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All questions of Locomotion and Movement for NEET Exam

 Pick out the correct match.
  • a)
    Pelvis = 3 bones
  • b)
    Sternum = 14 bones
  • c)
    Ribs = 20 bones
  • d)
    Face = 5 bones
Correct answer is option 'A'. Can you explain this answer?

Krishna Iyer answered
The pelvic girdle, as above, is made up of three fused bones: the ischium, the ilium, and the pubis. The pubis forms the anterior part of the pelvic girdle. It is a flattened, irregular-shaped bone that articulates with the pubic symphysis, a cartilaginous joint.
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A sesamoid bone is
  • a)
    Palatine
  • b)
    Patella
  • c)
    Pterygoid
  • d)
    Presphenoid
Correct answer is option 'B'. Can you explain this answer?

Rajeev Saxena answered
Patella is the small bone in knee joint between femur and tibia. It is a sesamoid bone developed in the tendon of quadriceps femoris muscle.

 Contractile unit of muscle fibres :-
  • a)
    H line
  • b)
    Sarcomere
  • c)
    H zone
  • d)
    None
Correct answer is option 'B'. Can you explain this answer?

Pioneer Academy answered
A sarcomere is the basic contractile unit of muscle fiber.
Each sarcomere is composed of two main protein filaments, actin and myosin, which are the active structures responsible for muscular contraction.

 Which of the following facial bones is unpaired?
  • a)
    Nasal
  • b)
    Vomer
  • c)
    Palatine
  • d)
    Lacrimal
Correct answer is option 'B'. Can you explain this answer?

Rajeev Saxena answered
The unpaired bones of the human skull are: frontal, occipital, ethmoid, sphenoid, mandible and vomer. The frontal bone is self explanatory in name.

Which of the following statements about the mechanism of muscle contraction are correct?
A. Acetylcholine is released when the neural signal reaches the motor end plate.
B. Muscle contraction is initiated by a signal sent by CNS via a sensory neuron.
C. During muscle contraction, the isotropic band gets elongated.
D. Repeated activation of the muscle can lead to accumulation of lactic acid.
  • a)
    B and C are correct.
  • b)
    A and D are correct.
  • c)
    A, Band C are correct.
  • d)
    A and C are correct.
Correct answer is option 'B'. Can you explain this answer?

Preeti Iyer answered
Following are the correct statements about the mechanism of muscle contraction: 
(i) Acetylcholine is released when the neural signal reaches the motor end plate.
(ii) Repeated activation of the muscles can lead to lactic acid accumulation.
So, the correct answer is (B).

Cardiac muscles Fibres :-
  • a)
    Involuntary
  • b)
    Non-fatigue
  • c)
    Striated like
  • d)
    All
Correct answer is option 'D'. Can you explain this answer?

Anand Jain answered
Cardiac muscle is found only in the walls of the heart. When cardiac muscle contracts, the heart beats and pumps blood. Cardiac muscle contains a great many mitochondria, which produce ATP for energy. This helps the heart resist fatigue. Contractions of cardiac muscle are involuntary, like those of smooth muscle. Cardiac muscle, like skeletal muscle, is arranged in bundles, so it appears striated, or striped.
Hence, the answer is (D)

ATP-ase activity found in :-
  • a)
    Myosin filament
  • b)
    Actin filament
  • c)
    Both
  • d)
    None
Correct answer is option 'A'. Can you explain this answer?

Wahid Khan answered
In all myosins, the head domain is a specialized ATPase that is able to couple the hydrolysis of ATP with motion. A critical feature of the myosin ATPase activity is that it is actin-activated. In the absence of actin, solutions of myosin slowly convertATP into ADP and phosphate.

 The contractile unit of muscle is a part of myofibril between
  • a)
    A band and I band
  • b)
    Z line and Z line
  • c)
    Z line and A band
  • d)
    Z line and I band
Correct answer is option 'B'. Can you explain this answer?

Naina Bansal answered
The region between two Z lines is called a sarcomere; sarcomeres can be considered the primary structural and functional unit of muscle tissue. Ultrastructure of a group of myofibrils, showing the sarcoplasmic reticulum and transverse tubules, which constitute the two membrane systems within a muscle fibre.

