Cell Biology MCQ Test - 1, State PMT - NEET MCQ

Main Function of Lysosome:
Lysosomes are membrane-bound organelles found in animal cells that contain digestive enzymes. They play a crucial role in intracellular digestion and the recycling of cellular components.
Key Functions of Lysosomes:
1. Intracellular Digestion: Lysosomes are responsible for the breakdown of various biomolecules, including proteins, carbohydrates, lipids, and nucleic acids. They contain hydrolytic enzymes, such as proteases, lipases, carbohydrases, and nucleases, which break down these molecules into smaller components that can be utilized by the cell.
2. Extracellular Digestion: In some cases, lysosomes fuse with phagosomes or endosomes to carry out extracellular digestion. This occurs mainly in specialized cells, such as macrophages, which engulf and digest foreign particles, pathogens, or cellular debris through a process called phagocytosis.
3. Cellular Waste Recycling: Lysosomes also play a vital role in autophagy, a process by which damaged or obsolete cellular components are engulfed by lysosomes and degraded. This recycling process helps maintain cellular homeostasis by removing unwanted or malfunctioning organelles and recycling their components for reuse.
4. Programmed Cell Death: Lysosomes are involved in a type of programmed cell death called apoptosis. During apoptosis, lysosomes release their hydrolytic enzymes into the cytoplasm, leading to the breakdown of cellular components and eventual cell death.
5. Defense against Pathogens: Lysosomes participate in the immune response by aiding in the degradation of engulfed pathogens, such as bacteria or viruses, within phagosomes.
In conclusion, the main function of lysosomes is intracellular digestion, extracellular digestion in specialized cells, cellular waste recycling, programmed cell death, and defense against pathogens.

Explanation:
The correct answer is Lecithin.
Here is a detailed explanation:
Cell wall:
- The cell wall is a rigid structure found in plant cells that provides support and protection.
- It is mainly composed of cellulose and does not maintain continuity between the water and lipid phases inside and outside the cells.
Lecithin:
- Lecithin is a phospholipid that is present in cell membranes.
- It has a hydrophilic (water-loving) head and hydrophobic (water-repellent) tail.
- This structure allows lecithin to form a lipid bilayer that separates the water-based cytoplasm inside the cell from the extracellular fluid outside the cell.
- The lipid bilayer acts as a barrier that maintains the continuity between the water and lipid phases.
Cell vacuole:
- The cell vacuole is a membrane-bound organelle found in plant and fungal cells.
- It is primarily involved in storage and maintaining turgor pressure in plant cells.
- While it plays a role in maintaining cell structure and function, it does not directly maintain continuity between the water and lipid phases inside and outside the cells.
Cell membrane of woody plants:
- The cell membrane of woody plants, also known as the plasma membrane, is composed of lipids and proteins.
- It separates the cell's cytoplasm from the external environment and controls the movement of substances in and out of the cell.
- However, it does not specifically maintain continuity between the water and lipid phases.
In summary, lecithin is the component that maintains continuity between the water and lipid phases inside and outside the cells.

Membrane surrounding cell vacuole:
The membrane surrounding the cell vacuole is called the tonoplast. It is a specialized membrane that separates the vacuolar contents from the cytoplasm of the cell. The tonoplast is essential for maintaining the integrity and function of the vacuole.
Function of the tonoplast:
1. Regulation of osmotic balance: The tonoplast controls the movement of water and solutes into and out of the vacuole, maintaining osmotic balance within the cell.
2. Storage of nutrients and waste products: The tonoplast plays a crucial role in storing various substances, such as ions, sugars, pigments, and waste products, within the vacuole.
3. Protection and support: The tonoplast provides structural support to the vacuole, helping to maintain its shape and integrity. It also acts as a barrier, preventing the diffusion of harmful substances into the cytoplasm.
4. Recycling and degradation: The tonoplast is involved in the process of autophagy, a cellular process that recycles and degrades damaged or unnecessary components within the vacuole.
Comparison with other cell membranes:
- The cell wall is a rigid structure found in plant cells that surrounds the plasma membrane. It provides support and protection to the cell, but it is not directly involved in the membrane surrounding the vacuole.
- The plasma membrane, also known as the cell membrane, is the outermost membrane of the cell. It regulates the movement of substances in and out of the cell and maintains its internal environment. It is distinct from the tonoplast, which is specific to the vacuole.
Conclusion:
The membrane surrounding the cell vacuole is known as the tonoplast. It plays a vital role in maintaining osmotic balance, storing nutrients and waste products, providing support and protection, and facilitating recycling and degradation processes within the vacuole. It is distinct from the cell wall and plasma membrane, which have different functions in the cell.

