Sindh Mdcat Exclusive Course Week 7 Test — Solved Past Paper with Answers

Q1. The ion that triggers the exposure of actin binding sites for myosin is:

• A. Mg2+
• B. Ca2+✓
• C. Na+
• D. K+

Explanation: Ca2+ binds troponin ---> moves tropomyosin ---> exposes actin binding sites.

Q2. Lack of relaxation between successive contractions is called :

• A. Spasm
• B. Tetany✓
• C. Arthritis
• D. Fatigue

Explanation: Tetany = sustained contraction without relaxation due to continuous stimul.

Q3. Which of the following joints would allow no movements?

• A. Synovial joint
• B. Ball and Socket joint
• C. Fibrous joint✓
• D. Cartilaginous joint

Explanation: Fibrous joints are also called fixed or immovable joints because they do not allow any movement. These joints are immovable as they have no joint cavity or space present between the bones. They are connected via fibrous connective tissue. There are three types of fibrous joints: sutures, syndesmosis, and gomphoses. Sutures are found only in the skull. An example of a syndesmosis is the joint of the tibia and fibula in the ankle. Gomphoses occur between teeth and their sockets.

Q4. Sliding filament theory can be best explained as:

• A. Actin and myosin filaments do not shorten but rather slide pass each other✓
• B. When myofilaments slide pass each other, myosin filaments shorten while actin filaments do not shorten
• C. When myofilaments slide pass each other, actin filaments shorten while myosin filaments do not shorten
• D. Actin and myosin filaments shorten and slide pass each other.

Explanation: During muscle contraction, the laterally projecting heads (cross-bridges) of the thick myosin myofilaments come in contact with the thin actin myofilaments and rotate on them. This pulls the thin myofilaments toward the middle of the sarcomere, past the thick myofilaments. The Z lines come closer together, and the sarcomere becomes shorter. Length of the A band remains constant. Myofilaments (both actin and myosin) stay the same length. Free ends of actin myofilaments move closer to the centre of the sarcomere, bringing Z lines closer together. I bands shorten, and the H zone narrows. A similar action in all the sarcomeres results in shortening of the entire myofibril and thereby of the whole fibre and the whole muscle.

Q5. Glenoid cavity articulates:

• A. Clavicle with scapula
• B. Humerus with scapula✓
• C. Clavicle with acromion
• D. Scapula with acromion

Explanation: The glenoid cavity, a part of the scapula, articulates specifically with the head of the humerus to form the shoulder joint, which allows for a wide range of motion. The other options mention joints that do not involve the glenoid cavity. For instance, the clavicle connects to the scapula at the acromion process, not the glenoid cavity.

Q6. The H-zone in the skeletal muscle fiber is due to the:

• A. Central gap between actin filaments extending through myosin filaments in the A band✓
• B. Extension of myosin filaments in the central portion of the A band
• C. Absence of myofibrils in the central portion of the A band
• D. Central gap between myosin filaments in the A band

Explanation: The H-zone in skeletal muscle fibers is defined as the region within the A band where actin filaments do not overlap with myosin filaments, resulting in a central gap. This option (Option A) accurately captures that definition, as it emphasizes the presence of actin filaments surrounding the H-zone while myosin filaments extend through it. The other options misinterpret the characteristics of the H-zone: Option B incorrectly suggests an extension of myosin without recognizing the absence of actin; Option C wrongly states that myofibrils are absent; and Option D incorrectly defines the H-zone as a gap between myosin filaments instead of highlighting the lack of actin overlap. Understanding the structural arrangement of the sarcomere is crucial for recognizing these distinctions.

Q7. Choose the incorrect one. The type of muscle present in our:

• A. Heart is involuntary and striated muscle
• B. Intestine contains non-striated and involuntary muscles.
• C. Thigh contains non-striated and involuntary muscles.✓
• D. Upper arm contains striated and voluntary muscles.

Explanation: The correct answer is that the thigh contains non-striated and involuntary muscles, which is incorrect since it actually contains striated and voluntary skeletal muscles. Skeletal muscles, which allow for deliberate movement, are characterized by their striations. The heart contains cardiac muscle, which is involuntary and striated; the intestine is made up of smooth muscle, which is non-striated and involuntary. The upper arm contains striated and voluntary skeletal muscles, similar to those in the thigh, but the thigh's characterization in option C makes it the incorrect statement in this context.

Q8. Three of the following pairs of the human skeletal parts are correctly matched with their respective inclusive skeletal category and one pair is not matched. Identify the non matching pair.

• A. Sternum and ribs - Axial skeleton
• B. Clavicle and glenoid cavity - Pelvic girdle✓
• C. Humerus and ulna - Appendicular skeleton
• D. Malleus and stapes - Ear ossicles

Explanation: The correct answer is Option B: Clavicle and glenoid cavity - Pelvic girdle. This pair is incorrectly matched because both the clavicle and glenoid cavity belong to the pectoral girdle in the appendicular skeleton, not the pelvic girdle. The pelvic girdle consists of the hip bones, which are essential for supporting the weight of the upper body when standing and for locomotion.Option A is correct because the sternum and ribs belong to the axial skeleton, forming the protective rib cage. Option C is correct as the humerus and ulna are part of the appendicular skeleton, specifically the upper limb. Option D is correct since the malleus and stapes are ear ossicles, functioning in the auditory system.

