Q1. Membranous extensions containing pigments in cyanobacteria are called:
Correct Answer: (b)
Chromatophores are pigment-containing membranous structures found in cyanobacteria and photosynthetic bacteria. They house chlorophyll and other photosynthetic pigments, enabling these organisms to perform photosynthesis.
Q2. Match the sedimentation coefficient subunit (Prokaryotes):
70S ribosome
Subunits
A. Large
(I) 50S
B. Small
(II) 30S
Correct Answer: (a)
The 70S prokaryotic ribosome consists of a large 50S subunit and a small 30S subunit. These subunits combine during protein synthesis to form a functional ribosome.
Q3. Regarding the nuclear envelope: (i) It has two parallel membranes. (ii) Outer membrane is continuous with ER. (iii) Nuclear pores allow one-way movement of molecules.
Correct Answer: (a)
The nuclear envelope consists of two membranes and the outer membrane is continuous with the ER. Nuclear pores allow bidirectional movement of RNA and proteins, not one-way, so (iii) is false.
Q4. Assertion: Eukaryotic cells have extensive compartmentalisation of cytoplasm.
Reason: Eukaryotic cells contain membrane-bound organelles.
Correct Answer: (a)
The presence of membrane-bound organelles such as the nucleus, ER, Golgi, mitochondria, and lysosomes compartmentalizes the eukaryotic cytoplasm, allowing specialized functions to occur in distinct compartments. This organization increases metabolic efficiency.
Q5. Match the inclusion bodies:
Type
Example
A. Phosphate granules
Inclusion body
B. Glycogen granules
Inclusion body
C. Gas vacuoles
In Blue green algae
Correct Answer: (a)
Phosphate granules, glycogen granules, and gas vacuoles are all examples of inclusion bodies found in prokaryotic cells. They serve as storage depots for nutrients and metabolic products.
Q6. The major site for synthesis of lipids in animal cells is:
Correct Answer: (b)
The smooth endoplasmic reticulum (SER) is the primary site for lipid synthesis, including phospholipids, steroids, and fats. It also plays a role in calcium storage and detoxification of drugs and poisons.
Q7. The Fluid Mosaic Model was proposed by:
Correct Answer: (b)
Singer and Nicolson proposed the Fluid Mosaic Model in 1972, describing the plasma membrane as a fluid lipid bilayer with embedded proteins that can move laterally. This model explains the dynamic nature of membranes and their functions.
Q8. Match the endomembrane system components:
Column I
Column II
A. RER
(I) Synthesis of steroidal hormones
B. SER
(II) Packaging site
C. Golgi
(III) Protein synthesis and secretion
D. Tonoplast
(IV) Membrane of vacuole
Correct Answer: (a)
RER is involved in protein synthesis and secretion (III); SER synthesizes lipids including steroidal hormones (I); Golgi apparatus is the packaging site (II); tonoplast is the vacuolar membrane (IV). These are distinct functions within the endomembrane system.
Q9. Assertion: Human RBCs lack a nucleus.
Reason: Mature mammalian RBCs are generally without a nucleus to provide more space for hemoglobin.
Correct Answer: (a)
Mature mammalian RBCs lack a nucleus, which allows them to have a biconcave shape and more space to carry hemoglobin. This adaptation maximizes oxygen transport capacity and is essential for efficient respiration.
Q10. Which organelle is non-membrane bound and found in animal cells to help in cell division?
Correct Answer: (b)
The centrosome is a non-membrane bound organelle found in animal cells that organizes microtubules and forms the spindle apparatus during cell division. It contains two centrioles, which are cylindrical structures made of microtubules.
Q11. Non-staining secondary constrictions at a constant location on chromosomes are called:
Correct Answer: (b)
Secondary constrictions, when present, are sites where nucleolar organizers are located and can form satellites. These constrictions do not stain intensely and are associated with the formation of nucleoli, which are sites of rRNA synthesis.
Q12. The layer of calcium pectate that glues neighboring cells together is:
Correct Answer: (c)
The middle lamella is a thin layer of calcium pectate that cements adjacent plant cells together. It is the first layer formed during cell division and provides structural integrity to tissues.
Q13. Match the bacterial shapes:
Column I
Column II
A. Bacillus
(I) Comma shaped
B. Coccus
(II) Spiral
C. Vibrio
(III) Rod like
D. Spirillum
(IV) Spherical
Correct Answer: (a)
Bacillus are rod-shaped (III); coccus are spherical (IV); vibrio are comma-shaped (I); spirillum are spiral (II). These are the four classic bacterial morphologies, often used for identification.