Answer:
The diagrammatic representation of chromosomes is known as idiogram.
Explanation:
The idiogram is a visual representation of the chromosomes in a cell. It displays the size, shape, and banding pattern of each chromosome. It is an essential tool in cytogenetics, which is the study of chromosomes and their abnormalities.
The idiogram is created by staining the chromosomes with a dye and then arranging them in a specific order based on their size and banding pattern. The resulting diagram allows scientists to study the structure and organization of the chromosomes and identify any abnormalities or genetic disorders.
The idiogram is helpful in various fields, including genetics, medicine, and evolutionary biology. It is used in genetic counseling to identify chromosomal abnormalities in individuals and determine the risk of passing on genetic disorders to offspring. It is also used in research to study the evolution of chromosomes and their role in disease.
In summary, the idiogram is the diagrammatic representation of chromosomes, and it is an important tool in the study of genetics and cytogenetics.

The spherical structured organelle that contains the genetic material is the nucleus.
Explanation:
- The nucleus is a membrane-bound organelle found in eukaryotic cells.
- It is typically spherical in shape and acts as the control center of the cell.
- The nucleus contains the genetic material of the cell, which is organized into structures called chromosomes.
- Chromosomes are made up of DNA molecules that carry the instructions for the cell's activities and hereditary traits.
- The genetic material in the nucleus determines the characteristics and functions of the cell.
- The nucleus also contains a dense region called the nucleolus, which is involved in the production of ribosomes.
- The nuclear envelope, a double membrane, surrounds the nucleus and regulates the passage of molecules in and out of the nucleus through nuclear pores.
- The nucleus plays a crucial role in cell division, gene expression, and the overall regulation of cellular activities.
In summary, the nucleus is a spherical organelle that contains the genetic material (DNA) of the cell and is involved in controlling the cell's activities and hereditary traits.

Chromosomes present in prolonged prophase in the salivary glands of Drosophila are:
- Polytene chromosomes: These are large and highly condensed chromosomes found in the salivary glands of Drosophila. They are formed by repeated rounds of DNA replication without cell division, resulting in the formation of multiple copies of the chromosome aligned side by side. Polytene chromosomes are visible as bands and interbands under a light microscope and are involved in gene amplification and regulation of gene expression.
- B-chromosomes: B-chromosomes, also known as accessory chromosomes or supernumerary chromosomes, are additional chromosomes that may be present in some individuals of a species. These chromosomes are not essential for the survival of the organism and can vary in number and structure. They are often smaller and have a different pattern of banding compared to the main set of chromosomes.
- Lampbrush chromosomes: Lampbrush chromosomes are found in the oocytes of many animals and are characterized by their extended, brush-like appearance. They are formed during meiotic prophase I and are involved in the transcription and processing of RNA. Lampbrush chromosomes are not present in the salivary glands of Drosophila.
- Supernumerary chromosomes: Supernumerary chromosomes, also known as B-chromosomes, are additional chromosomes that may be present in some individuals of a species. These chromosomes are not essential for the survival of the organism and can vary in number and structure. They are often smaller and have a different pattern of banding compared to the main set of chromosomes.
In the salivary glands of Drosophila, the chromosomes present in prolonged prophase are the polytene chromosomes. These chromosomes play a crucial role in gene amplification and gene expression regulation. They are visible as bands and interbands under a light microscope and are formed by repeated rounds of DNA replication without cell division.