Which one of the following pairs of chemical substances is correctly categorized? [2012M]
  • a)
    Calcitonin and thymosin - Thyroid hormones
  • b)
    Pepsin and prolactin - Two digestive enzymes secreted in stomach
  • c)
    Troponin and myosin - Complex proteins in striated muscles
  • d)
    Secretin and rhodopsin - Polypeptide hormones
Correct answer is option 'C'. Can you explain this answer?

Shounak Nair answered
Troponin is a protein which is found on actin filament and myosin protein is found in myosin filament. Both actin and myosin are complex proteins in striated muscles.
Thymosin is a hormone secreted by the thymus that stimulates development of T cells. Prolactin is a hormone released by the pituitary gland that stimulates breast development and milk production in women. Rhodopsin, also known as visual purple, is not a hormone. It is a biological pigment in photoreceptor cells of the retina that is responsible for the first events in the perception of light

ATPase enzyme needed for muscle contraction is located in
  • a)
    Myosin
  • b)
    Actin
  • c)
    Troponin
  • d)
    Actinin
Correct answer is option 'A'. Can you explain this answer?

Rajeev Saxena answered
During muscle contraction, hydrolysis of ATP into ADP and inorganic phosphate occurs. The energy released during the process raises the meromyosin head to a high-energy state. The enzyme myosin ATPase catalyses the reaction in the presence of Ca2+ and Mg2+.

During contraction of muscles :-
  • a)
    Actin Filament slide over actin
  • b)
    Myosin filament slide over actin
  • c)
    Actin filament slide over myosin
  • d)
    none 
Correct answer is option 'C'. Can you explain this answer?

Prem Darade answered
Mechanism of muscle contraction is best explained by the sliding filament theory, which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments. The actin filament slide over myosin filament thus reduces the length of the sarcomere and contracts the muscle fibre.

So, the correct answer is option C.

Which ion is essential for muscle contraction? [1994]
  • a)
    Na
  • b)
    K
  • c)
    Ca
  • d)
    Cl
Correct answer is option 'C'. Can you explain this answer?

Anirudh Datta answered
Movement of Ca2+ out in sarcoplasmic reticulum controls the making and breaking of actin and myosin complex actomyosin due to which muscle contraction and relaxation takes place. Albert Szent Gyorgyi worked out biochemical events of muscle contraction.

Skeletal muscle bundles [fascicles] are held together by a common connective tissue layer called:
  • a)
    Perimysium
  • b)
    Endomysium
  • c)
    Fascia
  • d)
    Aponeurosis
Correct answer is option 'C'. Can you explain this answer?

Ananya Das answered
Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons. A skeletal muscle refers to multiple bundles (fascicles) of cells joined together called muscle fibers. The fibers and muscles are surrounded by connective tissue layers called fasciae.

Each pectoral girdle :
i. has 2 pairs of bones, a pair of clavicle and a pair of scapula.
ii. scapula contains expanded process and glenoid cavity, the latter is for articulation of the head of humerus.
  • a)
    Both are correct
  • b)
    Statement i) is wrong and ii) is correct. 
  • c)
    both are wrong
  • d)
    Statement i) is correct and ii) is wrong.
Correct answer is option 'A'. Can you explain this answer?

Vaibhav Basu answered
Statement 1: Each pectoral girdle has two pairs of bones: a pair of clavicles and a pair of scapulae. The pectoral girdle, also known as the shoulder girdle, is a skeletal structure that connects the upper limb to the axial skeleton.
Statement 2: The head of the humerus bone articulates with the glenoid cavity of the pectoral girdle.
Hence both are correct.

Elbow joint is an example of: [2009]
  • a)
    hinge joint
  • b)
    gliding joint
  • c)
    ball and socket joint
  • d)
    pivot joint
Correct answer is option 'A'. Can you explain this answer?

Subham Chavan answered
Elbow joint is an example of hinge joint. The elbow is a hinge joint; it can open and close like a door. Hinge joint is a form of diarthrosis (freely movable joint) that allows angular movement in one plane only, increasing or decreasing the angle between the bones e.g. elbow joint, knee joint etc.

Which of these disorders is caused due to low concentrations of calcium ions?
  • a)
    Muscular dystrophy
  • b)
    Gout
  • c)
    Tetany
  • d)
    Osteoporosis
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
Muscular dystrophy, gout, tetany and osteoporosis are disorders of the muscular system and the skeletal system. Out of these, tetany is caused due to low concentrations of calcium ions.