Q14. G.N. Ramachandran is famous for his discovery of the triple helical structure of:
Correct Answer: (c)
G.N. Ramachandran proposed the triple helical model of collagen in 1954, which explained its unique fibrous structure. Collagen is the most abundant protein in mammals and provides structural support to connective tissues.
Q15. Which of the following is NOT part of the endomembrane system?
Correct Answer: (c)
The endomembrane system includes the nuclear envelope, ER, Golgi, lysosomes, and vacuoles. Mitochondria and chloroplasts are not part of this system because they are semi-autonomous organelles with their own DNA and ribosomes.
Q16. The movement of water across the membrane by diffusion is called:
Correct Answer: (c)
Osmosis is the passive movement of water molecules across a selectively permeable membrane from a region of lower solute concentration to higher solute concentration. It does not require energy and is driven by the concentration gradient.
Q17. Which of the following is correct regarding cell theory? (i) All living organisms are composed of cells and products of cells. (ii) All cells arise from pre-existing cells. (iii) Cells are formed de novo from abiotic materials.
Correct Answer: (a)
Cell theory states that all organisms are made of cells, and new cells arise from existing cells. The idea of spontaneous generation (de novo formation) is incorrect and has been disproven.
Q18. Assertion: The axoneme has 9 peripheral doublets and 2 central microtubules.
Reason: This arrangement is known as the 9+2 array.
Correct Answer: (a)
The 9+2 array is the defining structure of the axoneme in eukaryotic cilia and flagella. The assertion describes the structure, and the reason provides the correct terminology, so both are true and the reason explains the assertion.
Q19. Which statements about the Golgi apparatus are true? (i) It was first observed by Camillo Golgi in 1898. (ii) It consists of flattened sacs called cisternae. (iii) It is the site for formation of glycoproteins and glycolipids.
Correct Answer: (a)
The Golgi apparatus was discovered by Camillo Golgi, is composed of cisternae, and plays a key role in modifying and packaging proteins and lipids into glycoproteins and glycolipids. All statements are correct.
Q20. Assertion: Ribosomes of chloroplasts are 70S.
Reason: Cytoplasmic ribosomes in plants are 80S.
Correct Answer: (b)
Both statements are true: chloroplasts have 70S ribosomes similar to prokaryotes, while plant cytoplasmic ribosomes are 80S. However, the size of cytoplasmic ribosomes does not explain why chloroplast ribosomes are 70S; it is due to their endosymbiotic origin.
Q21. Which statement is true for ribosomes? (i) They are not surrounded by any membrane. (ii) George Palade observed them as dense particles. (iii) They are composed of RNA and proteins.
Correct Answer: (a)
Ribosomes are non-membrane bound, composed of RNA and proteins, and were first observed as dense particles by George Palade. All three statements are correct.
Q22. Which statements about chromatin are correct? (i) Stained by basic dyes. (ii) Named by Flemming. (iii) Elaborate nucleoprotein fibers.
Correct Answer: (a)
Chromatin is stained by basic dyes due to its acidic nature, was named by Walther Flemming, and consists of nucleoprotein fibers (DNA + histones). All statements are correct.
Q23. Match the proteinous filaments of cytoskeleton:
A. Microtubules
B. Microfilaments
C. Intermediate filaments
Correct Answer: (a)
The cytoskeleton is composed of three types of protein filaments: microtubules, microfilaments, and intermediate filaments. Together they provide structural support, enable cell movement, and facilitate intracellular transport.
Q24. The main arena of cellular activities in both plant and animal cells is:
Correct Answer: (c)
The cytoplasm is the semi-fluid matrix where most metabolic reactions occur, including glycolysis, protein synthesis, and many biosynthetic pathways. It houses organelles and provides a medium for cellular processes.
Q25. The eukaryotic 80S ribosome is composed of subunits:
Correct Answer: (b)
Eukaryotic ribosomes are 80S and consist of a large 60S subunit and a small 40S subunit. The S value reflects sedimentation rate, and the subunits work together to translate mRNA into proteins during protein synthesis.
Q26. The size of a prokaryotic ribosome is:
Correct Answer: (b)
Prokaryotic ribosomes are 70S, composed of a 50S large subunit and a 30S small subunit. The S value (Svedberg unit) reflects sedimentation rate, not a simple additive measure, due to shape and density.