Q9. Elbow joint is an example of:

• A. Pivot joint
• B. Hinge joint✓
• C. Ball and socket joint
• D. Gliding joint

Explanation: The elbow allows only flexion and extension, hence it has a hinge joint.

Q10. In the human body, which one of the following is anatomically correct?

• A. Collar bones - 3 pairs
• B. Salivary glands - 1 pair
• C. Cranial nerves - 10 pairs
• D. Floating ribs - 2 pairs✓

Explanation: In the human body, there are normally 12 pairs of ribs. Among these, the floating ribs (11th and 12th pairs) do not connect to the sternum, distinguishing them anatomically from the other ribs. This makes Option D correct. In contrast, Option A incorrectly states the number of collar bones, Option B incorrectly lists the number of salivary gland pairs, and Option C underestimates the number of cranial nerve pairs, making them all incorrect.

Q11. The contractile protein of skeletal muscle involving ATPase activity is:

• A. Troponin
• B. Tropomyosin
• C. Myosin✓
• D. Actinin

Explanation: The correct answer is Myosin. Myosin is a contractile protein with intrinsic ATPase activity, essential for muscle contraction. Its role involves the hydrolysis of ATP, which provides the necessary energy for muscle movement by interacting with actin filaments. On the other hand, Troponin and Tropomyosin are regulatory proteins that do not possess ATPase activity but are crucial in regulating the interaction between actin and myosin. Alpha-actinin is a structural protein that helps maintain the organization of the muscle structure rather than directly participating in contraction.

Q12. Which of the following pairs is correctly matched?

• A. Hinge joint between vertebrae
• B. Gliding joint between zygapophyses of the successive vertebrae✓
• C. Cartilaginous joint of skull bones
• D. Fibrous joint between phalanges

Explanation: The correct answer is the gliding joint between the zygapophyses of successive vertebrae. These joints allow sliding movements which provide flexibility to the spine. In contrast, hinge joints permit movement in one plane only, such as in the elbow and knee. Cartilaginous joints, found in the spine, allow slight movement but are not found in the skull, which has fibrous joints (sutures) that are immobile. Lastly, joints between phalanges are synovial hinge joints, not fibrous, allowing for flexion and extension.

Q13. Which cartilage is present at the end of long bones?

• A. Fibrous cartilage
• B. Hyaline cartilage✓
• C. Elastic cartilage
• D. Calcified cartilage

Explanation: Articular cartilage at the ends of long bones is hyaline cartilage, reducing friction in joints.

Q14. What is sarcomere?

• A. Part between two H zones
• B. Part between two A bands
• C. Part between two I bands
• D. Part between two Z lines✓

Explanation: The sarcomere is the fundamental unit of a striated muscle fiber, delineated by two Z lines. It contains alternating dark and light bands, specifically the A band, I band, and H zone, which collectively enable muscle contraction. The correct definition is the region between two Z lines. Other options incorrectly describe regions within or aspects of the sarcomere, but they do not accurately define its boundaries.

Q15. The sternum is connected to ribs by?

• A. Areolar tissue
• B. Bony matter
• C. Hyaline cartilage✓
• D. White fibrous cartilage

Explanation: Costal cartilages are hyaline cartilage, providing flexibility during breathing.

Q16. Bone related with skull is:

• A. Coracoid
• B. Arytenoid
• C. Pterygoid✓
• D. Atlas

Explanation: The correct answer is Pterygoid. The pterygoid processes are extensions of the sphenoid bone, integral to the skull's structure and located near its base. The other options are incorrect: The Coracoid is in the shoulder girdle, the Arytenoid is in the larynx, and the Atlas, although it supports the skull, is a cervical vertebra and not part of the skull itself.

Q17. The contractile protein of a muscle is?

• A. Actin
• B. Myosin✓
• C. Tubulin
• D. Tropomyosin

Explanation: Myosin interacts with actin filaments for contraction and has ATPase activity.

Q18. Which one of the following are the correct pairing of a body part and the kind of muscle tissue that moves it?

• A. Biceps of the upper arm – Smooth muscle fibres
• B. Abdominal wall – Smooth muscles
• C. Iris – Involuntary smooth muscle✓
• D. Heart wall – Involuntary unstriated muscle

Explanation: Smooth muscles are called involuntary muscles because the action of these muscles is controlled by the autonomic nervous system, meaning they are not under conscious control. The iris of the eyes contains smooth involuntary muscles, making option C the correct answer. The biceps of the upper arm are skeletal muscles, not smooth muscles as mentioned in option A. Option B is incorrect as the abdominal wall does contain skeletal muscles not smooth muscles. Option D is incorrect since the heart wall is primarily composed of cardiac muscles, not unstriated muscles.

Q19. The supportive skeletal structures in the human external ears and in the nose tip are examples of:

• A. Bone
• B. Cartilage✓
• C. Ligament
• D. Tendon

Explanation: The pinna (ear) and nose tip are supported by elastic cartilage, which provides flexibility.

Q20. Identify the tissue shown in the diagram and match with its characteristics and its location.

