Multiple Choice Questions
Q.1. Match the following and mark the correct option
Options:
(a) A-i, B-ii, C-iv, D-iii
(b) A-ii, B-i, C-iii, D-iv
(c) A-ii, B-i, C-iv, D-iii
(d) A-iii, B-ii, C-iv, D-i
Ans. (c)
Solution:
Fast muscle fibres → Lactic acid (A-ii)
Fast (white) muscle fibres depend mainly on anaerobic respiration. During repeated activity, lactic acid accumulates, leading to fatigue.
Slow muscle fibres → Myoglobin (B-i)
Slow (red) muscle fibres contain a high amount of myoglobin, which stores oxygen and supports aerobic respiration.
Actin filament → I-band (C-iv)
The I-band of a myofibril contains only thin (actin) filaments.
Sarcomere → Contractile unit (D-iii)
The sarcomere is the functional/contractile unit of a muscle fibre.
Hence, the correct matching is A-ii, B-i, C-iv, D-iii, which corresponds to option (c).
Q.2. Ribs are attached to
(a) Scapula
(b) Sternum
(c) Clavicle
(d) Ilium
Ans. (b)
Solution: Ribs are attached to the sternum, ventrally via costal cartilages. This arrangement forms the anterior wall of the thoracic cage, protecting thoracic organs.
Q.3. What is the type of movable joint present between the atlas and axis?
(a) Pivot
(b) Saddle
(c) Hinge
(d) Gliding
Ans. (a)
Solution: Pivot joint: The joint between the first cervical vertebra (atlas) and the second (axis) is a pivot-type synovial joint called the atlantoaxial joint, allowing rotation of the head.
Q.4. ATPase of the muscle is located in
(a) Actinin
(b) Troponin
(c) Myosin
(d) Actin
Ans. (c)
Solution: The ATPase activity of muscle is located in the head region of the myosin molecule; myosin ATPase hydrolyses ATP to provide energy for cross-bridge cycling.
Q.5. Intervertebral disc is found in the vertebral column of
(a) Birds
(b) Reptiles
(c) Mammals
(d) Amphibians
Ans. (c)
Solution: Intervertebral discs (fibrocartilaginous pads between adjacent vertebrae) are characteristic of mammals, providing cushioning and flexibility.
Q.6. Which one of the following is showing the correct sequential order of vertebrae in the vertebral column of human beings?
(a) Cervical - lumbar - thoracic - sacral - coccygeal
(b) Cervical - thoracic - sacral - lumbar - coccygeal
(c) Cervical - sacral - thoracic - lumbar - coccygeal
(d) Cervical - thoracic - lumbar - sacral - coccygeal
Ans. (d)
Solution: The correct sequence from top to bottom is cervical - thoracic - lumbar - sacral - coccygeal.
Q.7. Which one of the following pairs is incorrect?
(a) Hinge joint: between Humerus and Pectoral girdle
(b) Pivot joint: between atlas and axis
(c) Gliding joint: between the carpals
(d) Saddle joint: between carpals and metacarpals of thumb
Ans. (a)
Solution: Option (a) is incorrect because the joint between the humerus and the pectoral girdle (shoulder joint) is a ball-and-socket joint, not a hinge joint. Typical hinge joints are the elbow and knee.
Q.8. Knee joint and elbow joint are examples of
(a) Saddle joint
(b) Ball and socket joint
(c) Pivot joint
(d) Hinge joint
Ans. (d)
Solution. Knee and elbow are examples of the hinge joint, permitting movement mainly in one plane (flexion and extension).
Q.9. Macrophages and leucocytes exhibit
(a) Ciliary movement
(b) Flagellar movement
(c) Amoeboid movement
(d) Gliding movement
Ans. (c)
Solution: Macrophages and many leukocytes (white blood cells) move by amoeboid movement, extending pseudopodia through cytoplasmic streaming; microfilaments of the cytoskeleton are involved.
Q.10. Which one of the following is not a disorder of bone?
(a) Arthritis
(b) Osteoporosis
(c) Rickets
(d) Atherosclerosis
Ans. (d)
Solution: Atherosclerosis is a disorder of the circulatory system (arterial walls), not a bone disorder.
Q.11. Which one of the following statement is incorrect?
(a) Heart muscles are striated and involuntary
(b) The muscles of hands and legs are striated and voluntary
(c) The muscles located in the inner walls of alimentary canal are striated and involuntary
(d) Muscles located in the reproductive tracts are unstriated and involuntary
Ans. (c)
Solution: Statement (c) is incorrect. The muscles in the inner walls of the alimentary canal are non-striated (smooth) and involuntary.
