NEET AIPMT Biology Chapter Wise Solutions – Cell: The Unit of Life
NEET AIPMT Biology Chapter Wise SolutionsPhysicsChemistry
1. Match the columns and identify the correct option.
| Column I | Column II | |
| A. | Thylakoids | (i) Disc-shaped sacs in Golgi apparatus |
| B. | Cristae | (ii) Condensed structure of DNA |
| C. | Cisternae | (iii) Flat membranous sacs in stroma |
| D. | Chromatin | (iv) Infoldings in mitochondria |
2. Which of the following structures is not found in a prokaryotic cell? (AIPMT 2015)
(a) Mesosome
(b) Plasma membrane
(c) Nuclear envelope
(d) Ribosome
3. Cellular organelles with membranes are (AIPMT 2015)
(a) endoplasmic reticulum, ribosomes and nuclei
(b) lysosomes, Golgi apparatus and mitochondria
(c) nuclei, ribosomes and mitochondria
(d) chromosomes, ribosomes and endoplasmic reticulum.
4. Which of the following are not membrane – bound? (AIPMT 2015)
(a) Lysosomes
(b) Mesosomes
(c) Vacuoles
(d) Ribosomes
5. DNA is not present in (AIPMT 2015, Cancelled)
(a) nucleus
(b) mitochondria
(c) chloroplast
(d) ribosomes.
6. Nuclear envelope is a derivative of (AIPMT 2015, Cancelled)
(a) microtubules
(b) rough endoplasmic reticulum
(c) smooth endoplasmic reticulum
(d) membrane of Golgi complex.
7. The structures that are formed by stacking of organised flattened membranous sacs in the chloroplasts are (AIPMT 2015, Cancelled)
(a) stroma lamellae
(b) stroma
(c) cristae
(d) grana.
8. Select the correct matching in the following pairs. (AIPMT 2015, Cancelled)
(a) Rough ER – Synthesis of glycogen
(b) Rough ER – Oxidation of fatty acids
(c) Smooth ER – Oxidation of phospholipids
(d) Smooth ER – Synthesis of lipids
9. The chromosomes in which centromere is situated close to one end are (AIPMT 2015, Cancelled)
(a) telocentric
(b) sub-metacentric
(c) metacentric
(d) acrocentric.
10. Which one of the following is not an inclusion body found in prokaryotes? (AIPMT 2015, Cancelled)
(a) Glycogen granule
(b) Polysome
(c) Phosphate granule
(d) Cyanophycean granule
11. The solid linear cytoskeletal elements having a diameter of 6 nm and made up of a single type of monomer are known as (AIPMT 2014)
(a) microtubules
(b) microfilaments
(c) intermediate filaments
(d) lamins.
12. The osmotic expansion of a cell kept in water is chiefly regulated by (AIPMT 2014)
(a) mitochondria
(b) vacuoles
(c) plastids
(d) ribosomes.
13. Match the following and select the correct answer. (AIPMT 2014)
(A) Centriole (i) Infoldings in mitochondria
(B) Chlorophyll (ii) Thylakoids
(C) Cristae (iii) Nucleic acids
(D) Ribozymes (iv) Basal body of cilia or
14. The Golgi complex plays a major role (NEET 2013)
(a) as energy transferring organelles
(b) in post translational modification of proteins and glycosylation of lipids
(c) in trapping the light and transforming it into chemical energy
(d) in digesting proteins and carbohydrates.
15. Which one of the following organelle in the figure correctly matches with its function? (NEET 2013)
(a) Golgi apparatus, formation of glycolipids
(b) Rough endoplasmic reticulum, protein synthesis
(c) Rough endoplasmic reticulum, formation of glycoproteins
(d) Golgi apparatus, protein synthesis.
16. A major site for synthesis of lipids is (NEET 2013)
(a) symplast
(b) nucleoplasm
(c) RER
(d) SER.
17. The term ‘glycocalyx’ is used for (Karnataka NEET 2013)
(a) a layer present between cell wall and membrane of bacteria
(b) cell wall of bacteria
(c) bacterial cell glyco-engineered to possess N-glycosylated proteins
(d) a layer surrounding the cell wall of bacteria
18. Which of the following types of plastid does not contain stored food material? (Karnataka NEET 2013)
(a) Chromoplasts
(b) Elaioplasts
(c) Aleuroplasts
(d) Amyloplas
19. Which of the following best illustrates “feedback” in development? (Karnataka NEET 2013)
(a) Tissue X secretes RNA which changes the development of tissue Y.
(b) As tissue X develops, it secretes enzymes that inhibit the development of tissue Y.
(c) As tissue X develops, it secretes something that induces tissue Y to develop.
(d) As tissue X develops, it secretes something that slows down the growth of tissue Y.
20. Select the alternative giving correct identification and function of the organelle ‘A’ in the diagram. (Karnataka NEET 2013)
(a) Mitochondria – Produce cellular energy in the form of ATP
(b) Golgi body – Provides packaging material
(c) Lysosomes – Secrete hydrolytic enzymes
(d) Endoplasmic reticulum – Synthesis of lipids
21. Select the correct statement from the following regarding cell membrane. (Prelims 2012)
(a)Na+ and K+ions move across cell membrane by passive transport.
(b) Proteins make up 60 to 70% of the cell membrane.
(c) Lipids are arranged in a bilayer with polar heads towards the inner part.
(d) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson.
22. What is true about ribosomes? (Prelims 2012)
(a) The prokaryotic ribosomes are 80S, where “S” stands for sedimentation coefficient.
(b) These are composed of ribonucleic acid and proteins.
(c) These are found only in eukaryotic cells.
(d) These are self-splicing introns of some RNAs.
23. Which one of the following does not differ in E.coli and Chlamydomonasl (Prelims 2012)
(a) Ribosomes
(b) Chromosomal organization
(c) Cell wall
(d) Cell membrane.
24. Which one of the following cellular parts is correctly described? (Mains 2012)
(a) Thylakoids – flattened membranous sacs forming the grana of chloroplasts.
(b) Centrioles – sites for active RNA synthesis.
(c) Ribosomes – those on chloroplasts are larger (80S) while those in the cytoplasm are smaller (70S).
(d) Lysosomes – optimally active at a pH of about 8.5.
25. Which one of the following structures is an organelle within an organelle? (Mains 2012)
(a) Ribosome
(b) Peroxisome
(c) ER
(d) Mesosome.
26. Peptide synthesis inside a cell takes place in (Prelims 2011)
(a) chloroplast
(b) mitochondria
(c) chromoplast
(d) ribosomes.
27. Important site for formation of glycoproteins and glycolipids is (Prelims 2011)
(a) vacuole
(b) Golgi apparatus
(c) plastid
(d) lysosome
28. Which one of the following is not considered as a part of the endomembrane system? (Mains 2011)
(a) Golgi complex
(b) peroxisome
(c) vacuole
(d) lysosome
29. The figure below shows the structure of a mitochondrion with its four parts labelled A, B, C and D. Select the part correctly matched with its function. (Mains 2011)
(a) D (outer membrane) – gives rise to inner membrane by splitting.
(b) B (inner membrane) – forms infoldings called cristae.
(c) C (crista) – possesses single circular DNA molecule and ribosomes.
(d) A (matrix) – major site for respiratory chain enzymes.
30. The plasma membrane consists mainly of (Prelims 2010)
(a) phospholipids embedded in a protein bilayer
(b) proteins embedded in a phospholipid bilayer
(c) proteins embedded in a polymer of glucose molecules
(d) proteins embedded in a carbohydrate bilayer.
31. The main area of various types of activities of a cell is (Prelims 2010)
(a) plasma membrane
(b) mitochondrion
(c) cytoplasm
(d) nucleus.
32. Which one of the following has its own DNA? (Prelims 2010)
(a) mitochondria
(b) dictyosome
(c) lysosome
(d) peroxisome.
33. Which one of the following structures between two adjacent cells is an effective transport pathway? (Prelims 2010)
(a) plasmodesmata
(b) plastoquinones
(c) endoplasmic reticulum
(d) plasmalemma.
