Which of the following is the smallest cell-
PPLO( pleuro pneumonia like organisms ) comes under the kingdom monerans . They lack cell wall and have size of 0.1 micrometre. That's why they are smallest.
Which of the following statements is not true-
Animal cells do not have chloroplasts. Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells. The entire process is called photosynthesis and it all depends on the little green chlorophyll molecules in each chloroplast. Plants are the basis of all life on Earth.
All cells are derived from pre-existing cells"
is the famous generalization of-
Which of the following is true of the carbohydrate portion of the cell membrane-
Plasmalemma of animal cells is elastic due to the presence of-
Plasma membrane is a lipid bilayer in which the proteins, cholesterol and carbohydrates are incorporated which give it a mosaic-like appearance. The lipid bilayer renders the flexibility to the cell membrane.
Causes of Cancer is -
Mitosis is closely controlled by the genes inside every cell. Sometimes, this control can go wrong. If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells. They continue to replicate rapidly without the control systems that normal cells have. Cancer cells will form lumps, or tumours, that damage the surrounding tissues. Sometimes, cancer cells break off from the original tumour and spread in the blood to other parts of the body. When a tumour spreads to another part of the body it is said to have metastasized. They continue to replicate and make more tumours. These are called secondary tumours. Medicines that are used to treat cancer are sometimes aimed at killing cells that are rapidly dividing by mitosis. They inhibit the synthesis or function of DNA - this type of treatment is called chemotherapy. More modern medicines target specific cancers in different ways. Many inhibit the growth signals for that type of cell.
The most abundant substance of middle lamella is-
Middle lamella connects cell walls of two adjacent cells. Pectic compounds are mainly present in the middle lamella.
Cell wall is the secretory product of-
The cell wall is derived from minute vesicles produced in the Golgi apparatus present in the cytoplasm. Hence, the cell wall is a secretory product of a plant cell cytoplasm. Immediately after nuclear division, the phragmoplast or cell plate appears across the equator of the cell. At the end of mitosis, granules arising from the Golgi complex arrange themselves on the equator of the cell. They then fuse to form the cell plate. The cell plate grows in thickness by the addition of new material from the complex and becomes cell wall.
Nucleoplasm is continuous with cytoplasm through-
In eukaryotic cells, nucleus is a membrane bound organelle. It is surrounded by double membrane. The nucleus communicates with the surrounding cell cytoplasm through the nuclear pores.
Role of nucleus in morphological differentiation was discovered in-
In his experiments, Hammerling grafted the stalk of one species of Acetabularia onto the foot of another species.
In all cases, the cap that eventually developed on the grafted cell matched the species of the foot rather than that of the stalk.
In this example, the cap that is allowed to grow on the grafted stalk looks like the base species one... A. mediterranea
This experiment shows that the base is responsible for the type of cap that grows. The nucleus that contains genetic information is in the base, so the nucleus directs cellular development.
Which one is not a part of nucleus-
Centrosome is a small body located near the nucleus. It has a dense center and radiating tubules. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell and produce microtubules.
The size of the nucleolus is large where-
Aerobic respiration is performed by-
Mitochondria, organelles specialized to carry out aerobic respiration, contain an inner membrane folded into cristae, which form two separate compartments: the inner membrane space and the matrix. The Krebs Cycle takes place in the matrix. The electron transport chain is embedded in the inner membrane and uses both compartments to make ATP by chemiosmosis. Mitochondria have their own DNA and ribosomes, resembling those of prokaryotic organisms.
Mitochondria are most abundant in-
Heart muscle cells have high number of mitochondria(5000 mitochondria per cell).That is because constantly beating heart works more than any other organ in our body. Heart cells have a high demand for ATP to keep pumping the blood 24 by 7.
Cytochrome oxidases are found-
In healthy cells, cytochrome c (Cyt c) is located in the mitochondrial intermembrane/intercristae spaces, where it functions as an electron shuttle in the respiratory chain and interacts with cardiolipin (CL)
Small particles present on inner mitochondrial membrane are called-
Lysosomes containing inactive enzymes are called-
Which of the following statements best describes the functional characteristics of lysosomes-
Lysosome is called suicidal bag hence contains enzymes which are capable of dissolving cellular apparatus.