Q.12. Which one of the following statements is true?
(a) Head of humerus bone articulates with acetabulum of pectoral girdle.
(b) Head of humerus bone articulates with the glenoid cavity of pectoral girdle.
(c) Head of humerus bone articulates with acetabulum of pelvic girdle.
(d) Head of humerus bone articulates with a glenoid cavity of pelvic girdle.
Ans. (b)
Solution: The head of the humerus articulates with the glenoid cavity of the scapula (pectoral girdle) to form the shoulder joint.
Q.13. Muscles with characteristic striations and involuntary are
(a) Muscles in the wall of alimentary canal
(b) Muscles of the heart
(c) Muscles assisting locomotion
(d) Muscles of the eyelids
Ans. (b)
Solution: Cardiac muscles (muscles of the heart) are striated and involuntary.
Q.14. Match the followings and mark the correct option
Options:
(a) A-ii, B-i, C-iii, D-iv
(b) A-iv, B-iii, C-i, D-ii
(c) A-ii, B-i, C-iv, D-iii
(d) A-iv, B-i, C-ii, D-iv
Ans. (b)
Solution:
Very Short Answer Type Questions
Q.1. Name the cells/tissues in the human body which
(a) exhibit ameboid movement
(b) exhibit ciliary movement
Ans. (a) Macrophages and leucocytes
(b) Epithelial cells with cilia in the respiratory tract (trachea, bronchioles) and epithelial lining of the fallopian tube exhibit ciliary movement to transport mucus or the ovum respectively.
Q.2. Locomotion requires a perfect coordinated activity of muscular, _____, _______ systems
Ans. Skeletal and Neural
Q.3. Sarcolemma, sarcoplasm and sarcoplasmic reticulum refer to a particular type of cell in our body. Which is this cell and to what parts of that cell do these names refer to?
Ans.
- These terms refer to a muscle fibre (muscle cell).
- Sarcolemma is the plasma membrane that surrounds the muscle fibre.
- Sarcoplasm is the cytoplasm of the muscle fibre; it contains many nuclei and organelles.
- Sarcoplasmic reticulum is the specialised endoplasmic reticulum of the muscle fibre; it stores and releases Ca++ ions required for contraction.
Q.4. Label the different components of actin filament in the diagram given below.
Ans.
Q.5. The three tiny bones present in the middle ear are called ear ossicles. Write them in correct sequence beginning from the eardrum.
Ans. Malleus, incus and stapes.
Q.6. What is the difference between the matrix of bones and cartilage?
Ans. Bone matrix is hard and non-pliable because it is mineralised with calcium salts (hydroxyapatite) and contains collagen fibres, giving strength and rigidity. Cartilage matrix is solid but resilient and pliable, rich in proteoglycans and collagen; cartilage resists compression. Cartilage cells (chondrocytes) reside in lacunae within their matrix.
Q.7. Which tissue is afflicted by Myasthenia gravis? What is the underlying cause?
Ans. Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction. It leads to fatigue, weakness and paralysis of skeletal muscles.
Q.8. How do our bone joints function without grinding noise and pain?
Ans. Synovial joints contain synovial fluid, a viscous lubricant produced by the synovial membrane, and articular cartilage covers bone ends. Together they reduce friction, prevent bone-bone grinding and allow smooth, pain-free movement.
Q.9. Give the location of a ball and socket joint in a human body
Ans. Ball-and-socket joints are present at the shoulder (head of humerus with glenoid cavity of scapula) and the hip (head of femur with acetabulum of pelvic girdle). Each side has one shoulder and one hip joint.
Q.10. Our forearm is made of three different bones. Comment.
Ans. The statement is incorrect. The forearm is made of two bones, not three: Radius and Ulna. The humerus is the bone of the upper arm, not the forearm. Thus, the forearm consists only of the radius and ulna, which articulate with the humerus at the elbow and with the carpal bones at the wrist.
Short Answer Type Questions
Q1. With respect to the rib cage, explain the following:
(a) Bicephalic ribs
(b) True ribs
(c) Floating ribs
Ans:
Rib Cage(a) Bicephalic ribs: A typical rib has two articular facets at its dorsal (vertebral) end that articulate with the bodies and transverse processes of thoracic vertebrae; because of these two heads, such ribs are called bicephalic.
(b) True ribs: The first seven pairs of ribs are called true ribs (1-7). They are attached dorsally to thoracic vertebrae and ventrally to the sternum through their own costal cartilages.