Q27. Several ribosomes attached to a single mRNA form a chain called:
Correct Answer: (a)
A polysome (or polyribosome) is a cluster of ribosomes simultaneously translating a single mRNA molecule. This allows efficient protein synthesis as multiple ribosomes move along the mRNA, producing multiple copies of the polypeptide.
Q28. The 'Na+/K+ Pump' is an example of:
Correct Answer: (d)
The Na+/K+ pump is an active transport mechanism that uses ATP to move sodium and potassium ions against their concentration gradients. It maintains electrochemical gradients essential for nerve impulse transmission and other cellular processes.
Q29. Match the following scientists with their contributions:
Column I
Column II
A. Robert Brown
(I) Discovered the live cell
B. Antonie von Leeuwenhoek
(II) Discovered the nucleus
C. Rudolf Virchow
(III) Discovered Ribosomes
D. George Palade
(IV) Omnis cellula-e cellula
Correct Answer: (a)
Robert Brown discovered the nucleus (II); Leeuwenhoek first observed live cells (I); Virchow proposed 'Omnis cellula-e cellula' (IV); Palade observed ribosomes under electron microscope (III). This matching correctly pairs each scientist with their landmark contribution.
Q30. Assertion: Lysosomes are called 'suicidal bags'.
Reason: They are rich in hydrolytic enzymes active at acidic pH.
Correct Answer: (a)
Lysosomes contain powerful hydrolytic enzymes that can digest cellular components if the lysosome bursts, hence they are called suicidal bags. Their enzymes work optimally at acidic pH, which is maintained by proton pumps in the membrane.
Q31. Who first saw and described a live cell?
Correct Answer: (c)
Antonie van Leeuwenhoek, using his improved microscopes, observed living cells like bacteria and protozoa in the 1670s. Robert Brown later discovered the nucleus in plant cells, while Schleiden and Schwann contributed to the cell theory.
Q32. Assertion: The Golgi apparatus remains in close association with the ER.
Reason: Materials to be packaged from the ER fuse with the cis face of the Golgi.
Correct Answer: (a)
The Golgi apparatus is closely associated with the ER because vesicles from the ER transport proteins and lipids to the cis face of the Golgi for processing. This close proximity facilitates efficient trafficking and modification of macromolecules.
Q33. Algal cell walls are made of cellulose, galactans, mannans and:
Correct Answer: (c)
Algal cell walls are composed of cellulose, galactans, mannans, and sometimes minerals like calcium carbonate. This composition differs from higher plants, which typically have cellulose, hemicellulose, and pectin.
Q34. George Palade first observed which organelle under an electron microscope in 1953?
Correct Answer: (b)
George Palade observed ribosomes as dense particles in the cytoplasm using electron microscopy. He also contributed to the understanding of protein synthesis and secretion, and was awarded the Nobel Prize for his work.
Q35. Assertion: The content of the nucleolus is continuous with the rest of the nucleoplasm.
Reason: The nucleolus is not a membrane-bound structure.
Correct Answer: (a)
The nucleolus is not enclosed by a membrane, so its contents are continuous with the nucleoplasm. This allows the free exchange of molecules and is essential for its role in ribosomal RNA synthesis and ribosome assembly.
Q36. Assertion: Mitochondria and chloroplasts are semi-autonomous organelles.
Reason: They possess their own DNA and 70S ribosomes.
Correct Answer: (a)
The presence of their own DNA and 70S ribosomes allows mitochondria and chloroplasts to synthesize some of their own proteins, making them semi-autonomous. This supports the endosymbiotic theory that they originated from prokaryotic organisms.
Q37. Assertion: Ribosomes are non-membrane bound organelles.
Reason: They are found only in eukaryotic cells.
Correct Answer: (c)
Ribosomes lack a membrane and are composed of RNA and proteins, but they are found in both prokaryotic and eukaryotic cells. The assertion is correct, but the reason is false because ribosomes are ubiquitous.
Q38. Ribosomes are found in which part of the eukaryotic cell besides the cytoplasm?
Correct Answer: (c)
Ribosomes are present in the cytoplasm, on the rough ER, and also inside mitochondria and chloroplasts (organellar ribosomes). These organelles have their own 70S ribosomes for protein synthesis, reflecting their endosymbiotic origin.
Q39. Assertion: All cells arise from pre-existing cells.
Reason: Rudolf Virchow modified the hypothesis of Schleiden and Schwann.
Correct Answer: (a)
Virchow's addition of 'Omnis cellula-e cellula' to the cell theory established that new cells are formed only from existing cells. This principle is fundamental to biology and explains cell division and continuity of life.