• A. Smooth muscles, show branching, found in the wall of the heart
• B. Cardiac muscles, unbranched muscles, found in the walls of the heart
• C. Unstriated muscles, tapering at both ends, attached with the bones of the ribs
• D. Skeletal muscles show striations and are closely attached with the bones of the limbs✓

Explanation: Locomotion (performed by limbs) in humans depends on the movements of muscle fibres. Skeletal muscles are attached to the bones by tendons and help in the movement of parts of the skeleton. These muscles are under the control of the conscious mind and are called voluntary muscles. Under the microscope, these muscles show transverse stripes and hence are designated as striated muscles.Options A, B, and C are incorrect because they describe characteristics of smooth, cardiac, and unstriated muscles respectively, which do not match the features of skeletal muscles shown in the diagram.

Q21. Antibodies attack joints in:

• A. Osteoarthritis
• B. Juvenile arthritis
• C. Gouty arthritis
• D. Rheumatoid arthritis✓

Explanation: Rheumatoid arthritis is the correct answer as it involves an autoimmune response where antibodies attack the synovium, leading to inflammation and joint damage. In contrast, osteoarthritis is due to mechanical wear, juvenile arthritis encompasses various types with differing causes, and gouty arthritis is due to uric acid crystal deposits.

Q22. Irregular striation and involuntary control is related to:

• A. Smooth muscle cells
• B. Cardiac muscle cells✓
• C. Skeletal muscle cells
• D. Fibroelastic cartilage cells

Explanation: The correct answer is Cardiac muscle cells because they possess irregular striations and operate under involuntary control, managed by the autonomic nervous system. In contrast, Smooth muscle cells lack striations and are involuntarily controlled, but they are associated with smooth, not irregular, muscle tissue. Skeletal muscle cells have regular striations and are under voluntary control, making them unsuitable for the characteristics described. Fibroelastic cartilage cells are not muscle cells and do not exhibit striations, further disqualifying them as an option.

Q23. Which one of the following is correct regarding ligaments and tendons?

• A. Both are inelastic
• B. Both are specialized connective tissue fibrils✓
• C. Both are elastic
• D. Both form joint capsule

Explanation: The correct answer is: Both are specialized connective tissue fibrils. Ligaments and tendons are both types of fibrous connective tissues but serve different functions. Ligaments connect bones to other bones and help stabilize joints by limiting excessive movement. Tendons connect muscles to bones and are involved in transmitting the force of muscle contractions to facilitate movement. While tendons are more elastic to accommodate muscle movements, ligaments are less so, focusing on joint stability. The option indicating both form the joint capsule is incorrect because only ligaments are involved in forming the fibrous layer of the joint capsule, not tendons.

Q24. Earliest form of muscles is:

• A. Cardiac
• B. Skeletal
• C. Smooth✓
• D. Striated

Explanation: Smooth muscle is considered the earliest form of muscle because it is simple in structure and function, and is found in both invertebrates and vertebrates, indicating its primitive nature. It controls involuntary movements essential for basic survival functions, such as digestion and blood flow, across a wide range of organisms. In contrast, cardiac and skeletal muscles are more specialized and complex, found primarily in vertebrates. Cardiac muscle is adapted for the rhythmic contractions of the heart, while skeletal muscle is used for voluntary movements, both of which suggest they evolved later. Striated muscle is another term often used interchangeably with skeletal muscle, highlighting its complexity and evolved function.

Q25. The main functional partners of bones are:

• A. Tendon
• B. Ligament
• C. Skeletal muscle✓
• D. Nerves

Explanation: The main functional partners of bones are skeletal muscles. These muscles are attached to bones by tendons and are responsible for facilitating voluntary movements by contracting and exerting force on the bones. Tendons and ligaments provide structural support and stability but do not directly generate movement. Nerves transmit signals to muscles to initiate movement but are not involved in the physical act of moving bones.

Q26. The type of muscle which exhibits striations at regular intervals, is multinucleatcd and whose control is neurogenic (controlled by the nervous system) is the:

• A. Smooth muscles
• B. Skeletal muscles✓
• C. Cardiac muscles
• D. Involuntary muscle

Explanation: The correct answer is skeletal muscles. Skeletal muscles are distinct due to their striated appearance from the structured arrangement of sarcomeres and are multinucleated. They are primarily under voluntary control through the somatic nervous system but can also be activated neurologically for reflex actions.Cardiac muscles, while striated, are usually uninucleate and are governed by the involuntary autonomic nervous system, possessing intrinsic pacemaker activity.Smooth muscles lack striations, are not multinucleated, and are involuntarily controlled.The term 'involuntary muscle' broadly refers to smooth and cardiac muscles, which do not meet the specific criteria of striations and multinucleation outlined in the question.

Q27. Which one of the following muscles is considered as “Voluntary muscle”?

• A. Smooth muscles
• B. Cardiac muscles
• C. Skeletal muscles✓
• D. Glandular muscles

Explanation: Muscles in the body are categorized into three main types: Smooth, Cardiac, and Skeletal. Skeletal muscles are classified as voluntary muscles because they are consciously controlled, allowing us to perform actions such as walking, lifting, and speaking. This contrasts with Smooth and Cardiac muscles, which are involuntary. Smooth muscles operate automatically within organs, and Cardiac muscles function independently in the heart's rhythmic contractions. Therefore, the correct answer is Option C: Skeletal muscles.

