101. Assertion: Long bones contribute to movement as well as weight bearing.
Reason: Skeletal muscles attached to bones can apply pulling forces that move them at joints.
ⓐ. Assertion is true; Reason is true; explanatory link is valid
ⓑ. Assertion is true; Reason is true; explanatory link is invalid
ⓒ. Assertion is true; Reason is false; explanatory link is invalid
ⓓ. Assertion is false; Reason is true; explanatory link is invalid
Correct Answer: Assertion is true; Reason is true; explanatory link is valid
Explanation: Long bones possess a hard matrix that allows them to bear weight and resist mechanical forces. They also form part of a movement system with skeletal muscles and joints. When a skeletal muscle shortens, the force is transmitted through its attachment to a bone. The bone then acts as a rigid structure that can be displaced at a joint. The reason explains the movement part of the assertion by connecting muscle contraction with bone displacement. Weight bearing depends strongly on the mineralised matrix, whereas movement depends on interaction among muscle, attachment, bone, and joint. Both roles can occur in the same long bone, illustrating how a specialised connective tissue contributes to structural support and coordinated body motion.
102. Associate each bone-related feature with its most appropriate description. Each Column II entry is used once.
| Column I | Column II |
|---|
| P. Osteocyte | W. Hardness of the extracellular matrix |
| Q. Lacuna | X. Living cell of bone tissue |
| R. Calcium salts | Y. Small cavity containing a bone cell |
| S. Bone marrow | Z. Formation of blood cells in some bones |
ⓐ. P-Y, Q-X, R-Z, S-W
ⓑ. P-W, Q-Z, R-X, S-Y
ⓒ. P-Z, Q-W, R-Y, S-X
ⓓ. P-X, Q-Y, R-W, S-Z
Correct Answer: P-X, Q-Y, R-W, S-Z
Explanation: The osteocyte is the living cellular component of bone, so P matches X. Each osteocyte occupies a small cavity known as a lacuna, linking Q with Y. Calcium salts deposited in the matrix contribute greatly to its hardness and rigidity, giving R with W. Marrow present in some bones participates in blood-cell formation, so S matches Z. The mapping distinguishes a cell, the space containing that cell, a matrix component, and an internal tissue region. These features work together within bone but cannot replace one another. Osteocytes maintain living bone tissue, lacunae house them, mineral salts help create a load-bearing matrix, and marrow adds a blood-forming function to particular bones.
103. Blood is classified as connective tissue even though its matrix is fluid and lacks the usual abundance of structural fibres. The best justification is that blood:
ⓐ. forms a compact sheet with a free surface
ⓑ. contains parallel contractile cells
ⓒ. contains cells with almost no intercellular matrix
ⓓ. contains cells suspended in a fluid matrix
Correct Answer: contains cells suspended in a fluid matrix
Explanation: Blood consists of red blood cells, white blood cells, and platelets suspended in a fluid matrix called plasma. Its matrix differs from the fibre-rich matrix of many solid connective tissues, but connective-tissue identity is not restricted to hardness or visible collagen bundles. Blood links distant body regions by transporting gases, nutrients, hormones, wastes, and other materials through the circulation. The plasma is an extracellular material surrounding the formed components, so blood is not a cell-only mixture. It also does not form a compact covering like epithelium or a contractile bundle like muscle. Its fluid matrix and body-wide transport role justify placing blood among specialised connective tissues while recognising it as an important exception to the common fibre-rich pattern.
104. Relate each blood component with its broad contribution. Each Column II entry is used once.
| Column I | Column II |
|---|
| P. Plasma | W. Defence-related cellular activity |
| Q. Red blood cells | X. Fluid medium carrying dissolved substances |
| R. White blood cells | Y. Transport of respiratory gases |
| S. Platelets | Z. Participation in blood clotting |
ⓐ. P-X, Q-Y, R-W, S-Z
ⓑ. P-Y, Q-X, R-Z, S-W
ⓒ. P-W, Q-Z, R-X, S-Y
ⓓ. P-Z, Q-W, R-Y, S-X
Correct Answer: P-X, Q-Y, R-W, S-Z
Explanation: Plasma is the liquid matrix of blood and carries dissolved materials, so P matches X. Red blood cells are specialised mainly for the transport of respiratory gases, linking Q with Y. White blood cells contribute to defence and protective cellular responses, which places R with W. Platelets participate in clot formation after blood-vessel injury, giving S with Z. These components travel together but contribute different functions to the circulating tissue. The fluid matrix permits distribution, red cells support gas transport, white cells provide defence, and platelets assist in limiting blood loss. Their combined activity shows why blood functions as an integrated connective tissue rather than as a uniform fluid with identical suspended particles.