Explanation:
The shape of chromosomes at anaphase is determined by the position of the centromere. The centromere is the region of the chromosome where the two sister chromatids are held together before they separate during cell division.
Here is a detailed explanation of each option:
A: Satellite
- Satellites are small, circular pieces of DNA that are found near the centromere of chromosomes.
- While satellites can affect the overall structure of the chromosome, they do not directly determine the shape of chromosomes at anaphase.
B: Chromonema
- Chromonema refers to the elongated, thread-like structure of chromatin during interphase.
- At anaphase, the chromatin condenses further into tightly coiled structures called chromosomes, and the shape of these chromosomes is determined by the position of the centromere.
C: Centromere
- The centromere is the region of the chromosome where the two sister chromatids are held together.
- During anaphase, the centromere splits, allowing the sister chromatids to separate and move towards opposite poles of the cell.
- The position of the centromere determines the shape of the chromosomes at anaphase.
D: DNA
- DNA is the genetic material that makes up chromosomes.
- While the DNA sequence can vary between chromosomes, it does not directly determine the shape of chromosomes at anaphase.
Therefore, the correct answer is C: Centromere. The position of the centromere determines the shape of chromosomes at anaphase.

The term "nucleosome" was given by Oudet Olins and Olins to describe a specific structure found in eukaryotic chromosomes. The nucleosome is made up of DNA wrapped around a core of histone proteins, which helps in the organization and compaction of DNA.
The specific histone that is absent in the nucleosome is H3a. This histone variant, known as H3a, is not present in the nucleosome structure.
To summarize:
- The term "nucleosome" was coined by Oudet Olins and Olins.
- Nucleosomes are structures found in eukaryotic chromosomes.
- Nucleosomes consist of DNA wrapped around a core of histone proteins.
- The histone variant that is absent in the nucleosome is H3a.
Therefore, option C, H3a, is the correct answer.

Explanation:
The nucleosome is the basic structural unit of chromatin, the material that makes up chromosomes. It consists of DNA wrapped around a core of histone proteins. The given statement mentions that a nucleosome has the following components:
A: About 2 turns of DNA
- DNA is wrapped around the histone core in a nucleosome.
- The DNA makes approximately two turns around the histone octamer, forming a compact structure.
B: 8 histone molecules of 4 types (2 molecules each of H₂a, H2b, H₃, and H₄)
- The histone core of a nucleosome consists of eight histone molecules.
- There are four types of histone proteins: H₂a, H2b, H₃, and H₄.
- Each type of histone protein has two molecules, resulting in a total of eight histone molecules.
C: 200 nitrogen base pairs
- A nucleosome consists of approximately 147 base pairs of DNA.
- These base pairs are wrapped around the histone core to form a nucleosome structure.
Therefore, the correct answer is D: all of the above, as all the given options are true regarding the components of a nucleosome.

Salivary/polytcne chromosomes were reported by Balbiani [1881) from cells of salivary glands of midges Chironomous larva (larva of Diptera group).

SAT chromosome and its components:
The SAT (Satellite) chromosome is a specific region of a chromosome located beyond the secondary constriction. It is known for containing specific components. Let's explore these components in detail:
1. Repetitive DNA:
- The SAT chromosome is primarily composed of repetitive DNA sequences.
- Repetitive DNA sequences are segments of DNA that are repeated multiple times within the genome.
- These repetitive sequences can vary in length and may be present in different copy numbers.
2. DNA:
- DNA is a fundamental component of the SAT chromosome.
- DNA, or deoxyribonucleic acid, is the genetic material that carries the hereditary information in all living organisms.
- It consists of a double helix structure made up of nucleotides, which contain the genetic code.
3. RNA:
- RNA, or ribonucleic acid, is another component found in the SAT chromosome.
- RNA is involved in various cellular processes, including gene expression and protein synthesis.
- It is synthesized from DNA through a process called transcription.
4. None of these:
- The option "None of these" indicates that the components mentioned above (repetitive DNA, DNA, and RNA) are present in the SAT chromosome.
- Therefore, this option is not the correct answer.
In conclusion, the SAT chromosome contains repetitive DNA, DNA, and RNA as its components. Therefore, the correct answer to the question is option C.

