Cell

81. Which organelle in animal cells can digest foreign materials ?

Which organelle in animal cells can digest foreign materials ?

[amp_mcq option1=”Endoplasmic reticulum” option2=”Lysosome” option3=”Golgi body” option4=”Mitochondria” correct=”option2″]

This question was previously asked in
UPSC CDS-2 – 2024
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Lysosomes are membrane-bound organelles found in animal cells containing hydrolytic enzymes. These enzymes are capable of breaking down various biological molecules, including waste materials, cellular debris, and foreign particles (like bacteria or viruses) that are taken into the cell through processes like phagocytosis. This digestive function helps in cellular waste removal, recycling, and defense against pathogens.
– Lysosomes contain powerful digestive enzymes.
– They are involved in phagocytosis (digestion of foreign particles) and autophagy (digestion of cellular components).
The Endoplasmic Reticulum is involved in protein and lipid synthesis. Golgi apparatus modifies, sorts, and packages proteins and lipids. Mitochondria are responsible for cellular respiration and energy production. None of these organelles primarily function in digesting foreign materials within the cell.

82. Cell wall is absent in which one of the following organisms ?

Cell wall is absent in which one of the following organisms ?

[amp_mcq option1=”Bacteria” option2=”Diatom” option3=”Mushroom” option4=”Tapeworm” correct=”option4″]

This question was previously asked in
UPSC CDS-2 – 2023
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A cell wall is a rigid layer found outside the plasma membrane of cells in plants, fungi, bacteria, algae, and some archaea. It provides structural support, protection, and helps maintain cell shape. Animal cells, however, do not have cell walls; they are surrounded only by a flexible cell membrane.
Let’s check the presence of cell walls in the given organisms:
A) Bacteria have cell walls typically made of peptidoglycan.
B) Diatoms are a type of algae belonging to Protista; they have unique cell walls made of silica, called frustules.
C) Mushrooms are fungi; fungal cells have cell walls made primarily of chitin.
D) Tapeworms are multicellular animals (Platyhelminthes). Animal cells characteristically lack cell walls.
The absence of a cell wall in animal cells allows for greater flexibility and motility compared to cells with rigid cell walls. It also facilitates processes like phagocytosis and tissue formation.

83. Which one of the following is the correct combination of organelles an

Which one of the following is the correct combination of organelles and their functions ?

[amp_mcq option1=”Mitochondria – Respiration; Chloroplast – Photosynthesis; Ribosome – Protein Synthesis; Rough endoplasmic reticulum – Transport of proteins” option2=”Mitochondria – Respiration; Chloroplast – Photosynthesis; Ribosome – Transport of proteins; Rough endoplasmic reticulum – Protein synthesis” option3=”Mitochondria – Respiration; Chloroplast – Protein synthesis; Ribosome – Photosynthesis; Rough endoplasmic reticulum – Transport of proteins” option4=”Mitochondria – Photosynthesis; Chloroplast – Respiration; Ribosome – Protein synthesis; Rough endoplasmic reticulum – Transport of proteins” correct=”option1″]

This question was previously asked in
UPSC CDS-2 – 2023
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Organelles are specialized structures within a cell that perform specific functions. Let’s examine the functions listed for each organelle:
Mitochondria are often called the “powerhouses” of the cell because they are the primary sites of cellular respiration, the process that generates ATP (energy) by breaking down glucose and other fuel molecules.
Chloroplasts (found in plant cells and algae) are the sites of photosynthesis, where light energy is converted into chemical energy in the form of glucose.
Ribosomes are responsible for protein synthesis, translating messenger RNA (mRNA) into polypeptide chains.
The endoplasmic reticulum (ER) is a network of membranes involved in protein and lipid synthesis. The Rough ER is studded with ribosomes and is particularly involved in synthesizing proteins that are destined for secretion, insertion into membranes, or transport to other organelles. It also plays a role in folding and transporting these proteins.
Based on these well-established functions, the combination in option A correctly matches each organelle with its primary role.

84. In the following simplified diagram of a plant cell, five parts/organe

In the following simplified diagram of a plant cell, five parts/organelles are marked from 1 to 5 :
[Image of a plant cell diagram with labels 1-5]
Which one of the following correctly represents the above parts/organelles ?