Q28. Connective tissue wrapping around a muscle that is found continuous with tendons:

• A. Perimysium
• B. Endomysium
• C. Epimysium✓
• D. Perichondrium

Explanation: The correct answer is Epimysium. This layer is the outermost connective tissue covering of a muscle, essential for enclosing the entire muscle and ensuring connectivity with tendons, which anchor the muscle to bone structures. The Perimysium and Endomysium are inner layers that wrap around smaller components within the muscle and do not extend to tendons. The Perichondrium is unrelated as it surrounds cartilage, not muscles.

Q29. Sarcoplasmic reticulum is like:

• A. Golgi bodies
• B. Smooth endoplasmic reticulum✓
• C. Cytoskeletal fibers
• D. Ribosomes

Explanation: The correct answer is smooth endoplasmic reticulum because the sarcoplasmic reticulum (SR) is a specialized form of it found in muscle cells. It is integral to muscle function by storing and releasing calcium ions, which are essential for muscle contraction and relaxation. The other options, such as Golgi bodies, cytoskeletal fibers, and ribosomes, do not have this specific function of calcium ion regulation in muscle cells.

Q30. Sarcolemma is primarily made up of:

• A. Lipoprotein✓
• B. Glycolipids
• C. Glycoprotein
• D. Nucleoproteins

Explanation: The correct answer is lipoprotein. The sarcolemma, as the cell membrane of muscle cells, consists mainly of a lipid bilayer with embedded proteins, together forming lipoproteins. These components are essential for maintaining the integrity and function of the sarcolemma. Options B, C, and D are incorrect because they either refer to minor components or are unrelated to the structural makeup of the sarcolemma.

Q31. Which one of the following structures serves as a center of sarcomere?

• A. H-zone
• B. Z-band
• C. M-line✓
• D. A-band

Explanation: The M-line is the correct answer as it is found at the center of the sarcomere. It is responsible for holding the thick filaments in place and ensuring proper alignment during muscle contraction. The H-zone is part of the A band but not at the center; it is the region with only thick filaments. The Z-band marks the boundaries of the sarcomere, not its center. The A-band consists of overlapping thick and thin filaments but is not specifically the center of the sarcomere.

Q32. T-tubules in human skeletal muscles are present at:

• A. Z-line
• B. M-line
• C. A-I junction✓
• D. H-zone

Explanation: T-tubules in human skeletal muscles are strategically positioned at the A-I junction, which is where the A band and I band meet. This location allows for effective propagation of electrical signals, ensuring simultaneous muscle fiber contraction. In contrast, the Z-line, M-line, and H-zone serve different structural roles in the sarcomere and do not host T-tubules in skeletal muscles.

Q33. How many moles of oxygen are needed for the complete combustion of two moles of butane

• A. 2
• B. 8
• C. 10
• D. 13✓

Explanation: The balanced chemical equation for the reaction is as follow 2 C4H10 + 13 O2 => 8 CO2 + 10 H2OFirst of all to construct a balanced chemical equation for any any hydrocarbon: 1.the number of moles of carbon dioxide is equal to the number of carbon in the hydrocarbon.2.the number of moles of water is equal to half the number of hydrogen in the hydrocarbon. 3. Then add oxygen to the reactant side until the number of oxygen is equal on both sides of equation.

Q34. The main reason for large number of organic compound is:

• A. Isomerism
• B. Complexity of structure
• C. Catenation✓
• D. Homologous series

Explanation: Catenation is the unique ability of carbon atoms to form strong covalent bonds with other carbon atoms, creating long chains and complex rings. This property is the fundamental reason for the immense diversity and sheer number of organic compounds.

Q35. Which of the following hydrocarbons is least reactive?

• A. Alkyne
• B. Alkane✓
• C. Benzene
• D. Alkene

Explanation: Alkanes are saturated hydrocarbons containing only strong, non-polar carbon-carbon and carbon-hydrogen single bonds (sigma bonds). The absence of weaker pi bonds or functional groups makes them relatively inert and the least reactive class of hydrocarbons.

Q36. Which of the following class of organic compounds contains a ring which has more than one kind of atom?

• A. Aromatic
• B. Heterocyclic✓
• C. Non-benzenoid
• D. Aliphatic

Explanation: Heterocyclic compounds are cyclic compounds in which one or more of the ring atoms are elements other than carbon. These other atoms, such as nitrogen, oxygen, or sulfur, are referred to as heteroatoms.

Q37. Compounds containing ring of three or more than three carbon atom and resembling_compounds are called alicyclic.

• A. Aliphatic✓
• B. Aromatic
• C. Benzene
• D. Heterocyclic

Explanation: Alicyclic compounds are compounds that are both aliphatic and cyclic. They contain one or more all-carbon rings which may be either saturated or unsaturated, but do not have aromatic character.

Q38. Cyclohexane can be classified as:

• A. Carbocyclic
• B. Aromatic
• C. Alicyclic
• D. Both A and C✓

Explanation: Cyclohexane is carbocyclic because its ring is composed solely of carbon atoms. It is also alicyclic because it is a cyclic compound that behaves chemically like an aliphatic (non-aromatic) compound.

Q39. The aliphatic compounds are of two types:

• A. Straight chain and cyclic
• B. Branched chain and alicyclic
• C. Straight chain and branched✓
• D. Homocyclic and alicyclic

Explanation: Aliphatic or open chain compounds are further classified as straight chain and branched compounds.

