This chemical energy can then be stored in the form of glucose or other organic compounds, allowing plants to grow and carry out essential metabolic functions.

Barrier between the protoplasm and outer environment in a plant cell:
The correct answer is C: Cell wall.
Explanation:
The barrier between the protoplasm (the living substance inside the cell) and the outer environment in a plant cell is the cell wall. The cell wall is a rigid, protective layer that surrounds the cell membrane and provides structural support to the cell. Here is a detailed explanation of each option:
- A: Cell membrane: The cell membrane is a selectively permeable barrier that surrounds the protoplasm and controls the movement of substances in and out of the cell. It is located inside the cell wall in a plant cell.
- B: Nuclear membrane: The nuclear membrane, also known as the nuclear envelope, surrounds the nucleus of the cell. It separates the nuclear contents from the cytoplasm, but it is not the barrier between the protoplasm and the outer environment.
- C: Cell wall: The cell wall is a rigid layer made up of cellulose and other polysaccharides. It is located outside the cell membrane and provides structural support and protection to the cell. It acts as the primary barrier between the protoplasm and the outer environment.
- D: Tonoplast: The tonoplast is a membrane that surrounds the vacuole, a large organelle found in plant cells. It regulates the movement of substances in and out of the vacuole but is not the main barrier between the protoplasm and the outer environment.
In conclusion, the correct answer is C: Cell wall, as it is the primary barrier between the protoplasm and the outer environment in a plant cell.

Lysosomes are the reservoirs of:
- Hydrolytic enzymes: Lysosomes are often referred to as the "digestive compartments" of the cell because they contain various hydrolytic enzymes. These enzymes are responsible for breaking down macromolecules such as proteins, carbohydrates, lipids, and nucleic acids into smaller molecules that can be used by the cell.
- Proteins: Lysosomes also serve as storage sites for secretory glycoproteins. These proteins are synthesized in the endoplasmic reticulum and then transported to the Golgi apparatus, where they are modified and packaged into vesicles. Some of these vesicles fuse with lysosomes, allowing the lysosomes to store and release these proteins as needed.
- Waste materials: Lysosomes also play a crucial role in the cell's waste management system. They can engulf and digest cellular debris, worn-out organelles, or invading pathogens through a process called autophagy. The hydrolytic enzymes within lysosomes help break down these waste materials into simpler components that can be recycled or excreted by the cell.
- Pathogens: Lysosomes are involved in the cell's defense against pathogens. They can fuse with phagosomes, which are vesicles that engulf and internalize foreign particles or microorganisms, such as bacteria or viruses. The hydrolytic enzymes within lysosomes help destroy these pathogens and contribute to the immune response of the cell.
In summary, lysosomes serve as reservoirs for hydrolytic enzymes, store secretory glycoproteins, aid in waste management, and contribute to the cell's immune response.

The membrane surrounding the vacuole of a plant cell is called the tonoplast.
Explanation:
The tonoplast is a specialized membrane that surrounds the vacuole, a large organelle found in plant cells. Here is a detailed explanation of the different options and why tonoplast is the correct answer:
- Tonoplast: The tonoplast is a membrane that surrounds the vacuole in plant cells. It is responsible for maintaining the integrity of the vacuole and regulating the movement of molecules in and out of the vacuole.
- Plasma membrane: The plasma membrane, also known as the cell membrane, surrounds the entire cell and separates the cell's contents from its external environment. It regulates the movement of molecules in and out of the cell.
- Nuclear membrane: The nuclear membrane, also known as the nuclear envelope, surrounds the nucleus of a cell. It separates the nucleus from the cytoplasm and regulates the movement of molecules between the nucleus and the cytoplasm.
- Cell wall: The cell wall is a rigid structure that surrounds plant cells, fungi, and some bacteria. It provides support and protection to the cell, but it is not involved in surrounding the vacuole.
In summary, the correct answer is A: Tonoplast, as it specifically refers to the membrane surrounding the vacuole in a plant cell.