Material exchange through nucleopores is facilitated by:

Lamina propria:

- Lamina propria is a layer of connective tissue that lines the inner surface of the nuclear envelope.
- It provides structural support to the nucleus and helps maintain its shape.
- However, it does not directly facilitate material exchange through nucleopores.

Lipid layer:

- The nuclear envelope is composed of a double lipid bilayer.
- This lipid layer acts as a barrier that separates the nucleus from the cytoplasm.
- Nucleopores, which are protein channels, are embedded in the lipid layer and allow for material exchange between the nucleus and cytoplasm.
- Thus, the lipid layer indirectly facilitates material exchange through nucleopores by providing the structure in which the nucleopores are embedded.

Nucleoplasmin:

- Nucleoplasmin is a protein that is involved in the assembly and disassembly of nucleosomes.
- It plays a role in the regulation of gene expression and chromatin structure.
- While nucleoplasmin is important for nuclear processes, it does not directly facilitate material exchange through nucleopores.

Nucleoli:

- Nucleoli are structures found within the nucleus that are involved in the production of ribosomes.
- They contain DNA, RNA, and proteins necessary for ribosome synthesis.
- However, nucleoli do not directly facilitate material exchange through nucleopores.

Therefore, the correct answer is c. Nucleoplasmin. Nucleoplasmin is not directly involved in material exchange through nucleopores, but it is involved in other nuclear processes.

Centriole is:
A: Microtubular and membraneless
- Centrioles are composed of microtubules, which are protein structures that form the cytoskeleton of the cell.
- They do not have a membrane surrounding them.
B: Absent in Amoeba, red algae, blue-green algae, conifers, and angiosperms and made up of a peripheral Triblet microtubules
- Centrioles are not present in certain organisms such as Amoeba, red algae, blue-green algae, conifers, and angiosperms.
- In organisms where centrioles are present, they are composed of a peripheral triplet of microtubules.
C: Basically locomotory and their role in spindle formation is secondary
- Centrioles are primarily involved in cell movement and organization.
- Their role in spindle formation during cell division is secondary.
D: All of the above
- All of the statements A, B, and C are correct.
Therefore, the correct answer is D. All of the above. Centrioles are microtubular and membraneless structures, absent in certain organisms, made up of a peripheral triplet of microtubules, involved in cell movement, and have a secondary role in spindle formation during cell division.

Association of a mRNA with several ribosomes is called Polysome.
Explanation:
A polysome, also known as a polyribosome, is a complex of multiple ribosomes bound to a single mRNA molecule. It is formed when multiple ribosomes simultaneously translate a single mRNA molecule. Here is a detailed explanation of the process:
- Translation: Translation is the process by which the genetic code carried by mRNA is decoded and converted into a sequence of amino acids to form a protein. This process occurs on ribosomes, which are protein-RNA complexes.
- Ribosomes: Ribosomes are composed of two subunits, a small subunit, and a large subunit. The small subunit is responsible for binding to the mRNA, while the large subunit catalyzes the formation of peptide bonds between amino acids.
- Polysome Formation: During translation, multiple ribosomes can simultaneously bind to a single mRNA molecule, forming a polysome. This occurs when the mRNA has a sequence of codons that can be simultaneously recognized by multiple ribosomes.
- Simultaneous Translation: In a polysome, each ribosome translates a different region of the mRNA molecule. The ribosomes move along the mRNA in a 5' to 3' direction, synthesizing multiple copies of the protein simultaneously.
- Advantages of Polysomes: Polysomes allow for efficient and rapid protein synthesis. They can increase the rate of protein production and ensure the coordinated synthesis of multiple copies of a protein.
In summary, the association of a mRNA with several ribosomes is called a polysome. This arrangement allows for simultaneous translation of multiple copies of a protein, increasing efficiency and protein production.

Cell was discovered by:

• Robert Hooke: Robert Hooke was the scientist who discovered the cell.

Explanation:

• Antonie van Leeuwenhoek: Antonie van Leeuwenhoek was a Dutch scientist who is credited with the discovery of microorganisms, but not the cell itself.