Q40. 1st synthetic organic compound is:

• A. Ammonium cyanate
• B. Urea✓
• C. Methane
• D. Benzene

Explanation: In 1828, Friedrich Wohler synthesized urea by heating the inorganic compound ammonium cyanate. This was a landmark experiment that disproved the "vital force" theory, which held that organic compounds could only be produced by living organisms.

Q41. The percentage of s character in sp2 hybrid orbital is

• A. 25%
• B. 33.3%✓
• C. 50%
• D. 75%

Explanation: In sp2 hybrid orbital% of s character =1/3 x 100=33.3%In sp3% of p character = 3/4 x 100 = 75%

Q42. When organic compounds contain more than one functional group, it is known as:

• A. Derivatives
• B. Heterocyclic
• C. Poly-functional✓
• D. Isomers

Explanation: 1. **Functional Groups:** In organic chemistry, a functional group is a specific group of atoms or bonds within a molecule that gives the compound its characteristic chemical properties. Examples include hydroxyl (-OH), carbonyl (C=O), amino (-NH2), etc. 2. **Polyfunctional Compounds:** When a molecule contains more than one type of functional group, it is termed polyfunctional. These compounds exhibit a combination of chemical reactivities associated with each functional group present. 3. **Versatility and Reactivity:** Polyfunctional compounds are often more versatile and reactive due to the diverse chemical properties of their functional groups. This can lead to a wide range of possible reactions and applications in organic synthesis. 4. **Polyfunctional Isomers:** The concept of polyfunctional compounds is related to isomerism. Isomers are compounds with the same molecular formula but different structural arrangements. In the case of polyfunctional compounds, isomerism arises from different arrangements or combinations of functional groups. 5. **Example:** Consider a molecule with both an alcohol (-OH) and an amine (-NH2) group. This compound would be polyfunctional as it contains two different functional groups. Depending on their relative positions within the molecule, different isomeric forms could exist. In summary, "polyfunctional" is a term used to describe organic compounds that possess more than one type of functional group, providing them with diverse chemical reactivity and potential applications in various chemical processes. Therefore option C is correct.

Q43. The major portion of natural gas is:

• A. Methane.✓
• B. Butane.
• C. Propane.
• D. Ethane.

Explanation: The major portion of natural gas consists of methane (CH₄). Methane is the primary component, typically making up a significant percentage (often around 70-90%) of natural gas. However, natural gas can also contain other hydrocarbons, such as ethane (C₂H₆), propane (C₃H₈), butanes, and traces of other gases like nitrogen, carbon dioxide, and hydrogen sulfide. The exact composition of natural gas can vary depending on the source and location of extraction. Methane, being the simplest hydrocarbon, is the primary contributor to the energy content of natural gas and is a valuable fuel source. Therefore, option A is correct.

Q44. In organic compounds carbon atoms form:

• A. Ionic bond
• B. Covalent bond✓
• C. Hydrogen bond
• D. Metallic bond

Explanation: Carbon has four valence electrons and a moderate electronegativity. It achieves a stable octet by sharing electrons with other atoms, forming strong covalent bonds, which is the hallmark of organic chemistry.

Q45. Each functional group represents a different class of organic compounds. They are divided into following classes of organic compound on the basis of functional group:

• A. Hydrocarbons
• B. Derivatives of hydrocarbons
• C. Both A and B✓
• D. Neither A nor B

Explanation: Classes of organic compounds contains , hydrocarbons as well as there derivatives.. Hence , C is the correct option.

Q46. Who proved that no vital force theory is involved in the synthesis of organic compounds?

• A. Lewis
• B. Wohler✓
• C. Berzelius
• D. Democritus

Explanation: In 1828, Friedrich Wohler synthesized urea from the inorganic compound ammonium cyanate. This experiment was a critical blow to the theory of vitalism, which claimed that organic compounds could only be made by living things.

Q47. Vital Force Theory was proposed by:

• A. Wohler
• B. Berzelius✓
• C. Faraday
• D. Bohr

Explanation: Berzelius was a Swedish scientist who in 1815 proposed that organic compounds could only be produced by some special force which must be existing in a living organism and could not be prepared in a laboratory. This force was called Vital Force and this theory came to be known as Vital Force Theory.

Q48. Carbon is:

• A. Trivalent
• B. Tetravalent✓
• C. Monovalent
• D. Pentavalent

Explanation: Carbon has four valence electrons and typically forms four covalent bonds to achieve a stable octet. This property of forming four bonds is known as being tetravalent.

Q49. According to Vital Force Theory organic compounds were only produced by the:

• A. Animals
• B. Plants
• C. Mineral
• D. Both A and B✓

Explanation: According to vital force theory, the organic compounds could only be produced in living organisms and could not be synthsized in laboratory.Both plants and animals are living organisms so D is correct.

Q50. Which one of the following is not an organic compound?

• A. Urea
• B. Methane
• C. Carbon dioxide✓
• D. Coal

Explanation: Apart from carbon, most of the organic compounds also contain hydrogen. Other elements which may also be present include oxygen, nitrogen, sulphur, etc.A few of the carbon compounds such as CO, CO2, carbonates, bicarbonates etc are studied as inorganic compounds.

Q51. The organic compounds having all C — C single bonds are called:

• A. Alkanes✓
• B. Alkenes
• C. Alkynes
• D. All of these

Explanation: Alkanes are the class of saturated hydrocarbons. By definition, they contain only single covalent bonds between their carbon atoms.