34. An elaborate network of filamentous proteinaceous structures present in the cytoplasm which helps in the maintenance of cell shape is called (Mains 2010)
(a) thylakoid
(b) endoplasmic reticulum
(c) plasmalemma
(d) cytoskeleton
35. Identify the components labelled A, B, C and D in the diagram below from the list (i) to (viii) given along with (Mains 2010)
Components:
(i) Cristae of mitochondria
(ii) Inner membrane of mitochondria
(iii) Cytoplasm
(iv) Smooth endoplasmic reticulum
(v) Rough endoplasmic reticulum
(vi) Mitochondrial matrix
(vii) Cell vacuole
(viii) Nucleus
The correct components are:
36. Middle lamella is composed mainly of (Prelims 2009)
(a) muramic acid
(b) calcium pectate
(c) phosphoglycerides
(d) hemicellulose
37. Cytoskeleton is made up of (Prelims 2009)
(a) callose deposits
(b) cellulosic micro fibrils
(c) proteinaceous filaments
(d) calcium carbonate granules
38. Plasmodesmata are (Prelims 2009)
(a) locomotary structures
(b) membranes connecting the nucleus with plasmalemma
(c) connections between adjacent cells
(d) lignified cemented layers between cells
39. In germinating seeds fatty acids are degarded exclusively in the (Prelims 2008)
(a) peroxisomes
(b) mitochondria
(c) proplastids
(d) glyoxysomes.
40. Vacuole in a plant cell (Prelims 2008)
(a) lacks membrane and contains air
(b) lacks membrane and contains water and excretory substances
(c) is membrane-bound and contains storage proteins and lipids
(d) is membrane-bound and contains water and excretory substances.
41. The two sub-units of ribosome remain united at a critical ion level of (Prelims 2008)
(a) magnesium
(b) calcium
(c) copper
(d) manganese.
42. Keeping in view the ‘fluid mosaic model for the structure of cell membrane, which one of the following statement is correct with respect to the movements of lipids and proteins from one lipid monolayer to the other (described as flipflop movement)? (Prelims 2008)
(a) while proteins can flip-flop, lipids can not
(b) neither lipids, nor proteins can flip-flop
(c) both lipids and proteins can flip-flop
(d) while lipids can rarely flip-flop, proteins can not.
43. Which one of the following is not a constituent of cell membrane? (2007)
(a) glycolipids
(b) proline
(c) phospholipids
(d) cholesterol.
44. Select the wrong statement from the following. (2007)
(a) both chloroplasts and mitochondria have an internal compartment, the thylakoid space bounded by the thylakoid membrane
(b) both chloroplasts and mitochondria contain DNA
(c) the chloroplasts are generally much larger than mitochondria
(d) both chloroplasts and mitochondria contain an inner and an outer membrane.
45. Biological organisation starts with (2007)
(a) cellular level
(b) organismic level
(c) atomic level
(d) submicroscopic molecular level.
46. Which of the following statements regarding mitochondrial membrane is not correct ? (2006)
(a) the outer membrane resembles a sieve
(b) the outer membrane is permeable to all kinds of molecules
(c) the enzymes of the electron transfer chain are embedded in the outer membrane
(d) the inner membrane is highly convoluted forming a series of infoldings
47. Which of the following statements regarding cilia is not correct ? (2006)
(a) cilia contain an outer ring of nine doublet microtubules surrounding two singlet microtubules
(b) the organized beating of cilia is controlled by fluxes of Ca2+across the membrane
(c) cilia are hair-like cellular appendages
(d) microtubules of cilia are composed of tubulin
48. A major breakthrough in the studies of cells came with the development of electron microscope. This is because (2006)
(a) the electron microscope is more powerful than the light microscope as it uses a beam of electrons which has wavelength much longer than that of photons
(b) the resolving power of the electron microscope is much higher than that of the light microscope
(c) the resolving power of the electron microscope is 200 – 350 nm as compared to 0.1 – 0.2 nm for the light microscope
(d) electron beam can pass through thick materials, whereas light microscopy requires thin sections
49. Chlorophyll in chloroplasts is located in (2005)
(a) grana
(b) pyrenoid
(c) stroma
(d) both grana and stroma.
50. A student wishes to study the cell structure under a light microscope having 10X eyepiece and 45X objective. He should illuminate the object by which one of the following colours of light so as to get the best possible resolution? (2005)
(a) blue
(b) green
(c) yellow
(d) red.
51. According to widely accepted “fluid mosaic model’’ cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statements is incorrect?
(a) proteins in cell membranes can travel within the lipid bilayer.
(b) proteins can also undergo flip-flop movements in the lipid bi layer.
(c) proteins can remain confined within certain domains of the membrane.
(d) many proteins remain completely embedded within the lipid bilayer.
52. Centromere is required for (2005)
(a) movement of chromosomes towards poles
(b) cytoplasmic cleavage
(c) crossing over
(d) transcription.
53. Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on (2005)
(a) membrane potential
(b) accumulation of Na ions
(c) accumulation of K ions
(d) proton gradient.
54. The main organelle involved in modification and outing of newly synthesized proteins to their destinations is (2005)
(a) chloroplast
(b) mitochondria
(c) lysosome
(d) endoplasmic reticulum.
55. The telomeres of eukaryotic chromosomes consist of short sequences of (2004)
(a) thymine rich repeats
(b) cytosine rich repeats
(c) adenine rich repeats
(d) guanine rich repeats.
56. In chloroplasts, chlorophyll is present in the (2004)
(a) outer membrane
(b) inner membrane
(c) thylakoids
(d) stroma.
57. Cellular totipotency is demonstrated by (2003)
(a) only gymnosperm cells
(b) all plant cells
(c) all eukaryotic cells
(d) only bacterial cells
58. Ribosomes are produced in (2002)
(a) nucleolus
(b) cytoplasm
(c) mitochondria
(d) golgi body.
59. In fluid mosaic model of plasma membrane (2002)
(a) upper layer is non-polar and hydrophilic
(b) upper layer is polar and hydrophobic
(c) phospholipids form a bimolecular layer in middle part
(d) proteins form a middle layer.
60. Element necessary for the middle lamella is (2001)
(a) Ca
(b) Zn
(c) K
(d) Cu.
61. Microtubules are absent in (2001)
(a) mitochondria
(b) flagella
(c) spindle fibres
(d) centrioles.
62. Proteinaceous pigment which controls the activities concerned with light is (2001)
(a) phytochrome
(b) chlorophyll
(c) anthocyanin
(d) carotenoids.
63. When water moves through a semipermeable ( membrane then which of the following pressure develops? (2001)
(a) osmotic pressure
(b) suction pressure
(c) turgor pressure
(d) wall pressure
64. Lysosome contains (2000)
(a) oxidative enzymes
(b) hydrolytic enzymes
(c) reductive enzymes
(d) anabolic enzymes.
65. Which of the following ribosomes are engaged in protein synthesis in animal cell? (2000)
(a) ribosomes which occur on nuclear membrane and E.R.
(b) ribosomes of only cytosol
(c) ribosomes of only nucleolus and cytosol
(d) ribosomes of only mitochondria and cytosol.
66. Function of telomeres in nucleus is (2000)
(a) poleward movement
(b) to initiate the RNA synthesis
(c) to seal the ends of chromosome
(d) to recognise the homologous chromosome.
67. Which cell organelle is concerned with glycosylation of protein? (2000)
(a) ribosome
(b) peroxisome
(c) endoplasmic reticulum
(d) mitochondria.
68. Which of the following organelles has single membrane? (1999)
(a) mitochondria
(b) spherosomes
(c) nucleus
(d) cell wall.
69. The proteins are synthesized at (1999)
(a) centrosomes
(b) golgi bodies
(c) ribosomes
(d) mitochondria.
70. Which of the following structures will not be common to mitotic cell of a higher plant? (1997)
(a) centriole
(b) spindle fibre
(c) cell plate
(d) centromere.
71. The mechanism of ATP formation both in chloroplast and mitochondria is explained by (1997)
(a) chemiosmotic theory
(b) Munch’s hypothesis (mass flow model)
(c) relay pump theory of Godlewski
(d) Cholodny-Wont’s model.
72. Protein synthesis in an animal cell, takes place (1997)
(a) in the cytoplasm as well as endoplasmic reticulum
(b) only on ribose attached to nucleon
(c) only in the cytoplasm
(d) in the nucleolus as well as in the cytoplasm.