Select the correct statement with respect to disorders of muscles in humans [NEET Kar. 2013]
  • a)
    Rapid contractions of skeletal muscles causes muscle dystrophy
  • b)
    Failure of neuromuscular transmission in myasthenia gravis can prevent normal swallowing
  • c)
    Accumulation of urea and creatine in the joints cause their inflammation
  • d)
    An over dose of vitamin D causes osteoporosis
Correct answer is option 'B'. Can you explain this answer?

Shounak Nair answered
Myasthenia gravis is a chronic autoimmune muscular disease. It causes 
breakdown of neuromuscular junction due to which the brain loses control over muscles. The symptoms may include drooping eyelids, difficulty in swallowing muscle fatigue, difficult breathing and inability to control facial expressions.

Which statement is correct for muscle contraction? [2001]
  • a)
    Length of H-line decreases
  • b)
    Length of A-band remains constant
  • c)
    Length of I-band increases
  • d)
    Length of two Z-lines increase
Correct answer is option 'B'. Can you explain this answer?

Anirudh Datta answered
When Ca+ ions combine with troponin contraction of muscles initiates. During Contraction the Z lines come closer  together and the sarcomere becomes shorter. The length of A band remains constant. I bands shortens  and H-band  narrows.

Read the following statements about muscle contraction in humans :
i. chemical energy is converted into mechanical energy during muscle contraction and the chemical is a neurotransmitter.
ii. a neurotransmitter acetylcholine at motor end plate converts electrical energy into mechanical energy.
iii. in a contracted muscle, volume remains the same.
iv. a contracted muscle becomes shorter and thicker.
  • a)
    only iv) is correct.
  • b)
    only i), iii) and iv) are correct.
  • c)
    only i) and iv) are correct.
  • d)
    only ii), iii) and iv) are correct.
Correct answer is option 'B'. Can you explain this answer?

Akash Khanna answered
Explanation:
Muscle contraction is a complex process that involves the conversion of chemical energy into mechanical energy. Let's analyze each statement to understand why option 'B' is the correct answer.

i. Chemical energy is converted into mechanical energy during muscle contraction, and the chemical is a neurotransmitter.
During muscle contraction, chemical energy stored in the form of adenosine triphosphate (ATP) is converted into mechanical energy. ATP is the primary energy source for muscle contraction. The release of a neurotransmitter called acetylcholine initiates the process of muscle contraction by transmitting the electrical signal from the nervous system to the muscle fibers.

ii. A neurotransmitter acetylcholine at the motor end plate converts electrical energy into mechanical energy.
This statement is incorrect. Acetylcholine released at the motor end plate does not directly convert electrical energy into mechanical energy. It acts as a chemical messenger that binds to receptors on the muscle fibers, triggering a series of events that lead to muscle contraction. The electrical energy from the nerve impulse is converted into a chemical signal (acetylcholine) which then initiates the release of calcium ions from the sarcoplasmic reticulum, leading to muscle contraction.

iii. In a contracted muscle, volume remains the same.
This statement is incorrect. During muscle contraction, the volume of the muscle decreases. As the muscle fibers generate force, they pull on the tendons, causing the muscle to shorten. This shortening leads to a decrease in muscle volume.

iv. A contracted muscle becomes shorter and thicker.
This statement is correct. When a muscle contracts, it becomes shorter and thicker. The individual muscle fibers slide past each other, causing the overlapping actin and myosin filaments to shorten. This sliding filament mechanism is responsible for muscle contraction. As the muscle fibers shorten, the muscle as a whole becomes thicker.

Based on the explanations above, we can conclude that only statements i), iii), and iv) are correct. Hence, the correct answer is option 'B' - only i), iii), and iv) are correct.

निम्नलिखित में से कौन भारत का पहला स्वदेशी रूप से डिजाइन और विकसित लड़ाकू विमान है?
  • a)
    तेजस
  • b)
    गुस्सा
  • c)
    हंसा
  • d)
    सरस
Correct answer is option 'B'. Can you explain this answer?

