Free NEET Biology multiple-choice questions on Plant Tissues & Families. Attempt each question and reveal the answer with a full explanation.
Which cranial bone is often called the 'keystone' of the cranial floor because it articulates with all other cranial bones? Sphenoid bone Ethmoid bone Frontal bone Occipital bone The human brain's 'Forebrain' consists of the Cerebrum, Thalamus, and which other structure? Hypothalamus Cerebellum Pons Medulla Which of the following is a 'Sesamoid bone' in the human body, formed by the ossification of a tendon? Patella Scapula Clavicle Sternum What is the primary function of the 'Macula' and 'Crista' in the vestibular apparatus? Maintenance of body balance and posture Amplification of sound vibrations Coordination of visual reflexes Regulating the pressure inside the ear The human 'Vertebral Formula' for an adult is correctly represented as: C 7 T 12 L 5 S (5) Co (4) C 7 T 10 L 5 S 5 Co 4 C 5 T 12 L 7 S 5 Co 4 C 7 T 12 L 5 S 1 Co 1 An age-related disorder characterized by decreased bone mass and increased chances of fractures, often linked to decreased levels of estrogen, is: Osteoporosis Myasthenia gravis Muscular dystrophy Rheumatoid arthritis The glomerular filtration membrane consists of three layers. Which of the following is the correct sequence from the blood side to the capsule side? Endothelium, Basement membrane, Epithelium of Bowman's capsule Epithelium of Bowman's capsule, Basement membrane, Endothelium Basement membrane, Endothelium, Epithelium of Bowman's capsule Endothelium, Epithelium of Bowman's capsule, Basement membrane As the glomerular filtrate moves towards the inner medullary region within the Loop of Henle, the osmolarity of the fluid reaches its maximum value of approximately: 1200 ,mOsmL -1 300 ,mOsmL -1 600 ,mOsmL -1 900 ,mOsmL -1 Certain regions of the human cerebral cortex are neither clearly sensory nor motor in function. These are called: Association areas Corpus callosum Limbic system Cerebral aqueduct The Atrio-ventricular Node (AVN), which receives the impulse from the SAN, is located in which region of the heart? Lower-left corner of the right atrium Upper-right corner of the right atrium Lower-right corner of the left atrium Upper-left corner of the left atrium Which type of joint is characterized by the presence of limited movement and is found between the adjacent vertebrae in the vertebral column? Cartilaginous joint Fibrous joint Synovial joint Gliding joint The pituitary gland is anatomically divided into Adenohypophysis and Neurohypophysis. The Adenohypophysis consists of which two portions? Pars distalis and Pars intermedia Pars nervosa and Pars distalis Pars intermedia and Pars nervosa Infundibulum and Pars distalis What is the name of the pigment found in red muscle fibers that gives them their color and allows them to store oxygen? Myoglobin Hemoglobin Bilirubin Rhodopsin In the Renin-Angiotensin system, the conversion of Angiotensin I to Angiotensin II primarily occurs in the blood vessels of which organ? Lungs Kidneys Liver Heart The Net Filtration Pressure ( NFP ) in the glomerulus is calculated by which of the following formulas? GHP - (BCOP + CHP) GHP + BCOP + CHP (GHP + BCOP) - CHP BCOP - (GHP + CHP) What happens to the A -band of a sarcomere during muscle contraction? It remains constant in length It shortens It lengthens It disappears The reabsorption of urea into the medullary interstitium occurs through which part of the nephron? Collecting duct Proximal Convoluted Tubule Descending limb of Loop of Henle Distal Convoluted Tubule Which region of the brain acts as a bridge between the two cerebellar hemispheres? Pons Varolii Medulla Corpus Callosum Midbrain In the 'Organ of Corti', located in the human internal ear, what is the name of the thin elastic membrane situated above the rows of hair cells? Tectorial membrane Reissner's membrane Basilar membrane Tympanic membrane In the kidney, the epithelial cells of the Bowman's capsule are called podocytes. The minute spaces left between their intricate arrangement are called: Filtration slits Fenestrae Vasa recta Sinusoids Red