73. Lysosomes are rich in (1996)
(a) nucleic acids
(b) hydrolytic enzymes
(c) carbohydrates
(d) hormones.
74. Colchicine is an inhibitory chemical, which (1996)
(a) stops the functioning of centriole
(b) prevents attaching of centromeres with rays
(c) prevents the spindle formation in mitosis
(d) prevents the formation of equatorial plane.
75. The prokaryotic flagella possess (1995)
(a) helically arranged protein molecule
(b) “9 + 2” membrane enclosed structure
(c) unit membrane enclosed fibre
(d) protein membrane enclosed fibre.
76. The desmosomes are concerned with (1995)
(a) cell division
(b) cell adherence
(c) cytolysis
(d) cellular excretion.
77. Which of the following organelles contain enzymes that have digestive action? (1994)
(a) ribosomes .
(b) polysomes
(c) plastids
(d) lysosomes
78. In mitochondria, cristae act as sites for (1994)
(a) protein synthesis
(b) phosphorylation of flavoproteins
(c) breakdown of macromolecules
(d) oxidation-reduction reaction.
78. In mitochondria, cristae act as sites for (1994)
(a) protein synthesis
(b) phosphorylation of flavoproteins
(c) breakdown of macromolecules
(d) oxidation-reduction reaction.
79. Centromere is required for (1994)
(a) replication of DNA
(b) chromosome segregation
(c) poleward movement of chromosomes
(d) cytoplasmic cleavage.
80. Which one of the following organelles is located near the nucleus and contains a collection of flattened membrane bound cistemae? (1994)
(a) nucleolus
(b) mitochondrion
(c) centriole
(d) golgi apparatus.
81. The inner membrane of the mitochondria is, usually, highly convoluted forming a series of infoldings known as (1994)
(a) thylakoids
(b) lamellae
(c) cristae
(d) grana.
82. Besides giving out secretory vesicles, the Golgi apparatus is also concerned with the formation of (1994)
(a) lysosomes
(b) plastids
(c) grana of chloroplasts
(d) cell plates after cell division in plants.
83. Active and passive transports across cell membrane differ in (1993)
(a) passive transport is nonselective
(b) passive transport is along the concentration gradient while active transport is due to metabolic energy
(c) active transport is more rapid
(d) passive transport is confined to anions while active transport in confined to cations.
84. Balbiani rings (puffs) are sites of (1993)
(a) DNA replication
(b) RNA and protein synthesis
(c) synthesis of polysaccharides
(d) synthesis of lipids.
85. In plant cells, peroxisomes are associated with (1993)
(a) photorespiration
(b) phototropism
(c) photoperiodism
(d) photosynthesis.
86. Membranous bag with hydrolytic enzymes which is used for controlling intracellular digestion of macro-molecules is (1993)
(a) endoplasmic reticulum
(b) nucleosome
(c) lysosome
(d) phagosome.
87. Golgi apparatus is absent in (1993)
(a) higher plants
(b) yeast
(c) bacteria and Blue-green algae
(d) none.
88. Cell recognition and adhesion occur due to biochemicals of cell membranes named (1993)
(a) proteins
(b) lipids
(c) proteins and lipids
(d) glycoproteins and glycolipids.
89. In salivary gland chromosomes/polytene chromosomes, pairing is (1993)
(a) absent
(b) occasional
(c) formed between nonhomologous chromosomes
(d) formed between homologous chromosomes.
90. Which is correct about cell theory in view of current status of our knowledge about cell structure? (1993)
(a) it needs modification due to discovery of subcellular structures like chloroplasts and mitochondria
(b) modified cell theory means that all living being are composed of cells capable of reproducing
(c) cell theory does not hold good because all living beings (e.g., viruses) do not have cellular organisation
(d) cell theory means that all living objects +consists of cells whether or not‘capable of reproducing.
91. Names of Schleiden and Schwann are associated with (1993)
(a) protoplasm as the physical basis of life
(b) cell theory
(c) theory of cell lineage
(d) nucleus fimctions as control centre of cell.
92. Binding of specific protein on regulatory DNA sequency can be studied by means of (1993)
(a) ultra centrifugation
(b) electron microscope
(c) light microscope
(d) X-rays crystallography.
93. All types of plastids possess essentially the same structure because they (1992)
(a) Perform the same function
(b) Store food materials like starch, fat and protein
(c) Occur in aerial parts
(d) Can transform from one form to another.
94. Experiments on Acetabularia by Hammerling proved the role of (1992)
(a) cytoplasm in controlling differentiation
(b) nucleus in heredity
(c) chromosomes in heredity
(d) nucleo-cytoplasmic ratio.
95. Which one is apparato reticolarel (1992)
(a) golgi apparatus
(b) endoplasmic reticulum
(c) microfilaments
(d) microtubules.
96. An outer covering membrane is absent over (1992)
(a) nucleolus
(b) lysosome
(c) mitochondrion
(d) plastid.
97. All plastids have similar structure because they can (1992)
(a) store starch, lipids and proteins
(b) get transformed from one type to another
(c) perform same function
(d) be present together.
98. Oxysomes of F0 – F1 particles occur on (1992)
(a) thylakoids
(b) mitochondrial surface
(c) inner mitochondrial membrane
(d) chloroplast surface.
99. Ribosomes are the centre for (1992)
(a) respiration
(b) photosynthesis
(c) protein synthesis
(d) fat synthesis.
100. Angstrom (A) is equal to (1992)
(a) 0.01 mm
(b) 0.001 mm
(c) 0.0001 mm
(d) 0.00001 mm
101. Electron microscope has a high resolution power. This is due to (1992, 90)
(a) Electromagnetic lenses
(b) Very low wavelength of electron beam
(c) Low wavelength of light source used
(d) High numerical aperture of glass lenses used.
102. Addition of new cell wall particles amongst the existing ones is (1991)
(a) deposition
(b) apposition
(c) intussusception
(d) aggregation.
103. Cell wall shows (1991)
(a) complete permeability
(b) semipermeability
(c) differential permeability
(d) impermeability.
104. Ribosomes were discovered by (1991)
(a) Golgi
(b) Porter
(c) De Robertis
(d) Palade.
105. Fluid mosaic model of cell membrane was put forward by (1991)
(a) Danielli and Davson
(b) Singer and Nicolson
(c) Garner and Allard
(d) Watson and Crick.
106. Resolution power is the ability to (1991)
(a) distinguish two close points
(b) distinguish two close objects
(c) distinguish amongst organelles
(d) magnify image.
107. Hammerling’s experiments of Acetabularia involved exchanging (1990)
(a) cytoplasm
(b) nucleus
(c) rhizoid and stalk
(d) gametes.
108. The latest model for plasma membrane is (1990)
(a) lamellar model
(b) unit membrane model
(c) fluid mosaic model
(d) molecular lipid model.
109. Magnification of compound microscope is not connected with (1990)
(a) numerical aperture
(b) focal length of objective
(c) focal length of eye piece
(d) tube length.
110. A bivalent consists of (1989)
(a) two chromatids and one centromere
(b) two chromatids and two centromeres
(c) four chromatids and two centromeres
(d) four chromatids and four centromeres.
111. Nucleoproteins are synthesised in (1989)
(a) nucleoplasm
(b) nuclear envelope
(c) nucleolus
(d) cytoplasm.
112. Polyribosomes are aggregates of
(a) ribosomes and rRNA
(b) only rRNA
(c) peroxisomes
(d) several ribosomes held together by string of mRNA. (1989)
113. Plasmamembrane is made of (1989)
(a) proteins and carbohydrates
(b) proteins and lipids
(c) proteins, lipids and carbohydrates
(d) proteins, some nucleic acid and lipids.
114. Organelles can be separated from cell homogenate through (1989)
(a) chromatography
(b) X-rays diffraction
(c) differential centrifugation
(d) auto-radiography.
115. Acetabularia used in Hammerling’s (1988)
nucleocytoplasmic experiments is
(a) unicellular fungus
(b) multicellular fungus
(c) unicellular uninucleate green algae
(d) unicellular multinucleate green algae.
116. A ccording to fluid mosaic model, plasma membrane is composed of (1988)
(a) phospholipids and oligosaccharides
(b) phospholipids and hemicellulose
(c) phospholipids and integral proteins
(d) phospholipids, extrinsic proteins and intrinsic proteins.