Meera Kapoor answered
भारत के 72 वें गणतंत्र दिवस के अवसर पर, आगंतुकों के लिए, लॉकडाउन अवधि के दौरान बहाल किए गए रेल लोकोमोटिव के अपने कलाकृतियों को नेहरू विज्ञान केंद्र, मुंबई ने फिर से समर्पित किया।
  • भारत का पहला स्वदेशी रूप से डिजाइन और विकसित लड़ाकू विमान मारुत अब जनता के देखने के लिए उपलब्ध होगा।
  • डीसी इलेक्ट्रिक लोको नं 20024 एन वी सी पी 2 को 1938 में ग्रेट इंडियन पेनिनसुलर रेलवे में कमीशन किया गया था और 40 साल तक कल्याण-पुणे सेक्शन पर पैसेंजर ट्रेनों को चलाने के लिए इस्तेमाल किया गया था।
  • इसमें मुंबई से पुणे तक प्रतिष्ठित डेक्कन क्वीन के शासन का गौरव है।
  • डीसी इलेक्ट्रिक लोको नं 20024 एन वी सी पी 2 भारतीय उप-महाद्वीप में इलेक्ट्रिक ट्रैक्शन की शुरूआत के बाद सेवा में शामिल किए गए पहले इलेक्ट्रिक इंजनों में से एक है
  • मारुत को शुरू में सुपरसोनिक गति को पार करने के लिए विकसित किया गया था, लेकिन कभी भी मच 1 को छू नहीं सकता था, इसलिए अब यह रिकॉर्ड तेजस एलसीए के साथ है। कुल 147 मारुत का निर्माण किया गया, और भारतीय वायुसेना ने 1967 में पहली इकाई को शामिल किया। एचएफ -24 मारुत ने 1961 में अपनी पहली उड़ान का संचालन किया। जबकि मारुत ने 1971 के भारत-पाक युद्ध के दौरान लोंगेवाला सीमा पर 1980 के दशक में एक बड़ी भूमिका निभाई। अप्रचलित हो गया और 1990 तक चरणबद्ध हो गया।

The correctorganisation of skeletal muscle is :
  • a)
    muscle bundles →→ myofibrils →→ muscle cells →→ sarcomere
  • b)
    fascicles →→ muscle fibres →→ myofilaments →→ sarcomere
  • c)
    muscle bundles →→ muscle cells →→ muscle fibres →→ sarcomere
  • d)
    fascia →→ muscle cells →→ myofibrils →→ sarcomere
Correct answer is option 'B'. Can you explain this answer?

Pooja Saha answered
Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called fascia. Each muscle bundle contains a number of muscle fibres. A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils. The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere.

The slow twitch muscle fibres which are rich in myoglobin and have abundant mitochondria are
  • a)
    white skeletal muscles
  • b)
    cardiac muscles
  • c)
    red skeletal muscles
  • d)
    involuntary muscles
Correct answer is option 'C'. Can you explain this answer?

Akshat Joshi answered
Red skeletal muscles, also known as slow twitch muscle fibers, are rich in myoglobin and have abundant mitochondria. These muscle fibers are responsible for endurance activities and are found in muscles that are used for sustained, repetitive movements.

Myoglobin is a protein that is responsible for storing and transporting oxygen within muscle cells. It has a high affinity for oxygen, allowing it to efficiently bind and release oxygen as needed during muscle contraction. Red skeletal muscles have a high concentration of myoglobin, which gives them their characteristic red color.

The abundance of mitochondria in red skeletal muscles is another key characteristic of these muscle fibers. Mitochondria are known as the "powerhouses" of the cell because they are responsible for producing energy in the form of ATP (adenosine triphosphate). The aerobic metabolism that takes place in mitochondria is essential for providing the sustained energy needed for endurance activities.

The high concentration of myoglobin and abundant mitochondria in red skeletal muscles allow them to generate energy efficiently and sustain muscle contractions for extended periods of time. This makes them well-suited for activities such as long-distance running, cycling, and swimming.

In contrast, white skeletal muscles, also known as fast twitch muscle fibers, have a lower concentration of myoglobin and fewer mitochondria. These muscle fibers are responsible for generating quick, powerful contractions but fatigue more quickly compared to red skeletal muscles. White skeletal muscles are typically used for activities that require short bursts of intense effort, such as weightlifting or sprinting.