Lysosomes are called "suicide bags" because they have-
Lysosomes are small vesicles which are bounded by a single membrane and contain hydrolytic enzyme in form of crystalline granules.
These enzymes are digestive enzymes also termed as ‘acid hydrolases'. Lysosomes are called suicide bags because of presence of these large number of acid hydrolases in them.
In which of the following cells the endoplasmic reticulum is absent-
If cells are broken up and sedimented by centrifugation, the new structures formed in
one of the fraction is-
Microsomes are the structures formed when cells are broken up in the laboratory. Differential centrifugation can be used to separate them from other cellular debris. They are used to imitate the activity of the endoplasmic reticulum in a test tube. They are also used to perform experiments that require protein synthesis on a membrane thus aiding in understanding the process of protein formation on the endoplasmic reticulum.
Which of the following enzyme is characteristic of Golgi complex-
Glycosyl transferases are enzymes that catalyze the formation of the glycosidic linkage to form a glycoside. These enzymes utilize 'activated' sugar phosphates as glycosyl donors, and catalyze glycosyl group transfer to a nucleophilic group, usually an alcohol.
The endoskeleton of the cell is made up of-
The Endoplasmic reticulum (ER) is a type of organelle found in eukaryotic cells that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures know as cisternae. Hence it forms endoskeleton.
Match the following
1. Microtubules - Structural component of cilia
2. Centrioles - Store hydrolases
3. Peroxisomes - Stores carbohydrate, fats and proteins in plants
Microtubules are the structural component of cilia.
Centrioles play role in cell division.
Perioxisomes contain enzymes that break down long and branched fatty acid chains, amino acids, and polyamines.
A genome can be defined as a set of genes present in a cell or organism or also it can also be said as a haploid set of chromosomes in a cell. Basically, it is a complete set of DNA which includes all the genes.
The carbohydrates which project out of the lipid bilayer in animal cell membrane are linked to -
In living cells mitochondria can be stained with-
Janus green is a basic dye used in straining mitochondria
The outer membrane of mitochondria is -
Mitochondrial outputs are -
The overcoat of the plasma membrane is the handiwork of -
The overcoat of the plasma membrane means phospholipids. And the function of the golgi apparatus is to synthesise lipids and proteins. Thus, it could be said that the overcoat of the plasma membrane is the handiwork of the golgi apparatus.
Find out the incorrect statement -
Which is an incorrect statement -
Centrioles are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell's skeletal system. They help determine the locations of the nucleus and other organelles within the cell.
Which of the following statements regarding cilia is not correct–
Microtubules of cilia are composed of tubulin
Cilia are minute, harilike processes on the surface of protozoans or of metazoans cells ehich by their motion accomplish locomotion or produce a current. Each cilium contains a peripheral circle of nine doublet microtubules arranged around two single microtubules. Each microtubule is composed of tubulin proteins.
Although the mechanism of ciliary movement is not completely under stood. It is known that the microtubules behave as sliding filament that move past one another much like the sliding filaments of vertebrate skeletal muscle.
The fluxes of Ca2+ across the membrance is not responsible for controlling the organized beating or cilia.
Selecting the wrong statement from the following–
All the following statement are correct except–
Peroxisomes are cytoplasmic organelles that play a central role in break down of fatty acids and other oxidation reactions in the cell.
How many divisions will occur in an isolated tip cell to form 128 cells -
A single mitotic division of one cell produces two cells. 2nd division of this two cells produces 4 cells and so on. 2n = Number Of cells after n divisions. Thus 7 generations of mitosis yields 128 cells from a single cell.
Synthesis of proteins for formation of spindle fibres takes place in -
The synthesis of proteins for formation of spindle fibers takes place in G2 phase. G2 phase, or pre-mitotic phase is the third and final subphase of Interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cells DNA is replicated.
O18 was used in H2O to prove that O2 comes from H2O in photosynthesis by Ruben and
Kamen. C14 was used by Calvin to discover dark reaction. N15 is used in the study of–
Smallest phase of mitosis is -
Cell division does not take a long time. Prophase is the longest phase of mitosis, but it occurs faster than interphase. Anaphase is the shortest phase of mitosis. In anaphase, the sister chromatids are pulled apart to opposite ends of the cell.