105. Equal blood samples are separated into components. Sample P retains plasma but has most red blood cells removed. Sample Q retains red blood cells but loses most plasma. Compared with normal blood, the most defensible prediction is:
ⓐ. P loses all dissolved transport, while Q circulates normally
ⓑ. P transports dissolved substances but fewer respiratory gases
ⓒ. P gains clotting ability, while Q becomes epithelial tissue
ⓓ. Q becomes an effective fluid matrix despite severe plasma loss
Correct Answer: P transports dissolved substances but fewer respiratory gases
Explanation: Plasma is the fluid matrix that carries many dissolved substances, so sample P can retain part of this transport function. Removal of most red blood cells greatly reduces its capacity to carry respiratory gases. Sample Q contains red blood cells but lacks much of the fluid medium required to suspend and circulate them efficiently, so it cannot behave like normal blood. The comparison separates the contributions of matrix and cellular components. Plasma alone does not reproduce every blood function, and red cells alone do not constitute an effective circulating tissue. Normal transport depends on formed elements being suspended and conveyed within an adequate fluid matrix. Sample P retains plasma. This preserved condition isolates the consequence of the selective change. The predicted outcome for P follows from preserving plasma while selectively reducing the component most directly associated with respiratory-gas transport.
106. A circulation carries nutrients from the intestine, hormones from glands, respiratory gases, and metabolic wastes between distant organs. This evidence supports the classification of blood as:
ⓐ. a fluid connective tissue producing body-wide transport links
ⓑ. an epithelial tissue forming a protective external covering
ⓒ. a muscular tissue generating movement by fibre shortening
ⓓ. a neural tissue transmitting only electrical disturbances
Correct Answer: a fluid connective tissue producing body-wide transport links
Explanation: The materials listed originate from or travel to different organs, yet they share a circulating pathway. Blood connects these regions functionally by transporting substances through its fluid matrix. This body-wide linkage is a major reason for its classification as connective tissue. Unlike a surface epithelium, blood does not form a compact boundary. It also does not move material through shortening of its own elongated fibres, and its transport is not limited to electrical signals. Plasma carries dissolved substances, while blood cells add specialised transport, defence, and clotting functions. The evidence describes a fluid tissue whose circulation integrates the activities of distant organs, extending the connective role beyond purely mechanical binding.
107. Place the events involved in a simple muscular response.
P. The muscle fibres shorten.
Q. A suitable stimulus acts on the muscle.
R. Movement or maintenance of position results.
S. The fibres relax after the response.
ⓐ. P followed by Q, then S, then R
ⓑ. Q followed by R, then P, then S
ⓒ. Q followed by P, then R, then S
ⓓ. R followed by Q, then P, then S
Correct Answer: Q followed by P, then R, then S
Explanation: A muscular response begins when an appropriate stimulus reaches the muscle tissue. The contractile machinery within its elongated fibres then causes shortening. This shortening produces force, which can move a body part or help maintain its position, depending on the arrangement and task of the muscle. Relaxation follows the active response and allows the fibres to return toward their earlier state. The defensible dependency order is stimulus, shortening, functional effect, and relaxation. Movement cannot precede force production, and fibre shortening is not initiated after the response has already occurred. The initial dependency is established when a suitable stimulus acts on the muscle; the terminal outcome appears when the fibres relax after the response; reversing any adjacent pair would place an effect before the process that produces it. The sequence captures the general contractile organisation shared by muscle tissues without importing the detailed molecular mechanism of contraction.
108. A muscle retains living elongated fibres and receives normal stimulation, but its myofibrils are severely disrupted. The most likely consequence is:
ⓐ. improved movement through increased extracellular matrix
ⓑ. conversion of the fibres into supporting neuroglia
ⓒ. reduced shortening and force production by the fibres
ⓓ. loss of all surrounding connective-tissue sheaths
Correct Answer: reduced shortening and force production by the fibres
Explanation: Myofibrils are contractile structures located within muscle fibres. Their organised shortening allows the fibre to generate tension and produce movement or maintain a body position. If myofibrils are severely disrupted, stimulation may still reach the living cell, but the machinery that converts stimulation into effective shortening is impaired. The immediate result is reduced force production rather than a change into another tissue type. Extracellular matrix cannot substitute for the internal contractile apparatus, and neuroglia belong to neural tissue. Connective-tissue sheaths surrounding certain muscle bundles may remain present even when the myofibrils inside fibres are damaged. The condition separates excitation from contraction and shows that an intact contractile organisation is required for a useful muscular response.