Cardiac muscles, on the other hand, are a type of involuntary muscle found in the heart. They also have a high concentration of myoglobin and abundant mitochondria to support their continuous contraction and pumping action.

In summary, the slow twitch muscle fibers found in red skeletal muscles are rich in myoglobin and have abundant mitochondria. These muscle fibers are well-suited for endurance activities and provide sustained energy for prolonged periods of muscle contraction.

Which of the following bones form a link between axial and appendicular skeleton?
  • a)
    First rib
  • b)
    Clavicle
  • c)
    Scapula
  • d)
    Both (a) and (b)
Correct answer is option 'B'. Can you explain this answer?

Vedika Singh answered
Clavicle is a bone that forms part of the pectoral girdle (part of appendicular skeleton) linking the scapula to the sternum (part of axial skeleton).

The property which doesn’t belong to muscle fibres is :
  • a)
    conductivity
  • b)
    Excitability
  • c)
    Contractility
  • d)
    elasticity
Correct answer is option 'A'. Can you explain this answer?

Rajeev Sharma answered
Muscle fibres have properties of excitability, elasticity and contractility but conductivity is not present in muscles fibers. These fibres help in movement of different body parts.

Actin binding sites are located on
  • a)
    troponin
  • b)
    tropomyosin
  • c)
    meromyosin
  • d)
    both (b) and (c)
Correct answer is option 'C'. Can you explain this answer?

Geetika Shah answered
Heavy meromyosin consists of two globular sub-frament (S-1) and one rod shaped fibre sub-fragment (S-2). Each S-1 segment contains an ATPase site and a binding site for actin.

The figures given here represent three different conditions of sarcomeres. Identify these conditions and select the correct option.
  • a)
    A - Contracting B - Relax C - Maximally contacted
  • b)
    A - Relax B - Contracting C - Maximally contacted
  • c)
    A - Maximally contacted B - Contracting C - Relax
  • d)
    A - Relax B - Contracting C - Contacting
Correct answer is option 'B'. Can you explain this answer?

Ananya Das answered
In the given figure A, the length of the two sarcomeres is normal i.e., the muscle is in relaxed state. In figure B. the length of sarcomeres, shortens, H-zone narrows and size of l-band decreases i.e., the muscle is contracting. In figure C, the length of sarcomere further shortens and H-zone disappears and l-band further decreases i.e., the muscle is maximally contracted.

Assertion (A): Red fibres in muscles have a high content of myoglobin, which contributes to their reddish appearance.
Reason (R): These fibres primarily rely on anaerobic metabolism for energy production.
  • a)
    If both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • b)
    If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • c)
    If Assertion is true but Reason is false
  • d)
    If both Assertion and Reason are false
Correct answer is option 'C'. Can you explain this answer?

Stepway Academy answered
 
- The Assertion is true because red fibres do indeed have a high content of myoglobin, which gives them a reddish appearance.
- The Reason is false because red fibres primarily rely on aerobic metabolism due to their high myoglobin and mitochondrial content, not anaerobic metabolism.
- Since the Assertion is true and the Reason is false, Option B is correct as both statements are true, but the Reason does not correctly explain the Assertion.
Line in NCERT: Muscle contains a red coloured oxygen storing pigment called myoglobin. Myoglobin content is high in some of the muscles which gives a reddish appearance. Such muscles are called the Red fibres. These muscles also contain plenty of mitochondria which can utilise the large amount of oxygen stored in them for ATP production. These muscles, therefore, can also be called aerobic muscles
 

Which of the statements given above is/are correct regarding the structure and function of actin filaments?
i. Each actin filament is composed of two helically wound 'F' (filamentous) actins.
ii. 'G' (Globular) actins are monomers that polymerize to form 'F' actins.
iii. Tropomyosin runs parallel to the 'F' actins and does not interact with them.
iv. Troponin is attached to tropomyosin at regular intervals and regulates the binding sites for myosin on the actin filaments.
  • a)
    i and ii
  • b)
    ii and iv
  • c)
    i, ii and iv
  • d)
    i, ii and iii
Correct answer is option 'C'. Can you explain this answer?

