Cell: The Unit of LifeNEET Botany · Class 11 · NCERT Chapter 6

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Mesosomes, which are invaginations of the plasma membrane in bacteria, perform functions similar to those of mitochondria, including respiration and energy production. NCERT XI chapter Cell: The Unit of Life describes mesosomes as the sites of respiratory enzymes in bacteria, so option (d) is correct.

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Microfilaments are solid, linear cytoskeletal elements with a diameter of 6 nm, composed of actin monomers. NCERT XI chapter Cell: The Unit of Life describes microfilaments as such, so option (b) is correct.

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Vacuoles regulate the osmotic expansion of a cell by controlling water uptake and maintaining turgor pressure. NCERT XI chapter Cell: The Unit of Life describes vacuoles as key organelles in osmoregulation, so option (b) is correct.

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- Centriole - (iv) Basal body cilia or flagella
- Chlorophyll - (ii) Thylakoids
- Cristae - (i) Infoldings in mitochondria
- Ribozymes - (iii) Nucleic acids

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Sea-fan (Gorgonia) is an animal, and animal cells lack cell walls. Cyanobacteria, Saccharomyces (yeast), and blue-green algae (cyanobacteria) all have cell walls, so option (b) is correct.

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Motile bacteria move using flagella, which are long, whip-like structures that propel the cell. NCERT XI chapter Cell: The Unit of Life describes flagella as the primary organelles for bacterial motility, so option (b) is correct.

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Option (b) is incorrect because the inhibition of succinic dehydrogenase by malonate is competitive, meaning that adding more succinate can reverse the inhibition by outcompeting malonate for the active site. NCERT XI chapter Cell The Unit of Life explains competitive inhibition in this context, so option (b) is the correct choice.

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Sucrose is a non-reducing sugar because it lacks a free aldehyde or ketone group due to the formation of a glycosidic bond between glucose and fructose. NCERT XI chapter Cell The Unit of Life classifies sucrose as a non-reducing carbohydrate, so option (b) is correct.

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Thylakoids – Flat membranous sacs in stroma of chloroplast. Cristae – Infoldings in mitochondria Cisternae – Disc-shaped sacs in golgiapparatus Chromatin – Condensed structure of DNA.

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True nucleus is absent in prokaryotic cell.

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Morels and truffles are edible fungi belong to class ascomycetes.

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Ribosomes are made up of r-RNA and proteins.

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Lysosomes, Golgi apparatus and mitochondria are membrane bound organelles.

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Mycoplasma is wall-less smallest living organism

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Plant cell — Cell wall = Protoplast

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Gap junctions are communicating junctions in animals which facilitates communication between two adjoining cells by protein bridges for rapid transfer of ions, small molecules and large molecules.

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The viroids were discovered by T.O. Diener.

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Balbiani rings are the large chromosome puff of polytene chromosomes. These are the sites of RNA and protein synthesis.

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Mitochondria and chloroplast are semi-autonomous organelles and they have their own ribosomes with help of which they can synthesize protein.

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Peroxisomes is a microbody. Chromatin consists of DNA and proteins and it condenses to form chromosomes. Nucleosome is the basic unit of chromatin. Microtubules are structures present in cilia, flagella, centrioles and spindle fibres.

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Many ribosomes are attached to a single strand of mRNA during protein synthesis. This is known as Polysome.

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Except lysosomes, all three are bounded by double membrane.

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Mitochondria are the site of aerobic oxidation of carbohydrates to generate ATP. 1 15. The process of separation and purification of expressed protein before marketing is called (1) Upstream processing (2) Downstream processing (3) Bioprocessing (4) Postproduction processing Answer (2) Sol. Biosynthetic stage for synthesis of product in recombinant DNA technology is called upstreaming process while after completion of biosynthetic stage, the product has to be subjected through a series of processes which include separation and purification are collectively referred to as downstreaming processing.

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DNA replication in bacteria occurs prior to fission. Prokaryotes do not show well marked S-phase due to their primitive nature.

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The Golgi complex is involved in the formation and modification of secretory vesicles, which transport substances out of the cell. NCERT XI chapter Cell: The Unit of Life describes the Golgi complex's role in packaging and secreting cellular products, so option (b) is correct.

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The nucleolus is the site for active ribosomal RNA synthesis and assembly of ribosomal subunits. NCERT XI chapter Cell: The Unit of Life describes the nucleolus as a non-membrane-bound structure involved in rRNA synthesis, so option (d) is correct.

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Phospholipid synthesis occurs in the smooth endoplasmic reticulum, not the rough endoplasmic reticulum. The rough endoplasmic reticulum is primarily involved in protein synthesis, folding, and modification, so option (d) is correct.

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Strings of ribosomes associated with a single mRNA to form multiple copies of a polypeptide simultaneously are termed as polysomes. NCERT XI chapter Cell: The Unit of Life describes this phenomenon, so option (c) is correct.

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Ref. XI NCERT Chapter- 05, Page No. 75

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In 𝐺0 phase cell is inactive for division but may again become active based on body requirements.

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Factual- NCERT

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Inclusion bodies are non-membrane-bound structures that lie free in the cytoplasm and store reserve materials like glycogen, lipids, and proteins. They are not involved in the ingestion of food particles, which is a function of phagocytosis, so option (b) is incorrect.

