Part 2 — Skeletal & Muscular Systems; Brief Locomotor Adaptations (Questions 26–50)

Part 2 — Skeletal & Muscular Systems; Brief Locomotor Adaptations (Questions 26–50)

26. The frog’s axial skeleton includes:
    A. Skull, vertebral column and ribs only
    B. Skull, vertebral column and urostyle
    C. Only skull and limbs
    D. Only limbs and girdles
    Answer: B — Skull, vertebral column and urostyle.
    Explanations:
    A: Incorrect — ribs are reduced/absent; urostyle is important.
    B: Correct — axial skeleton includes skull, vertebral column, and urostyle (fused posterior element).
    C: Incorrect — limbs are appendicular skeleton, not axial.
    D: Incorrect — limbs/girdles are appendicular.

27. The frog’s vertebral column ends in a rod-like structure formed by fusion of posterior vertebrae called:
    A. Sacrum
    B. Urostyle
    C. Coccyx
    D. Scapula
    Answer: B — Urostyle.
    Explanations:
    A: Incorrect — sacrum is a fused sacral region in some vertebrates, but urostyle is the distinctive fused element in frogs.
    B: Correct — urostyle is characteristic, formed by fusion of vertebral elements.
    C: Incorrect — coccyx is a human term.
    D: Incorrect — scapula is shoulder blade.

28. Which of the following limb bone fusions is present in frogs?
    A. Radius and ulna fused into radioulna
    B. Tibia and fibula fused into tibiofibula
    C. Femur and tibia fused into femubia
    D. Humerus and femur fused
    Answer: B — Tibia and fibula fused into tibiofibula.
    Explanations:
    A: Incorrect — in frogs the radius and ulna are separate or sometimes partially fused into radio-ulna in some species; main well-known fusion is tibia+fibula.
    B: Correct — tibia and fibula are fused (tibiofibula) aiding strength for jumping.
    C: Incorrect — femur and tibia are separate.
    D: Incorrect — humerus and femur are distinct bones in different limbs.

29. The pectoral girdle of frog includes which of the following bones?
    A. Scapula and clavicle (and coracoid elements)
    B. Ilium and ischium
    C. Urostyle and sacrum
    D. Sternum only
    Answer: A — Scapula and clavicle (and coracoid elements).
    Explanations:
    A: Correct — pectoral girdle consists of scapula, clavicle, coracoid and associated elements.
    B: Incorrect — ilium and ischium are pelvic girdle bones.
    C: Incorrect — urostyle and sacrum are axial.
    D: Incorrect — sternum alone does not define pectoral girdle.

30. Which muscle action in frog is chiefly responsible for straightening the hind limb during the jump?
    A. Flexors of knee only
    B. Extensors of knee and ankle like triceps femoris and gastrocnemius
    C. Constrictors of cloaca
    D. Orbicularis oculi contraction
    Answer: B — Extensors of knee and ankle like triceps femoris and gastrocnemius.
    Explanations:
    A: Incorrect — flexors bend limb, not extend it.
    B: Correct — powerful extensors (thigh and calf muscles) extend limb to produce jump.
    C: Incorrect — cloacal muscles unrelated.
    D: Incorrect — orbicularis oculi is around eye.

31. Frog long bones are hollow to some extent — this adaptation primarily:
    A. Adds weight for strength
    B. Reduces weight and increases limb efficiency for jumping
    C. Protects soft tissues from injury by being hollow
    D. Stores extra marrow for respiration
    Answer: B — Reduces weight and increases limb efficiency for jumping.
    Explanations:
    A: Incorrect — hollowing reduces weight, not adds.
    B: Correct — light bones reduce energy cost and increase agility during leaps.
    C: Incorrect — hollow bones are about weight, not protection.
    D: Incorrect — marrow storage is secondary; hollowing not for respiration.