(c) Floating ribs: The 11th and 12th pairs are floating ribs; they are attached dorsally to the vertebrae but have no anterior attachment to the sternum or costal cartilage, so their anterior ends are free.
Q2. In old age, people often suffer from stiff and inflamed joints. What is this condition called? What are the possible reasons for these symptoms?
Ans: In old age, people often suffer from arthritis, which is characterised by inflammation of joints. This condition causes pain, swelling and stiffness in the joints, leading to difficulty in movement.
Q3. The exchange of calcium between bone and extracellular fluid takes place under the influence of certain hormones
(a) What will happen if more of Ca++ is in extracellular fluid?
(b) What will happen if very less amount of Ca++ is in the extracellular fluid?
Ans:
(a) When calcium level in extracellular fluid increases, thyrocalcitonin promotes deposition of calcium in bones.
(b) When calcium level in extracellular fluid decreases, parathyroid hormone (PTH) causes release of calcium from bones into blood.
Q4. Name at least two hormones which result in fluctuation of Ca++ level
Ans: Thyrocalcitonin (Calcitonin) lowers blood calcium by promoting bone deposition. Parathyroid hormone (PTH) raises blood calcium by stimulating bone resorption and renal/intestinal mechanisms.
Q5. Rahul exercises regularly by visiting a gymnasium. Of late he is gaining weight. What could be the reason? Choose the correct answer and elaborate.
(a) Rahul has gained weight due to accumulation of fats in body.
(b) Rahul has gained weight due to increased muscle and less of fat.
(c) Rahul has gained weight because his muscle shape has improved.
(d) Rahul has gained weight because he is accumulating water in the body.
Ans: Rahul has gained weight due to increased muscle and less of fat.
Regular exercise, especially resistance training, increases muscle mass by hypertrophy of muscle fibres: increased sarcoplasm, thicker myofibrils, greater protein synthesis and mitochondrial content. Muscle is denser than fat, so body mass may increase while body fat decreases.
Q6. Radha was running on a treadmill at a great speed for 15 minutes continuously. She stopped the treadmill and abruptly came out. For the next few minutes, she was breathing heavily/fast. Answer the following questions.
(a) What happened to her muscles when she did strenuously exercised?
(b) How did her breathing rate change?
Ans: (a) During strenuous exercise, lactic acid accumulates in muscles due to anaerobic respiration, causing fatigue.
(b) Her breathing rate increases to supply more oxygen and remove carbon dioxide.
Q7. Write a few lines about Gout.
Ans: Gout is a metabolic disorder caused by deposition of uric acid crystals (monosodium urate) in joints and periarticular tissues. The crystal accumulation provokes inflammation, severe pain, redness and swelling, commonly affecting the big toe but can affect other joints.
Q8. What is the source of energy for muscle contraction?
Ans: The immediate source of energy for muscle contraction is ATP (adenosine triphosphate). Myosin head contains an enzyme myosin ATPase that hydrolyses ATP to ADP and inorganic phosphate (Pi), releasing energy used for cross-bridge cycling.
ATP → ADP + Pi + Energy
Q9. What are the points for the articulation of Pelvic and Pectoral girdles?
Ans: The pelvic girdle is formed by the fused bones ilium, ischium and pubis; they meet at the acetabulum where the head of the femur articulates to form the hip joint. The pectoral girdle consists of the scapula and clavicle; the glenoid cavity (glenoid fossa) of the scapula articulates with the head of the humerus to form the shoulder joint.
Long Answer Type Questions
Q1. Calcium ion concentration in blood affects muscle contraction. Does it lead to tetany in certain cases? How will you correlate fluctuation in blood calcium with tetany?
Ans: Yes, fluctuation in blood calcium ion concentration can lead to tetany in certain cases.Calcium ions (Ca²⁺) play an important role in muscle contraction. During muscle contraction, Ca²⁺ ions are released from the sarcoplasmic reticulum into the sarcoplasm, where they help in initiating interaction between actin and myosin filaments.
Tetany is a condition characterised by rapid, involuntary and sustained muscle contractions. It occurs due to a decrease in the level of calcium ions in blood or body fluids (hypocalcaemia).
When the concentration of Ca²⁺ in blood falls below normal:
Normal regulation of muscle contraction is disturbed
Muscles become excessively excitable
This results in repeated spasms and contractions, known as tetany
Thus, low blood calcium level leads to tetany, showing a direct correlation between fluctuation of calcium ion concentration in blood and muscle function.
