Organelles such as the nucleus, rER, sER, Golgi apparatus, and mitochondria are embedded in the cytoplasm of prokaryotic and eukaryotic cells. Viruses are non living and do not have a cytoplasm, so their linear genetic material (RNA or DNA) is simply enclosed within a protein coat/capsid Answer : (c)

In the Ribosomes, the subunits are classified as per Sedimentation rate. S is the Svedberg's unit. The sedimentation rate for a particle of a given size and shape measures how fast the particle 'settles'. Answer : (c)

Ribonucleic Acid (RNA) is a single chain polyribonucleotide which functions as carrier of coded genetic information from DNA to cytoplasm, and takes part in protein and enzyme synthesis. RNA is more common and abundant than DNA. There are six types of RNAs-ribosomal (most abundant), transfer RNA (15% to total RNA),messenger RNA (2-5%), small sized nuclear RNA, small cytoplasmic RNA, and genetic RNA (in viruses called riboviruses). Answer : (b)

The cytoplasm of all eukaryotic cells is crisscrossed by a network of protein fibres that support the shape of the cell and anchor organelles to fixed locations. This network is called cytoskeleton. It consists of three types of cytoskeletal filaments namely act filaments or microfilaments (formed of globular protein actin), microtubules (formed of tubulin protein) and intermediate filaments (formed of variety of proteins like vimentin, keratin, desmin, periphenn, laimn.etc). Answer : (b)

Na-K pump's job is to move potassium ions into the cell while simultaneously moving sodium ions out of the cell. Answer : (d)

Answer : (c)

Answer:(d)

Glyoxysomes are peroxisomes that contain the enzymes of the glyoxylate pathway in addition to flavine oxidases and catalase. Peroxisomes or glyoxysomes are found in all major groups of eukaryotic organisms including yeasts, fungi, protozoa, plants and animals. in all peroxisomes, in glyoxysomes the fatty acids are oxidized to acetyl-CoA by peroxisomal β-oxidation enzymes. Answer : (a)

Cellular Totipotency is the ability of a single cell to produce all cell types and to organize them into an entire organism when cultured in a suitable culture medium at an appropriate temperature and aeration conditions. Answer : (d)

Peroxisomes differ from mitochondria and chloroplasts in many ways. Most notably, they are surrounded by only a single membrane, and they do not contain DNA or ribosomes. Peroxisomes resemble the ER in being a self-replicating, membrane-enclosed organelle that exists without a genome of its own. Answer : (a)

Rough endoplasmic reticulum, (RER), has large numbers of ribosomes attached to the outer surfaces of the lamella membranes. Answer : (a)

Lysosomes are known as suicide bags of the cell because they contain lytic enzymes capable of digesting cells and unwanted materials. When lysosomes burst, the lytic enzymes within the organelle spill all over the cell, rupturing the cell membrane or cell wall and inducing the death of the cel Answer : (b)

Amyloplasts are found in roots and storage tissues and store and synthesize starch for the plant through the polymerization of glucose. Answer : (a)

ATP-synthetase :Located within the thylakoid membrane and the inner mitochondrial membrane, ATP synthase consists of two regions FO and F1 Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory Complex II is an enzyme complex, found in many bacterial cells and in the inner mitochondrial membrane of eukaryotes. It is the only enzyme that participates in both the citric acid cycle and the electron transport chain. The inner mitochondrial membrane containing the enzymes of the respiratory electron and proton transport chain that leads to the production of ATP, including five multiprotein enzyme complexes (I–V) and two electron carriers –coenzyme Q10 and cytochrome c. Answer : (a)

A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle. Answer : (b)

The point of the contractile vacuole is to pump water out of the cell through a process called osmoregulation, the regulation of osmotic pressure. Answer : (c)

Chromoplasts a coloured plastid other than a chloroplast, typically containing a yellow or orange pigment. Answer : (d)