Deoxyribonucleic acid (DNA)
- DNA is the expanded form of deoxyribonucleic acid.
- It is a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.
- DNA is composed of two long chains of nucleotides, which are made up of a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine).
- The structure of DNA is a double helix, where the two chains are held together by hydrogen bonds between the bases.
- DNA is responsible for the transmission of genetic information from one generation to the next.
- It is involved in various cellular processes, including DNA replication, transcription, and translation.
- DNA also serves as a template for the synthesis of ribonucleic acid (RNA), which plays a crucial role in protein synthesis.
- Mutations in DNA can lead to genetic disorders and diseases.
- DNA profiling is used for identification purposes in forensic science and paternity testing.

The cell organelle associated with cell secretion is the Golgi apparatus.
The Golgi apparatus is a cellular organelle that plays a crucial role in the secretion of various substances from the cell. It is responsible for modifying, sorting, and packaging proteins and lipids produced in the endoplasmic reticulum (ER) for transport to their final destinations.
The Golgi apparatus functions in cell secretion through several important processes:
1. Protein modification: Proteins produced in the ER are transported to the Golgi apparatus, where they undergo further modifications such as glycosylation, phosphorylation, and sulfation. These modifications can alter the protein's structure and function.
2. Sorting and packaging: The Golgi apparatus sorts the modified proteins into vesicles for transport to their specific destinations. It determines where the proteins will be sent based on specific molecular signals or tags attached to them.
3. Vesicle formation: The Golgi apparatus forms vesicles, which are small membrane-bound sacs, to transport the modified and sorted proteins. These vesicles bud off from the Golgi apparatus and carry the proteins to their target locations within or outside the cell.
4. Secretion: Once the vesicles reach their target locations, they fuse with the cell membrane and release their contents into the extracellular space. This process is known as exocytosis and is essential for the secretion of hormones, enzymes, and other substances.
In conclusion, the Golgi apparatus is the cell organelle associated with cell secretion. It plays a vital role in modifying, sorting, and packaging proteins and lipids for secretion from the cell.

Brain of the Cell: Nucleus
The nucleus is often referred to as the brain of the cell because it plays a crucial role in controlling all cellular activities. Here's why the nucleus is considered the brain of the cell:
1. Structure and Function:
- The nucleus is a membrane-bound organelle found in eukaryotic cells.
- It contains the cell's genetic material in the form of DNA, which is organized into chromosomes.
- The nucleus acts as the control center of the cell, regulating gene expression and coordinating cellular activities.
2. Genetic Information:
- The nucleus houses and protects the DNA, which contains the instructions for building and maintaining the cell.
- It controls the synthesis of proteins through transcription and translation processes.
- It regulates the cell cycle, ensuring proper cell division and growth.
3. Nuclear Envelope:
- The nucleus is surrounded by a double membrane called the nuclear envelope, which separates its contents from the cytoplasm.
- Nuclear pores in the envelope allow the exchange of molecules, such as RNA and proteins, between the nucleus and the cytoplasm.
4. Nucleolus:
- The nucleus contains a structure called the nucleolus, which is involved in the production of ribosomes.
- The nucleolus synthesizes ribosomal RNA (rRNA) and assembles ribosomal subunits.
In conclusion, the nucleus is rightfully called the brain of the cell because it controls genetic information, regulates cellular activities, and is responsible for the synthesis of ribosomes. Other organelles, such as mitochondria, ribosomes, and the plasma membrane, have important functions but do not have the same level of control and coordination as the nucleus.

The common feature amongst nucleus, chloroplast, and mitochondrion is DNA.

1. Nucleus:

- The nucleus is a membrane-bound organelle found in eukaryotic cells.
- It contains the cell's genetic material, which is organized into chromosomes.
- The DNA in the nucleus carries the hereditary information and controls the cell's activities.

2. Chloroplast:

- Chloroplasts are organelles found in plant cells and some protists.
- They are responsible for photosynthesis, the process by which plants convert sunlight into energy.
- Chloroplasts contain their own DNA, known as chloroplast DNA or cpDNA.
- This DNA carries specific genes necessary for photosynthesis and other chloroplast functions.

3. Mitochondrion:

- Mitochondria are organelles found in most eukaryotic cells.
- They are responsible for generating energy in the form of ATP through a process called cellular respiration.
- Mitochondria have their own DNA, known as mitochondrial DNA or mtDNA.
- This DNA carries genes that are essential for the mitochondria to produce ATP.
Therefore, the common feature amongst nucleus, chloroplast, and mitochondrion is DNA.