Q52. Organic compounds in which tetravalency of carbon atom is fully satisfied, are called:

• A. Saturated✓
• B. Unsaturated
• C. Alkenes
• D. Alkynes

Explanation: Organic compounds in which tetravalency of carbon atom is fully satisfied are called saturated compounds. This means that each carbon atom in the compound has four bonds, either with other carbon atoms or with atoms of other elements.Saturated compounds are the most common type of organic compound. They are found in a wide variety of natural and synthetic products, including fats.Here are some examples of saturated compounds:Methane (CH4): The carbon atom in methane is bonded to four hydrogen atoms.Ethane (C2H6): The carbon atoms in ethane are bonded to each other and to two hydrogen atoms each.Propane (C3H8): The carbon atoms in propane are bonded to each other and to three hydrogen atoms each.

Q53. Fractions of crude petroleum can be obtained by using _?

• A. Destructive distillation
• B. Fractional distillation✓
• C. Vacuum distillation
• D. Dry distillation

Explanation: Fractional distillation is the industrial process used to separate crude oil into its various components, or fractions. This process works because the different hydrocarbons in the crude oil have different boiling points, allowing them to be separated as they vaporize and condense at different temperatures in a fractionating column.

Q54. Compounds having benzene ring are called:

• A. Alicyclic
• B. Aliphatic compounds
• C. Aromatic compounds✓
• D. Acyclic compounds

Explanation: The compounds in which the ring consists of only carbon atoms are Homocyclic or carbocyclic compounds. Homocyclic compounds are further classified as :1. Alicyclic compounds( cyclic compounds that do not follow Huckle's Rule)2. Aromatic compounds(cyclic compounds that follows Huckle's Rule).So benzene is an aromatic cmpound.

Q55. Aliphatic compound is the other name for _

• A. Acyclic compounds✓
• B. Alicyclic compounds
• C. Ring compounds
• D. Closed chain compounds

Explanation: Option A is correct because aliphatic compounds are a class of organic compounds that contain carbon atoms arranged in straight chains, branched chains, or non-aromatic rings. They may be either saturated (containing only single bonds) or unsaturated (containing double or triple bonds).For Example: Butane and Iso-butane.

Q56. Find the odd one among the following.

• A. Alicyclic compounds
• B. Heterocyclic compounds
• C. Branched chain compounds✓
• D. Aromatic compounds

Explanation: The correct answer is 'Branched chain compounds' because they are open chain or acyclic compounds, distinct from the others which are cyclic. Alicyclic, heterocyclic, and aromatic compounds all feature closed chain structures, with aromatic compounds also displaying unique stability owing to resonance. In contrast, branched chain compounds do not form rings, making them the odd one out.

Q57. The element least likely to be found in an organic compound is

• A. Oxygen
• B. Sulfur
• C. Nitrogen
• D. Silicone✓

Explanation: Silicon is not commonly found in organic compounds because it is not a biologically essential element. While silicon does form some organic compounds, such as silanes and siloxanes, these are not typically found in living organisms. Silicon is primarily found in rocks and minerals and is used in a variety of industrial applications.

Q58. One of the major sources of organic compounds is

• A. Natural gas✓
• B. Fermentation
• C. Sea water
• D. Atmosphere

Explanation: Natural gas is a major source of organic compounds because it is primarily composed of hydrocarbons, which are organic compounds made up of carbon and hydrogen atoms. These hydrocarbons can be used as fuels, such as methane, propane, and butane.

Q59. Stable organic compounds, carbon will always form

• A. 2 bonds
• B. 3 bonds
• C. 4 bonds✓
• D. 5 bonds

Explanation: C forms 4 bonds in the most stable compounds.

Q60. An emf of 120 volts of negligible internal resistance is connected across a resistance of 1000 ohm. The current flowing through the circuit will be:

• A. 120 A
• B. 120 x 103A
• C. 120 x 10-3 A✓
• D. None

Explanation: The current(I) can be calculated using the equation V=IR(120)=(1000)(I)120/1000=II=120 x 10-3 A

Q61. The fractional change in resistance per kelvin is known as:

• A. None
• B. Temperature coefficient of resistance✓
• C. Thermal coefficient
• D. Volumetric coefficient of expansion
• E. Linear coefficient of expansion

Explanation: The fractional change in resistance per kelvin is called the temperature coefficient.The temperature coefficient of resistance is a measure of how much the electrical resistance of a material changes with temperature. It is expressed in units of ohms per ohm per degree Celsius (Ω/Ω/°C) or ohms per ohm per kelvin (Ω/Ω/K). This coefficient is denoted by the symbol α (alpha) and is an important factor in understanding and designing electronic circuits, particularly when dealing with components like resistors whose resistance can vary with temperatureResistance coefficient, abbreviated as K, a dimensionless number, is how much resistance to the flow an obstacle has. Volumetric coefficient increases in volume per unit original volume per Kelvin rise in temperature is called the coefficient of volumetric expansion.The ratio increase in length original length for the 1-degree rise in temperature is called the coefficient of linear expansion

Q62. A wire of resistance R is bent in the form of a circle the resistance between two points on the circumference of the wire and at the end of the diameter of circle is

• A. R/4✓
• B. R/2
• C. R
• D. 2R

Explanation: Solution is given below

Q63. When a potential difference is applied across the ends of a uniform wire of length l and radius r, a current I flows in the wire. If same potential difference is applied to the ends of another wire of the same material but of length 2l and radius 2r, the current in the wire is:

• A. I/4
• B. 2I✓
• C. I
• D. I/2

Explanation: R=ρl/AWhen radius is doubled : Area=2*pi*(2r) = 2*pi*4rHence the area has increased by 4 times.New resistance : Rx = ρ*2l/4A = ½ RV=IR where V remains same and R becomes halfI = V / ½RI become equal to 2I.