32. Which of the following describes the pelvic girdle adaptation in frog for jumping?
    A. Short ilium and mobile sacrum
    B. Elongated ilium, strong sacral articulation and urostyle support
    C. Free-floating pelvis with no firm attachments
    D. Pelvis fused to skull
    Answer: B — Elongated ilium, strong sacral articulation and urostyle support.
    Explanations:
    A: Incorrect — short ilium would not aid jumping.
    B: Correct — elongated ilium and strong pelvic-sacro-urostyle complex transmit jumping forces.
    C: Incorrect — pelvis has strong attachments.
    D: Incorrect — pelvis not fused to skull.

33. Which muscle group on the ventral side of frog helps in swallowing by lifting the floor of buccal cavity?
    A. Levator bulbi (also elevates eye) and submandibular muscles
    B. Triceps femoris
    C. Pectoralis major only
    D. External oblique only
    Answer: A — Levator bulbi (also elevates eye) and submandibular muscles.
    Explanations:
    A: Correct — levator bulbi helps raise buccal floor and eyes which assist swallowing.
    B: Incorrect — triceps femoris is leg extensor.
    C: Incorrect — pectoralis unor strongly related.
    D: Incorrect — external oblique is abdominal muscle.

34. The presence of a strong pectoral girdle in frogs is primarily to:
    A. Enable digging with forelimbs
    B. Absorb impact during landing from jumps
    C. Hold eggs during breeding
    D. Support gills for respiration
    Answer: B — Absorb impact during landing from jumps.
    Explanations:
    A: Incorrect — pectoral girdle’s main function is shock absorption.
    B: Correct — sturdy pectoral girdle and specialized elements cushion landing forces.
    C: Incorrect — pectoral girdle not for holding eggs.
    D: Incorrect — not related to gills.

35. Which bone transmits force from hindlimb jump to the vertebral column?
    A. Humerus
    B. Femur
    C. Ilium attached to urostyle and vertebral column
    D. Metatarsals
    Answer: C — Ilium attached to urostyle and vertebral column.
    Explanations:
    A: Incorrect — humerus is forelimb.
    B: Incorrect — femur transmits force to pelvis but ilium anchors pelvis to vertebral column.
    C: Correct — ilium connects hindlimb to vertebral column and urostyle, transmitting forces.
    D: Incorrect — metatarsals are foot bones, distal.

36. The frog’s belly muscles (abdominal muscles) serve primarily to:
    A. Facilitate jumping through direct contraction of limbs
    B. Aid in buccal ventilation and defecation; support viscera and contribute to locomotion indirectly
    C. Secrete mucus for skin lubrication
    D. Produce eggs in females
    Answer: B — Aid in buccal ventilation and defecation; support viscera and contribute to locomotion indirectly.
    Explanations:
    A: Incorrect — abdominal muscles don’t directly extend limbs.
    B: Correct — abdominal muscles assist in respiration, protect organs and aid bodily functions.
    C: Incorrect — mucus glands are in skin.
    D: Incorrect — gonads produce eggs, not muscles.

37. Which of the following statements about frog ribs is correct?
    A. Frogs possess well-developed ribs attached to sternum
    B. Ribs are rudimentary or absent in frogs
    C. Ribs are fully developed and used for respiration like mammals
    D. Frogs have gill arches instead of ribs
    Answer: B — Ribs are rudimentary or absent in frogs.
    Explanations:
    A: Incorrect — frogs lack well-developed ribs.
    B: Correct — ribs are reduced; thus thoracic expansion is not by ribs.
    C: Incorrect — not like mammals.
    D: Incorrect — gill arches belong to embryonic pharyngeal arch region.

38. The “knee” joint in frog is between which bones?
    A. Femur and tibiofibula
    B. Femur and humerus
    C. Tibiofibula and metatarsals
    D. Humerus and ulna
    Answer: A — Femur and tibiofibula.
    Explanations:
    A: Correct — knee is the femur–tibiofibula articulation.
    B: Incorrect — humerus is forelimb.
    C: Incorrect — distal foot bones not knee.
    D: Incorrect — forelimb elbow would be humerus + radius/ulna.

