The plasma membranes of adjacent cells essentially fuse together tightly in order to limit the leakage of various substances between the two cells. Tight junctions are also called zonula occludens. The word zonula comes from words that mean small zone or encircling belt, while occludens comes from the Latin word occludere, which means to close up. Answer : (b)

Plastids were discovered and named by Ernst Haeckel in the year 1886 Answer : (a)

The most prominent substructure within the nucleus is the nucleolus , which is the site of rRNA transcription and processing, and of ribosome assembly. Answer : (a)

Oxidative phosphorylation is a mechanism for ATP synthesis in both plant and animal cells. It involves the chemiosmotic coupling of electron transport and ATP synthesis. Oxidative phosphorylation occurs in the inner membrane of mitochondria , termed cristae. Answer : (c)

Ulothrix. : a genus (the type of the family Ulotrichaceae) of green algae that are common in ponds and consist of simple filaments with girdle -shaped green chloroplasts. Answer : (c)

Answer : (c)

Polymorphism, i.e. existence of a structure in more than one form, is an important feature of lysosomes. Several different forms of lysosomes have been identified within the cell as primary lysosomes, secondary lysosomes, residual bodies and autophagic vacuoles. Answer : (c)

Ribosomal RNA (rRNA), molecule in cells that forms part of the protein-synthesizing organelle known as a ribosome and that is exported to the cytoplasm to help translate the information in messenger RNA (mRNA) into protein Answer : (c)

Animal cells and plant cells share the common components of a nucleus, cytoplasm, mitochondria and a cell membrane. Answer : (c)

Erythrocytes (Red blood cells), biconcave disks packed with an oxygen-carrying compound called hemoglobin. Answer : (b)

Protein synthesis is a complex process, it essentially involves DNA for the synthesis of mRNA (transcription) which contains information for the synthesis of proteins (translation). The process of translation takes place on ribosomes which are found in cytoplasm (in attached form on ER) and in mitochondria (in the free form). Answer : (b)

Mesosomes are areas in the cell membrane of prokaryotic (bacterial) cells that fold inward. They play a role in cellular respiration, the process that breaks down food to release energy. Answer : (c)

Colour of rose petals is due to water-soluble pigment present in the vacuoles. The plant vacuoles consist of various water-soluble pigments such as carotenoids, anthocyanins and xanthophylls etc. Anthocyanins are also water-soluble pigments which are red, purple, or blue in colour depending on the pH (blueberry, raspberry etc). The colour of flower petals (red, pink, blue and purple) is mainly from the pigments called anthocyanins. the correct answer is 'Vacuoles'. Answer : (d)

Cilia are minute, hair like processes on the surface of protozoans or of metazoans cells each by their motion accomplish locomotion or produce a current. 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 membrane is not responsible for controlling the organized beating or cilia. Answer : (a)

The endoplasmic reticulum is little or poorly developed in meristematic cells, young dividing cells etc. Membranes of Endoplasmic reticulum are thinner than most other cell membranes. Answer : (b)

Anthocyanins are colored water-soluble pigments belonging to the phenolic group. The pigments are in glycosylated forms. Anthocyanins responsible for the colors, red, purple, and blue, are in fruits and vegetables A thoroughly washed beet root slice kept in water at room temperature does not lose anthocyanin pigment , does not come out.This indicates that most likely the plasma membrane is impermeable to anthocyanin Thin slices have a larger surface area and so leak more pigment; freezing the beetroot first bursts the cell membranes and kills the cells, thus allowing the pigment to be extracted much more quickly. Answer : (b)

A chromosome is metacentric if its two arms are roughly equal in length. Answer : (a)

Surface area to the volume ratio gets smaller as the cell gets larger. Or Surface area to the volume ratio gets larger as the cell gets smaller Answer : (b)

All plastids, including chloroplasts, develop from proplastids, small (0.2 to 1 μm in diameter) undifferentiated organelles present in the rapidly dividing cells of plant roots and shoots. Answer : (b)

Oxysomes refers to small round structures present within the folds of the cristae of the inner mitochondrial membrane. They are called elementary particles or Parson’s particle or Fernandez-Moran particle or F0F1-particles. Mitochondria consists of about 104 -105 oxysomes. Answer : (c)

The blue-green algae lack definite chloroplasts; instead they possess loosely arranged membranes in the cytoplasm on which the photosynthetic pigments are layered. The shape too vary considerably Answer : (d)

Fibrillar arrangement of a flagella represents the arrangement of the microtubules in the flagella The fibrillar arrangement of eukaryotic flagella and cilia is 9+2 It means that the microtubules are arranged in a nine fold radial symmetry called the axoneme They consist of a total of 11 longitudinal fibrils of which 2 are present in the center and 9 on the periphery" Answer : (b)