muscle fibers are rich in myoglobin and mitochondria. This specialization allows them to primarily perform: Aerobic respiration for a long duration Anaerobic respiration resulting in lactic acid accumulation Rapid, short bursts of contraction Storage of large amounts of glycogen only Which of the following pairs of ribs in the human body are referred to as 'Vertebrochondral' or false ribs? 8th, 9th, and 10th pairs 1st to 7th pairs 11th and 12th pairs 8th to 12th pairs Which specific blood vessels are responsible for delivering oxygenated blood to the tissues of the heart (myocardium)? Coronary arteries Pulmonary veins Carotid arteries Hepatic arteries Which of the following is an example of a 'fibrous joint' that allows no movement? Sutures in the skull Joint between atlas and axis Joint between carpals Pubic symphysis The double-layered 'Pleura' protects the lungs and contains pleural fluid. What is the primary function of this fluid? Reduces friction on the lung surface Facilitates gas exchange in the alveoli Acts as a surfactant to prevent collapse Filters dust particles from inhaled air Which component of the thin filament in a skeletal muscle is a complex protein that masks the active binding sites for myosin in a resting state? Troponin Tropomyosin Meromyosin Actin Which plasma protein is primarily responsible for maintaining the 'Colloid Osmotic Pressure' (osmotic balance) of the blood? Albumin Globulin Fibrinogen Prothrombin During muscle contraction, which of the following stays the same length? A-band I-band H-zone Sarcomere Which of the following structures in the ear is responsible for maintaining dynamic equilibrium? Semicircular canals Cochlea Eustachian tube Tympanic membrane Which mechanism is primarily responsible for maintaining a high osmolarity of the interstitial fluid in the inner renal medulla? Countercurrent mechanism between Henle's loop and vasa recta Active secretion of H + in the PCT Selective reabsorption of glucose in the PCT Ultrafiltration in the Malpighian corpuscle Compared to white muscle fibers, red muscle fibers are characterized by: High myoglobin content and more mitochondria Low myoglobin content and more mitochondria High sarcoplasmic reticulum content and less myoglobin Fewer blood capillaries and more mitochondria The Juxtaglomerular Apparatus (JGA) releases Renin in response to a fall in: Glomerular Filtration Rate (GFR) Blood glucose levels Blood CO 2 levels Interstitial fluid osmolarity The adrenal cortex is divided into three layers. From the outer layer to the inner layer, the correct sequence is: Zona glomerulosa, Zona fasciculata, Zona reticularis Zona reticularis, Zona fasciculata, Zona glomerulosa Zona fasciculata, Zona glomerulosa, Zona reticularis Zona glomerulosa, Zona reticularis, Zona fasciculata During the process of muscle contraction, the hydrolysis of ATP by the myosin head occurs specifically at which stage? Before the myosin head binds to the active site on actin While the cross-bridge is already formed During the power stroke (pulling of actin) When the myosin head detaches from the actin Which of the following structures is NOT part of the 'Hindbrain'? Corpus callosum Pons Cerebellum Medulla oblongata Which of the following shifts the oxygen-haemoglobin dissociation curve to the left? Low PCO 2 High H + concentration High temperature High 2,3-BPG levels Which subunit of troponin masks the binding sites for myosin on the actin filaments in a resting muscle? Troponin I Troponin C Troponin T Calmodulin During strenuous exercise, why does the oxygen-hemoglobin dissociation curve shift to the right? Increase in H + concentration Decrease in PCO 2 Decrease in temperature Increase in pH Which of the following is the 'Haldane Effect' related to gas transport in the blood? Deoxygenation of blood increases its ability to carry CO 2 Increased PCO 2 decreases the affinity of haemoglobin for O 2 Increased H + concentration shifts the oxygen-haemoglobin curve to the right Binding of CO to haemoglobin prevents O 2 binding In a skeletal muscle 'Triad', which structures are involved? One T-tubule and two terminal