Q64. A battery whose emf is 40 V has an internal resistance of 5 Ohms. If this battery is connected to a 15 Ohms resistor ‘R’, what will be the voltage drop across ‘R’:

• A. 10 V
• B. 30 V✓
• C. 40 V
• D. 50 V
• E. 70 V

Explanation: 40 = I x (15+ 5) 40= I x 20 I = 40/20 I= 2 AVoltage drop across resistor R V= IR V= 2 x 15 V= 30 V (hence B is the correct option)

Q65. An electric bulb is rated at 220 V, 100 W. What is its resistance?

• A. 250 Ohms
• B. 350 Ohms
• C. 450 Ohms
• D. 484 Ohms✓

Explanation: In this case, we are given the voltage (V) of the bulb, which is 220 V, and the power (P) of the bulb, which is 100 W. We can use the formula for power:Power (P) = V2/RR = V2/P= (220)2/100= 22 x 22= 484 Ohms

Q66. A wire of uniform area of cross-section A and length L is cut into two equal parts, the resistivity of each part _.

• A. Doubles
• B. Halves
• C. Remains the same✓
• D. Increases three times

Explanation: The resistivity is dependent on the material. If the length and/or the cross-sectional area change, it does not affect the resistivity. Therefore, the resistivity of the material remains the same.

Q67. If you wish to decrease the resistance of a circuit, you will add the resistors in _.

• A. Series
• B. Parallel✓
• C. Does not make a difference
• D. Cannot be determined
• E. 160

Explanation: As more and more resistors are added in parallel to a circuit, the equivalent resistance of the circuit decreases, and the total current of the circuit increases. Adding more resistors in parallel is equivalent to providing more branches through which charge can flow.

Q68. If we increase the cross-section area of a conductor having a length L, the resistance R of that conductor will be:

• A. Zero
• B. Constant
• C. Increasing
• D. Decreasing✓

Explanation: The resistance of a conductor decreases with increase in cross-sectional area. ○If we increase the area of cross section of conductor then More electrons results in more charge crossing the cross section, thus more current. Thus if you increase the area of cross section then resistance of the wire (keeping length and resistivity same) will decrease. Resistance R = ρ L/A Result: From the above discussion and the formula of resistance that with increase in area of cross section resistance decrease and vice versa.

Q69. The resistivity in SI units is measured in:

• A. Ω x m✓
• B. Ω - m2
• C. Ω / m
• D. Ω / m2

Explanation: The SI unit of electrical resistivity is the ohm-meter (Ω⋅m). For example, if a 1 m × 1 m × 1 m solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ω⋅m.

Q70. The correct form of Ohm's law is:

• A. I = VR
• B. V ∝ I
• C. V = IR
• D. Both Options B and C are correct✓

Explanation: According to Ohm’s law,I ∝ VOr I = GVOr V = (1/G)IOr V = RI or V = IR

Q71. When a wire is compressed and it’s radius becomes 2R then it’s resistance will be:

• A. 16R
• B. 4 R
• C. 1 / 16 R✓
• D. 1 / 4 R

Explanation: Taking volume constant… A- Cross sectional area of wire (pi x r^2) L-Length of wire. A2.L2=A1.L1 r2=2r1; as it is written that diameter is doubled. So A2=4A (as r^2 goes in the formula.) If the radius is doubled length becomes ¼ ,resistance is proportional to L/A Thus, R2=R1/16

Q72. One of the following is an Ohmic device:

• A. Filament bulb
• B. Semiconductor diode
• C. Transistor
• D. Copper wire✓

Explanation: Copper wire is the Ohmic device in the given options. It exhibits Ohmic behavior within its normal operating conditions, meaning that its resistance remains constant and follows Ohm's Law over a range of voltages and currents.

Q73. A battery of 6 volts is connected to two resistors of 3 ohm and 2 ohm joined together in series. What will be the current through the circuit?

• A. 6.2 A
• B. 5.2 A
• C. 4.2 A
• D. 2.2 A
• E. 1.2 A✓

Explanation: Resistance of resistors placed in series is calculated by adding the resistance,3+2=5 ohms.Formula connecting voltage,resistance and current is V=IR.V=IR(6)=(5)(I)6/5=I=1.2 Ohms.

Q74. If in a circuit, 2 Ampere current is drawn from the battery in 10 minutes. How much charge will flow through the circuit in this time?

• A. 1200 Coulombs✓
• B. 600 Coulombs
• C. 500 Coulombs
• D. 20 Coulombs

Explanation: DATA: Current I = 2 amp Time T = 10 minutes = 600 secCharge Q = ??SOLUTION : I= Q/TQ = ITQ = 600×2 Q = 1200 coloumb ans

Q75. The power of an electric bulb is 100W. It is connected to 110V power supply. The resistance of electric bulb will be?