1. (d)
2. (c)
A prokaryotic cell is characterised by absence of an organised nucleus and membrane bound cell organelles. DNA is naked i.e., without a nuclear envelope and lies variously coiled in the cytoplasm. It is commonly called nucleoid or genophore. Mesosomes, plasma membrane and 70S ribosomes are present in a prokaryotic cell.
3. (b)
Endoplasmic reticulum, nuclei, lysosomes, Golgi apparatus and mitochondria are membrane bound cell organelles whereas ribosomes are naked ribonucleoprotein protoplasmic particles. Chromosomes are the hereditary particles present in the nucleus.
4. (d)
Endoplasmic reticulum, nuclei, lysosomes, Golgi apparatus and mitochondria are membrane bound cell organelles whereas ribosomes are naked ribonucleoprotein protoplasmic particles. Chromosomes are the hereditary particles present in the nucleus.
5. (d)
Ribosome is a small spherical body within a living cell that is the site of protein synthesis. Ribosomes consist of two subunits, one large and one small, each of which comprises some RNA (called ribosomal RNA) and protein. They are found in both eukaryotic and prokaryotic cells. In prokaryotes, 70S ribosomes and in eukaryotes, 80S ribosomes are found where ‘S’ denotes Svedberg unit. They do not have any DNA.
6. (b)
Recent developments have shown that nuclear membrane is derived from rough endoplasmic reticulum. During cell division, nuclear membrane is disintegrated. The nuclear envelope transmembrane proteins are absorbed in the RER. Once the division is completed, RER reassembles the nuclear envelope.
7. (d)
A chloroplast is a vesicle, bound by an envelope of two unit membranes and filled with a fluid matrix called stroma. The lamellae, after separation from the inner membrane, usually take the form of closed, flattened, ovoid sacs, the thylakoids, which lie closely packed in piles, the grana.
8. (d)
Smooth endoplasmic reticulum (SER) is a system of smooth membranes (i.e., membranes not having ribosomes) within the cytoplasm of plant and animal cells. It forms a link between the cell and nuclear membranes. It is the site of important metabolic reactions, including phospholipid and fatty acid synthesis. In animal cells lipid-like steroidal hormones are also synthesized.
9. (d)
Centromere is a part of a chromosome that attaches to the spindle during cell division. The position of the centromere is a distinguishing feature of individual chromosomes. A chromosome with the centromere at its centre is described as metacentric; one with the centromere close to one end is acrocentric; and a chromosome with terminal centromere is telocentric. The centromere usually appears as a constriction when chromosomes contract during cell division.
10. (b)
Polysome is a not an inclusion body. It is an aggregation of ribosomes formed under conditions of high concentration of magnesium. An inclusion body is any of various particulate structures, usually I proteins, formed after viral infections in a prokaryotic or eukaryotic cell.
11. (b)
Microtubules are hollow microscopic tubular structures with an external diameter of 24 nm and of variable length. They are composed of tubulin. Intermediate filaments are the numerous microscopic protein fibres of about 10 nm thickness that form part of the cytoskeleton. They are made up of a variety of proteins e.g. keratin in nails. Microfilaments are 7-9 nm in diameter and composed of actin. Each microfilament consists of two helically twisted strands, each comprising a chain of globular sub units of actin proteins.
12. (b)
Vacuoles are non cytoplasmic areas present inside cytoplasm and separated from 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 cell.
13. (a)
14. (b)
Post translational modification (PTM) is a step in protein biosynthesis. Proteins are created on ribosomes translating mRNA into polypeptide chains. These polypeptide chains undergo PTlfa, such as folding, cutting and other processes, before becoming the mature protein product. Proteins synthesized by the rough endoplasmic reticulum and lipids synthesized by smooth endoplasmic reticulum reach the cisternae of the Golgi apparatus. Here, they combine with carbohydrates to form glycoproteins and glycolipids. This process is called glycosylation.
15. (b)
The given figure shows endoplasmic reticulum bearing ribosomes on their surface. It is called rough endoplasmic reticulum or RER. RER is actively involved in protein synthesis and secretion.
16. (d)
Smooth endoplasmic reticulum (SER) is a system of smooth membranes (i.e., membranes not having ribosomes) within the cytoplasm of plant and animal cells. It forms a link between the cell and nuclear membranes. It is the site ofimportant metabolic reactions, including phospholipid and fatty-acid synthesis.In animal cells lipid-like steroidal hormones are also synthesized.
17. (d)
Glycocalyx is a sticky, gelatinous material that collects outside the cell wall of bacteria to form an additional surface layer. When this layer is firmly attached to the surface of the cell, it is called a capsule. If it is loosely distributed around the cell, the glycocalyx is called a slime layer.
18. (a)
Chromoplasts are yellow or reddish in colour because of the presence of carotenoid pigments. They do not contain stored food material. Chromoplasts are formed either from leucoplasts or chloroplasts. Chromoplasts provide colour to many flowers for attracting pollinating insects. They provide bright red or orange colour to fruits for attracting animals for dispersal. Amyloplasts are starch containing leucoplasts, e.g., potato tuber. Elaioplasts or lipidoplasts or oleoplasts are colourless plastids which store lipids e.g., tube rose. Aleuroplasts orproteoplasts or proteinoplasts are protein storing plastids, e.g., aleurone cells of maize grain, endosperm cells of castor.
19. (c)
As tissue X develops it secretes something i that induces tissue Y to develop indicating positive feedback mechanism.
20. (a)
Mitochondria are small spheres or short rod¬like structures. It is a vesicle bounded by an envelope of two unit membranes and filled with a fluid matrix. Mitochondria are the main sites of cell respiration. They bring about complete oxidation of food stuffs or respiratory substrates into carbon dioxide and water and form energy rich ATP which helps in performing various energy requiring processes. On this account, mitochondria are often described as the power house or storage batteries or ATP mills of the cell.
21. (d)
According to the fluid mosaic model of cell membrane structure proposed by Singer and Nicolson (1972) plasma membrane contains about 50-60% proteins and 50-40% lipids. Lipids form a bilayer with hydrophilic heads pointing outwards. Cell membrane allows transport of some molecules by passive transport e.g., water, neutral solutes while some are transported actively e.g., Na+ /K+pump.
22. (b)
Ribosome is a small spherical body within a living cell that is the site of protein synthesis. Ribosomes consist of two subunits, one large and one small, each of which comprises a type of RNA (called ribosomal RNA) and protein. They are found in both eukaryotic and prokaryotic cells. In prokaryotes 70 S ribosomes and in eukaryotes 80 S ribosomes are found where ‘S’ denotes Svedberg Unit.
23. (d)
E. coli (bacteria) is a prokaryote while Chlamydomonas (algae) is a eukaryote. Ribosomes of both groups differ being 70S in prokaryotes and 80S in eukaryotes. Prokaryotic chromosomes lack histone protein unlike eukaryotic ones. Cell wall organization also differs as bacterial cell wall is rich in muramic acid while algal cell wall is cellulosic. It is the cell membrane which has similar organization in both the groups.
24. (a)
Thylakoid are the flattened sac-like membranous structures that are stacked on top of one another to form the grana of plant chloroplast. Chlorophyll and other photosynthetic pigments are situated in the thylakoid membranes, which are the site for the light-dependent reactions of photosynthesis. The centrioles form the basal body of cilia or flagella, and spindle fibres that give rise to spindle apparatus during cell division in animal cells. It is made up of nine evenly spaced peripheral fibrils of tubulin protein. Lysosomes are rich in hydrolytic enzymes (acid hydrolases) which are optimally active at acidic pH (pH of 4 – 5). Chloroplast ribosomes are 70S. They resemble the ribosomes of prokaryotes. With the help of ribosomes the chloroplast is able to synthesize most of the enzymes required by it.
25. (a)
Ribosomes occur in all living cells except mammalian erythrocytes or red blood corpuscles. Depending upon the place of their occurrence, ribosomes are of two types-cytoplasmic ribosomes and organelle ribosomes. The cytoplasmic ribosomes (cytoribosomes) may remain free in the cytoplasmic matrix or attached’ to the cytosolic’ surface of endoplasmic reticulum with the help of special ribophorin or SRP protein. The organelle ribosomes are found in plastids (plastiribosomes) and mitochondria (mitoribosomes) Cytoplasmic ribosome are of 80S type in eukaryotic cell whereas organelle ribosomes are of 70S type.