Lamark anticipated the work of Schleiden & Schwann in cell theory in stating that: . . . no body can have life if its constituent parts are not cellular tissue or are not formed by cellular tissue. Lamarck acquired characteristic as one that has developed in the course of the life of an individual in the somatic or body cells, usually as a direct response to some external change in the environment or through the use or disuse of a part. Answer : (a)

plasmid is a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. Plasmid are considered as genetic elements that exist exclusively or predominantly outside of the chromosome and can replicate autonomously. Plasmids are transmitted from one bacterium to another (even of another species) mostly through conjugation. Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells Plasmids are much used in the laboratory manipulation of genes Answer : (b)

microtubule is a microscopic tubular structure present in numbers in the cytoplasm of cells, sometimes aggregating to form more complex structures.1 correct The main function of centrioles is to produce cilia during interphase and the aster and the spindle during cell division. 2 is wrong Peroxisomes are membrane-bound organelles in most eukaryotic cells, primarily involved in lipid metabolism and the conversion of reactive oxygen species such as hydrogen peroxide into safer molecules like water and oxygen. 3 is wrong Answer : (b)

The endoplasmic reticulum is always attached to the nuclear membrane. ER is a part of the cytoplasmic vesicular system which also consists of nuclear envelope, lysosomes, endosomes and Golgi complex. Ribosomes are attached to the membrane of the ER, making it “rough.” The RER is also attached to the nuclear envelope that surrounds the nucleus. This direct connection between the perinuclear space and the lumen of the ER allows for the movement of molecules through both membranes Answer : (c)

A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organelle. Answer : (d)

Rudolf Virchow (1821-1902), a German pathologist proposed for the first time that all cells arise from pre-existing cells. Explanation: Rudolf Virchow wrote “Omnis cellula e cellula” which literally translates to ''all cells come from other cells” Answer : (b)

glyoxysomes (as all peroxisomes) contain enzymes that initiate the breakdown of fatty acids and additionally possess the enzymes to produce intermediate products for the synthesis of sugars by gluconeogenesis Answer : (b)

Rough endoplasmic reticulum is an organelle found in eukaryotic cells. Its main function is to produce proteins. Answer : (c)

The cytoplasm is the main arena of cellular activities in both the plant and animal cells. Various chemical reactions occur in it to keep the cell in the ‘living state’. Though biochemical reactions occur all over a cell, important reactions related to maintaining osmolarity, resting potential (in neurons, muscles and othe electrically excitable cell) occur in cytoplasm - which keeps it 'alive' Answer : (b)

Enzymes which use NADP+ as an electron acceptor or as a cofactor. Nicotinamide adenine dinucleotide phosphate, a redox coenzyme that participates in a variety of enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NADP+) and reduced (NADPH). Answer : (b)

Ribosomes comprise a complex macromolecular machine, found within all living cells, that serves as the site of biological protein synthesis (translation). Answer : (c)

Elaioplasts: for storing fat In plants, plastids may differentiate into several forms, depending upon which function they play in the cell. Undifferentiated plastids (proplastids) may develop into any of the following variants Chloroplasts: green plastids for photosynthesis; see also etioplasts, the predecessors of chloroplasts Chromoplasts: coloured plastids for pigment synthesis and storage Gerontoplasts: control the dismantling of the photosynthetic apparatus during plant senescence Leucoplasts: colourless plastids for monoterpene synthesis; leucoplasts sometimes differentiate into more specialized plastids: Amyloplasts: for starch storage and detecting gravity (for geotropism) Elaioplasts: for storing fat Proteinoplasts: for storing and modifying protein Tannosomes: for synthesizing and producing tannins and polyphenols Answer : (c)

The smooth endoplasmic reticulum lacks ribosomes and functions in lipid synthesis but not metabolism. SER main function is the synthesis of lipids, steroids, and carbohydrates, as well as the metabolism of exogenous substances, such as drugs or toxins. Lipid metabolism is the synthesis and degradation of lipids in cells, involving the breakdown or storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes Answer : (c)

The fluid mosaic model is the most acceptable model of the plasma membrane Answer : (c)

The plasma membrane is composed of a phospholipid bilayer, which is two layers of phospholipids back-to-back. Phospholipids are lipids with a phosphate group attached to them. Answer : (a)

