31 Years NEET Previous Year Questions: Cell: The Unit of Life - NEET MCQ

• When the centromere is situated in the middle of two equal arms of chromosomes, the chromosome is called Metacentric.
• When the centromere is present slightly away from the middle, it is called sub-metacentric chromosome.
• When the centromere is present very close to one end of the chromosome, it is known acrocentric chromosome.
• When the centromere is present at terminal position, chromosome is refers as telocentric.

Topic in NCERT: Types of chromosomes based on the position of centromere

Line in NCERT: "the metacentric chromosome has middle centromere forming two equal arms of the chromosome."

• Proteins and lipids are formed in the endoplasmic reticulum and some of them are modified to form glycoproteins and glycolipids in the Golgi apparatus.
• Enlarged image of Endoplasmic reticulum and golgi apparatus (relation). Only golgi bodies given here.

Hence, the correct option is A

Topic in NCERT: Golgi apparatus

Line in NCERT: "golgi apparatus is the important site of formation of glycoproteins and glycolipids."

• Lysosomes are formed by the process of packaging in the Golgi apparatus.
• They are membrane-bound and possess hydrolytic enzymes which work optimally in acidic pH.
• Lysosomes bud off from the trans face to Golgi bodies.
• Precursors of lysosomal enzymes are synthesized by RER and then sent to Golgi bodies for further processing.

Hence, the correct option is A
NCERT Reference: Page no. 134 of sub-topic “8.5.3.3 Lysosomes” of chapter 8 of NCERT

Topic in NCERT: Golgi apparatus

Line in NCERT: "these are membrane bound vesicular structures formed by the process of packaging in the golgi apparatus."

• Nucleolus is naked (devoid of membrane), round or slightly irregular structure which is attached to the chromatin at a specific region called nucleolar organiser region (NOR).
• Nucleolus is a site for rRNA synthesis.
• Nucleolus disappears when the cell undergoes division and reappears after its completion.

Hence, the correct option is D

Topic in NCERT: Nucleolus

Line in NCERT: "it is a site for active ribosomal rna synthesis."

• Mitochondria are miniature biochemical factories where food stuffs or respiratory substrates are completely oxidised to carbon dioxide and water.
• During aerobic respiration, carbohydrates are completely oxidised in mitochondria. In mitochondria, the Krebs cycle and electron transport chain occur, and ATP is generated. As a result, mitochondria are known as a cell's powerhouse.

• ATP comes out of mitochondria and helps perform various energy-requiring processes of the cell like muscle contraction, nerve impulse conduction, biosynthesis, membrane transport, cell division, movement, etc. Because of the formation of ATP, the mitochondria are called power houses of the cell.

Hence, the correct option is C
NCERT Reference: Page no. 135 of topic “8.5.4 Mitochondria” of chapter 8 of NCERT

Topic in NCERT: Mitochondria

Line in NCERT: "mitochondria are the sites of aerobic respiration. they produce cellular energy in the form of atp, hence they are called 'power houses' of the cell."

• Smooth endoplasmic reticulum is the major site for synthesis of lipids.
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• Rough endoplasmic reticulum contains ribosomes found attached to it, therefore RER synthesise proteins.
• Phospholipids are different from simple lipids as simple lipids are esters of fatty acid with various alcohols while compound or conjugated lipids like phospholipids are esters of fatty acids with alcohol but contain some other substances also like phosphate group in phospholipid.
• The smooth endoplasmic reticulum(SER) packages proteins for transportation, synthesizes membrane phospholipids, and releases calcium.

Hence, the correct option is A

Topic in NCERT: The endoplasmic reticulum (er)

Line in NCERT: "the smooth endoplasmic reticulum is the major site for synthesis of lipid."

• Ribosomes are the protein factory of a cell. These are non-membranous organelle which attach to the endoplasmic reticulum by transcolon.

• Lysosomes are membrane-bound vesicular structures formed by the process of packaging in the Golgi apparatus. 
• Mesosomes are a specialised differentiated form of cell membrane and is the characteristic of prokaryotes. They are essentially infoldings of cell membrane.
• The vacuole is the membrane-bound space found in the cytoplasm. It contains water, sap, excretory product and other materials not useful for the cell.

Hence, the correct option is A

Topic in NCERT: Ribosomes and inclusion bodies

Line in NCERT: "ribosomes are non-membrane bound organelles found in all cells – both eukaryotic as well as prokaryotic."

• Cellular organelles with membranes are Lysosomes, Golgi apparatus and mitochondria.
• Lysosomes are single membrane-bound organelles which contain acid hydrolases or digestive enzymes that digest excess or worn out organelles, food particles, engulfed viruses or bacteria and macromolecules.
• Golgi apparatus is a single membrane-bound organelle consisting of folded and flattened membranes that are involved in secretion and helps in intracellular transport.
• The mitochondria is a double-membraned cell organelle, known as the powerhouse of the cell which is present in all eukaryotic cells.

Hence, the correct option is C

Topic in NCERT: Cell organelles

Line in NCERT: "lysosomes, golgi apparatus and mitochondria."

• The cell wall is the hard protective covering of all plant, fungal and some bacterial cells.
• Mycoplasma is a genus of bacteria that lack a cell wall and are surrounded by their cell membrane only.