• Robert Swanson: Robert Swanson was a venture capitalist and co-founder of Genentech, a biotechnology company. He did not discover the cell.


• Robert Brown: Robert Brown was a Scottish botanist who discovered the cell nucleus, but not the cell itself.

Therefore, the correct answer is B: Robert Hooke.

Lampbrush chromosome is found in:
Answer: A. Oocyte of amphibians
Explanation:
Lampbrush chromosomes are large and highly extended chromosomes that are found in the nucleus of oocytes (immature eggs) of amphibians, particularly in the germinal vesicle stage. These chromosomes are named "lampbrush" due to their brush-like appearance, with numerous lateral loops extending from a central axis.
Here are some key points about lampbrush chromosomes:
1. Structure: Lampbrush chromosomes have a unique structure, with a central axis and lateral loops that extend outwards. These loops contain active transcription sites where RNA synthesis occurs.
2. Role in gene expression: Lampbrush chromosomes are actively involved in gene expression. The loops contain genes that are being transcribed, allowing for the production of mRNA. This mRNA is then used to synthesize proteins required for oocyte development.
3. Study of chromosome structure and gene expression: Lampbrush chromosomes have been extensively studied to understand the structure and function of chromosomes, as well as the regulation of gene expression during oocyte development.
4. Presence in other organisms: While lampbrush chromosomes are most commonly found in amphibian oocytes, similar structures have also been observed in the oocytes of other organisms, including birds and some invertebrates.
In conclusion, lampbrush chromosomes are specialized chromosomes that are found in the oocytes of amphibians, playing a crucial role in gene expression and oocyte development.

Prokaryotic Ribosomes - Structure and Composition
- Ribosomes are essential cellular components responsible for protein synthesis. They are found in both prokaryotic and eukaryotic cells, but there are some differences in their structure and composition.
Prokaryotic Ribosomes
- Prokaryotic cells, such as bacteria, have ribosomes that are smaller and structurally different from those found in eukaryotic cells.
- Prokaryotic ribosomes are composed of two subunits, the 30S subunit and the 50S subunit, which combine to form a functional ribosome of 70S.
- The 30S subunit is made up of one ribosomal RNA (rRNA) molecule (16S rRNA) and around 21 different proteins. It has a sedimentation coefficient of 30S.
- The 50S subunit is composed of two rRNA molecules (23S rRNA and 5S rRNA) and approximately 34 different proteins. It has a sedimentation coefficient of 50S.
- When the 30S and 50S subunits come together, they form a 70S ribosome, which is responsible for protein synthesis in prokaryotic cells.
- The S unit (Svedberg unit) is a measure of the sedimentation rate of a particle in a centrifuge. It is related to the size and shape of the particle, with larger and more complex particles having higher S values.
- Therefore, the correct answer is option C: 70S, as prokaryotic ribosomes have a sedimentation coefficient of 70S.
Conclusion
- Prokaryotic ribosomes are composed of a 30S subunit and a 50S subunit, which combine to form a 70S ribosome.
- The 30S subunit has a sedimentation coefficient of 30S and consists of one rRNA molecule and several proteins.
- The 50S subunit has a sedimentation coefficient of 50S and is made up of two rRNA molecules and numerous proteins.
- Understanding the structure and composition of prokaryotic ribosomes is crucial for studying protein synthesis in these organisms.

Mesosomes of prokaryotes perform functions similar to mitochondria.

The mesosomes in prokaryotes are invaginations of the plasma membrane that perform various functions similar to mitochondria in eukaryotes. Here are the key points explaining the similarity:

- Energy production: Both mesosomes and mitochondria are involved in energy production.
- Respiration: Mesosomes provide a large surface area for respiration, just like mitochondria.
- ATP synthesis: Mesosomes, like mitochondria, are involved in ATP synthesis through oxidative phosphorylation.
- Electron transport chain: Both mesosomes and mitochondria have an electron transport chain that generates ATP.
- Protein synthesis: Mesosomes, similar to mitochondria, contain ribosomes that are involved in protein synthesis.
- Cellular metabolism: Mesosomes, like mitochondria, play a role in the metabolism of macromolecules such as lipids and carbohydrates.
Therefore, the correct answer is option A: Mesosomes of prokaryotes perform functions similar to mitochondria in eukaryotes.