26. (d)
Peptide synthesis inside a cell takes place in ribosome. Ribosomes are found in all cells and are involved in protein synthesis. The major constituents of ribosomes are RNA and proteins present in approximately equal amounts.
27. (b)
Eukaryotic cells contain a unique cluster of membrane vesicles known as Golgi apparatus. It principally performs the function of packaging materials. The newly synthesized proteins are handed over to the Golgi apparatus which is catalysed by the addition of carbohydrates, lipid or sulphates moieties to the proteins. Golgi apparatus is the important site of formation of glycoproteins and glycolipids.
28. (b)
While each of the membranous organelles is distinct in terms of its structure and function, many of these are considered together as an endomembrane system because their functions are coordinated. The endomembrane system include endoplasmic reticulum (ER), Golgi complex, lysosomes and vacuoles. Since the functions of the mitochondria, chloroplast and , peroxisomes are not coordinated with the above components, these are not considered as part of the endomembrane system.
29. (b)
Each mitochondrion is a double membrane- bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments, i.e., the outer compartment and the inner compartment. The inner compartment is called the matrix. The outer membrane forms the continuous limiting boundary of the organelle. The inner membrane forms a number of infoldings called the cristae towards the matrix. The cristae increase the surface area. The two membranes have their own specific enzymes associated with the mitochondrial function.
30. (b)
Plasma membrane consists of lipids (20-79%), proteins (20-70%), carbohydrates (1-5%) and water (20%). Lipid molecules possess both hydrophobic and hydrophilic ends and are thus arranged in the form of lipid bilayer. Most common lipid of the bilayer is phospholipid. Protein molecules occur at places both inside (intrinsic proteins) and on the outer side (extrinsic proteins) of the phospholipid bilayer.
31. (c)
Cytoplasm is granular, crystallo-colloidal complex that forms the living protoplasm of a cell excluding its nucleus. It consists of proteins, nucleic acids, fats, carbohydrates, vitamins, minerals, waste metabolites, and all the organelles. It is the main area for various types of activities of a cell like respiration, nutrition, storage, etc.
32. (a)
Mitochondrion is a structure within the cytoplasm of eukaryotic cells that carries out aerobic respiration. It is the site of the Krebs’ cycle and electron transport chain, and therefore the cell’s energy production. Mitochondria vary greatly in shape, size, and number but are typically oval or sausage-shaped and bounded by two membranes, the inner one being folded into finger-like projections (cristae); they contain their own DNA and 70S ribosomes.
33. (a)
Plasmodesmata are fine cytoplasmic strands that connect the protoplasts of adjacent plant cells by passing through their cell walls. Plasmodesmata are cylindrical in shape (about 20-40 nm in diameter) and are lined by the plasma membrane of the two adjacent cells. They permit the passage between cells of substances including ions, sugars, amino acids, and macromolecules.
34. (d)
35. (a)
A – Rough endoplasmic reticulum
B – Smooth endoplasmic reticulum
C – Nucleus
D – Cytoplasm
36. (b)
Middle lamella of cell wall is composed of calcium and magnesium pectate. It joins the adjoining cells together and thus acts as a cementing layer.
37. (c)
The ability of eukaryotic cells to adopt a variety of shapes and to carry out coordinated and directed movements depends on the cytoskeleton. The cytoskeleton extends througout the cytoplasm and is a complex network of three types of protein filaments microtubules, microfilaments (or actinfilaments) and intermediate filaments (IFs). The main proteins that are present in the cytoskeleton are tubulin (in the microtubules), actin, myosin, tropomyosin and other (in the microfilaments) and keratins, vimentin, desmin,lamin and other (in intermediate filaments).
38. (c)
Plasmodesmata are fine cytoplasmic strands that connect the protoplasts of adjacent plant cells by passing through their cell walls. Plasmodesmata are cylindrical in shape (about 20-40 nm in diameter) and are lined by the plasma membrane of the two adjacent cells. They permit the passage between cells of substances including ions, sugars, amino acids, and macromolecules.
39. (d)
Glyoxysomes are small, spherical vesicles enclosed by a single unit membrane. Glyoxysomes are generally found in cells of yeast, Neurospora and in germinating fatty seeds where fat is being converted into carbohydrates, i.e., glyoxylate cycle (gluconeogenesis).
40. (d)
In a plant cell, vacuole may be defined as a non-living reservoir, bounded by a differentially or selectively permeable membrane, the tonoplast. It is filled with a highly concentrated solution called vascular sap or cell sap which contains many dissolved solutes such as organic acids, soluble carbohydrates, soluble nitrogenous compounds as nitrates, enzyme, tannins, chlorides, phosphates, amino acids, alkaloids and anthocyanin pigments.
41. (a)
Ribosomes are very small organelles having a diameter of 150 A – 250 A. Each ribosome is made up of two subunits, a smaller subunit and another larger subunit. These two subunits are associated with the I help of Mg2+ ions (at 0.001 M concentration). If the Mg2+ions concentration is less in cytoplasm, the two units of ribosome separate but when the Mg2+ ions concentration is increased ten times, the two unites and form a dimer.
42. (d)
According to fluid mosaic model there is rapid internal motion involving flexing within each lipid molecule a rapid lateral diffusion of the lipids is possible and a slow ‘flip-flop’ motion, i.e., a transfer of lipid molecules from one side of the bilayer to the other, is also possible. The lipid molecules might also rotate about 1 their axes. The proteins of the membrane are concerned with the enzymatic activity of the membrane, with transport of molecules, and with a receptor function whereas, the lipid bilayer provides the permeability barrier.
43. (b)
Chemically a biomembrane consists of lipids (20-70%), proteins (20-70%), carbohydrates (1 -5%) and water (20%). The important lipids of the membrane are phospholipids (some hundred types), sterols, (e.g. cholesterol), glycolipids, sphingolipid (e.g., ; sphingomyelin, cerebrosides). Protein can be fibrous or globular structural carrier, receptor or enzymatic. The lipid molecules are amphiatic or amphipathic, that is, they possess both polar hydrophilic (water loving) and non-polar hydrophobic (water repelling) ends. The hydrophilic region is in the form of head while hydrophobic part contains two tails of fatty acids. It results in formation of a lipid bilayer. Most common lipid of the bilayer is phospholipids. Protein molecules also possess both polar and non-polar side chains. Usually their poly hydrophilic linkages are towards the outer side. The non-polar or hydrophobic linkage are either kept folded inside or used to establish connections with hydrophobic parts of the lipids.
44. (a)
Both chloroplasts and mitochondria contain DNA and are double membrane bound organelles having an inner membrane and outer membrane. Mitochondria occur in cytoplasm of both plants and animal cells. A mitochondria contains two chambers. The inner membrane forms mitochondrial cristae. Chloroplast is also a double membranous organelle but found only in plants. The membrane bound matrix of chloroplasts is stroma and inside the stroma thylakoids are present which form grana.
45. (d)
Molecular assemblies are large organised sets of molecular units that make up parts of organelles. For example one common macromolecular assembly is the microtubule which is important in forming structure in the cell related to maintaining the cell structure or related to cell movement. The cell (plasma) membrane that surrounds many organelles and the cell is a highly organised molecular assembly.
46. (c)
The outer membrane of mitochondrion is smooth, freely permeable to most small molecules, contains fewer enzymes and is poor in proteins. It has porin proteins which form channels for the passage of molecules through it. It allows uptake of substrates and release of ATP. The inner membrane is semipermeable and regulates the passage of materials into and out of the mitochondrion. It is rich in enzymes and carrier proteins (permeases). It is usually produced into numerous infolds called cristae (singular crista). It bears minute regularly spaced lollipop-shaped particles known as oxysomes. The rest of the inner membrane contains the electron carrier molecules of the electron transport chain.