Hence, the correct option is B

Topic in NCERT: Cell envelope and modifications

Line in NCERT: "prokaryotes have a cell wall surrounding the cell membrane except in mycoplasma."

• The cytoskeleton is unique to eukaryotic cells. It is a dynamic three-dimensional structure that fills the cytoplasm. This structure acts as both muscle and skeleton, for movement and stability. The long fibres of the cytoskeleton are polymers of subunits. The primary types of fibres comprising the cytoskeleton are microfilaments, microtubules, and intermediate filaments.
• Microfilaments are fine, thread-like protein fibres, 3-6 nm in diameter. They are composed predominantly of a contractile protein called actin.

• Microtubules are cylindrical tubes, 20-25 nm in diameter. They are composed of subunits of the protein tubulin--these subunits are termed alpha and beta. 
• Intermediate filaments are about 10 nm diameter and provide tensile strength for the cell. Lamin is the protein present in intermediary filaments.
• Lamin is the protein present in intermediary filaments.

Hence, the correct option is B

Topic in NCERT: Cytoskeleton

Line in NCERT: "microfilaments are solid linear cytoskeletal elements having a diameter of 6 nm and made up of a single type of monomer."

• Vacuoles are non cytoplasmic areas present inside cytoplasm and separated from the latter by tonoplast.
• They are believed to be formed by expansion and pinching off from ER.
• There occurs a large central vacuole and many small vacuoles in plant cells.
• They play a major role in osmotic expansion of cells.
• Mitochondria are the sites of aerobic respiration. They produce cellular energy in the form of ATP, hence they are called ‘power houses’ of the cell.
• Plastids are found in all plant cells and in euglenoides. These are easily observed under the microscope as they are large. They bear some specific pigments, thus imparting specific colours to the plants.
• Ribosomes are the site of protein synthesis. Several ribosomes may attach to a single mRNA and form a chain called polyribosomes or polysome. The ribosomes of a polysome translate the mRNA into proteins.

Hence, the correct option is B

Topic in NCERT: Vacuoles

Line in NCERT: "in amoeba the contractile vacuole is important for osmoregulation and excretion."

1. Centriole: There are two main functions of centrioles

• Cell division :The main function of the centriole is to help with cell division in animal cells.  The centrioles help in the formation of the spindle fibres that separate the chromosomes during cell division (mitosis).
• Ciliogenesis :The second function of centrioles that we will focus on is ciliogenesis. Ciliogenesis is simply the formation of cilia and flagella on the surface of cells.  Cilia and flagella help the cell move. 

2. Chlorophyll molecules are arranged in and around photosystems that are embedded in the thylakoid membranes of chloroplasts.
3. A crista is a fold in the inner membrane of a mitochondrion.
4. Ribosomes comprise a complex macromolecular machine, found within all living cells, that serves as the site of biological protein synthesis  (translation). Ribosomes link amino acids together in the order specified by messenger RNA(mRNA) molecules.

Hence, the correct option is A
NCERT Reference: Topics “8.5.9 Centrosome and Centrioles”, “8.5.5 Plastids”, “8.5.4 Mitochondria” and “8.5.6 Ribosomes” of chapter 8 of NCERT

• In some bacteria, (e.g., Bacillus subtilis) the plasma membrane forms certain invaginations or in foldings called mesosomes in the cytoplasm.
• The mesosomes have various functions, viz., respiratory, secretory etc. Mesosomes are the infolding of the bacterial cell membrane.
• These structures are thought to be analogous to the eukaryotic mitochondria.

Hence, the correct option is D

NCERT Reference: Page no. 129 of topic “8.4.1 Cell Envelope and its Modifications” of chapter 8 of NCERT

• Prokaryotes are the primitive organism which lacks membrane-bounded organelles and nucleus. Prokaryotic cells have some microscopic structures in their cytoplasm. They serve specific purposes for the cell.
• Inclusions are aggregates of specific chemical compounds and often serve as a reservoir of energy or carbon. Common inclusions are poly--hydroxyalkanoate, sulfur globules, cyanophycin globules, and polyphosphate.
• Polyribosomes (or polysomes) also known as ergosomes are a cluster of ribosomes, bound to the mRNA molecule during translation process found in the eukaryotes.

Hence, the correct option is C

Topic in NCERT: Inclusion bodies

Line in NCERT: "inclusion bodies: reserve material in prokaryotic cells are stored in the cytoplasm in the form of inclusion bodies. these are not bound by any membrane system and lie free in the cytoplasm, e.g., phosphate granules, cyanophycean granules and glycogen granules."

• RER is frequently observed in the cells actively involved in protein synthesis and secretion.
• RER is well developed in cells engaged in synthesis of secretory products.

Hence, the correct option is C

Topic in NCERT: The endoplasmic reticulum (er)

Line in NCERT: "rer is frequently observed in the cells actively involved in protein synthesis and secretion."

• Lysosomes are enclosed by a single membrane while Mitochondria, Chloroplasts and Nuclei are enclosed by double membranes.

Hence, the correct option is C

NCERT Reference: Page no. 134 of topic “8.5.3.3 Lysosomes” of chapter 8 of NCERT