cisternae Two T-tubules and one terminal cisterna Three T-tubules One T-tubule and one terminal cisterna During 'Saltatory Conduction', the nerve impulse jumps from one: Node of Ranvier to the next Dendrite to an axon Axon to a synapse Myelin sheath to another myelin sheath An important step in the manufacture of pulp for paper industry from the woody tissues of plants is the - Removal of water form the wood by prolonged heating at approximately 50° Treatment of wood with chemicals that break down cellulose Removal of oils present in the wood by treatment with suitable chemicals Preparation of pure cellulose by removing lignin A common structural feature of vessel elements and sieve tube elements is- Thick secondary walls Pores on lateral wall Presence of p-protein Enucleate condition The floral formula ⊕ ⚥ K (5) C (5) A 5 G (2) is that of : Tobacco Tulip Soybean Sunnhemp Tricarpellary syncarpous gynoecium is found in flowers of : Liliaceae Solanaceae Fabaceae Poaceae Which part of the human brain is mainly responsible for thermoregulation? Hypothalamus Cerebellum Medulla oblongata Corpus callosum Which of the following statements is true for phloem in plants? Phloem fibres are made up of collenchymatous cells Sieve tube elements are multicellular with wide lumen and rich cytoplasm. Companion cells help in maintaining the pressure gradient in sieve tubes. Phloem parenchyma is abundantly present in monocots Match List-I with List-II. array llll ; & List - I & ; & List - II (a) & Cells with active cell division capacity & (i) & Vascular tissues (b) & Tissue having all cells similar in structure and function & (ii) & Meristematic tissue (c) & Tissue having different types of cells & (iii) & Sclereids (d) & Dead cells with highly thickened walls and narrow lumen & (iv) & Simple tissue array Select the correct answer from the options given below. a-iv, b-iii, c-ii, d-i a-i, b-ii, c-iii, d-iv a-iii, b-ii, c-iv, d-i a-ii, b-iv, c-i, d-iii Family Fabaceae differs from Solanaceae and Liliaceae. With respect to the stamens, pick out the characteristics specific to family Fabaceae but not found in Solanaceae or Liliaceae. Diadelphous and Dithecous anthers Polyadelphous and epipetalous stamens Monoadelphous and Monothecous anthers Epiphyllous and Dithecous anthers Which of the following floral formula is the correct floral formula of Solanaceae family? ⊕ ⚥ K (5) C (5) A 5 G (2) ⊕ ⚥ K 5 C 5 A 5 G (2) Match Column-I with Column-II (a) % ⚥ K (5) C 1+2+(2) A (9)+1 G 1 (i) Brassicaceae (b) ⊕ ⚥ K (5) C (5) A 5 G (2) (ii) Liliaceae (c) ⊕ ⚥ P (3+3) A 3+3 G (3) (iii) Fabaceae (d) ⊕ ⚥ K 2+2 C 4 A 2+4 G (2) (iv) Solanaceae Choose the correct answer from the options given below. a-i, b-ii, c-iii, d-iv a-ii, b-iii, c-iv, d-i a-iv, b-ii, c-i, d-iii a-iii, b-iv, c-ii, d-i Which of the following are characteristic features of Solanaceae family? (a) Flowers are bisexual and actinomorphic (b) Calyx have five sepals and are united (c) Androecium have five stamens and are epipetalous (d) Ovary is inferior Choose the correct answer from the options given below : (a), (b) and (c) only (d) only (a) and (b) only (b), (c) and (d) only What is the total number of 'Cranial Bones' in the adult human skull? 8 14 22 6 The human skull is composed of two sets of bones—cranial and facial. What is the total number of 'facial bones' present in a normal adult human? 14 8 22 12 Each actin (thin) filament is made of two 'F' (filamentous) actins helically wound to each other. Each 'F' actin is a polymer of monomeric: G (Globular) actins Tropomyosin Troponin Meromyosin The fluid-filled cavities within the brain that contain Cerebrospinal Fluid (CSF) are known as: Ventricles Atria Sinuses Sulci The rapid 'Saltatory Conduction' of nerve impulses occurs in which type of nerve fibers? Myelinated nerve fibers Non-myelinated nerve fibers Only in autonomic neurons Only in sensory neurons The 'Foramen Magnum' is a large opening found in which bone of the human skeleton? Occipital bone Parietal bone Temporal bone Sphenoid bone The electrical potential difference across the resting plasma membrane of a neuron is called the: Resting potential Action potential Spike potential Threshold potential Which part of the skeletal system contains the 'Glenoid Cavity'? Pectoral girdle Pelvic girdle Skull Vertebral column How many 'Occipital Condyles' are present in the human skull, making it dicondylic? Two One Four Six The C-shaped cartilaginous rings that support the trachea are made of which type of cartilage? Hyaline cartilage Elastic cartilage Fibrocartilage Calcified cartilage At which level of the thoracic vertebra does the trachea divide into the right and left primary bronchi? 