47. (b)
Cilia are fine hair like vibratile, cytoplasmic processes borne by certain cell types. Their movement either propel the organism or move the medium past a fixed cell. The cilia are enclosed by a unit membrane which is an extension of the plasma membrane of the cell. Within the membrane, is a fluid matrix having a supporting axial shaft, or axoneme. The axoneme is composed of eleven microtubules. Two microtubules are single and lie at the centre with a gap inbetween. They are called central singlets. The remaining nine microtubules are double and lie in a ring around the central microtubules. The two microtubules forming a doublet are named A and B subtubules. The microtubules, single as well as double, are composed of the globular units of the protein tubulin. The arms of A microtubules contain a protein dynein. The latter is ATPase enzyme which catalyzes hydrolysis of ATP to ADP, and transfers the free energy released direct to ciliary work.
48. (b)
Microscopes are used for studying cellular structures. They are used to magnify small objects. In electron microscopes, a high energy beam of electrons is focused through electromagnetic lenses. It can magnify very small details with high resolving power. The increased resolution results from the shorter i wavelength of the electron beam.
49. (a)
A chloroplast is a vesicle bounded by an envelope of two unit membranes and filled with a fluid matrix called stroma. The lamellae, after separation from the inner membrane, usually take the form of closed, flattened, ovoid sacs, the thylakoids, which lie closely packed in piles, the grana. The thylakoid membrane contains photosynthetic pigments namely, chlorophyll a, chlorophyll b, carotenoids (carotene, xanthophylls) and plastoquinone. The thylakoid membranes also contain ‘ coupling factors that bring about ATP synthesis.
50. (a)
Resolution of microscope is inversely proportional to wavelength of light used. Out of four options given, blue light has minimum wavelength and hence maximum resolution.
51. (b)
According to fluid mosaic model there is rapid internal motion involving flexing within each lipid molecule a rapid lateral diffusion of the lipids is possible and a slow ‘flip-flop’ motion, i.e., a transfer of lipid molecules from one side of the bilayer to the other, is also possible. The lipid molecules might also rotate about 1 their axes. The proteins of the membrane are concerned with the enzymatic activity of the membrane, with transport of molecules, and with a receptor function whereas, the lipid bilayer provides the permeability barrier.
52. (a)
Centromere is the point at which the two chromatids of a chromosome are held together. During movement of chromosomes, the spindle fibres (on which the chromatids move) are attached to the centromere. Crossing over involves physical exchange of genetic material between non-sister chromatids of homologous chromosomes. Cytoplasmic cleavage is the division of cytoplasm. Transcription is the process in which the genetic information of DNA is transferred to mRNA as the first step in protein synthesis.
53. (d)
Chemiosmotic coupling hypothesis is the most widely accepted explanation for oxidative phosphorylation in mitochondria and photophos-phorylation in thylakoid membranes. Mitchell proposed the idea of chemiosmotic coupling. He suggested that a concentration gradient of protons is established across the mitochondrial membrane because there is an accumulation of hydrogen ions on one side of the mitochondrial membrane. The proton accumulation is necessary for energy transfer to the endergonic ADP phosphorylation process.
54. (d)
The proteins formed on ribosomes pass into the ER lumen where they are modified. Then the modified proteins move on into the transitional area, where the ER buds off membranous sacs, the transport vesicles, carrying the proteins to the Golgi apparatus. Here, they are further processed and packaged into secretory vesicles for export by exocytosis at the plasma membrane. Chloroplasts are specialized to perform photosynthesis. Mitochondria is the power house of the cell. Lysosomes contain hydrolytic enzymes.
55. (d)
Telomeres are highly conserved element throughout the eukaryotes both in structure and function. Telomeric DNA has been shown to consist of simple randomly repeated sequences, characterised by clusters of G residues in one strand and C residues in other strand. A short sequence of (12-16 nucleotides in length) of G rich strand as 3′ overhang is another feature of telomere.
56. (c)
A chloroplast is a vesicle bounded by an envelope of two unit membranes and filled with a fluid matrix called stroma. The lamellae, after separation from the inner membrane, usually take the form of closed, flattened, ovoid sacs, the thylakoids, which lie closely packed in piles, the grana. The thylakoid membrane contains photosynthetic pigments namely, chlorophyll a, chlorophyll b, carotenoids (carotene, xanthophylls) and plastoquinone. The thylakoid membranes also contain ‘ coupling factors that bring about ATP synthesis.
57. (b)
Totipotency is the ability of a living somatic plant cell to develop into a complete plant. It was first demonstrated by Steward et. al (1964) using phloem cells of carrot. This technique is now used for multiplying rare and endangered plants through micro¬propagations. This technique is widely used for multiplying plants e.g. – Chrysanthemum, Dioscorea floribunda, Coleus, Crotons, carnation plants etc.
58. (a)
Nucleolus synthesizes and stores RNA. The ribosomal proteins are synthesized in the cytoplasm and shift to the nucleolus for the formation of ribosomal subunits by complexing with rRNA.
59. (c)
Chemically a biomembrane consists of lipids (20-70%), proteins (20-70%), carbohydrates (1 -5%) and water (20%). The important lipids of the membrane are phospholipids (some hundred types), sterols, (e.g. cholesterol), glycolipids, sphingolipid (e.g., ; sphingomyelin, cerebrosides). Protein can be fibrous or globular structural carrier, receptor or enzymatic. The lipid molecules are amphiatic or amphipathic, that is, they possess both polar hydrophilic (water loving) and non-polar hydrophobic (water repelling) ends. The hydrophilic region is in the form of head while hydrophobic part contains two tails of fatty acids. It results in formation of a lipid bilayer. Most common lipid of the bilayer is phospholipids. Protein molecules also possess both polar and non-polar side chains. Usually their poly hydrophilic linkages are towards the outer side. The non-polar or hydrophobic linkage are either kept folded inside or used to establish connections with hydrophobic parts of the lipids.
60. (a)
Middle lamella is the first formed layer, present between the two adjacent cells. It is situated outside the primary cell wall. It is made up of calcium and magnesium pectate.
61. (a)
Microtubule is a microscopic tubular stmcture, with an external diameter of 24 nm and of variable length, found in a wide range of eukaryotic cells. Microtubules are composed of numerous subunits of the globular protein tubulin and occur singly or in pairs, triplets, or bundles. Microtubules help cells to maintain their shape. They also occur in cilia and eukaryotic flagella and the centrioles and form the spindle during nuclear division. A further role is in the intracellular transport of materials and movement of organelles.
62. (a)
Phytochrome is a plant pigment that can detect the presence or absence of light and is involved in regulating many processes that are linked to day length (photoperiod), such as seed germination and initiation of flowering. It consists of a light-detecting portion, called a chromophore, linked to a small protein and exists in two intercovertible forms with different physical properties, particularly in the ability to bind to membranes. Chlorophyll occurs in all land plants and are responsible for their green colour. Chlorophyll molecules are the principal sites of light absorption in the light-dependent reactions of photosynthesis. Anthocyanin occur in the cell vacuoles of various plant organs and are responsible for many of the blue, red and purple colours in plants. Carotenoids are responsible for the characteristic colour of many plant organs, such as ripe tomatoes, carrots, and autumn leaves. They also occur in certain algae and other photosynthesizing organisms (such as phototrophic bacteria), in which they function as accessory pigments in the light-dependent reaction of photosynthesis.
63. (a)
The pressure required to stop the flow of pure water into a solution across a semi permeable membrane is a characteristic of the solution, and is called the osmotic pressure. Thus water will move from a region of low osmotic pressure to a region of high osmotic pressure. Turgor pressure is the hydrostatic pressure set up within a cell by the water present acting against the elasticity of the wall. Suction pressure when referred to a cell, is the force which is available for taking in water.
64. (b)
A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc. However, all the enzymes do not occur in the same lysosome. There are different sets of enzymes in different lysosomes. The lysosome enzymes can break down all major biological macromolecules present in the cells or entering the cells from outside into their building block subunits by addition of water. The lysosome enzymes are active in acid medium, at about pH 5, hence their name.
65. (a)
Ribosomes present in nuclear membrane and endoplasmic reticulum take part in protein synthesis. Two or more ribosomes simultaneously engaged in protein synthesis on the same /wRNA strand forming polyribosomes. The ribosome functions as a template, bringing together different components required for protein synthesis.
66. (c)
67. (c)
Glycolysation of protein means linking of sugars to proteins which starts in rough endoplasmic reticulum and completed in golgi complex.