Harsh Chauhan answered
Understanding Actin Filaments
Actin filaments are crucial components of the cytoskeleton in eukaryotic cells, playing vital roles in muscle contraction, cell shape, and motility. Let's analyze the statements regarding their structure and function.
Statement Analysis
- i. Each actin filament is composed of two helically wound F (filamentous) actins.
This statement is correct. Actin filaments, or F-actin, are formed by the polymerization of G-actin monomers into long, helical structures.
- ii. G (Globular) actins are monomers that polymerize to form F actins.
This statement is also correct. G-actin monomers assemble to create F-actin, highlighting the dynamic nature of actin filaments.
- iii. Tropomyosin runs parallel to the F actins and does not interact with them.
This statement is incorrect. Tropomyosin binds to F-actin and stabilizes it, playing a significant role in muscle contraction and regulation of myosin binding sites.
- iv. Troponin is attached to tropomyosin at regular intervals and regulates the binding sites for myosin on the actin filaments.
This statement is correct. Troponin interacts with tropomyosin and, in the presence of calcium ions, regulates the exposure of binding sites for myosin, which is essential for muscle contraction.
Conclusion
Given the analysis, the correct statements are ii and iv. Therefore, the correct answer is option 'C' (i, ii, and iv). Understanding these components is crucial for comprehending the mechanisms of muscle contraction and cellular movement.

Which of the following statements about the molecular arrangement of actin and myosin in myofibrils is/are incorrect?
(i) Each actin (thin filament) is made of 2F (filamentous) actins.
(ii) F-actin is the polymer of G (globular) actin.
(iii) 2F-actins are twisted into a helix.
(iv) Two strands of tropomyosin (protein) lie in the grooves of F-actin.
(v) Troponin molecules (complex proteins) are distributed at regular intervals on the tropomyosin.
(vi) Troponin forms the head of the myosin molecule.
(vii) The myosin is a polymerised protein.
  • a)
    (i), (iii) and (vii)
  • b)
    (ii), (iv) and (v)
  • c)
    Only (vi)
  • d)
    Only (iii)
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
A complex troponin protein of three globular peptides (Troponin T - Binding to tropomyosin as well as to the other two troponin components; Troponin I - inhibiting the F-actin - myosin interaction, also binding to other components of troponin; Troponin C - calcium binding polypeptide) is distributed at regular intervals on the tropomyosin. In the resting stage of muscle fibre, a sub - unit of troponin masks the active sites for myosin on the actin filaments.

Which of these is a genetic disorder?
  • a)
    Gout
  • b)
    Myasthenia gravis
  • c)
    Muscular dystrophy
  • d)
    Tetany
Correct answer is option 'C'. Can you explain this answer?

Priya Menon answered
Muscular dystrophy is a genetic disorder of the muscular system. It leads to the progressive degeneration of skeletal muscles and loss of muscle mass. The life span of patients is often shortened.

Assertion (A): Myasthenia gravis is primarily characterized by the rapid degeneration of skeletal muscle fibers.
Reason (R): Myasthenia gravis affects the neuromuscular junction, leading to fatigue and weakness in skeletal muscles.
  • a)
     
    If both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • b)
    If both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • c)
     
    If Assertion is true but Reason is false
  • d)
     
    If both Assertion and Reason are false
Correct answer is option 'D'. Can you explain this answer?

Nipuns Institute answered
  • The Assertion (A) is false because myasthenia gravis does not primarily involve the degeneration of muscle fibers; rather, it is an autoimmune disorder affecting the communication at the neuromuscular junction.
  • The Reason (R) is true as it correctly describes the mechanism of myasthenia gravis, which indeed leads to fatigue and weakness in skeletal muscles due to the disruption at the neuromuscular junction.
  • Therefore, since the Assertion is false and the Reason is true, the correct answer is Option 4: If both Assertion and Reason are false.

The functional unit of contractile system in a striated muscle is
  • a)
    sarcomere
  • b)
    Z-band
  • c)
    cross bridges
  • d)
    myofibril
Correct answer is option 'A'. Can you explain this answer?

Hansa Sharma answered
Sarcomere is the functional unit of myofibril. It contains two types of protein filaments called actin and myosin. These filaments slide upon each other to bring about the contraction of the muscles.