5th Thoracic vertebra 3rd Thoracic vertebra 7th Thoracic vertebra 12th Thoracic vertebra The 'Mons pubis' in the human female external genitalia is a: Cushion of fatty tissue covered by skin and pubic hair Thin fold of mucous membrane covering the vaginal opening Fleshy fold of tissue surrounding the vaginal opening Tiny finger-like structure at the upper junction of labia minora Pentamerous, actinomorphic flowers, bicarpellary ovary with oblique septa, and fruit a capsule or berry, are characteristic features of- Asteraceae Brassicaceae Solanaceae Liliaceae Middle lamella is composed mainly of : Phosphoglycerides Hemicellulose Muramic acid Calcium pectate Tracheids differ from other tracheary elements in : having casparian strips being imperforate lacking nucleus being lignified Specialised epidermal cells surrounding the guard cells are called :- Complementary cells Subsidiary cells Bulliform cells Lenticels On the scapula (shoulder blade), there is a prominent ridge called the spine which projects as a flattened, expanded process called the: Acromion Coracoid process Glenoid cavity Acetabulum The chief function of vessels in the plant body is to : Eliminate excess of water Transport food materials manufactured in the leaves to other parts of the plant Store food material in the form of starch or fat Conduct water and mineral salts Tetradynamous stamens are characteristic of: Brassicaceae Solanaceae Fabaceae Liliaceae Given below are two statements: Statement I : Parenchyma is living but collenchyma is dead tissue. Statement II : Gymnosperms lack xylem vessels but presence of xylem vessels is the characteristic of angiosperms. In the light of the above statements, choose the correct answer from the options given below: Both Statement I and Statement II are true Both Statement I and Statement II are false Statement I is true but Statement II is false Statement I is false but Statement II is true The secondary xylem and phloem in a dicot stem are produced by the activity of the: Vascular cambium Phellogen Apical meristem Axillary bud The cork cambium, cork and secondary cortex are collectively called: Periderm Phelloderm Phellogen Phellem Match the following and choose the correct option: (a) Meristem (b) Parenchyma (c) Collenchyma (d) Sclerenchyma -- (i) Photosynthesis, storage (ii) Mechanical support to growing parts (iii) Actively dividing cells (iv) Sclereids (a)-iii, (b)-i, (c)-ii, (d)-iv (a)-i, (b)-iii, (c)-ii, (d)-iv (a)-iii, (b)-ii, (c)-i, (d)-iv (a)-iv, (b)-i, (c)-ii, (d)-iii Heartwood differs from sapwood in: Having dead and non-conducting elements Presence of rays and fibres Absence of vessels and parenchyma Being susceptible to pests and pathogens Which constituent of phloem is chemically composed of cellulose and lacks a nucleus at maturity, yet remains living? Sieve tube elements Companion cells Phloem parenchyma Phloem fibres Which of the following statements about heartwood is INCORRECT? It conducts water and minerals efficiently. It contains organic compounds like tannins and resins. It is highly durable and resistant to microbes. It comprises dead elements with highly lignified walls. During secondary growth in a dicot stem, the wood formed during the spring season is called 'early wood'. It is characterized by: Xylem elements with wider vessels Xylem elements with narrow vessels Greater density and darker color Low metabolic activity of cambium What is the functional unit of contraction in a muscle fiber, located between two successive Z-lines? Sarcomere Sarcolemma Sarcoplasm Fascicle At