[amp_mcq option1=”1 – cell membrane; 2 – cell wall; 3 – vacuole; 4 – endoplasmic reticulum; 5 – nucleus” option2=”1 – cell wall; 2 – cell membrane; 3 – endoplasmic reticulum; 4 – nucleus; 5 – vacuole” option3=”1 – cell wall; 2 – cell membrane; 3 – endoplasmic reticulum; 4 – vacuole; 5 – nucleus” option4=”1 – cell wall; 2 – cell membrane; 3 – vacuole; 4 – endoplasmic reticulum; 5 – nucleus” correct=”option4″]

This question was previously asked in
UPSC CDS-2 – 2023
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The diagram shows a typical plant cell. The outermost layer (1) of a plant cell is the rigid cell wall. Just inside the cell wall is the cell membrane (2). Plant cells usually have a large central vacuole (3) that occupies a significant portion of the cell volume, pushing the cytoplasm and other organelles towards the periphery. Within the cytoplasm is a network of membranes known as the endoplasmic reticulum (4). The nucleus (5) is a prominent, usually somewhat spherical, organelle containing the genetic material, often located near the periphery due to the large central vacuole.
Identifying key features of plant cells, such as the presence of a cell wall outside the cell membrane and a large central vacuole, is crucial for interpreting such diagrams. The relative position and appearance of organelles like the nucleus and endoplasmic reticulum within the cytoplasm should also be considered.
Option D correctly labels the parts as identified: 1 – cell wall, 2 – cell membrane, 3 – vacuole, 4 – endoplasmic reticulum, and 5 – nucleus. This arrangement is consistent with the structure of a plant cell, particularly the position of the large central vacuole. Options A, B, and C mislabel one or more of the indicated parts or their positions relative to each other.

85. Bacteria have an undefined nuclear region which lacks a nuclear membra

Bacteria have an undefined nuclear region which lacks a nuclear membrane and contains only DNA without proteins. Such a region is called :

[amp_mcq option1=”Nucleosome” option2=”Nucleus” option3=”Nucleoprotein” option4=”Nucleoid” correct=”option4″]

This question was previously asked in
UPSC CDS-2 – 2023
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Bacteria are prokaryotic organisms, meaning their cells lack a membrane-bound nucleus and other membrane-bound organelles. The genetic material (DNA) in a bacterial cell is located in an irregularly shaped region within the cytoplasm. This region, where the bacterial chromosome (usually a single, circular DNA molecule) is concentrated, is called the nucleoid. Unlike eukaryotic chromosomes, bacterial DNA is not associated with histone proteins to the same extent.
The nucleoid contains the genomic DNA and associated proteins in a prokaryotic cell, but it is not enclosed by a nuclear membrane, distinguishing it from the true nucleus found in eukaryotic cells.
A nucleosome (option A) is the basic structural unit of DNA packaging in eukaryotes, consisting of DNA wrapped around histone proteins. A nucleus (option B) is the membrane-bound organelle containing genetic material in eukaryotes. Nucleoprotein (option C) is a general term for any complex of nucleic acid and protein, and while the nucleoid contains nucleoproteins, “nucleoid” is the specific term for the region itself.

86. Chromosomes are composed of DNA and :

Chromosomes are composed of DNA and :

[amp_mcq option1=”lipids” option2=”vitamins” option3=”proteins” option4=”carbohydrates” correct=”option3″]

This question was previously asked in
UPSC CDS-2 – 2023
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Chromosomes in eukaryotic cells are complex structures primarily composed of deoxyribonucleic acid (DNA) and proteins. The main proteins associated with DNA in chromosomes are a group of basic proteins called histones. DNA wraps around histones to form nucleosomes, which are further condensed into chromatin fibers that make up chromosomes.
The DNA carries the genetic information, while the proteins, especially histones, play a crucial role in packaging and organizing the DNA within the limited space of the nucleus. This DNA-protein complex is known as chromatin.
Lipids, vitamins, and carbohydrates are essential biomolecules found in cells, but they are not the primary structural components that make up chromosomes along with DNA. The fundamental composition of chromosomes is DNA and protein (primarily histones).

87. Which one of the following is a feature of Membrane ?

Which one of the following is a feature of Membrane ?