Explanation:
The rough endoplasmic reticulum (RER) is responsible for protein synthesis in the cells. It is characterized by the presence of ribosomes on its surface. The ribosomes are responsible for translating mRNA into proteins. The RER plays a crucial role in the synthesis, folding, and modification of proteins before they are transported to their final destinations within the cell or secreted outside the cell.
Key Points:
- The rough endoplasmic reticulum (RER) is responsible for protein synthesis in the cells.
- The RER is characterized by the presence of ribosomes on its surface.
- Ribosomes are responsible for translating mRNA into proteins.
- The RER plays a crucial role in the synthesis, folding, and modification of proteins.
- Proteins synthesized in the RER are transported to their final destinations within the cell or secreted outside the cell.
Therefore, the rough endoplasmic reticulum (RER) in the cells is present because of the ribosomes on its surface.

Explanation:
Definition of Crossing Over: Crossing over is the exchange of genetic material between homologous chromosomes during meiosis. It occurs during the prophase I stage of meiosis.
The process of Crossing Over:
During crossing over, segments of DNA from one homologous chromosome are exchanged with the corresponding segments of DNA from the other homologous chromosome. This results in the recombination of genetic material, leading to genetic variation.
Participating Structures in Crossing Over:
Crossing over takes place between sister chromatids of homologous chromosomes.
Options:
A: 2 sister chromatids - Incorrect. Crossing over occurs between non-sister chromatids of homologous chromosomes, not between sister chromatids.
B: 2 non-sister chromatids - Correct. Crossing over occurs between non-sister chromatids of homologous chromosomes. This exchange of genetic material between non-sister chromatids results in genetic recombination.
C: 3 homologous chromosomes - Incorrect. Crossing over occurs between non-sister chromatids of homologous chromosomes, not between homologous chromosomes themselves.
D: 4 non-homologous chromosomes - Incorrect. Crossing over occurs between non-sister chromatids of homologous chromosomes, not between non-homologous chromosomes.
Therefore, the correct answer is B: 2 non-sister chromatids.

Cellular recognition is facilitated by components of plasma membrane. These components are generally:
- Protein molecules alone: This option is incorrect because protein molecules alone cannot facilitate cellular recognition. While proteins play a crucial role in cellular recognition, they are not the only components involved.
- Lipid molecules alone: This option is incorrect because lipid molecules alone cannot facilitate cellular recognition. Lipids are an essential component of the plasma membrane, but they do not have the ability to recognize and interact with other cells or molecules.
- Both lipid and protein molecules: This option is correct. Cellular recognition is facilitated by a combination of lipid and protein molecules in the plasma membrane. Lipids provide the structural framework for the membrane, while proteins serve as receptors and transporters that recognize and interact with other cells or molecules.
- Glycolipids and glycoproteins: This option is incorrect because cellular recognition is not solely facilitated by glycolipids and glycoproteins. While these molecules are involved in cell-cell recognition and communication, they are not the only components responsible for cellular recognition.
In conclusion, the correct answer is option C: Both lipid and protein molecules. The combination of lipid and protein molecules in the plasma membrane enables cellular recognition and interactions with other cells or molecules.