Q2. An elderly woman slipped into the bathroom and had severe pain in her lower back. After X-ray examination doctors told her it is due to a slipped disc. What does that mean? How does it affect our health?
Ans: A slipped disc refers to the displacement of an intervertebral disc present between two adjacent vertebrae of the vertebral column. Intervertebral discs are cartilaginous structures that act as shock absorbers and provide flexibility to the vertebral column.
When a disc slips from its normal position, it may compress the spinal nerves passing through the vertebral column.
Effect on health:
It causes severe pain, especially in the lower back
Movement becomes difficult and painful
Compression of nerves may lead to discomfort and restricted mobility
Thus, a slipped disc affects normal movement and causes pain due to pressure on spinal nerves.
Q3. Explain sliding filament theory of muscle contraction with neat sketches.
Ans: The sliding filament theory explains muscle contraction at the molecular level. Key points:
- Sarcomere is the functional unit of striated muscle, bounded by Z-lines; it contains thin (actin) filaments and thick (myosin) filaments arranged in an interdigitating pattern.
- Upon neural stimulation, action potentials trigger release of Ca++ from the sarcoplasmic reticulum into the sarcoplasm.
- Ca++ binds to troponin on actin, causing tropomyosin to move and expose myosin-binding sites on the actin filament.
- Myosin heads, energized by ATP hydrolysis, attach to actin, forming cross-bridges; conformational changes in myosin pull actin filaments toward the centre of the A-band.
- Repeated cycles of cross-bridge formation and release (powered by ATP) produce sliding of thin filaments past thick filaments, shortening the sarcomere and contracting the muscle.
- During contraction the I-band and H-zone shorten, while the A-band length remains essentially constant.
Sliding-filament Theory of Muscle Contraction (Movement of the thin Filaments and the Relative Size of the I Band and H Zones)Relaxation occurs when Ca++ is actively pumped back into the sarcoplasmic reticulum; troponin-tropomyosin complex again blocks binding sites on actin and cross-bridge cycling ceases.
Q4. How does a muscle shorten during its contraction and return to its original form during relaxation?
Ans: Shortening during contraction occurs because sliding of actin (thin) filaments toward the centre of the sarcomere brings the Z-lines closer together; the sarcomere shortens and the muscle fibre shortens. The myosin filaments walk along actin through cyclic cross-bridge formation, power stroke, release (on ATP binding), and re-cocking (on ATP hydrolysis).
Relaxation occurs when Ca++ ions are removed from the cytoplasm by calcium pumps into the sarcoplasmic reticulum; troponin-tropomyosin re-covers the myosin-binding sites on actin, cross-bridges stop forming, and elastic elements return the sarcomere and muscle fibre to resting length.
Q5. Discuss the role of Ca2+ ions in muscle contraction. Draw neat sketches to illustrate your answer.
Ans: Role of Ca2+ (Ca++) in muscle contraction:
- Neural excitation at the neuromuscular junction generates an action potential that travels along the sarcolemma and T-tubules to the sarcoplasmic reticulum.
- Sarcoplasmic reticulum releases stored Ca++ into the sarcoplasm.
- Ca++ binds to the troponin complex on actin filaments, inducing a conformational change that moves tropomyosin away from myosin-binding sites.
- Exposed binding sites allow myosin heads to attach and, using energy from ATP hydrolysis, perform the power stroke that slides actin filaments and produces contraction.
- When Ca++ is pumped back into the sarcoplasmic reticulum, the binding sites are masked again and the muscle relaxes.
Stages in Cross-bridge Formation, Rotation of Head and Breaking of Cross-bridgeA concise sequence: neural signal → Ca++ release → troponin activation → cross-bridge cycling (ATP dependent) → sliding of filaments → contraction. Ca++ reuptake → cessation of cross-bridges → relaxation.
Q6. Differentiate between Pectoral and Pelvic girdle.
Ans:
| Feature | Pectoral girdle | Pelvic girdle |
| Primary bones | Scapula and clavicle (each half) | Ilium, ischium and pubis fused (each half) |
| Function | Attachment and mobility of upper limb (shoulder joint) | Attachment and weight support for lower limbs (hip joint) |
| Articulation with limb bone | Glenoid cavity articulates with head of humerus | Acetabulum articulates with head of femur |
| Mobility vs stability | More mobile (allows wide range of motion) | More stable and robust for weight bearing |
Both girdles are composed of paired halves that articulate anteriorly and posteriorly to support limb attachment; the pelvic girdle is more robust due to its role in supporting body weight and locomotion.