Q40. Select the correct statements about the cytoskeleton: (i) It is an elaborate network of filamentous proteinaceous structures. (ii) It provides mechanical support and motility. (iii) It is involved in maintenance of the shape of the cell.
Correct Answer: (a)
The cytoskeleton is a network of protein filaments (microtubules, microfilaments, intermediate filaments) that provides structural support, facilitates cell movement, and maintains cell shape. All statements are correct.
Q41. Regarding the cell wall, which is correct? (i) It is a non-living rigid structure. (ii) Primary wall of young plant is capable of growth. (iii) Secondary wall is formed on the outer side of the cell.
Correct Answer: (a)
The cell wall is non-living and rigid. The primary wall is flexible and can grow. The secondary wall is deposited on the inner side (not outer) after growth stops, so (iii) is false.
Q42. Which organism is the smallest cell known with a length of only 0.3 μm?
Correct Answer: (b)
Mycoplasmas are the smallest known cells, measuring about 0.3 μm in diameter, and lack a cell wall. They are pleomorphic and can survive without oxygen, making them unique among prokaryotes.
Q43. Match the vacuole types:
Type
Function/Organism
A. Contractile vacuole
(I) Engulfing food
B. Food vacuole
(II) Osmoregulation in Amoeba
C. Sap vacuole
(III) Occupies 90% of plant cell
Correct Answer: (a)
Contractile vacuoles help in osmoregulation (II); food vacuoles are involved in engulfing and digesting food (I); sap vacuoles are large central vacuoles in plant cells (III). These vacuoles have distinct roles in different organisms.
Q44. Matthias Schleiden was a German:
Correct Answer: (b)
Matthias Schleiden was a German botanist who studied plant tissues and concluded that all plants are composed of cells. His work in 1838, along with Theodor Schwann's studies on animals, laid the foundation for the cell theory.
Q45. Match the chromosome types with centromere positions:
Column I
Column II
A. Metacentric
(I) Centromere at terminal end
B. Sub-metacentric
(II) Centromere in the middle
C. Acrocentric
(III) Centromere slightly away from middle
D. Telocentric
(IV) Centromere close to end
Correct Answer: (a)
Metacentric: centromere in the middle (II); sub-metacentric: slightly away (III); acrocentric: close to end (IV); telocentric: at terminal end (I). This classification is based on the position of the centromere and affects chromosome arms.
Q46. The prokaryotic flagellum is composed of:
Correct Answer: (b)
The bacterial flagellum consists of three parts: the filament (long helical structure), the hook (curved connector), and the basal body (anchored in the membrane). This structure rotates to propel the bacterium, unlike eukaryotic flagella which have a 9+2 arrangement.
Q47. Match the 'S' in ribosomes:
Symbol
Meaning
S
Svedberg's Unit
Measure
Sedimentation coefficient
Correct Answer: (a)
The 'S' stands for Svedberg unit, which is a measure of the sedimentation coefficient. It reflects the rate of sedimentation during centrifugation, influenced by size and shape, not simply mass.
Q48. Which of the following lacks membrane-bound organelles?
Correct Answer: (c)
Prokaryotic cells (bacteria and archaea) do not have membrane-bound organelles such as mitochondria, ER, or Golgi. Their genetic material is not enclosed in a nucleus, and they lack compartmentalization found in eukaryotes.
Q49. A metacentric chromosome has centromere:
Correct Answer: (c)
In metacentric chromosomes, the centromere is located exactly in the middle, dividing the chromosome into two equal arms. This position influences chromosome movement during cell division and karyotype analysis.
Q50. Match the following for RBC membrane:
Component
Percentage
A. Protein
(I) ~52%
B. Lipid
(II) ~40%
Correct Answer: (a)
Human RBC membranes contain about 52% protein and 40% lipids. The high protein content is essential for transport proteins and maintenance of the biconcave shape.
Q51. Plastids that store oils and fats are called:
Correct Answer: (b)
Elaioplasts are leucoplasts that store oils and fats. Amyloplasts store starch, aleuroplasts store proteins, and chromoplasts contain pigments like carotenoids, providing color to fruits and flowers.
Q52. Assertion: Mycoplasmas can survive without oxygen.
Reason: They are the smallest living cells and lack a cell wall.
Correct Answer: (b)
Mycoplasmas are indeed anaerobic and can survive without oxygen, and they are the smallest known cells lacking a cell wall. However, their ability to survive without oxygen is due to their metabolic adaptations, not simply their size or lack of a cell wall.