Which of the following is the better explanation of earlier discovery of the "Nucleus" than the "Cell Theory"–
Choose the correct statement–
Which of the following observations most strongly support the view that mitochondria have elctron transport system/enzymes–
In the inner membrane of the mitochondria, electrons from NADH and FADH2 go through the electron transport chain to O2, to yield water. It consists of a series of reactions that transfer electrons from donors to acceptors and couples this exchange with the transfer of H+ ions across the membrane creating an electrochemical proton gradient which drives the formation of a molecule that stores energy in the form of highly strained bonds. This energy rich molecule is adenosine triphosphate (ATP). The enzyme responsible for ATP synthesis is ATP synthase.
What is correct ?
The eukaryotic cells are essentially two envelope system because they contain–
Which of the following statement justifies that "the cell is a self-contained unit"–
The significance of phospholipid bilayer in plasma membrane is to form–
Bilayer in the plasma membrane because the outer membrane of the bilayer is hydrophilic so that it protects inner hydrophobic layer which should not face water
A bivalent consists of
The two replicated homologous chromosomes associate to form a bivalent. It is also known as tetrad and It is mainly formed during the pachytene stage of the meiosis. They undergo chiasmata formation for recombination
Muramic acid is present in cell walls of -
Muramic acid (N-acetyl muramic acid, that constitutes peptidoglycan) is a typical cell wall component of bacteria.
Hence, from the given options it is clear that only bacteria / blue green algae would be having muramic acid, as the cell wall component.
Growth of cell wall during cell elongation takes place by -
Plasmodesmata are -
Plasmodesmata connect protoplasm of adjacent cells.
Continuity in cytoplasm of adjacent cells remains by
Which element mainly occurs in middle lamella -
Middle lamella is a pectin layer and is made up of calcium and magnesium pectates. Its function is to strengthen the cell wall of two adjoining cells. Main element present in the middle lamella is calcium.
Cell membrane is composed of -
Which of the following is main enzyme of plasma membrane -
ATPase are a class of enzymes that catalyze the dephosphorylation of ATP into ADP and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life. Such enzymes are integral membrane proteins anchored within biological membranes (plasma membrane), and move solutes across the membrane, typically against their concentration gradient.
Percentage of intrinsic proteins in the total proteins of plasma membrane -
About 70% of the proteins of the plasma membrane are intrinsic proteins. The intrinsic proteins, as their name implies, are firmly embedded in the phospholipid bilayer. Almost all intrinsic proteins contain special amino acid sequences.
Cell wall was discovered by -
Cell wall was discovered by Robert Hooke, in 1665, when he saw an empty box like compartments in a very thin slice of cork under his microscope. He wrote a book Micrographia and coined the term Cellula which was later on changed into cells. Robert Hooke thought cells to be passages for conducting fluids.
Cell wall is -
The cell wall is dead at maturity in plants.Hence,cell wall cannot regulate entry or exit of solute or solvents particals across it .In other words, the cell wall is fully permeable to both solute and solvents molecules.
Decision of cell division occurs at -
At the End of G1 Phase cell decides to further divide or to be a Permanent cell by going to G0 phase which is also known as Quiscent Stage.
Crossing over takes place on -
Carbohydrates which present in the cell membrane take part in -
Carbohydrates which are present in the cell membrane take part in cell recognition. Cell recognition is defined as an active process giving rise to a specific response.
Cell adhesion is a good example of cell recognition when it can be demonstrated that the adhesion is mediated by molecules having specific binding properties. Such cell adhesion molecules have now been identified in several cellular systems. Carbohydrates, or sugars, are sometimes found attached to proteins or lipids on the outside of a cell membrane.
Plasma membrane is fluid structure due to presence of -
The plasma membrane or cell membrane is the outer covering of all cells but in a plant cell, it is present below the cell wall. It is mainly composed of phospholipid bilayer structure with the embedded proteins. The fluid nature of membranes is due to the lipids. The lipids can be saturated or unsaturated.
When the prophase chromosome are stained
with acetocarmine they take differential
staining. This phenomenon is called -
Heterochromatin is closely associated with the nucleolus. So, when the prophase chromosome are stained with acetocarmine they take differential staining due to presence os heterochromatin and euchromatin regions. This phenomenon is called as heteropycnosis.