The nucleolus is a round body located inside the nucleus of a eukaryotic cell. It is not surrounded by a membrane but sits in the nucleus. The nucleolus makes ribosomal subunits from proteins and ribosomal RNA, also known as rRNA Answer : (b)

In plant, Golgi apparatus is called dictyosomes. Polymrisation of carbohydrates i.e. the formation of complex sugars from simple sugars. Packaging and secretion of proteins. Formation of lysosomes Answer : (c)

All eukaryotic cilia and flagella are similar in their organisation. The core of cilia and flagella is known as axoneme. The axoneme consists of nine pairs of doublets of radially arranged peripheral microtubules. A pair of microtubules is located centrally. Such arrangement of microtubules in the axoneme is referred to as 9 + 2 array. The central microtubules are connected to each other by a bridge, and they are enclosed by a central sheath. The central sheath is connected to one of the peripheral tubules from each doublet by nine spokes. Answer : (c)

Svedberg units (S) a measure of how quickly particles sediment in an ultracentrifuge. Large the particle, the greater its S value Smaller subunit of ribosome sinks slower than the larger subunit Answer : (a)

actinobacterial proteins show higher levels of similarity to those of the peroxisome than to those of other prokaryotes. Answer : (d)

The fluid mosaic model is used to represent the structure of the cell membrane. The proteins are important because they act like doors that allow certain molecules to enter into or leave the cell. The cell membrane is a bilayer. Important points 1. fluid (can move) 2. mosaic (made up of a lot of differnt parts integrated together) 3. bilayer (helps regulate what goes in and out) 4. proteins (serve as markers on the surface for identification purposes and to allow certain molecules in and out) 5. transport (passive and active, allows molecules across membrane) Answer : (b)

Lysosomes are membranous bags of hydrolytic enzymes including proteases, nucleases, glycosidases, lipases, phospholipases, and phosphatases. Answer : (c)

Stromal connective tissues are found in the stroma; this tissue belongs to the group connective tissue proper. Extracellular matrix is primarily composed of ground substance - a porous, hydrated gel, made mainly from proteoglycan aggregates - and connective tissue fibers.. Answer : (b)

The epithelium lining the respiratory tract has a specialised role - it produces mucus to catch any foreign bodies entering the body. Mucin is produced intracellularly, packaged into vesicles by the Golgi and then secreted. Answer : (d)

Cell inclusions are considered various nutrients or pigments that can be found within the cell, but do not have activity like other organelles. Answer : (b)

Balbiani rings are exceptionally large puffs on the polytene chromosomes in the dipteran Chironomus tentans. These puffs are particularly well suited for studies of the structure of active genes and the synthesis and transport of specific RNA-protein (RNP) particles. Answer : (b)

Ribosomes were first observed in the mid-1950s by Romanian-American cell biologist George Emil Palade, using an electron microscope, as dense particles or granules. Answer : (d)

Desmosomes connect adjacent cells when cadherins in the plasma membrane connect to intermediate filaments. Answer : (b)

A Nissl body, also known as Nissl substance and Nissl material, is a large granular body found in neurons. These granules are of rough endoplasmic reticulum (RER) with rosettes of free ribosomes, and are the site of protein synthesis. Answer : (a)

The absorption of glucose and amino acids is mediated by carrier ions like Na+The concentration of Na+ is higher in the intestinal lumen compared to mucosal cells. Na+, therefore moves into the cells along its concentration gradient and simultaneously glucose is transported into the intestinal cells. Thus Na1 diffuses into the cell and it drags glucose along with it. The intestinal Na+gradient is the immediate energy source. The mechanism for transport of amino acid is same as glucose. Fructose absorption does not require energy and is independent of Na+transport Answer : (d)

Cystolith is a botanical term for outgrowths of the epidermal cell wall, usually of calcium carbonate, formed in a cellulose matrix in special cells called lithocysts, generally in the leaf of plants. Answer : (a)

Purines include the nucleobases adenine and guanine. Answer : (a)

Cell Wall is not present in any type of gametes, plant or animal. If cell wall would have been present then the zygote couldn't have progressed for further embryological development Answer : (c)