Which of these is disorder of the muscular system?
  • a)
    Crohn’s Disease
  • b)
    Celiac Disease
  • c)
    Myasthenia gravis
  • d)
    Gastroenteritis
Correct answer is option 'C'. Can you explain this answer?

Suresh Iyer answered
Myasthenia gravis is an autoimmune disorder of the muscular system which affects neuromuscular junctions. Crohn’s Disease, Celiac Disease and gastroenteritis are disorders of the digestive system.

Which of these disorders lead to rapid spasms?
  • a)
    Gout
  • b)
    Myasthenia gravis
  • c)
    Muscular dystrophy
  • d)
    Tetany
Correct answer is option 'D'. Can you explain this answer?

Dev Patel answered
Tetany is a disorder of the muscular system characterized by rapid spasms or wild contractions. It occurs due to low concentrations of calcium ions in body fluids. Calcium ions play an important role in muscle contraction.

Appendicular skeleton includes
  • a)
    girdles and their limbs
  • b)
    vertebrae
  • c)
    skull and vertebral column
  • d)
    ribs and sternum
Correct answer is option 'A'. Can you explain this answer?

Gitanjali Dasgupta answered
Appendicular skeleton includes

The appendicular skeleton includes the bones of the limbs and their associated girdles. It is one of the two main divisions of the human skeleton, with the other being the axial skeleton. The appendicular skeleton provides support and enables movement of the limbs.

1. Girdles
The appendicular skeleton includes two girdles: the pectoral girdle and the pelvic girdle.

- Pectoral Girdle: The pectoral girdle, also known as the shoulder girdle, consists of the clavicle (collarbone) and the scapula (shoulder blade). It connects the upper limbs to the axial skeleton, allowing for the movement of the arms and shoulders.

- Pelvic Girdle: The pelvic girdle, also known as the hip girdle, consists of two hip bones, also called coxal bones or innominate bones. The pelvic girdle connects the lower limbs to the axial skeleton and supports the weight of the body.

2. Limbs
The appendicular skeleton also includes the bones of the limbs, including the upper limbs (arms) and the lower limbs (legs).

- Upper Limbs: The upper limbs consist of the humerus (upper arm bone), radius and ulna (forearm bones), carpals (wrist bones), metacarpals (hand bones), and phalanges (finger bones). These bones provide support and allow for various movements of the arms, hands, and fingers.

- Lower Limbs: The lower limbs consist of the femur (thigh bone), tibia and fibula (leg bones), tarsals (ankle bones), metatarsals (foot bones), and phalanges (toe bones). These bones provide support and enable movements such as walking, running, and jumping.

3. Function
The appendicular skeleton plays a crucial role in maintaining posture, supporting the body's weight, and facilitating movement. The girdles connect the limbs to the axial skeleton and provide a stable base for the movement of the arms and legs. The bones of the limbs allow for various movements and actions, such as reaching, grasping, walking, running, and performing fine motor skills.

4. Conclusion
In conclusion, the appendicular skeleton includes the girdles and the bones of the limbs. It provides support, stability, and enables movement of the limbs, allowing for a wide range of activities and functions.

Smallest bone in human system is
  • a)
    stapes
  • b)
    patella
  • c)
    malleus
  • d)
    incus
Correct answer is option 'A'. Can you explain this answer?

Yash Shah answered
Smallest Bone in Human System - Stapes
The smallest bone in the human body is called the stapes. It is located in the middle ear and is one of the three tiny bones known as the ossicles. The stapes is also commonly referred to as the stirrup bone due to its stirrup-like shape.

Function of Stapes
The primary function of the stapes is to transmit sound vibrations from the eardrum to the inner ear. It plays a crucial role in the process of hearing by amplifying and transferring sound waves through the middle ear.

Size and Structure
Despite its small size, the stapes is a significant component of the auditory system. It measures approximately 3 millimeters in length and resembles a stirrup, with a head, neck, and two branches known as the crura.

Importance in Hearing
The stapes is vital for the process of hearing as it helps convert sound waves into mechanical vibrations that can be interpreted by the brain. Any damage or abnormalities in the stapes can lead to hearing loss or other auditory problems.

Conclusion
In conclusion, the stapes is the smallest bone in the human body and plays a crucial role in the auditory system. Its small size belies its importance in the process of hearing, making it an essential component of the middle ear.

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