Significance of Meiosis:
Meiosis is a specialized form of cell division that occurs in sexually reproducing organisms. It involves the production of gametes, or sex cells, which have half the number of chromosomes as the parent cells. The significance of meiosis lies in:
Maintaining constancy in the number of chromosomes in an organism:
- Meiosis ensures that the number of chromosomes in a species remains constant from generation to generation.
- It prevents the doubling of chromosomes with each generation, which would lead to an unmanageable number of chromosomes.
Production of genetic variability in the population of species:
- Meiosis introduces genetic variability through the process of recombination, or crossing over, which occurs during prophase I.
- During recombination, maternal and paternal chromosomes exchange genetic material, creating new combinations of alleles on the chromosomes.
- This genetic variability is essential for the survival and adaptation of a species to changing environments.
- It allows for the generation of individuals with different traits, increasing the chances of a population to evolve and adapt.
Reduction of the diploid number of chromosomes to haploid:
- Meiosis reduces the number of chromosomes in a cell by half, from diploid (2n) to haploid (n).
- This is crucial for sexual reproduction because when gametes fuse during fertilization, the resulting zygote will have the correct number of chromosomes for the species.
- The diploid number is restored when the zygote undergoes mitosis to form a new organism.
All of the above:
- Meiosis encompasses all of the mentioned significances.
- It maintains chromosome number, produces genetic variability, and reduces the diploid number of chromosomes to haploid.
- These processes are fundamental for the continuation of a species and the generation of diversity among individuals.
In conclusion, the significance of meiosis lies in maintaining the constancy of chromosome number, producing genetic variability, and reducing the diploid number of chromosomes to haploid. These processes are vital for the survival, adaptation, and evolution of sexually reproducing organisms.

Answer:
The following can be seen only under the electron microscope:
- Ribosome: Ribosomes are small organelles responsible for protein synthesis. They are too small to be seen with a light microscope and can only be observed under an electron microscope.
The other options mentioned in the question can be seen under a light microscope:
- Chloroplast: Chloroplasts are organelles found in plant cells that are responsible for photosynthesis. They contain the pigment chlorophyll and can be observed under a light microscope.
- Leucoplast: Leucoplasts are organelles found in plant cells that are responsible for storing nutrients. They can be observed under a light microscope.
- Nucleus: The nucleus is a membrane-bound organelle that contains the genetic material of a cell. It can be observed under a light microscope.
In conclusion, only the ribosome can be seen only under an electron microscope, while the other options can be observed under a light microscope.

Because a mature plant cell is fully developed cell parts and organelles too

The large subunit in 80s ribosome is:
The large subunit in 80s ribosome is the 60s subunit.
Explanation:
- Ribosomes are composed of two subunits, the large subunit and the small subunit.
- In eukaryotic cells, the ribosomes are larger and are called 80s ribosomes.
- The large subunit of the 80s ribosome is further divided into two subunits, the 60s subunit and the 40s subunit.
- The 60s subunit is responsible for the catalytic activity of the ribosome and contains the peptidyl transferase center, which is responsible for the formation of peptide bonds during protein synthesis.
- The 40s subunit, on the other hand, is responsible for the decoding of mRNA and contains the decoding center.
- Together, the 60s and 40s subunits of the large subunit in the 80s ribosome work together to carry out protein synthesis.
Therefore, the correct answer is B: 60s.

Golgi bodies are absent in Bacteria.
The Golgi apparatus, also known as Golgi bodies or Golgi complex, is a membrane-bound organelle found in eukaryotic cells. It is involved in the modification, sorting, and packaging of proteins and lipids for transport to their final destinations.
Reasons for the absence of Golgi bodies in bacteria:
1. Prokaryotic structure: Bacteria are prokaryotic organisms, which means they lack membrane-bound organelles found in eukaryotic cells, including Golgi bodies.
2. Simplified protein processing: Bacteria have a simplified protein processing system compared to eukaryotic cells. They do not require the extensive modification and packaging of proteins carried out by the Golgi apparatus.
3. Surface proteins: Bacteria often have proteins located on their cell surface that play essential roles in their interactions with the environment. These proteins are synthesized and transported directly to the cell surface without the need for Golgi-mediated processing.
4. Enzymatic functions: Bacteria have specialized enzymes and pathways for processing proteins and lipids that are different from those found in eukaryotic cells. These alternative mechanisms eliminate the need for Golgi bodies in bacteria.
In conclusion, Golgi bodies are absent in bacteria due to their prokaryotic nature, simplified protein processing, direct transport of surface proteins, and the presence of alternative enzymatic functions.