109. Read the arrangement described below. A tissue contains long cylindrical fibres arranged in parallel bundles. Alternating light and dark bands are visible, connective-tissue sheaths surround the bundles, and the tissue is closely attached to bones. It is:
ⓐ. smooth muscle tissue
ⓑ. cardiac muscle tissue
ⓒ. dense regular connective tissue
ⓓ. skeletal muscle tissue
Correct Answer: skeletal muscle tissue
Explanation: Skeletal muscle contains long, cylindrical, striated fibres arranged in parallel bundles. The visible alternating bands provide the striated appearance, while connective-tissue sheaths enclose and organise groups of fibres. Close attachment to bones links this tissue with voluntary body movement and maintenance of posture. Smooth muscle lacks striations and consists of tapering fusiform cells in the walls of internal organs. Cardiac muscle is also striated but contains branched cells joined into a coordinated network and occurs only in the heart. Dense regular connective tissue may form a tendon near muscle, yet its collagen bundles do not have the cellular striations or contractile fibres described here. The full feature set identifies skeletal muscle.
110. Assess the following statements about skeletal muscle tissue.
I. Its fibres are long, cylindrical, and striated.
II. Its fibres commonly occur in parallel bundles.
III. Its activity is generally voluntary.
IV. Its cells are branched and confined to the heart.
ⓐ. I, II and III only
ⓑ. I and IV only
ⓒ. II, III and IV only
ⓓ. I, II, III and IV
Correct Answer: I, II and III only
Explanation: Skeletal muscle fibres are elongated, cylindrical, and visibly striated. They are commonly arranged in parallel bundles, an organisation suited to producing force in a defined direction. Their activity is generally under voluntary control, supporting deliberate movement of bones and maintenance of posture. Statement IV describes cardiac rather than skeletal muscle. Cardiac cells are branched, striated, joined through specialised contacts, and restricted to the heart. The two tissues share striation, so that feature alone cannot distinguish them. Cell shape, branching, location, arrangement, and control must be considered together. Statements I, II, and III form the valid set for skeletal muscle, while the heart-specific branched organisation belongs to a different muscle category.
111. A person voluntarily bends the forearm. The relevant skeletal muscle shortens normally, but its attachment to the forearm bone is completely severed. The most likely outcome is:
ⓐ. the bone moves normally since contraction alone is sufficient
ⓑ. the muscle becomes smooth muscle after losing the attachment
ⓒ. voluntary control disappears from every skeletal muscle
ⓓ. the muscle contracts although movement of that bone is reduced
Correct Answer: the muscle contracts although movement of that bone is reduced
Explanation: Skeletal muscle generates force by shortening, but movement of a particular bone requires that this force be transmitted through an intact attachment. In the stated condition, stimulation and contraction remain normal, so the muscle can still shorten. The severed connection prevents most of that pulling force from reaching the forearm bone. Effective movement is reduced even though the contractile tissue itself remains active. Losing an attachment does not convert skeletal muscle into smooth muscle, nor does it remove voluntary control from unrelated muscles. The case distinguishes force production from force transmission. Both are required for normal skeletal movement: the muscle supplies the pull, and the attachment conveys that pull to the bone.
112. A skeletal muscle fibre is long, cylindrical, striated, and generally under voluntary control. Which relation best explains how these features support its usual role?
ⓐ. Fusiform cells permit slow involuntary narrowing of internal tubes
ⓑ. Parallel contractile fibres generate directed force that can be transmitted to bones
ⓒ. Branched cells joined by intercalated discs coordinate the heartbeat
ⓓ. Abundant extracellular matrix stores fat beneath the skin
Correct Answer: Parallel contractile fibres generate directed force that can be transmitted to bones
Explanation: Skeletal muscle fibres are elongated and arranged in parallel bundles, so shortening by many fibres can sum into a strong pull along a common direction. Their striated contractile machinery generates force, and attachments transmit that force to bones to produce voluntary movement or maintain posture. The other descriptions belong to neighbouring tissue categories: fusiform non-striated cells characterise smooth muscle, branched junction-linked fibres characterise cardiac muscle, and fat storage is performed by adipose connective tissue. The decisive relation is not striation alone, since cardiac muscle is also striated. Fibre shape, parallel arrangement, control, and attachment must agree. Together they explain how skeletal muscle converts voluntary stimulation into directed mechanical force rather than merely identifying a striped microscopic appearance.