Longest phase of mitosis is -
Cell division does not take a long time. Prophase is the longest phase of mitosis, but it occurs faster than interphase. Anaphase is the shortest phase of mitosis. In anaphase, the sister chromatids are pulled apart to opposite ends of the cell
Amphipathic molecule in plasma membrane is -
The lipids in the plasma membrane are phospholipids with one polar hydrophilic head and two nonpolar hydrophobic tail. Thus, the lipids are amphipathic. The hydrophilic head is exposed to the surface whereas the hydrophobic tail is embedded in the inner region of the membrane.
The average thickenss of plasma membrane is -
The electron microscopic studies reveal that a typical cell/plasma membrane is 75-100 Å (7.5-10.0 nm) in thickness. The cell membranes are primarily composed of lipids (about 40%) & proteins (about 60%).
Unit membrane model of plasma membrane
was proposed by -
Robertson proposed unit membrane concept for biological membranes. According to this concept, the biological membrane is a lipid bilayer surrounded on either side by proteins with a difference in their type for the outer and inner side. All biomembranes have a trilaminar structure with an electron transparent lipid bilayer (35 A˚) lying sandwiched between electron dense protein layers (20 A˚ each).
Pit membrane of simple pit is formed by -
Pits are discontinuities in the secondary cell wall. there are two main types of pits – simple and bordered. All pits have two essential components – the pit cavity and the pit membrane. In the simple pit, the cavity is nearly constant in width. In the bordered pit, the cavity narrows towards the cell lumen; typically, the membrane is arched over by the secondary cell wall. The pit membrane cosists of primary wall and middle lamella. As a rule, pits in the walls of adjoining cells appear in pairs called pit-pairs, and the common membrane is therefore composed of two primary walls and middle lamella.
Term plasmodesmeta was first used by -
In plants, cell wall possesses minute cytoplasmic bridges between adjacent cells. They are called plasmodesmata. Term plasmodesmata was first used by Strasburger in 1901. So, the correct answer is 'Strasburger'.
Primary cell wall formed by -
Intussusception is the growth of the cell wall by the deposition of cellulose. The plant cell wall is a product of protoplasmic activity and in the higher plants its development begins with the formation of the cell plate, immediately after nuclear division. This thin cell plate quickly acquires the form of a primary cell wall, which is defined as the structure which encloses the protoplasts during the period of cell enlargement. Once, the period of cell enlargement is over the cell wall becomes thickened to become the secondary wall. The secondary wall is regarded as the structural component of the plant.
Cell wall of prokaryotes is made up of -
Butter Sandwich model of plasma membrane
was proposed by -
Sandwich or Lamellar models explained that cell membranes contain both proteins and lipids in distinct layers. According to the Danielli and Davson model, plasma membrane consists of a double phospholipid layer and is surrounded on either side by a layer of hydrated globular proteins or P-L-L-P structure. The hydrophobic or non polar tails of the two lipid layers are towards the centre.
The Singer’s Model of Plasma membrane
differs from the Robertson’s model in the -
Robertson proposed a trilaminar structure for plasma membrane which comprised of an electron transparent lipid bilayer sandwiched between electron dense protein layers. Singer and Nicolson proposed a fluid mosaic model in which the proteins are interspersed and floating like the mosaic on a lipid bilayer.
Ingestion of solid food by plasma membranes
Phagocytosis means “cellular eating” while Pinocytosis means “cellular drinking”. Pinocytosis and Phagocytosis are the two categories of Endocytosis. Both are the active process and requires energy (ATP) as adenosine triphosphate for the uptake of materials. Phagocytosis is an intake of solid particles with the formation of vesicles called phagosomes, while pinocytosis is the intake of liquid particles with the formation of vesicles called pinosomes.
In order to find out quickly whether the cells
are living one must observe -
Cytoplasmic matrix is often differentiated into outer gel part called as ectoplasm and inner sol part called as endoplasm. In a living cell, the endoplasm is usually in perpetual motion called as cyclosis or cytoplasmic or protoplasmic streaming. So, the movement of cytoplasm can be used find out whether the cells are living or not.
Which one is widely distributed in a cell -
Maximum enzymes are found in -
Mitochondria is the site for aerobic respiration in cell and produces energy in the form of ATP. For the formation of energy different pathways like electron transport chain, kreb's cycle are involved and operated by the different enzymes. Thus, the maximum number of enzymes are found in mitochondria.