Endoplasmic reticulum is more developed in young cells.
The endoplasmic reticulum (ER) is a membrane-bound organelle found in eukaryotic cells. It plays a crucial role in the synthesis, folding, and transport of proteins, as well as lipid metabolism. The ER can be classified into two types: rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).
Key Points:
- The RER is studded with ribosomes, giving it a rough appearance, and is involved in protein synthesis and modification. It plays a vital role in the production of secretory and membrane proteins.
- The SER lacks ribosomes and is involved in lipid synthesis, detoxification of drugs and poisons, and calcium storage.
- Young cells are more metabolically active and have a higher demand for protein synthesis and modification. Therefore, they require more developed RER to fulfill this demand.
- As cells mature and become specialized, their protein synthesis needs may decrease, resulting in a reduced development of the RER.
- Green cells and bacteriophages (viruses that infect bacteria) do not have a well-developed endoplasmic reticulum as they are prokaryotic cells and lack many of the organelles found in eukaryotic cells.
- Therefore, the correct answer is option B: Young cells.
In conclusion, the endoplasmic reticulum is more developed in young cells due to their higher demand for protein synthesis and modification.

Mitochondria are related to eukaryotic cells. Here is a detailed explanation:
Eukaryotic Cell:
- Mitochondria are membrane-bound organelles found in eukaryotic cells.
- Eukaryotic cells are characterized by having a nucleus and other membrane-bound organelles.
- Mitochondria are one of the organelles present in eukaryotic cells, along with the nucleus, endoplasmic reticulum, Golgi apparatus, etc.
Key Points:
- Mitochondria are known as the powerhouse of the cell because they generate most of the cell's energy in the form of ATP (adenosine triphosphate) through cellular respiration.
- They have their own DNA, known as mitochondrial DNA, which is separate from the nuclear DNA present in the cell's nucleus.
- Mitochondria are involved in various cellular processes, including metabolism, apoptosis (programmed cell death), and calcium signaling.
- They play a crucial role in providing energy for cellular activities, such as muscle contraction, cell division, and maintaining membrane potential.
- Mitochondrial dysfunction is associated with various diseases, including mitochondrial disorders, neurodegenerative diseases, and metabolic disorders.
In conclusion, mitochondria are related to eukaryotic cells and play a vital role in energy production and various cellular processes.

The main function of lysosomes is:
- Digestion: Lysosomes are responsible for digesting various materials within the cell. They contain enzymes that break down macromolecules, such as proteins, carbohydrates, and lipids, into smaller molecules that can be used by the cell for energy or other purposes.
- Cellular Waste Disposal: Lysosomes also play a crucial role in removing and recycling cellular waste. They can engulf and break down damaged organelles, cellular debris, and foreign substances that enter the cell.
- Autophagy: Lysosomes are involved in a process called autophagy, which is the degradation and recycling of unnecessary or dysfunctional cellular components. This helps maintain cellular homeostasis and prevents the accumulation of damaged molecules or organelles.
- Cellular Defense: Lysosomes contribute to the cell's defense mechanisms by destroying invading microorganisms, such as bacteria or viruses, through a process known as phagocytosis. They fuse with the engulfed particles, forming a phagosome, and then release enzymes to break down and neutralize the pathogens.
- Programmed Cell Death: Lysosomes also play a role in programmed cell death, or apoptosis. They release enzymes that degrade the cell's components, leading to its controlled destruction and removal.
In summary, the main function of lysosomes is digestion, cellular waste disposal, autophagy, cellular defense, and programmed cell death. They are essential for maintaining the overall health and functionality of the cell.

Features of a prokaryotic cell:
- Enzymes: Enzymes are present in prokaryotic cells and are involved in various metabolic processes.
- Ribosomes: Prokaryotic cells contain ribosomes which are responsible for protein synthesis.
- DNA: Prokaryotic cells have DNA, which is a genetic material that carries the information necessary for cell functioning and replication.
- A plasma membrane: Prokaryotic cells have a plasma membrane that acts as a barrier between the cell and its environment, regulating the movement of substances in and out of the cell.
What is NOT a feature of a prokaryotic cell?
- A nuclear membrane: Prokaryotic cells do not have a distinct nuclear membrane. Instead, their DNA is present in the cytoplasm in a region called the nucleoid.
Therefore, the correct answer is B: A nuclear membrane.