Discovery of the Cell

• Background: The discovery of the cell is a significant milestone in the field of biology. It provided a fundamental understanding of the basic unit of life and revolutionized our understanding of living organisms.


• Robert Hooke: Robert Hooke, an English scientist, is credited with the discovery of the cell.


• Microscopic Observation: In 1665, Hooke examined a thin slice of cork under a compound microscope that he had designed. He observed a series of small, box-like structures that resembled the cells of a monastery, leading him to coin the term "cell."


• Publication: Hooke published his observations in his book titled "Micrographia," which became a landmark in the history of science.


• Significance: Hooke's discovery of the cell laid the foundation for the development of cell theory, which states that all living organisms are composed of cells and that cells are the basic structural and functional units of life.

Therefore, the correct answer is D: Robert Hooke. His discovery of the cell has had a profound impact on our understanding of biology and remains a fundamental concept in the field.

Cell Organelles in Plant Cells
There are several organelles in plant cells that perform different functions. The Golgi bodies, also known as Golgi apparatus or Golgi complex, are responsible for processing and packaging proteins and lipids. However, in certain circumstances, other organelles can take over the functions of the Golgi bodies. One such organelle is the Dictyosome.
1. Dictyosome
- The Dictyosome is an organelle found in plant cells that is involved in the processing and packaging of proteins and lipids.
- It is composed of stacks of flattened sacs called cisternae, which resemble the structure of the Golgi bodies.
- The Dictyosome is responsible for modifying proteins and lipids by adding sugar molecules, lipids, or other functional groups.
- It also sorts and packages these molecules into vesicles for transport to other parts of the cell or for secretion.
2. Glyoxysome
- The Glyoxysome is another organelle found in plant cells, but it is primarily involved in lipid metabolism.
- It is responsible for converting stored lipids into carbohydrates during seed germination or periods of energy deprivation.
- While the Glyoxysome does play a role in lipid metabolism, it does not take over the functions of the Golgi bodies.
3. Peroxisome
- The Peroxisome is an organelle found in both plant and animal cells that is involved in various metabolic processes.
- It is responsible for detoxifying harmful substances, such as hydrogen peroxide, and for lipid metabolism.
- However, the Peroxisome does not take over the functions of the Golgi bodies in processing and packaging proteins and lipids.
4. Endoplasmic Reticulum
- The Endoplasmic Reticulum (ER) is a network of membranes found in eukaryotic cells, including plant cells.
- It is involved in protein synthesis, lipid metabolism, and the transportation of molecules within the cell.
- While the ER is connected to the Golgi bodies and plays a role in the processing and packaging of proteins and lipids, it does not replace the Golgi bodies entirely.
Conclusion:
In summary, the organelle that takes part in place of Golgi bodies in plant cells is the Dictyosome. It performs similar functions in the processing and packaging of proteins and lipids. Other organelles, such as the Glyoxysome, Peroxisome, and Endoplasmic Reticulum, have their own specific functions but do not replace the Golgi bodies.

Endoplasmic Reticulum and its Components
The endoplasmic reticulum (ER) is a network of membranous tubules and sacs found throughout the cytoplasm of eukaryotic cells. It plays a crucial role in the synthesis, modification, and transport of proteins and lipids within the cell. The ER can be divided into two main types: the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER).
The rough endoplasmic reticulum (RER)
- The RER is studded with ribosomes, giving it a rough appearance under a microscope. These ribosomes are responsible for protein synthesis.
- The RER is involved in the production of proteins that are destined for secretion, insertion into the plasma membrane, or transport to other organelles.
- It is also responsible for the synthesis of membrane proteins and proteins that are modified with carbohydrates (glycoproteins).
The smooth endoplasmic reticulum (SER)
- The SER does not have ribosomes attached to its surface, giving it a smooth appearance.
- It is involved in various metabolic processes, including lipid synthesis, detoxification of drugs and toxins, and calcium ion storage.
- The SER is also responsible for the synthesis of steroid hormones and the metabolism of carbohydrates.
Conclusion:
In conclusion, the endoplasmic reticulum contains ribosomes, specifically in the rough endoplasmic reticulum (RER). Therefore, option A is correct - Endoplasmic Reticulum sometimes contains ribosomes.