• A. 11Ω
• B. 121Ω✓
• C. 20Ω
• D. 200Ω

Explanation: We use the formula,P= V²/RR= V²/P = 110²/100 = 12100/100 = 121Ω

Q76. Terminal voltage Vi of the battery is greater than emf of the battery when:

• A. Battery is charging✓
• B. Battery is discharging
• C. Battery is connected with R
• D. Battery is connected with voltmeter

Explanation: When a battery is charging, it requires a higher external voltage to overcome its emf and internal resistance. This results in a terminal voltage (V) greater than the emf (E) of the battery, as described by the equation V = E + Ir. Option A is correct because it correctly identifies the condition under which the terminal voltage exceeds the emf. Options B, C, and D describe scenarios where the terminal voltage is either equal to or less than the emf due to the nature of discharging or when there is no current flow.

Q77. If length of the wire becomes two times to the original value and area becomes one half to its original value, then resistance of the wire becomes:

• A. Double
• B. Four times✓
• C. One half
• D. One fourth

Explanation: R= ρL/AL' = 2LA' = 1/2AR' = 2L/(1/2A)R' = 4L/AR' = 4 R

Q78. The electrons in a conductor drift with a velocity of:

• A. 10-3 ms-1✓
• B. 104 ms-1
• C. 10-6 ms-1
• D. 107 ms-1

Explanation: Drift velocity refers to the average velocity at which charged particles, such as electrons, move through a conductor in the presence of an electric field. While individual electrons within a conductor undergo random motion, the application of an electric field causes a net directional movement of electrons. When an electric field is applied across a conductor, it exerts a force on the free electrons within the material. This force, known as the electric force, causes the electrons to accelerate in the direction opposite to the electric field. However, the electrons also experience frequent collisions with atoms or other electrons, which disrupt their motion and cause them to lose some of their momentum. The net effect of these collisions is that electrons experience a resistive force, known as the drag force, which opposes their motion. As a result, the electrons attain a steady-state average velocity known as the drift velocity. The drift velocity represents the average speed and direction at which electrons move through the conductor. It is important to note that the drift velocity is typically quite small. Even in a typical metallic conductor, the drift velocity of electrons is typically on the order of millimeters per second. This is due to the high number density of electrons and the large number of collisions they experience within the conductor. The concept of drift velocity helps in understanding phenomena such as electrical current, Ohm's Law, and the behavior of conductors under the influence of electric fields. Free electrons have a speed in the order of several hundred kilometers while the drift velocity of electrons in a conductor is 10-3 m/s. (PTB)

Q79. A steady current of 5 A is drawn from an electric source at a voltage of 100 V. The power consumed (in Watts) is:

• A. 0.05
• B. 5
• C. 500✓
• D. 50000

Explanation: Option A: This is the power consumed if the current is 0.05 A. However, the current is given as 5 A, so this option is incorrect. Option B: This is the power consumed if the current is 5 A and the voltage is 1 V. However, the voltage is given as 100 V, so this option is also incorrect. Option C: The power consumed is 500 Watts.Power is defined as the rate at which energy is consumed. It is calculated by multiplying the voltage by the current. In this case, the voltage is 100 V and the current is 5 A, so the power is:Power = Voltage * Current = 100 V * 5 A = 500 WattsThe answer is 500. Option D: This is the power consumed if the current is 5 A and the voltage is 1000 V. However, the voltage is given as 100 V, so this option is also incorrect.

Q80. If two or more resistors are joined to each other side by side, this combination is called:

• A. Series combination of resistors
• B. Parallel combination of resistors✓
• C. Y delta combination of resistors
• D. None of the above

Explanation: When two or more resistors are joined side by side, this combination is called "parallel." In a parallel circuit, the voltage across each resistor is the same, and the total current is the sum of the currents through each resistor.

Q81. A light bulb has resistance of 150 ohms, find the voltage while the current is 1.5 A?

• A. 350 V
• B. 300 V
• C. 224 V
• D. 225 V✓

Explanation: V=IR V=1.5 x 150=225V

Q82. The reciprocal of resistivity is called:

• A. Resistance
• B. Inductance
• C. Conductivity✓
• D. Flexibility

Explanation: Conductivity is the measure of a material's ability to conduct electric current. It is the reciprocal of resistivity.The higher the conductivity, the better the material is at allowing the flow of electric current

Q83. Which one of the following is correct?

• A. Joule = Coulomb / volt
• B. Joule = volt x ampere
• C. Joule = volt / ampere
• D. Joule = Coulomb x volt✓

Explanation: V = W/q W = qV Joule = CV

Q84. Resistivity of a conductor depends upon

• A. temperature✓
• B. length
• C. cross-sectional area
• D. None of these

Explanation: The resistivity of a material depends on its nature and the temperature of the conductor. The resistivity of a material doesn't depend on its shape and size (length and area).

Q85. _ is a source of electrical energy having fixed polarity and terminals

• A. Motor
• B. Metals
• C. Battery✓
• D. Generator

Explanation: An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices.When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal.

Q86. Electrical power is given by P=

• A. VI
• B. I^2 R
• C. V^2 / R
• D. all✓

Explanation: Electrical power has 3 formulas which are P= IV, P= I^R and P= V^2 / R