68. (b)
The spherosomes are, spherical bodies, about 0.5-1 pm wide and enclosed by a single unit membrane. They contain granular contents rich in lipids but also have some proteins. They occur in most plant cells but are abundant in the endosperm cells of oil seeds. Spherosomes, arise from the endoplasmic reticulum.
69. (c)
The ribosomes provide space for the synthesis of proteins in the cell. Hence, they are known as the “protein factories” of the cell. The ribosomes bound to the membranes generally synthesize proteins for export as secretions by exocytosis, or for incorporation into membranes, or for inclusion into lysosomes. The free ribosomes generally produce enzymic proteins for use in the cell itself.
70. (a)
The centrioles occur in nearly all animal cells and in motile plant cells, such as zoospores of algae, sperm cells of ferns, and motile algae. They are absent is amoebae, prokaryotic cells, higher gymnosperms and all angiosperms. An interphase (undividing) cell has a pair of centrioles (diplosome) usually near the nucleus. They lie in a small mass of specialized, distinctly staining cytoplasm that lacks other cell organelles. The centrioles and the centrosphere are together referred to as centrosome. Before cell division, the centrioles duplicate so that a dividing cell has a pair of centrioles at each pole of the spindle. Spindle fibre, cell plate and centromere are present in all plant cells.
71. (a)
Chemiosmotic coupling hypothesis is the most widely accepted explanation for oxidative phosphorylation in mitochondria and photophos-phorylation in thylakoid membranes. Mitchell proposed the idea of chemiosmotic coupling. He suggested that a concentration gradient of protons is established across the mitochondrial membrane because there is an accumulation of hydrogen ions on one side of the mitochondrial membrane. The proton accumulation is necessary for energy transfer to the endergonic ADP phosphorylation process.
72. (d)
Protein synthesis in an animal cell, takes place in the nucleolus as well as in the cytoplasm. Main part ofprotein synthesis (transcription and translation) occurs in nucleolus. Chain elongation occurs in cytoplasm.
73. (b)
A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc. However, all the enzymes do not occur in the same lysosome. There are different sets of enzymes in different lysosomes. The lysosome enzymes can break down all major biological macromolecules present in the cells or entering the cells from outside into their building block subunits by addition of water. The lysosome enzymes are active in acid medium, at about pH 5, hence their name.
74. (c)
Colchicine’is an alkaloid derived from the autumn crocus, Colchicum autumnale. It inhibits spindle formation in cells during mitosis so that chromosomes cannot separate during anaphase, thus inducing multiple sets of chromosomes. Colchicine is used in genetics, cytology, and plant breeding research and also in cancer therapy to inhibit cell division.
75. (a)
Prokaryotic flagellum is not surrounded by any membrane. It consists of a single thread. The thread is made of numerous identical spherical protein sub-units called, flagellin. Each subunit is about 40 A in diameter. The flagellin sub-units are arranged in helical spirals and form a hollow cylinder. Each flagellum is about 120-150 A thick.
76. (b)
In desmosomes circular patches of cell membranes are held together by interaction of proteins that extend through each membrane into the space between cells. The cell membrane has on the inner side a dense plate of protein for mechanical support and bears fine filaments, the tonofibrils, radiating into the cell. The desmosomes act as “spot welds” and keep the cells firmly together.
77. (d)
A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc. However, all the enzymes do not occur in the same lysosome. There are different sets of enzymes in different lysosomes. The lysosome enzymes can break down all major biological macromolecules present in the cells or entering the cells from outside into their building block subunits by addition of water. The lysosome enzymes are active in acid medium, at about pH 5, hence their name.
78. (d)
Respiratory chain is located in the inner membrane (cristae) of mitochondria. It consists of a series of proteins containing oxidation-reduction groups. Chemical treatment of the mitochondrial membrane results in the isolation of five complexes which have been designated as complexes I, II, III, IV and V.
79. (c)
Centromere is a part of a chromosome that attaches to the spindle during cell division. The position of the centromere is a distinguishing feature of individual chromosomes a chromosome with the centromere at its centre is described as metacentric; one with the centromere towards one end is acrocentric; and a chromosome with the centromere at either end is telocentric. The centromere usually appears as a constriction when chromosomes contract during cell division. During anaphase, the centromere of each chromosome divides into two, so that each chromatid comes to have its own centromere. The two chromatids now start repelling each other and separate completely to become daughter chromosomes. The daughter chromosomes move towards the poles of spindle along the path of their chromosome fibres. In anaphasic movement of chromosomes, the centromeres lead the path while the limbs trail behind.
80. (d)
Golgi apparatus is a stack of parallel, flattened, intercommunicating sacs or cistemae and many peripheral tubules and vesicles. The cistemae vary in number from 3 to 7 in most animal cells and from 10 to 20 in plant cells. They are usually equally spaced in the pile, separated from each other by thin layers of intercistemal cytoplasm. The latter may contain a layer of parallel fibres, called intercistemal elements, that support the cistemae. The cistemae are free of ribosomes and have swollen ends. They look like the smooth endoplasmic reticulum.
81. (c)
The inner membrane of the mitochondria is infolded variously to form involutions called cristae. The cristae extend inward to varying degrees and may fuse with those from the opposite side, dividing the mitochondrion into compartments. The cristae are arranged in characteristic ways in different cells. They may be simple or branched, straight or zigzag, lamellar or tubular. The cristae have in them a narrow intracristal space. It is continuous with the intermembrane space. They greatly increase the inner surface area of the mitochondria to hold a variety of enzymes.
82. (a)
The Golgi apparatus is present in all eukaryotic ; cells. It is specially extensive in the secretory cells. It is a central stack (pile) of parallel, flattened, intercommunicating sacs or cistemae and many peripheral tubules and vesicles. The two poles of a Golgi apparatus are called i cis face and trans face, which act respectively as the receiving and shipping departments. The vesicles lie near the ends and concave surface of the Golgi complex. They are pinched off from the tubules of the cistemae. They are of two types smooth or secretory vesicles, which have a smooth surface and contain secretions of the cell; and coated vesicles, that have rough surface and elaborate membrane proteins. They carry materials to or from the cistemae. The Golgi complex gives rise to primary lysosomes by budding from the trans face of cistemae.
83. (b)
Active and passive transports across cell membrane differ in passive transport is due to metabolic energy. There is always expenditure of energy in active transport.
84. (b)
Balbiani rings (puffs) are site of RNA and protein synthesis. These chromosomes show distinct dark and light bands. Euchromatin is present in dark bands and heterochromatin is present in light bands. These bands helps in mapping of chromosomes in cytogenetic studies. These chromosomes form puffs or loops (in region of dark bands) which are called Balbiani puffs or Balbiani rings where synthesis of /MRNA occurs.
85. (a)
In plant cells, peroxisomes are associated with photorespiration. Peroxisomes are found onlyin C3plants where a wasteful phenomenon of photorespiration occurs. The other organelles associated with this process are chloroplast and mitochondria. Peroxisomes are also reported in animal cells, i.e., liver and kidney cells. The peroxisome contains several enzyme such as amino transferse, glycolate oxidase, glyoxylate reductase, peroxidase and catalase etc.
86. (c)
A lysosome is a tiny sac bounded by a single unit membrane of lipoprotein. It contains a dense, finely granular fluid. The latter consists of glycoprotein hydrolytic (digestive) enzymes called acid hydrolases. These include proteases, lipases, nucleases, glycosidases, sulphatases, acid phosphatases, etc. However, all the enzymes do not occur in the same lysosome. There are different sets of enzymes in different lysosomes. The lysosome enzymes can break down all major biological macromolecules present in the cells or entering the cells from outside into their building block subunits by addition of water. The lysosome enzymes are active in acid medium, at about pH 5, hence their name.
87. (c)
Golgi apparatus is absent in bacteria and blue green algae. Golgi bodies are absent in prokaryotic cells and present in eukaryotic cells except in male gametes of bryophytes and pteridophytes, mammalian RBCs, sieve tubes of plants and in cells of fungi.
88. (d)
Cell recognition and adhesion occur due to biochemicals of cell membranes named glycoproteins and glycolipids. These are formed due to small carbohydrate molecules present on lipids and extrinsic proteins.