Nucleolus is a factory of:
- Ribosomes: The nucleolus is responsible for the production and assembly of ribosomes, which are essential for protein synthesis.
- Nuclear sap: The nucleolus is not involved in the production of nuclear sap. Nuclear sap, also known as nucleoplasm, is the fluid within the nucleus that contains various molecules and structures.
- Sat chromosome: The nucleolus is not directly involved in the production or formation of satellite chromosomes. Satellite chromosomes are small, condensed segments of DNA that are loosely attached to the main chromosome.
- Giant chromosome: The nucleolus is not responsible for the production or formation of giant chromosomes. Giant chromosomes are often found in certain organisms, such as salivary glands of insects, and are characterized by their large size and unique banding patterns.
Therefore, the correct answer is A: Ribosomes. The nucleolus functions as a factory for the production and assembly of ribosomes, which play a crucial role in protein synthesis.

Components of Nucleus:
Nuclear Envelope:
- Double membrane that surrounds the nucleus.
- It separates the contents of the nucleus from the cytoplasm.
Nucleolus:
- A small, dense region within the nucleus.
- It is responsible for the production of ribosomes.
Chromatin:
- A complex of DNA and proteins.
- It condenses to form chromosomes during cell division.
Nucleoplasm:
- The gel-like substance within the nucleus.
- It contains various molecules and ions necessary for cellular processes.
Nuclear Matrix:
- A network of fibers within the nucleus.
- It provides structural support and helps organize the chromatin.
Summary:
The components of the nucleus include the nuclear envelope, nucleolus, chromatin, nucleoplasm, and nuclear matrix. The nuclear envelope separates the nucleus from the cytoplasm, while the nucleolus is responsible for ribosome production. Chromatin consists of DNA and proteins and condenses into chromosomes during cell division. The nucleoplasm is the gel-like substance within the nucleus, and the nuclear matrix provides structural support and organization.

Calcium deposition in plant cells:
Calcium is an essential nutrient for plant growth and development. It is deposited in plant cells in different forms, such as calcium carbonate, calcium oxalate, and calcium sulphate. Let's discuss each form in detail:
1. Calcium carbonate:
- Calcium carbonate is a common form of calcium deposition in plant cells.
- It is formed by the combination of calcium ions (Ca2+) and carbonate ions (CO32-).
- Calcium carbonate is insoluble and can be found as crystals or granules in plant tissues.
- It is often found in the form of calcified structures, such as calcium oxalate crystals.
2. Calcium oxalate:
- Calcium oxalate is another form of calcium deposition in plant cells.
- It is formed by the combination of calcium ions (Ca2+) and oxalate ions (C2O42-).
- Calcium oxalate can be found in various crystal forms, including needle-shaped crystals, druse crystals, and raphide crystals.
- This form of calcium deposition is often observed in specialized cells, such as crystal idioblasts, which store calcium oxalate crystals.
3. Calcium sulphate:
- Calcium sulphate is also found as a form of calcium deposition in plant cells.
- It is formed by the combination of calcium ions (Ca2+) and sulphate ions (SO42-).
- Calcium sulphate can be found as gypsum, which is a hydrated form of calcium sulphate.
- It is less common than calcium carbonate and calcium oxalate as a form of calcium deposition in plant cells.
4. All the above:
- Calcium can be deposited in plant cells as calcium carbonate, calcium oxalate, and calcium sulphate.
- Different plant species may preferentially deposit calcium in different forms.
- The deposition of calcium in plant cells is influenced by various factors, including the availability of calcium ions in the soil, plant genetics, and environmental conditions.
In conclusion, calcium is deposited in plant cells as calcium carbonate, calcium oxalate, and calcium sulphate. These different forms of calcium deposition play important roles in plant physiology and provide structural support to various plant tissues.