[amp_mcq option1=”Bilayer of phospholipid molecule in which proteins and cholesterol are embedded” option2=”Bilayer of proteins molecule in which lipid and cholesterol are embedded” option3=”Bilayer of neutral lipid in which proteins and cholesterol are embedded” option4=”Bilayer of neutral lipid lacking cholesterol and proteins” correct=”option1″]

This question was previously asked in
UPSC CDS-2 – 2022
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A key feature of a biological membrane (like the plasma membrane) is that it is a bilayer of phospholipid molecules in which proteins and cholesterol are embedded.
– The fluid mosaic model describes the structure of the cell membrane.
– It consists of a double layer (bilayer) of phospholipid molecules, with their hydrophilic heads facing outwards and inwards, and hydrophobic tails facing each other in the interior.
– Various proteins are embedded within, associated with, or spanning this lipid bilayer, performing functions like transport, signaling, and enzymatic activity.
– Cholesterol molecules are also interspersed within the phospholipid bilayer in animal cells, helping to regulate membrane fluidity.
– Option B is incorrect because the fundamental structure is a lipid bilayer, not a protein bilayer.
– Options C and D are incorrect because biological membranes are primarily composed of phospholipids (amphipathic lipids), not neutral lipids, and typically contain proteins and often cholesterol (in animal cells).

88. Which one of the following statements about starch and glycogen is cor

Which one of the following statements about starch and glycogen is correct ?

[amp_mcq option1=”Both starch and glycogen are found in plant cells.” option2=”Both starch and glycogen are found in animal cells.” option3=”Starch is present in plant cells and glycogen is present in animal cells.” option4=”Both starch and glycogen are present in plant cells as well as animal cells.” correct=”option3″]

This question was previously asked in
UPSC CDS-2 – 2022
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Starch and glycogen are polysaccharides that serve as energy storage molecules in living organisms. Their occurrence differs between plant and animal cells.
– Starch is the primary storage carbohydrate in plants. It is stored in plastids (like chloroplasts and amyloplasts) and is the main form of carbohydrate consumed by humans from plant sources (e.g., grains, potatoes).
– Glycogen is the primary storage carbohydrate in animals and fungi. In animals, it is primarily stored in the liver and muscles, where it can be quickly mobilized to provide glucose for energy.
Therefore, starch is characteristic of plant cells, while glycogen is characteristic of animal cells.
Both starch and glycogen are polymers of glucose. Starch is a mixture of amylose (unbranched) and amylopectin (branched), while glycogen is more highly branched than amylopectin, allowing for rapid glucose release.

89. In plant cells

In plant cells

[amp_mcq option1=”Nucleus does not need a membrane but chloroplasts are surrounded by their own membrane.” option2=”Nucleus and chloroplasts are surrounded separately by their own membrane.” option3=”Nucleus is surrounded by membrane but chloroplasts do not need membrane.” option4=”Both nucleus and chloroplasts are not surrounded by any membrane.” correct=”option2″]

This question was previously asked in
UPSC CDS-2 – 2022
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Plant cells, like most eukaryotic cells, contain various membrane-bound organelles. The question asks about the membranes surrounding the nucleus and chloroplasts.
– The nucleus in plant cells is a prominent organelle enclosed by a double membrane known as the nuclear envelope.
– Chloroplasts, the sites of photosynthesis in plant cells, are also enclosed by a double membrane.
Therefore, both the nucleus and chloroplasts are surrounded separately by their own membranes.
Other double-membraned organelles in eukaryotic cells include mitochondria. Single-membraned organelles include the endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles. Ribosomes are not membrane-bound organelles.

90. Which one of the following is not found in animal cells ?

Which one of the following is not found in animal cells ?

[amp_mcq option1=”Free ribosomes” option2=”Mitochondria” option3=”Nucleolus” option4=”Cell wall” correct=”option4″]

This question was previously asked in
UPSC CDS-2 – 2019
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Animal cells and plant cells share many common organelles like the nucleus, mitochondria, ribosomes, endoplasmic reticulum, and Golgi apparatus. However, there are key structural differences.
A cell wall is a rigid outer layer that provides structural support and protection to the cell. It is a characteristic feature of plant cells (made primarily of cellulose), fungi, algae, and bacteria, but it is *not* found in animal cells. Animal cells are enclosed only by a cell membrane.
Free ribosomes (involved in protein synthesis) are found in the cytoplasm of both animal and plant cells. Mitochondria (responsible for cellular respiration) are present in both. The nucleolus (involved in ribosome synthesis) is located within the nucleus of both animal and plant cells.
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