89. (d)
In salivary gland chromosomes/polytene chromosomes, pairing is formed between homologous chromosomes. A characteristics feature of these chromosomes is that somatic pairing occurs in them and hence their number appears half of normal somatic cells.
90. (c)
Cell theory does not hold good because all living beings (e.g., viruses) do not have cellular organisation. Viruses are an exceptions to the cell theory as they are obligate parasites (subcellular in nature). Paramecium, Rhizopus, Vaucheria are some examples which may or may not be exceptions to the theory.
91. (b)
Names of Schleiden and Schwann are associated with cell theory in 1839. The concept that “All living organisms are composed of cell” is known as cell theory.
92. (d)
X-rays crystallography is a technique which is used to study of binding protein on regulatory DNA sequence. In this technique, X-rays pass through a crystal of a substance and form a diffraction pattern. With the help of this technique, the arrangement of atoms in the molecular structure of enzymes, proteins, DNA, etc. can be studied. Wilkins, Watson and Crick used this technique to determine the molecular configuration of double helix of DNA.
93. (d)
All the plastids have a common origin and one type of plastid can change into another. Plastids are of 2 main types lencoplasts and chromoplasts. The leucoplasts are colourless and occur in the cells not exposed to sunlight. The chromoplasts are coloured occur in the cells exposed to sunlight.
94. (b)
A cetabularia used in Hammerling’s nucleocytoplasmic experiment is unicellular uninucleate green algae. Hammerling’s experiment of Acetabularia involved exchanging rhizoid and stalk. Presence of hereditary information in the nucleous was proved by the work of Hammerling on single celled alga Acetabularia.
95. (a)
Apparato reticolare are Golgi apparatus. The Golgi apparatus was named after Camillo Golgi (1906) who discovered this cell structure in nerve cells (1898) and assigned it the role of a cell organelle. Inspired by its appearance, Golgi named this cell structure the inner reticular apparatus (apparato I reticolare interno).
96. (a)
An outer covering membrane is absent over nucleolus. Nucleolus is a dense, spherical, colloidal body which remains attached with nucleolar organizing chromosomes. It was discovered by Fontana (1781) and termed as nucleolus by Bowman (1840). The main function of nucleolus is the synthesis of ribosomal RNA and it is called store house of RNA. It plays important role in cell division also.
97. (b)
All the plastids have a common origin and one type of plastid can change into another. Plastids are of 2 main types lencoplasts and chromoplasts. The leucoplasts are colourless and occur in the cells not exposed to sunlight. The chromoplasts are coloured occur in the cells exposed to sunlight.
98. (c)
Oxysomes of F0– F1, particles occurs on inner mitochondrial membrane. Each particle is made up of base, stalk and head and is about 10 mm in length. The number of oxysomes per mitochondrion varies from 104-105 Chemically these are made up of phospholipid core and protein cortex. Oxysomes have ATP as enzyme molecules and therefore, responsible for ATP synthesis. These elementary particles are also called F0– F1 particles by some workers. The base of these is called F0 subunit and head is called F1 subunit.
99. (c)
Ribosomes are the centre for protein synthesis. Free ribosomes synthesize structural proteins, proteins normally found in microbodies, chloroplast and mitochondria and proteins destained to remain in cytosol such as enzymes of glycolysis or proteins of cytoskeleton. On the other hand, ribosomes attached on ER synthesize proteins for transport, integral or intrinsic proteins of membrane and proteins of certain organelles like golgi complex, lysosomes and plant vacuoles.
100. (c)
An angstrom (symbol A) is a non-SI unit of length that is internationally recognised, equal to 0.1 nanometer (nm). It can be written in scientific notations as 1 x 10-10 m. It is used in expressing the size of atoms, length of chemical bonds etc. It is named after Anders Jonas Angstrom. Angstrom = 0.0001mm.
101. (b)
Electron microscope has a high resolution power. This is due to very low wavelength of electron beam (0.005 mu) of the electron beam used as light source. It is produced when a metal filament is heated in a vaccum tube at high temperature, i.e., 50,000 volts.
102. (c)
Addition of new cell wall particles amongst the existing one is intussusception. Growth of cell wall 1 occurs by two methods – By intussusception and by apposition. By intussusception, the primary wall is stretched and materials of secondary wall are deposited. By apposition, material of secondary wall are deposited in the form of thin layers.
103. (a)
Cell wall shows complete permeability because it helps in the transport of substances into and out of the cell. The main function of cell wall is to provide mechanical support.
104. (d)
Ribosomes are minute cellular, non- i membranous particles having an average diameter of 23 mm (230 A0). In plant cells ribosomes were first of all i observed by Robinson and Brown (1953) in bean roots. In animal cells, these were discovered by Palade (1955), hence are called Palade particles. Ribosomes form a part of fraction microsome, a term given by A. claude (made of broken ER, ribosomes and Golgi bodies).
105. (b)
According to the fluid mosaic model of cell membrane structure proposed by Singer and Nicolson (1972) plasma membrane contains about 50-60% proteins and 50-40% lipids. Lipids form a bilayer with hydrophilic heads pointing outwards. Cell membrane allows transport of some molecules by passive transport e.g., water, neutral solutes while some are transported actively e.g., Na+ /K+ pump.
106. (b)
Resolution power is the ability to distinguish two close objects. It is the ability of a system to distinguish two close points as two separate points. Resolving power of microscope depends upon the numerical aperature of the objective lens system and its wavelength.
107.(c)
A cetabularia used in Hammerling’s nucleocytoplasmic experiment is unicellular uninucleate green algae. Hammerling’s experiment of Acetabularia involved exchanging rhizoid and stalk. Presence of hereditary information in the nucleous was proved by the work of Hammerling on single celled alga Acetabularia.
108. (c)
The latest model of plasmamembrane is Fluid Mosaic Model. It was discovered by Singer andNicolson, 1972.
109. (a)
Magnification of compound microscope is not connected with numerical aperature. The magnifying power is represented by the symbol ‘X’. The total magnification of a microscope is obtained by multiplying the objective magnification and ocular lens magnification e.g., if the magnifying power of an ocular lens is 10X and of the objective is 40X, then the total magnifying power of a microscope is 10 x 40 = 40X.
110. (c)
A bivalent consist of four chromatids and two centromeres. Bivalent is a pair of homologous chromosome lying together in the zygotene stage of prophase I of first meiotic division.
111. (d)
Nucleoproteins are compounds present in cells of living organisms that consist of nucleic acids with proteins. Nucleoproteins are synthesized in cytoplasm. These are conjugated proteins. They are of two types – Deoxyribonucleoproteins and ribo-nucleoproteins.
112. (d)
Polyribosomes are aggregates of several ribosomes held together by string of mRNA. Polyribosomes consists of 4 – 8 ribosomes which are attached to a single strand of messenger RNA or mRNA. This mechanism help in synthesis of several copies of the same protein.
113. (c)
Plasma membrane consists of lipids (20-79%), proteins (20-70%), carbohydrates (1-5%) and water (20%). Lipid molecules possess both hydrophobic and hydrophilic ends and are thus arranged in the form of lipid bilayer. Most common lipid of the bilayer is phospholipid. Protein molecules occur at places both inside (intrinsic proteins) and on the outer side (extrinsic proteins) of the phospholipid bilayer.
114. (c)
Organelles can be separated from cell homogenate through differential centrifugation. The basic principle involved here is sedimentation of particles in a suspension by centrifugal force. In a centrifuge, the particles sediment at different rates when an accelerating force is subjected. The rate of sedimentation depends upon the size of the particles, its shape and density.
115. (c)
A cetabularia used in Hammerling’s nucleocytoplasmic experiment is unicellular uninucleate green algae. Hammerling’s experiment of Acetabularia involved exchanging rhizoid and stalk. Presence of hereditary information in the nucleous was proved by the work of Hammerling on single celled alga Acetabularia.
116. (d)
Plasma membrane consists of lipids (20-79%), proteins (20-70%), carbohydrates (1-5%) and water (20%). Lipid molecules possess both hydrophobic and hydrophilic ends and are thus arranged in the form of lipid bilayer. Most common lipid of the bilayer is phospholipid. Protein molecules occur at places both inside (intrinsic proteins) and on the outer side (extrinsic proteins) of the phospholipid bilayer.
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