Q53. Assertion: Mesosomes help in respiration and secretion in prokaryotes.
Reason: They increase the surface area of the plasma membrane and enzymatic content.
Correct Answer: (a)
Mesosomes are infoldings of the plasma membrane that increase surface area, allowing more enzymes for respiration and secretion to be embedded. This structural adaptation enhances metabolic efficiency in prokaryotic cells.
Q54. Which organelle is known as the 'Power House' of the cell?
Correct Answer: (c)
Mitochondria are called the powerhouses of the cell because they generate ATP through oxidative phosphorylation. They have a double membrane, with the inner membrane folded into cristae to increase surface area for energy production.
Q55. Who modified the cell theory to state 'Omnis cellula-e cellula'?
Correct Answer: (c)
Rudolf Virchow in 1855 added the concept that new cells arise from pre-existing cells, refining the earlier cell theory. This principle is a cornerstone of modern biology, emphasizing that cells divide and give rise to new cells.
Q56. The arrangement of microtubules in eukaryotic cilia and flagella is:
Correct Answer: (b)
Eukaryotic cilia and flagella have a 9+2 arrangement of microtubules, with nine peripheral doublets and two central singlet microtubules. This axonemal structure is essential for their beating motion, driven by dynein motors.
Q57. A thick and tough glycocalyx in bacteria is known as:
Correct Answer: (b)
When the glycocalyx is thick and firmly attached, it is called a capsule, which protects bacteria from desiccation, phagocytosis, and immune responses. A loose, diffuse layer is termed a slime layer.
Q58. The physico-chemical approach to study and understand living organisms is called:
Correct Answer: (b)
Reductionist biology breaks down complex systems into simpler components to understand life at the molecular and chemical levels. This approach focuses on the physical and chemical principles underlying biological processes.
Q59. Assertion: Chromatin contains DNA and histones.
Reason: Histones are basic proteins that help in DNA packaging.
Correct Answer: (a)
Chromatin is composed of DNA wound around histone proteins, which are positively charged and bind to the negatively charged DNA. This packaging compacts the DNA into chromosomes and regulates gene expression.
Q60. Match the sedimentation coefficient subunit (Eukaryotes):
80S ribosome
Subunits
A. Large
(I) 60S
B. Small
(II) 40S
Correct Answer: (a)
The 80S eukaryotic ribosome is composed of a large 60S and a small 40S subunit. The larger size reflects additional ribosomal RNA and proteins compared to prokaryotic ribosomes.
Q61. Match the plant cell wall composition:
Organism Group
Cell Wall Component
A. Algae
(I) Cellulose, Hemicellulose, Pectin
B. Plants
(II) Cellulose, Galactans, Mannans
Correct Answer: (a)
Algal cell walls are made of cellulose, galactans, mannans, and sometimes minerals (II); higher plant cell walls contain cellulose, hemicellulose, and pectin (I). This reflects differences in evolutionary adaptations.
Q62. The outermost layer of the bacterial cell envelope is the:
Correct Answer: (c)
The bacterial cell envelope consists of the glycocalyx (outermost), cell wall, and plasma membrane. The glycocalyx may be a loose slime layer or a thick capsule, providing protection and aiding in adhesion.
Q63. Match the centriole arrangement:
A. Centrioles
Perpendicular to each other
B. Organization
Like the cartwheel
Correct Answer: (a)
Centrioles are arranged perpendicular to each other, and their organization resembles a cartwheel with nine triplets of microtubules. Both statements correctly describe centriole structure.
Q64. Assertion: Prokaryotic cells multiply more rapidly than eukaryotic cells.
Reason: Prokaryotic cells are generally smaller in size.
Correct Answer: (b)
Prokaryotes often divide faster due to their simpler structure and lack of compartmentalization, but smaller size alone does not directly cause rapid multiplication. The reason is true but does not explain the assertion; rapid division is primarily due to a shorter cell cycle and simpler genome.
Q65. In human erythrocytes (RBCs), the percentage of protein in the membrane is:
Correct Answer: (b)
Human RBC membranes contain approximately 52% protein, 40% lipids, and 8% carbohydrates. The high protein content supports membrane functions like transport, signaling, and maintaining cell shape.
Q66. Bacteria that take up the Gram stain are called:
Correct Answer: (b)
Gram-positive bacteria retain the crystal violet stain due to a thick peptidoglycan layer in their cell wall. Gram-negative bacteria have a thinner layer and do not retain the stain, appearing pink after counterstaining.