certain regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These cells rupture the epidermis, forming lens-shaped openings called: Lenticels Stomata Hydathodes Phelloderm Companion cells are closely associated with sieve tube elements. The primary function of companion cells is to: Maintain the pressure gradient in the sieve tubes Load sucrose into the sieve tubes by active transport Provide mechanical support to the sieve elements Store food materials and resins Phloem fibres (bast fibres) are generally absent in primary phloem but found in secondary phloem. These cells are made of: Sclerenchyma Parenchyma Collenchyma Chlorenchyma Annual rings are distinct in plants growing in temperate regions because: The activity of cambium varies with seasons The plant produces only secondary xylem in spring The cork cambium is more active than vascular cambium There is no secondary growth in tropical regions During secondary growth in a dicot stem, the cells of medullary rays, adjoining the intrafascicular cambium, become meristematic and form the: Interfascicular cambium Phellogen Procambium Secondary phloem Which of the following is the correct definition of 'Bark' in botanical terms? All tissues exterior to the vascular cambium Only the phellem and phellogen The secondary xylem and heartwood The periderm and secondary xylem The layer of the cell wall that holds neighboring cells together is the middle lamella, which is primarily composed of Calcium pectate Hemicellulose Cellulose Muramic acid In plant cells, cytokinesis occurs by the formation of a cell plate, which grows Centrifugally (from the center to the periphery) Centripetally (from the periphery to the center) Randomly Simultaneously at all points Which of the following statements regarding the cell wall is correct? The primary wall is capable of growth and gradually diminishes as the cell matures. The secondary wall is formed on the outer side of the primary wall. The middle lamella is primarily made of cellulose. Cell wall is a living structure that protects the cell. The primary cell wall of a young plant cell is characterized by its: Capability to grow, which gradually diminishes as the cell matures Rigidity due to heavy lignin deposition Absence of hemicellulose Location on the inner side of the secondary wall Nearly all mammals, including humans, have a fixed number of cervical vertebrae. What is this number? 7 8 12 5 Cellulose is a homopolymer consisting of repeating units of: -D-Glucose -D-Glucose -D-Fructose N-acetylglucosamine The 'Secondary Cell Wall' of a plant cell is formed: Inner to the primary wall as the cell matures Outer to the primary wall during initial growth In the middle lamella to join cells Only in the embryonic stage Chitin is a homopolymer of: N-acetyl glucosamine N-acetyl muramic acid D-Glucose D-Fructose Which of the following is a homopolymer of N-acetylglucosamine ( NAG )? Chitin Cellulose Glycogen Inulin The cell wall of a young plant cell, the primary wall, is capable of growth, which gradually diminishes as the cell matures and the is formed on the inner side of the cell. Secondary wall Tertiary wall Middle lamella Glycocalyx Which component of the plant cell wall is specifically responsible for the reduction of water loss and protection against microbial attack in woody tissues? Lignin Pectin Hemicellulose Cellulose The structure that connects the cytoplasm of adjacent plant cells for transport and communication is the Plasmodesmata Middle lamella Gap junction Tight junction The cell walls of endodermal cells in plant roots are impregnated with a water-impermeable, waxy material called: Suberin Chitin Pectin Cellulose The proximally situated segment of the nephron, the Proximal Convoluted Tubule (PCT), is lined by which type of epithelium? Simple cuboidal brush border epithelium Simple squamous epithelium Ciliated columnar epithelium Compound epithelium Which part of the nephron is impermeable to water but allows transport of electrolytes actively or passively? Ascending limb of loop of Henle Descending limb of loop of Henle Proximal convoluted tubule Collecting duct The