113. A muscle sample consists of spindle-shaped cells that taper at both ends. No striations are visible, and the tissue forms part of the intestinal wall. It is:
ⓐ. cardiac muscle with branched striated fibres
ⓑ. smooth muscle with spindle-shaped non-striated cells
ⓒ. skeletal muscle with long striated fibres
ⓓ. dense irregular connective tissue with collagen bundles
Correct Answer: smooth muscle with spindle-shaped non-striated cells
Explanation: Smooth muscle consists of fusiform or spindle-shaped cells that are broader in the middle and taper toward both ends. Its cells lack visible striations and commonly occur in the walls of internal organs such as the stomach, intestine, and blood vessels. Activity in these locations is involuntary, allowing internal movements to proceed without deliberate control. Skeletal muscle has long cylindrical striated fibres arranged in parallel bundles and is usually attached to bones. Cardiac muscle is striated and branched and occurs only in the heart. Dense irregular connective tissue contains collagen in varied orientations but does not consist of contractile fusiform muscle cells. Cell shape, absence of striation, and organ-wall location together identify smooth muscle.
114. A drug blocks voluntary motor commands but leaves involuntary activity in the intestinal wall intact. The contracting cells there are spindle-shaped and lack visible striations. They are:
ⓐ. skeletal muscle fibres activated voluntarily
ⓑ. cardiac muscle cells joined by intercalated discs
ⓒ. smooth muscle cells acting involuntarily
ⓓ. collagen fibres of dense regular connective tissue
Correct Answer: smooth muscle cells acting involuntarily
Explanation: The intestinal wall contains smooth muscle, whose cells are fusiform, non-striated, and generally involuntary. Preserved contraction after voluntary motor commands are blocked therefore fits smooth rather than skeletal muscle. Skeletal fibres are long, cylindrical, striated, and usually controlled voluntarily. Cardiac cells are also involuntary, but they are branched, striated, connected by specialised junctions, and restricted to the heart. Collagen fibres are extracellular connective-tissue components and cannot shorten as muscle cells do. The case uses both the retained control pattern and the observed cell form. Either clue alone would be weaker: involuntary activity is shared by smooth and cardiac muscle, while spindle shape and absence of striations specifically support smooth muscle in an internal-organ wall.
115. Smooth muscle in a section of the intestinal wall becomes unable to contract, while the epithelial lining and connective support remain intact. The most direct effect is:
ⓐ. impaired involuntary movement of contents through that region
ⓑ. loss of the epithelial barrier between the lumen and body
ⓒ. disappearance of all collagen from the intestinal wall
ⓓ. conversion of the wall into voluntarily controlled skeletal muscle
Correct Answer: impaired involuntary movement of contents through that region
Explanation: Smooth muscle in the intestinal wall produces involuntary contractions that help move and mix contents within the digestive tract. Selective loss of its contractility removes this mechanical activity even though the epithelial lining and connective framework remain present. The epithelium can continue forming a boundary, and connective tissue can continue providing support, but neither performs the shortening needed to propel material. The tissue does not transform into skeletal muscle, since muscle classification depends on cellular structure and organisation rather than on the temporary presence or absence of contraction. The epithelial lining and connective support remain intact; this unaffected baseline separates the primary defect from a general collapse of the organ or tissue. The predicted defect is local failure of involuntary movement, illustrating how different tissues in one organ contribute distinct yet cooperating functions.
116. Assertion: Smooth muscle can regulate the internal diameter of a blood vessel without voluntary effort.
Reason: Smooth muscle is present in vessel walls and contracts involuntarily.
ⓐ. Assertion is true; Reason is true; explanatory link is valid
ⓑ. Assertion is true; Reason is true; explanatory link is invalid
ⓒ. Assertion is true; Reason is false; explanatory link is invalid
ⓓ. Assertion is false; Reason is true; explanatory link is invalid
Correct Answer: Assertion is true; Reason is true; explanatory link is valid
Explanation: The assertion is valid, as contraction or relaxation of smooth muscle in a vessel wall can alter the width of the passage. The reason is also valid and explains why this adjustment can occur without deliberate control. Smooth muscle is positioned within the wall and its activity is involuntary, so changes in its contraction can modify vessel diameter as part of internal regulation. Skeletal muscle would not suit this role, since it is organised mainly in long bundles attached to bones and is generally voluntary. The location and control stated in the reason directly support the functional outcome described in the assertion. This relation connects tissue organisation with an organ-level change in passage size.