Q67. Assertion: Centrioles form the basal body of cilia and flagella.
Reason: They also give rise to the spindle apparatus in animal cells during division.
Correct Answer: (b)
Centrioles do form basal bodies and also organize the spindle apparatus, but the reason does not explain why they form basal bodies. The two functions are separate; the explanation for the basal body role is not provided by the spindle apparatus function.
Q68. Which structure in bacteria helps in cell wall formation and DNA replication?
Correct Answer: (c)
Mesosomes are specialized infoldings of the plasma membrane that participate in cell wall synthesis, DNA replication, and the partitioning of chromosomes during cell division. They also play a role in respiration and secretion.
Q69. What confers the unique phenotypic character of antibiotic resistance to some bacteria?
Correct Answer: (c)
Plasmids are small, circular, extrachromosomal DNA molecules that often carry genes for antibiotic resistance, toxin production, or other accessory traits. They can be transferred between bacteria, facilitating the spread of resistance.
Q70. Match the organelles with their functions:
Column I
Column II
A. Mitochondria
(I) Packaging of materials
B. Golgi Apparatus
(II) Protein synthesis
C. Ribosomes
(III) Digestion
D. Lysosomes
(IV) ATP production
Correct Answer: (a)
Mitochondria produce ATP (IV); Golgi apparatus packages and modifies proteins (I); ribosomes synthesize proteins (II); lysosomes contain digestive enzymes (III). These are fundamental functions of each organelle.
Q71. Which statements are correct regarding the nucleus? (i) Robert Brown described it in 1831. (ii) Perinuclear space is 100-500 nm wide. (iii) Nucleolus is the site for active rRNA synthesis.
Correct Answer: (a)
Robert Brown discovered the nucleus in 1831. The nucleolus is the site of rRNA synthesis. However, the perinuclear space is typically 10-50 nm wide, not 100-500 nm, so (ii) is false.
Q72. Identify the correct statements for chromosomes: (i) A single human cell has approx. 2m long DNA. (ii) Centromere holds two chromatids. (iii) Kinetochores are disc-shaped structures on the sides of centromere.
Correct Answer: (a)
Human cells contain about 2 meters of DNA per nucleus, which is compacted into chromosomes. The centromere holds sister chromatids together, and kinetochores are protein structures on the centromere where spindle fibers attach.
Q73. Match the plastid types with their storage products:
Column I
Column II
A. Amyloplasts
(I) Store proteins
B. Elaioplasts
(II) Store starch
C. Aleuroplasts
(III) Store oils and fats
Correct Answer: (a)
Amyloplasts store starch (II); elaioplasts store oils and fats (III); aleuroplasts store proteins (I). These are leucoplasts that differentiate based on the type of stored nutrient.
Q74. Which of the following phylum is being described by the given statements? (i) These are unicellular organisms capable of independent existence. (ii) They can perform essential functions of life. (iii) Anything less than a complete structure of this does not ensure independent living.
Correct Answer: (b)
The statements describe the cell as the basic structural and functional unit of life. A cell is the smallest entity that can carry out all life processes independently; organelles or subcellular components cannot survive alone.
Q75. In prokaryotes, the genomic DNA is:
Correct Answer: (b)
Prokaryotic DNA is typically a single, circular, double-stranded molecule that is not associated with histone proteins and lies free in the nucleoid region. This naked DNA is not enclosed by a nuclear membrane.
Q76. Match the cell types with their characteristics:
Column I
Column II
A. Mycoplasma
(I) About 7.0 μm in diameter
B. Ostrich egg
(II) Smallest cell (0.3 μm)
C. Human RBC
(III) Longest cells
D. Nerve cell
(IV) Largest isolated single cell
Correct Answer: (a)
Mycoplasma is the smallest cell (~0.3 μm); ostrich egg is the largest isolated single cell; human RBC is ~7.0 μm in diameter; nerve cells are the longest cells. These measurements are standard references in cell biology.
Q77. Which of the following is true for mitochondria? (i) They are double membrane-bound. (ii) The inner membrane forms infoldings called cristae. (iii) They divide by mitosis.
Correct Answer: (a)
Mitochondria have a double membrane, with the inner membrane folded into cristae. They divide by fission, not mitosis, which is a feature of eukaryotic cell division. So (i) and (ii) are correct.