Rough E.R. mainly responsible for -
Rough endoplasmic reticulum carry ribosomes on their surface. The ribosomes present on rough endoplasmic reticulum synthesize secretory proteins. The proteins required for internal use of cell are synthesized on cytoplasmic ribosomes.
Besides producing secretory vesicles, the
function of golgibody is -
It plays an important role in the storage, packaging and secretion of certain cell products. It is involved in the formation of lysosomes and other enzyme-containing cellular inclusions, and in the formation of secretory granules.
Mitochondria supply most of the necessary
biological energy through -
TCA or Tricarboxylic Acid Cycle or Krebs cycle oxidizes the compounds like acetyl-CoA obtained from carbohydrates, fats and proteins and leads to the production of carbon dioxide and energy in form of ATP.
Enzymes for ETS occurs in (mitochondria)-
Mitochondria are cell organelles involved in aerobic respiration. Krebs cycle occurs in the mitochondrial matrix. Krebs cycle produces reduced coenzymes which are oxidized by electron carriers of Electron Transport System or ETS to produce ATP through oxidative phosphorylation. The electron carriers of ETS are located in the inner mitochondrial membrane in eukaryotes.
Mitochondrial DNA is -
Which structures are responsible for lipid synthisis repectively in plants and animal cells-
Sphaerosomes are single half unit membrane covered small spherical organelles in plants which synthesize and store fats. They develop from endoplasmic reticulum. Smooth endoplasmic reticulum are devoid of ribosomes and carry out synthesis of lipids, detoxification, synthesis of steroids in animals.
Which cell organelle secretes zymogen
A zymogen or proenzyme is an inactive enzyme precursor. A zymogen requires a biochemical change such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site for it to become an active enzyme. Smooth endoplasmic reticulum secretes zymogen. The smooth endoplasmic reticulum has functions in several metabolic processes. It synthesizes lipids, phospholipids, and steroids. The general structure of the endoplasmic reticulum is a network of membranes called cisternae. These sac-like structures are held together by the cytoskeleton. The network of smooth endoplasmic reticulum allows for an increased surface area to be devoted to the action or storage of key enzymes and the products of these enzymes.
Lysosomes are not helpful in -
Lysosomes are useful in metamorphosis in eating away larval organs, removal of obstructions, intracellular scavenging, fertilization etc. They do not perform any biosynthetic activity, hence, are not useful in lipogenesis. Lipids are synthesized in smooth endoplasmic reticulum and spherosomes.
Digestion of hormonal vesicle by lysosome
is called -
Lysosomes carry a variety of hydrolytic enzymes. Lysosomes show polymorphism. There are different forms of lysosomes. Crinophagy is the term which is used to describe the disposal of excess secretory granules by lysosomes. This is a process in which excess amounts of hormone are fused with lysosomes to degrade the hormones. This digestion of the hormones is performed in the hormone vesicles
The function of cristae in a mitochondrion is
Mitochondrial cristae are folds of the mitochondrial inner membrane that provide an increase in the surface area. This allows a greater space for processes that happen across this membrane. The electron transport chain and chemiosmosis are the processes which help produce ATP in the final steps of cellular respiration.
Which of the following provides mechanical
support and shape to the cell -
The endoplasmic reticulum (ER) is a system of membrane-lined channels found in all eukaryotic cells except mature erythrocytes. It constitutes more than 30 to 60 percent of total cell membranes. The membranes of ER act as an ultrastructural skeletal framework in the cell and provide mechanical support as it helps in formation and transportation of protein and lipid in membrane biogenesis.
Mitochondria are site of respiration first
reported by Kingsbury and supported by
Hogeboom. Mitochondira are related with the
oxidation of -
Peptidyl tranferase enzyme found on -
Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. Ribozymes are the only enzymes which are not made up of proteins, but ribonucleotides. All other enzymes are made up of proteins.
Which of the following transport the cell well
material from dictyosome -
Microtubules transport the cell wall material from dictyosome. Microtubules are very important in a number of cellular processes. They are involved in maintaining the structure of the cell and together with microfilaments and intermediate filaments, they form the cytoskeleton
Golgibody is absent in -
Golgi body is a cellular organelle that is part of the cytoplasmic membrane system; it is composed of regions of stacked cisternae and it functions in secretory processes. Prokaryotes, mature mammalian RBCs and the akaryotes (cells without the nucleus) lack the Golgi bodies.