Cell Membrane Composition
The cell membrane, also known as the plasma membrane, is a vital component of all cells. It surrounds the cell, separating its internal environment from the external environment. The composition of the cell membrane primarily consists of:
1. Phospholipids:
- Phospholipids are the main structural component of the cell membrane.
- They have a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails.
- The arrangement of phospholipids forms a lipid bilayer, with the hydrophilic heads facing outward and the hydrophobic tails facing inward.
2. Proteins:
- Proteins are embedded within the phospholipid bilayer or attached to its surface.
- They play various roles, such as transport of molecules across the membrane, cell signaling, and structural support.
3. Cholesterol:
- Cholesterol molecules are present within the lipid bilayer.
- They help regulate the fluidity and stability of the cell membrane.
4. Carbohydrates:
- Carbohydrates are present on the outer surface of the cell membrane.
- They are attached to lipids or proteins and play a role in cell recognition and communication.
5. Glycoproteins and Glycolipids:
- Glycoproteins and glycolipids are molecules that have carbohydrate chains attached to them.
- They are involved in cell-cell recognition, immune responses, and cell adhesion.
6. Other Lipids:
- Besides phospholipids, the cell membrane also contains other lipids such as glycerolipids and sphingolipids.
- These lipids contribute to the overall structure and function of the membrane.
Overall, the cell membrane is a dynamic structure composed of phospholipids, proteins, cholesterol, carbohydrates, and other lipids. This composition allows the cell membrane to regulate the movement of molecules, maintain cell integrity, and participate in various cellular processes.

Genetic Material in Different Cell Components

There are different cell components in a cell, each with its own specific functions and genetic material. Let's explore the genetic material present in each of the given options:

A. Mitochondria:
- Mitochondria have their own genetic material known as mitochondrial DNA (mtDNA).
- mtDNA is a circular double-stranded DNA molecule that codes for some essential proteins and RNA molecules involved in mitochondrial function.
- It is inherited maternally and is separate from the nuclear DNA present in the cell's nucleus.


B. Lysosomes:
- Lysosomes are membrane-bound organelles that contain digestive enzymes.
- Lysosomes do not have their own genetic material. They are formed by the Golgi apparatus and their enzymes are synthesized in the endoplasmic reticulum.


C. Cell Wall:
- The cell wall is an extracellular structure found in plant cells, bacteria, and fungi.
- It provides structural support and protection to the cell.
- The cell wall does not contain genetic material. The genetic material is present within the cell's nucleus or other organelles.


D. Ribosomes:
- Ribosomes are cellular structures responsible for protein synthesis.
- Ribosomes do not have their own genetic material. They consist of ribosomal RNA (rRNA) and proteins that are encoded by the nuclear DNA and synthesized in the nucleolus.


Conclusion:
- Among the given options, only mitochondria have their own genetic material in the form of mitochondrial DNA.
- Therefore, the correct answer is option A: Mitochondria.

Plasmolysis:
Plasmolysis refers to the process in which a plant cell loses water and the cell contents shrink away from the cell wall. This occurs when a plant cell is placed in a hypertonic solution, meaning the solute concentration outside the cell is higher than inside the cell. The water from inside the cell moves outwards in an attempt to balance the concentrations, leading to plasmolysis.
Key Points:
- Plasmolysis is the shrinkage of cell contents away from the cell wall.
- It occurs when a plant cell is placed in a hypertonic solution.
- The solute concentration outside the cell is higher than inside the cell.
- Water moves out of the cell to balance the concentrations.
- The cell contents, including the cytoplasm and organelles, shrink and pull away from the cell wall.
- Plasmolysis can be reversible if the cell is placed in a hypotonic solution where water moves back into the cell.
Conclusion:
Plasmolysis is a vital phenomenon that occurs in plant cells when exposed to a hypertonic solution. It leads to the shrinkage of the cell contents away from the cell wall. Understanding plasmolysis is crucial in the study of plant physiology and the effects of different solute concentrations on plant cells.