Q78. Regarding the chloroplast, identify the correct statements: (i) Thylakoids are arranged in stacks called grana. (ii) Stroma contains enzymes for carbohydrate synthesis. (iii) It contains large 80S ribosomes.
Correct Answer: (a)
Chloroplasts have thylakoids stacked as grana, and the stroma contains Calvin cycle enzymes for carbohydrate synthesis. However, chloroplasts have 70S ribosomes, not 80S, so (iii) is false.
Q79. Regarding active transport: (i) It is an energy-dependent process. (ii) Molecules move against the concentration gradient. (iii) ATP is utilized.
Correct Answer: (a)
Active transport requires energy (ATP) to move solutes against their concentration gradient. This is essential for maintaining cellular ion balances and uptake of nutrients.
Q80. Regarding the fluid nature of membrane: (i) Enables lateral movement of proteins. (ii) Important for cell growth and endocytosis. (iii) Fluidity is measured by lipid movement.
Correct Answer: (a)
Membrane fluidity allows proteins to diffuse laterally, which is crucial for cell growth, endocytosis, and cell signaling. Fluidity is not solely measured by lipid movement; it also involves protein mobility, so (iii) is incomplete.
Q81. Theodore Schwann concluded that the presence of ______ is a unique character of plant cells.
Correct Answer: (c)
Schwann, a zoologist, observed that plant cells have a rigid cell wall while animal cells do not. This distinction helped differentiate plant and animal cells; the cell wall provides structural support and protection to plant cells.
Q82. The space limited by the inner membrane of the chloroplast is called:
Correct Answer: (c)
The stroma is the fluid-filled space inside the inner membrane of the chloroplast, surrounding the thylakoid system. It contains enzymes for the Calvin cycle, DNA, ribosomes, and other molecules involved in photosynthesis.
Q83. Assertion: The number of mitochondria per cell is variable.
Reason: It depends on the physiological activity of the cells.
Correct Answer: (a)
Cells with high energy demands, such as muscle cells, contain more mitochondria. The number of mitochondria is regulated to meet the ATP requirements, so the assertion and reason are both true and the reason correctly explains the variability.
Q84. Mitochondrial matrix contains which type of ribosomes?
Correct Answer: (b)
Mitochondria contain 70S ribosomes, similar to prokaryotic ribosomes, reflecting their endosymbiotic origin. These ribosomes are involved in translating mitochondrial genes into proteins essential for oxidative phosphorylation.
Q85. Assertion: Animal cells do not have a cell wall.
Reason: The cell wall is a unique character of plant cells.
Correct Answer: (a)
Animal cells lack a cell wall, while plant cells have a rigid cell wall made of cellulose. This distinction was noted by Theodor Schwann, who observed that the cell wall is a characteristic feature of plant cells, providing structural support.
Q86. A specialized differentiated form of cell membrane characteristic of prokaryotes is:
Correct Answer: (c)
Mesosomes are infoldings of the plasma membrane in bacteria, increasing its surface area. They are involved in cell wall formation, DNA replication, and respiration, and are often seen in Gram-positive bacteria.
Q87. Match the cell envelope components with their descriptions:
Column I
Column II
A. Slime layer
(I) Thick and tough glycocalyx
B. Capsule
(II) Loose sheath glycocalyx
C. Cell wall
(III) Determines cell shape
D. Plasma membrane
(IV) Selectively permeable
Correct Answer: (a)
Slime layer is a loose glycocalyx (II); capsule is a thick, tough glycocalyx (I); cell wall maintains shape (III); plasma membrane is selectively permeable (IV). These are key features of the bacterial envelope.
Q88. Regarding the cell membrane, which are correct? (i) Phospholipids are arranged in a bilayer. (ii) Polar heads are towards the inner part. (iii) Hydrophobic tails are protected from the aqueous environment.
Correct Answer: (a)
In the lipid bilayer, phospholipids form two layers with polar heads facing the aqueous exterior and interior, and hydrophobic tails facing each other. Thus (i) and (iii) are correct; (ii) is false because polar heads are on the surface, not the inner part.
Q89. Select correct statements about cilia and flagella: (i) Cilia are shorter and work like oars. (ii) Flagella are longer and responsible for cell movement. (iii) Eukaryotic flagella are structurally same as prokaryotic flagella.
Correct Answer: (a)
Cilia are short, numerous, and beat like oars; flagella are longer and propel cells. However, eukaryotic flagella have a 9+2 microtubule arrangement, whereas prokaryotic flagella are composed of flagellin and are structurally different.