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Golgi bodies are the primary site for the formation of glycoproteins and glycolipids in eukaryotic cells. NCERT XI chapter Cell The Unit of Life describes the Golgi apparatus as the site where proteins and lipids are modified, sorted, and packaged for secretion or delivery to other organelles, so option (c) is correct.

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- Cristae are infoldings in mitochondria.
- Thylakoids are flattened membranous sacs in the stroma of plastids.
- Centromere is the primary constriction in a chromosome.
- Cisternae are disc-shaped sacs in the Golgi apparatus.

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- Protein: Peptide bonds link amino acids.
- Unsaturated fatty acid: C = C double bonds are characteristic.
- Nucleic acid: Phosphodiester bonds connect nucleotides.
- Polysaccharide: Glycosidic bonds link monosaccharides.

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The endomembrane system includes the endoplasmic reticulum, Golgi complex, lysosomes, and vacuoles. These organelles are interconnected and involved in the synthesis, processing, and transport of cellular materials, as described in NCERT XI chapter Cell: The Unit of Life, so option (b) is correct.

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Histones are basic proteins with a pH above 7, not acidic. They are rich in positively charged amino acids like Lysine and Arginine, which help in DNA binding. NCERT XI chapter Cell The Unit of Life describes histones as basic proteins, so option (b) is incorrect.

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Lecithin is indeed a phospholipid, and trihydroxy propane is the chemical name for glycerol. However, palmitic acid has 16 carbon atoms, not 20, and arachidonic acid has 20 carbon atoms, not 16. Therefore, the correct statements are (b) and (c), so option (c) is correct.

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Heterochromatin is transcriptionally inactive. A typical nucleosome contains 200 bp of DNA helix. Euchromatin is the loosely packed chromatin region. The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome. Histones are rich in basic amino acid residues lysine and arginine. - 46 - NEET (UG)-2022 (Code-Q1)

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In metacentric chromosome, centromere is in the middle of the chromosomes. Acrocentric chromosome has centromere close to the end of the chromosome. In submetacentric chromosome, centromere is slightly away from the middle of the chromosome. Telocentric chromosome has terminal centromere. - 50 - NEET (UG)-2022 (Code-Q1)

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Option (3) is the correct answer because statements (c), (d) and (e) are correct as oils have lower melting point and hence remain oil in winters. Lipids are generally insoluble in water but soluble in some organic solvents. Option (1), (2) and (4) are incorrect because statements (a) and (b) are incorrect. Lecithin is a type of phospholipid found in plasma membrane. Saturated fatty acids are without double bond . - 51 - NEET (UG)-2022 (Code-Q1)

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In prokaryotes, ER is absent be it RER or SER.

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Movement and accumulation of ions against their concentration gradient requires energy and is an example of active transport. NCERT XI chapter Cell: The Unit of Life explains that active transport involves the use of ATP to move ions or molecules against their concentration gradient, so option (a) is correct.

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Cellulose does not form a blue colour with iodine because it lacks the complex helical structure found in starch, which is necessary to trap iodine molecules. NCERT XI chapter Cell: The Unit of Life explains that the helical structure of starch is responsible for the blue colour with iodine, so option (d) is correct.

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Both Assertion A and Reason R are true, and R correctly explains A. ATP is indeed used in glycolysis at the steps where glucose is converted to glucose-6-phosphate and fructose-6-phosphate to fructose-1-6-diphosphate, as described in NCERT XI chapter Cell: The Unit of Life. Therefore, option (b) is correct.

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Spindle fibers attach to kinetochores of chromosome in metaphase stage.

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The DNA present in chloroplast is circular double stranded. - 61 - NEET (UG)-2024 (Code-Q1)

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• Axoneme is seen in cilia and flagella • Centriole shows cartwheel appearance • Crista is found in mitochondria • Satellite is present in chromosomes

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Both mitochondria and chloroplasts are double membrane bound cell organelles. Transport of ions occurs across the inner membrane of mitochondria. The inner membrane of chloroplast is impermeable to ions and metabolites. Therefore, it is said that inner membrane of mitochondria is relatively more permeable to that of chloroplast.

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The eukaryotic ribosomes are 80S and prokaryotic ribosomes are 70S type.

Each ribosome has two sub-units.

The two sub-units of 80S ribosome are 60S and 40S while that of 70S are 50S and 30S.

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Centromere - Helps in cell division
Cilium - Helps in cell movement
Cristae - Finger like structures of mitochondria
Cell membrane - Is a phospholipid bilayer

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A mesosome is a specialized membranous structure in prokaryotic cells that helps in cell wall formation, DNA replication, and respiration. NCERT XI chapter Cell: The Unit of Life describes mesosomes as invaginations of the plasma membrane, so option (a) is correct.

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Sol. In eukaryotes, packaging of DNA is much more complex. There is a set of positively charged, basic proteins called histones.

Histones are organised to form a unit of light molecules called histone octamer.

They are rich in the basic amino acid residues lysine and arginine.

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There are number of cases in which non-protein constituents called co-factors are bound to the enzyme to make the enzyme catalytically active.

In these instances, the protein portion of the enzymes is called the apoenzyme.

Three kinds of co-factors are identified prosthetic groups, co-enzymes and metal ions. Prosthetic groups are organic compounds and they are tightly bound with apoenzyme. Co-enzymes are also organic compounds but their association with apoenzyme is only transient.