117. Examine the arrangement described below. A tissue from the heart contains striated cells that branch and join neighbouring cells through specialised junctions. The tissue is:
ⓐ. smooth muscle adapted for intestinal movement
ⓑ. skeletal muscle attached directly to a long bone
ⓒ. cardiac muscle adapted for coordinated contraction
ⓓ. dense connective tissue arranged for tensile strength
Correct Answer: cardiac muscle adapted for coordinated contraction
Explanation: Cardiac muscle occurs only in the heart and consists of striated cells that branch rather than forming only long unbranched parallel fibres. Adjacent cells are joined through specialised junctions that provide mechanical attachment and communication. This organisation allows activity to spread through the tissue and supports coordinated contraction as a functional unit. Smooth muscle lacks striations and has fusiform cells, while skeletal muscle contains long cylindrical striated fibres arranged mainly in parallel bundles. Dense connective tissue contains extracellular collagen rather than branched contractile cells. The supplied features act together, preventing a nearby structure with only one shared property from fitting equally well. The combined clues of heart location, striation, branching, and junctional connection identify cardiac muscle and explain its suitability for repeated coordinated pumping.
118. Three muscle samples are compared.
| Sample | Striation | Cell form | Location and control |
|---|
| P | Present | Long, cylindrical, unbranched | Attached to bones; generally voluntary |
| Q | Absent | Fusiform | Wall of intestine; involuntary |
| R | Present | Branched and junction-linked | Heart; involuntary |
Sample R is classified as cardiac muscle mainly from the combined evidence of:
ⓐ. spindle-shaped non-striated fibres under voluntary control
ⓑ. branched striated fibres without intercalated discs
ⓒ. parallel striated fibres arranged in the intestinal wall
ⓓ. branched striated fibres joined by intercalated discs
Correct Answer: branched striated fibres joined by intercalated discs
Explanation: Sample R possesses a feature combination characteristic of cardiac muscle. It occurs in the heart, its cells are striated, the cells branch, and specialised junctions connect neighbouring cells. No single feature should be used alone. Striation is also present in skeletal muscle, and involuntary activity is also found in smooth muscle. Branching and junctional organisation, interpreted together with heart location, make the identification secure. Sample P represents skeletal muscle through its long cylindrical fibres, bone attachment, and general voluntary control. Sample Q represents smooth muscle through fusiform non-striated cells in an internal-organ wall. Cell form, location, and control provide complementary evidence. Reading these features together distinguishes cardiac muscle from skeletal and smooth muscle without relying on striation alone. The table demonstrates that muscle classification requires synthesis of shape, striation, location, control, and cellular connections.
119. Communication through the junctions between neighbouring cardiac muscle cells is selectively impaired, but individual cells remain capable of shortening. The most likely result is:
ⓐ. improved synchronisation of contractions throughout the heart
ⓑ. less coordinated contraction among neighbouring cardiac cells
ⓒ. conversion of cardiac cells into smooth muscle cells
ⓓ. loss of every striation from each affected cell
Correct Answer: less coordinated contraction among neighbouring cardiac cells
Explanation: Cardiac muscle cells can generate contractile force individually, but effective pumping requires their activity to be coordinated across the tissue. Communication junctions between adjacent cells permit rapid transfer that helps neighbouring cells respond as a functional unit. Selective impairment of this communication leaves the basic contractile machinery present, so individual cells may still shorten. Their timing, however, becomes less effectively linked, producing poorer coordination. The cells do not change tissue type, and striations are structural features not automatically removed by a communication defect. The predicted outcome separates the capacity to contract from the ability to contract together. Individual cells remain capable of shortening; this retained condition restricts the conclusion to the measured process and the stated experimental conditions. Cardiac performance depends on both properties, with junctional communication supplying the integration needed for organised heart activity.
120. Evaluate the following statements about skeletal, smooth, and cardiac muscle.
I. All three possess contractile ability.
II. Striation alone distinguishes cardiac muscle from skeletal muscle.
III. Smooth and cardiac muscles generally act involuntarily.
IV. Branching and junctional coordination help distinguish cardiac muscle from skeletal muscle.
ⓐ. I is true; II is true; III is true; IV is true
ⓑ. I is true; II is true; III is false; IV is false
ⓒ. I is false; II is true; III is false; IV is true
ⓓ. I is true; II is false; III is true; IV is true
Correct Answer: I is true; II is false; III is true; IV is true
Explanation: Contractility is the shared functional property of skeletal, smooth, and cardiac muscle, so statement I is valid. Smooth muscle and cardiac muscle normally operate without voluntary control, supporting statement III. Cardiac cells are branched and joined through specialised junctions that support coordinated contraction, making statement IV valid. Statement II is not acceptable since both skeletal and cardiac muscles are striated. Striation can separate smooth muscle from the other two, but it cannot distinguish skeletal muscle from cardiac muscle by itself. That distinction requires additional evidence such as fibre shape, branching, junctions, location, and control. The valid combination recognises both shared properties and features that genuinely discriminate among the three muscle types.