Q90. Which of the following is correct? (i) Robert Brown discovered the cell. (ii) Schleiden and Schwann formulated cell theory. (iii) A unicellular organism carries out life activities in a single cell.
Correct Answer: (a)
Robert Brown discovered the nucleus, not the cell, so (i) is false. Schleiden and Schwann proposed the cell theory, and unicellular organisms perform all life functions within a single cell. Therefore (ii) and (iii) are correct.
Q91. Match the organelle structure terms:
Column I
Column II
A. Cristae
(I) Flattened sacs in stroma
B. Cisternae
(II) Infoldings in mitochondria
C. Thylakoids
(III) Disc-shaped sacs in Golgi
Correct Answer: (a)
Cristae are infoldings of the mitochondrial inner membrane (II); cisternae are flattened sacs in the Golgi apparatus (III); thylakoids are flattened sacs in the chloroplast stroma (I). These terms describe membrane structures in different organelles.
Q92. Identify the correct statements about prokaryotic cells: (i) They generally multiply more rapidly than eukaryotic cells. (ii) They contain a well-defined nucleus. (iii) Plasmids are found in many bacteria.
Correct Answer: (a)
Prokaryotes lack a membrane-bound nucleus, so (ii) is false. They do multiply faster and often contain plasmids. Therefore, (i) and (iii) are correct.
Q93. Which statements correctly describe the endomembrane system? (i) ER, Golgi, Lysosomes, and Vacuoles are its components. (ii) Their functions are coordinated. (iii) Peroxisomes are also a part of this system.
Correct Answer: (a)
The endomembrane system includes the ER, Golgi, lysosomes, and vacuoles, and they work together in protein and lipid processing. Peroxisomes are not part of this system; they are involved in oxidative reactions and are considered separate.
Q94. Assertion: SER is involved in lipid synthesis.
Reason: Steroidal hormones are synthesized in SER in animal cells.
Correct Answer: (a)
The smooth endoplasmic reticulum (SER) is the major site for lipid synthesis, including phospholipids and steroids. The synthesis of steroidal hormones in SER is a specific example that directly supports the assertion that SER is involved in lipid synthesis.
Q95. Match the cilia/flagella components:
Column I
Column II
A. Axoneme
(I) 9 triplets
B. Central sheath
(II) Core of cilium
C. Radial spoke
(III) Encloses central microtubules
D. Centriole
(IV) Connects doublet to sheath
Correct Answer: (a)
Axoneme is the core of cilium (II); central sheath encloses central microtubules (III); radial spokes connect the doublets to the sheath (IV); centrioles have 9 triplets (I). These components are critical for the structure and movement of cilia and flagella.
Q96. Match the nucleus components:
Column I
Column II
A. Perinuclear space
(I) Stained with basic dyes
B. Chromatin
(II) Site for active rRNA synthesis
C. Nucleolus
(III) 10 to 50 nm
D. Nuclear pore
(IV) Passage for RNA/Proteins
Correct Answer: (a)
Perinuclear space is the gap between nuclear membranes (10–50 nm) (III); chromatin is stained by basic dyes (I); nucleolus is site of rRNA synthesis (II); nuclear pores allow passage of RNA and proteins (IV). These are key features of the nucleus.
Q97. Assertion: Secondary wall is formed on the inner side of the plant cell.
Reason: Primary wall gradually diminishes as the cell matures.
Correct Answer: (a)
After growth ceases, the secondary wall is deposited on the inner side of the primary wall. The primary wall remains, so the reason that it 'diminishes' is inaccurate; rather, secondary wall is added internally, making the cell wall thicker.
Q98. The diameter of a human red blood cell is approximately:
Correct Answer: (c)
Human RBCs have a diameter of about 7.0 μm, which is an optimal size for oxygen transport through capillaries. Their biconcave shape increases surface area for efficient gas exchange.
Q99. Assertion: Plasma membrane is selectively permeable.
Reason: It allows all substances to pass through it equally.
Correct Answer: (c)
The plasma membrane is selectively permeable, meaning it permits only certain molecules to cross, not all. The reason incorrectly states that all substances pass equally, which contradicts the concept of selective permeability.
Q100. Which is true for centrosomes? (i) It usually contains two cylindrical structures called centrioles. (ii) They are surrounded by amorphous pericentriolar materials. (iii) Both centrioles lie parallel to each other.
Correct Answer: (a)
Centrosomes contain two centrioles, which are surrounded by pericentriolar material. The two centrioles are arranged perpendicular, not parallel, so (iii) is false.