humerus articulates with the pectoral girdle at a specific depression called the: Glenoid cavity Acetabulum Foramen magnum Obturator foramen The pivot joint between the atlas and axis vertebrae is an example of: Synovial joint Cartilaginous joint Fibrous joint Saddle joint The 'Organ of Corti' is a structure present in the human ear that contains hair cells acting as auditory receptors. Where is it specifically located? Basilar membrane Reissner's membrane Tectorial membrane Tympanic membrane Which process in the nephron is non-selective and relies on the pressure gradient between the glomerulus and Bowman's capsule? Ultrafiltration Tubular reabsorption Tubular secretion Osmoregulation The inner wall of the Bowman's capsule contains specialized cells called podocytes. What is their primary role? Creating filtration slits for ultrafiltration Secreting renin into the blood Active reabsorption of Na + ions Phagocytosis of bacteria in the filtrate During muscle contraction, Ca 2+ ions released from the sarcoplasmic reticulum bind to which protein to initiate the process? Troponin Tropomyosin Actin Myosin The Atrial Natriuretic Factor (ANF) is secreted by the heart in response to high blood pressure. What is its effect? Vasodilation and decreased blood pressure Vasoconstriction and increased blood pressure Increased reabsorption of Na + Stimulation of Renin secretion In the human brain, which structure acts as a major relay station for sensory and motor signaling to the cerebral cortex? Thalamus Hypothalamus Pons Medulla Which structure in the heart prevents the bicuspid and tricuspid valves from turning inside out (eversion) into the atria during ventricular contraction? Chordae tendineae Purkinje fibers SA node Bundle of His In the human skeletal system, how many pairs of ribs are known as 'floating ribs' because they are not connected ventrally? 2 pairs 3 pairs 5 pairs 7 pairs The resting membrane potential of a neuron is maintained primarily by the active transport of ions. How many Na + and K + ions are moved by the sodium-potassium pump? 3 Na + out and 2 K + in 2 Na + out and 3 K + in 3 Na + in and 2 K + out 1 Na + out and 1 K + in In the human rib cage, which pairs of ribs are called 'True Ribs' because they are attached dorsally to thoracic vertebrae and ventrally to the sternum? First 7 pairs 8th, 9th and 10th pairs 11th and 12th pairs First 5 pairs The 'Vasa Recta' is a minute vessel of the peritubular capillary network that runs parallel to which part of the nephron? Henle's loop Proximal Convoluted Tubule Distal Convoluted Tubule Bowman's capsule The 'Saddle joint' is found between which of the following bones? Carpal and metacarpal of thumb Humerus and pectoral girdle Between the carpals Atlas and Axis The midbrain contains four round swellings (lobes) on the dorsal portion, which are collectively called: Corpora quadrigemina Corpus callosum Cerebral aqueduct Pons varolii The acetabulum is a cavity found in the pelvic girdle where which bone articulates? Femur Humerus Tibia Radius The maximum amount of glucose is reabsorbed in which part of the renal tubule under normal physiological conditions? Proximal Convoluted Tubule (PCT) Loop of Henle Distal Convoluted Tubule (DCT) Collecting Duct In the human shoulder girdle, the clavicle articulates with a process of the scapula called the: Acromion Glenoid cavity Coracoid process Spine During the relaxation of a muscle, which protein masks the active binding sites for myosin on the actin filaments? Tropomyosin Troponin Meromyosin Actin The 'Limbic System' or the emotional brain is formed by the inner parts of cerebral hemispheres and a group of associated deep structures like: Amygdala and Hippocampus Cerebellum and Medulla Corpora quadrigemina Pons and Thalamus A canal called the 'Cerebral Aqueduct' (Aqueduct of Sylvius) passes through which part of the human brain? Midbrain Forebrain Hindbrain Medulla oblongata The large tract of nerve fibers that connects the two cerebral hemispheres in the human brain is the: Corpus callosum Corpus albicans Corpus luteum Cerebral aqueduct The skull of a human being is 