Lysosomal Activity
Lysosomal activity refers to the functions performed by lysosomes, which are membrane-bound organelles found in animal cells. Lysosomes are known as the "suicidal bags" or the "garbage disposals" of the cell because they play a crucial role in intracellular digestion and the removal of cell waste and debris.
The lysosomal activity includes the following processes:
1. Intracellular digestion: Lysosomes contain various enzymes, such as proteases, lipases, and nucleases, which break down macromolecules (proteins, lipids, nucleic acids) into smaller components. This process enables the cell to obtain nutrients from intracellular sources and recycle cellular components.
2. Suicidal bag: Lysosomes have a self-destructive function in certain situations. For example, during programmed cell death (apoptosis), lysosomes release their enzymes, causing the breakdown of cellular components and ultimately leading to cell death.
3. Removal of cell garbage: Lysosomes also play a vital role in the removal of cell waste and debris. They fuse with endocytic vesicles containing extracellular material that has been taken up by the cell through processes like endocytosis or phagocytosis. The enzymes within the lysosomes then degrade and break down the engulfed material.
Therefore, the correct answer is D: All the above, as all of the mentioned options (intracellular digestion, suicidal bag, removal of cell garbage) are part of lysosomal activity.

Glycolysis:
Glycolysis is the metabolic pathway that converts glucose into pyruvate. It is the first step in both aerobic and anaerobic respiration and occurs in the cytoplasm of cells. Here's a detailed explanation of glycolysis:
Process:
Glycolysis involves a series of ten chemical reactions that occur in the cytoplasm of cells. These reactions can be grouped into three main phases: energy investment phase, cleavage phase, and energy generation phase.
1. Energy Investment Phase:
- Glucose, a six-carbon sugar, is phosphorylated by ATP to form glucose-6-phosphate.
- Glucose-6-phosphate is then converted to fructose-6-phosphate through an isomerization reaction.
- Another ATP molecule is used to phosphorylate fructose-6-phosphate, resulting in the formation of fructose-1,6-bisphosphate.
2. Cleavage Phase:
- Fructose-1,6-bisphosphate is cleaved into two three-carbon molecules, namely dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P).
3. Energy Generation Phase:
- DHAP is isomerized into G3P, so now there are two molecules of G3P.
- G3P is oxidized, and NAD+ is reduced to NADH. This reaction also produces ATP through substrate-level phosphorylation.
- The final step involves the conversion of phosphoenolpyruvate (PEP) to pyruvate, which generates another ATP molecule through substrate-level phosphorylation.
Outcome:
The net result of glycolysis is the conversion of one molecule of glucose into two molecules of pyruvate, along with the production of two molecules of ATP and two molecules of NADH. Pyruvate can then enter the citric acid cycle (in aerobic conditions) or undergo fermentation (in anaerobic conditions).
In conclusion, glycolysis is the process by which glucose is converted into pyruvate through a series of enzymatic reactions. It plays a crucial role in cellular metabolism and energy production.

Golgi apparatus takes part in the synthesis of:
Glycolipids:
- The Golgi apparatus is involved in the synthesis of glycolipids.
- Glycolipids are a type of lipid that contains carbohydrate chains attached to them.
- The Golgi apparatus modifies and adds carbohydrate chains to lipids, forming glycolipids.
Glycoproteins:
- The Golgi apparatus is also involved in the synthesis of glycoproteins.
- Glycoproteins are proteins that have carbohydrate chains attached to them.
- The Golgi apparatus adds carbohydrate chains to proteins, forming glycoproteins.
Hormones:
- The Golgi apparatus plays a role in the synthesis and packaging of hormones.
- Hormones are chemical messengers that regulate various bodily functions.
- The Golgi apparatus modifies and packages hormones before they are transported to their target cells.
All the above:
- The Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones.
- It plays a crucial role in modifying and packaging these molecules before they are transported to their respective destinations.
In conclusion, the Golgi apparatus is involved in the synthesis of glycolipids, glycoproteins, and hormones. It plays a vital role in modifying and packaging these molecules before they are transported to their target cells or released into the bloodstream.

Unit of Protoplasm with a Nucleus and Plasmamembrane
The correct answer is B: Cell.
A cell is the basic structural and functional unit of all living organisms. It is responsible for carrying out all the processes necessary for the survival and functioning of the organism. A cell is characterized by having a nucleus, which contains the genetic material, and being covered by a plasma membrane, which separates the cell from its environment.
Explanation:
- The term "unit of protoplasm" refers to the basic structural and functional component of all living organisms.
- The presence of a nucleus is a key characteristic of a cell. The nucleus contains the genetic material, such as DNA, which controls the cell's activities and determines its characteristics.
- The plasma membrane, also known as the cell membrane, surrounds the cell and acts as a barrier between the cell and its external environment. It regulates the movement of substances in and out of the cell.
- The options provided are:
- A) Ectoplast: This term is not commonly used in biology and does not accurately describe a unit of protoplasm with a nucleus and plasma membrane.
- B) Cell: This is the correct answer. A cell is a unit of protoplasm that has a nucleus and is covered by a plasma membrane.
- C) Cytoplast: This term is not commonly used in biology and does not accurately describe a unit of protoplasm with a nucleus and plasma membrane.
- D) All the above: This option is incorrect because option A and C are not valid terms.
In conclusion, the correct answer is B: Cell.