The glyoxylate cycle, a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants, bacteria, protists, and fungi. Net result of the glyoxylate cycle is therefore the production of glucose from fatty acids. Answer : (c)

Plants get carbon dioxide from the atmosphere which is released by animals and burning of fuels. With the help of carbon dioxide and water, plants synthesize its own food by photosynthesis. More carbon dioxide means more photosynthesis. Answer : (a)

According to the biogenic theory, new cells can only arise from pre-existing cells. Only complete cells, in favourable conditions, can give rise to new cells. Answer : (c)

peroxisomes are enclosed in membranes they are not considered part of the endomembrane system Answer : (c)

The middle lamella is made up of calcium and magnesium pectates. In a mature plant cell it is the outermost layer of cell wall. Answer : (b)

Bacteria are prokaryotes and are primitive cell or organism, so they have simple organization and are deprived of membraned bounded organelles. Answer : (a)

Answer : (b)

Plastids are semiautonomous cell organelles which are surrounded by double membrane envelope and are found only in plants cells and some unicellular organisms like Euglena. Plastids are of three main types - leucoplasts, chromoplasts and chloroplasts. The common among all the three organelles are that they have ability to multiply by a fission like process because these organelles contain their own genetic material and protein synthesizing machinery, i.e., DNA, RNA and ribosomes. Answer : (d)

Lysosomes are formed by the fusion of transport vesicles budded from the trans Golgi network with endosomes, which contain molecules taken up by endocytosis at the plasma membrane Answer : (b)

Elie Metchnikoff, a Russian scientist who was the first to discover phagocytosis Answer : (d)

In a plant, pectin is present in the middle lamella, primary cell and secondary walls and is deposited in the early stages of growth during cell expansion Answer : (b)

Eukaryotic ribosomes are also known as 80S ribosomes, referring to their sedimentation coefficients in Svedberg units Answer : (c)

Ribosome is also present in the organelles: chloroplast(in plant cells) and mitochondria. Thus ribosomes are called organelles within organelle. Answer : (d)

According to cell theory, cells are fundamental structural units of organisms Answer : (a)

This detoxification process occurs in the liver, which contains an abundance of smooth endoplasmic reticulum. The smooth endoplasmic reticulum plays an important role in detoxification of chemicals. Answer : (c)

Glycocalyx is the outermost layer of cell envelope. It is made up of mucopolysaccharides and it provides protection to bacterial cell. It also helps in adhesion. Glycocalyx is may be in the form of loose sheath ( Slime layer) or in the form of tough layer( Capsule) . Statement A is correct Statement B, C is wrong Mesosomes or chondrioids are folded invaginations in the plasma membrane of bacteria that are produced by the chemical fixation Statement D is correct Prokaryotic organism such as bacteria have hundreds of hair-like appendages or bristle like fibres sprouting out of cells called fimbriae, Statement E is correct Answer : (c)

All of nucleus, chloroplasts and mitochondria have their own DNA. Nucleic acid is a complex organic substance present in living cells, especially DNA or RNA, whose molecules consist of many nucleotides linked in a long chain Answer : (c)

Answer : (b)

Polytene chromosomes are present in secretory tissues of dipteran insects such as the Malpighian tubules of Sciara and also in protists, plants, mammals, or in cells from other insects. Some of the largest polytene chromosomes described thus far occur in larval salivary gland cells of the chironomid genus Axarus. Answer : (a)

F0 and F1 (oxysomes) particles are found in the inner mitochondrial region and are attached to the cristae and help in ATP production and oxidation Answer : (a)

The first cells from an organism (cork) were observed by Hooke in the 1600s. Soon after, microscopist van Leeuwenhoek observed many other living cells. Answer : (c)

Plasmodesmata is a narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells and allows communication between them. Answer : (c)

Vacuoles are non-living cell inclusions present in the cytoplasm which contain inorganic and organic molecules. Vacuoles are non-living as it does not have the parts to sustain life as itself, as without a nucleus and its own organelles Answer : (c)

Answer : (a)

Answer : (c)

A channel protein is a special arrangement of amino acids which embeds in the cell membrane, providing a hydrophilic passageway for water and small, polar ions. Like all transport proteins, each channel protein has a size and shape which excludes all but the most specific molecules Answer : (b)

The cytoskeleton of a cell is made up of microtubules, actin filaments, and intermediate filaments. These structures give the cell its shape and help organize the cell's parts. In addition, they provide a basis for movement and cell division. Answer : (b)

Mitochondria and chloroplasts divide by fission, much like bacteria. When the cell divides, the Mitochondria and chloroplasts are distributed to the daughter cells. Most of the proteins in the mito and chloro are encoded by the nuclear genome and they are imported, Mitochondria divide and are split amongst the daughter cells during cell proliferation Answer : (a)