'dicondylic'. This means it possesses: Two occipital condyles Two parietal bones Two temporal bones Two foramen magnums A group of muscle fibers is held together in a bundle called a fascicle, which is surrounded by a layer of connective tissue called: Perimysium Epimysium Endomysium Fascia The vestibular apparatus, responsible for maintaining body balance and posture, consists of: Semicircular canals and Otolith organ Organ of Corti and Tectorial membrane Malleus, Incus, and Stapes Cochlea and Eustachian tube Which specialized cells of the Juxtaglomerular Apparatus (JGA) act as chemoreceptors to sense the change in NaCl concentration in the tubular fluid? Macula densa cells Juxtaglomerular cells Lacis cells Podocytes The 'Sella turcica' is a bony depression in the skull that lodges which of the following glands? Pituitary gland Pineal gland Thyroid gland Adrenal gland What happens to the sarcomere during the 'sliding filament theory' of muscle contraction? The distance between two Z-lines decreases The A-band shortens The I-band increases in length The actin filaments shorten The transport of water and electrolytes through the 'Descending Limb' of the Loop of Henle is characterized by: Permeability to water and impermeability to electrolytes Impermeability to water and permeability to electrolytes Permeability to both water and electrolytes Active transport of sodium ions into the medulla The amount of filtrate formed by the kidneys per minute is called the Glomerular Filtration Rate (GFR). What is its average value in a healthy individual? 125 ml/min 180 ml/min 500 ml/min 75 ml/min In the counter-current mechanism of the kidney, which structure acts as the 'counter-current exchanger'? Vasa recta Loop of Henle Proximal Convoluted Tubule Collecting duct The 'H-zone' in the center of a skeletal muscle sarcomere represents the region that contains: Only thick filaments Only thin filaments Both thick and thin filaments The Z-line Which type of rib is characterized by not being attached directly to the sternum but joining the seventh rib with the help of hyaline cartilage? Vertebrochondral ribs Vertebrosternal ribs Floating ribs Cervical ribs During the generation of a nerve impulse, the influx of which ion is responsible for the 'depolarization' of the axonal membrane? Na + ions K + ions Ca 2+ ions Cl - ions Which specific part of the mammalian ear is responsible for converting mechanical sound vibrations into electrical nerve impulses? Cochlea Pinna Tympanic membrane Incus The production of platelets (Thrombocytes) in the bone marrow is carried out by specialized cells called: Megakaryocytes Erythroblasts Lymphocytes Monocytes In the human heart, where is the 'Bundle of His' specifically located? Interventricular septum Right atrium Left atrium Sino-atrial node Which part of the renal tubule is the main site for the selective secretion of H + and K + ions to maintain the pH and ionic balance of body fluids? Proximal Convoluted Tubule (PCT) Descending limb of Loop of Henle Ascending limb of Loop of Henle Distal Convoluted Tubule (DCT) What is the value of the 'Resting Membrane Potential' in a typical human neuron? -70 ,mV +30 ,mV 0 ,mV -55 ,mV Which lymphoid organ is large at the time of birth but keeps reducing in size with age and is almost replaced by fat in old age? Thymus Spleen Tonsils Peyer's patches Which segment of the nephron is most responsible for the 'Obligatory Reabsorption' of water, independent of ADH levels? Proximal Convoluted Tubule (PCT) Distal Convoluted Tubule (DCT) Collecting Duct Ascending limb of Loop of Henle In the mechanism of muscle contraction, the enzyme 'Myosin ATPase' is located on which part of the protein? Globular head of Meromyosin Short arm of Meromyosin Tail of Meromyosin Troponin subunit Which part of the sarcomere contains only thin (actin) filaments and no thick (myosin) filaments? I-band A-band H-zone M-line In the human heart, the 'Semilunar valves' are located at the junction of: Ventricles and the main arteries (Aorta/Pulmonary artery) Atria and the Ventricles Vena cava and the Right atrium Pulmonary veins and the Left atrium