Protein synthesis occurs on ribosomes:
- Ribosomes are the cellular structures responsible for protein synthesis.
- They are found in the cytoplasm of the cell and on the endoplasmic reticulum (ER).
- Protein synthesis begins with the production of messenger RNA (mRNA) in the nucleus.
- The mRNA then travels out of the nucleus and attaches to a ribosome.
- The ribosome reads the mRNA sequence and translates it into a specific amino acid sequence.
- Transfer RNA (tRNA) molecules bring the corresponding amino acids to the ribosome.
- The ribosome assembles the amino acids in the correct order to form a polypeptide chain.
- This chain then folds into its functional protein structure.
- Ribosomes can be free in the cytoplasm or bound to the ER, depending on the destination of the protein.
- Once the protein is synthesized, it may undergo further modifications in the ER or other cellular compartments before being transported to its final location.
- In summary, protein synthesis occurs on ribosomes, which read the mRNA sequence and assemble the amino acids into a polypeptide chain.

Loss of Water Through Cell Membrane:
There are several factors that can contribute to the loss of water through the cell membrane. In this case, the correct answer is option D: Exosmosis.
Exosmosis refers to the process by which water molecules move out of a cell through its membrane. This occurs when the concentration of solute particles outside the cell is higher than inside the cell, creating a concentration gradient that drives the movement of water out of the cell.
Factors contributing to the loss of water through the cell membrane:
- Degeneration of cell walls: When the cell walls degenerate or become damaged, they may lose their ability to retain water, leading to water loss through the cell membrane.
- Partial solubilisation of pectic compounds: Pectic compounds are a type of polysaccharide found in plant cell walls. When these compounds are partially solubilized, the integrity of the cell wall may be compromised, resulting in increased permeability to water and subsequent water loss.
- Metabolism of tannins: Tannins are a class of compounds found in plants that can have a variety of effects on cells. If tannins are metabolized within the cell, they may alter the permeability of the cell membrane, leading to water loss.
- Exosmosis: Exosmosis, as mentioned earlier, occurs when water molecules move out of a cell due to a higher concentration of solute particles outside the cell. This process can result in the loss of water through the cell membrane.
In summary, the loss of water through the cell membrane can be caused by various factors, including the degeneration of cell walls, partial solubilization of pectic compounds, metabolism of tannins, and exosmosis. However, in this specific scenario, the correct answer is exosmosis (option D).

Phagocytosis
Phagocytosis is the process of taking in food material by infolding of a membrane. It is a vital process for the survival of many organisms, including single-celled organisms like amoebas and multicellular organisms like humans. Here's a detailed explanation of phagocytosis:
1. Definition:
Phagocytosis is a type of endocytosis, which is the process by which cells engulf external material by forming a pocket or vesicle around it.
2. Steps involved in phagocytosis:
- Recognition: The cell recognizes and attaches to the food material or particle that needs to be engulfed.
- Engulfment: The cell membrane extends and surrounds the particle, forming a phagosome.
- Fusion: The phagosome fuses with lysosomes, which are organelles containing digestive enzymes.
- Digestion: The lysosomal enzymes break down the ingested material into smaller molecules.
- Absorption: The digested molecules are absorbed into the cell for energy or other metabolic processes.
3. Importance of phagocytosis:
- Nutrition: Phagocytosis allows organisms to obtain nutrients from external sources.
- Defense: Phagocytosis plays a crucial role in the immune response, as immune cells engulf and destroy pathogens or foreign particles.
- Waste elimination: Phagocytosis helps in the removal of cellular debris and dead cells from the body.
In conclusion, phagocytosis is the process by which cells engulf and digest external material for nutrition, defense, and waste elimination.