39. Which of the following muscular adaptations helps frog swallow prey large relative to head size?
    A. Strong tongue protrusion and backward movement of eyes aiding swallowing
    B. Teeth force prey into stomach with no help from tongue
    C. Using forelimbs to push food down the throat
    D. Hindlimbs insertion into mouth to compress food
    Answer: A — Strong tongue protrusion and backward movement of eyes aiding swallowing.
    Explanations:
    A: Correct — frog’s sticky tongue captures prey; eyeballs push food into oesophagus during swallowing.
    B: Incorrect — teeth are small; tongue and eye movement crucial.
    C: Incorrect — forelimbs don’t aid swallowing.
    D: Incorrect — hindlimbs not involved.

40. Which of the following is a feature of frog skull that reduces weight?
    A. Presence of many heavy bones and dense ossification
    B. Large openings (fenestrae) and reduction of bone mass
    C. Skull completely cartilaginous in adult
    D. Skull fused to pelvic girdle
    Answer: B — Large openings (fenestrae) and reduction of bone mass.
    Explanations:
    A: Incorrect — heavy ossification increases weight.
    B: Correct — light skull with openings reduces weight for mobility and jumping.
    C: Incorrect — skull is ossified though lighter.
    D: Incorrect — skull not fused to pelvis.

41. Which statement is true for the origin of limb muscles in frogs?
    A. Limb muscles originate from somites (myotomes) during development
    B. Limb muscles arise from endoderm only
    C. Limb muscles are derived from epidermis
    D. Limb muscles are partially skeletal and partially cartilage
    Answer: A — Limb muscles originate from somites (myotomes) during development.
    Explanations:
    A: Correct — skeletal muscles derive embryologically from mesodermal somites.
    B: Incorrect — endoderm forms gut lining, not muscles.
    C: Incorrect — epidermis gives skin, not muscle.
    D: Incorrect — muscles are not cartilage.

42. The skeletal muscles of frog are striated because:
    A. They lack sarcomeres
    B. They have organized actin and myosin filaments forming sarcomeres
    C. They are identical to smooth muscle in arrangement
    D. They are involuntary only and thus unstriated
    Answer: B — They have organized actin and myosin filaments forming sarcomeres.
    Explanations:
    A: Incorrect — striations arise from sarcomeres presence.
    B: Correct — striated (skeletal) muscles show sarcomeres with banding.
    C: Incorrect — smooth muscles are non-striated.
    D: Incorrect — skeletal muscles are usually voluntary and striated.

43. Which of these is true about frog limb girdles?
    A. Pectoral girdle connects to skull directly
    B. Pelvic girdle is robust and transmits force during jumping to vertebral column
    C. Girdles are immaterial for locomotion
    D. Pelvic girdle has no connection to vertebral column
    Answer: B — Pelvic girdle is robust and transmits force during jumping to vertebral column.
    Explanations:
    A: Incorrect — pectoral girdle does not articulate with skull.
    B: Correct — pelvic girdle strong to transmit leg forces through ilium to vertebral column.
    C: Incorrect — girdles are essential to locomotion.
    D: Incorrect — pelvic girdle articulates with sacro-urostyle region.

44. The presence of a flexible pectoral girdle in frogs helps to:
    A. Increase force during jumping
    B. Absorb shock of landing and protect internal organs
    C. Store food during hibernation
    D. Enhance cutaneous respiration
    Answer: B — Absorb shock of landing and protect internal organs.
    Explanations:
    A: Incorrect — pelvic girdle chiefly transmits jump force.
    B: Correct — pectoral girdle cushions landing and acts as a shock absorber.
    C: Incorrect — not for food storage.
    D: Incorrect — unrelated to respiration.

45. In frog’s muscular system, the gastrocnemius muscle is located in:
    A. Forelimb — used for prey capture
    B. Hindlimb — calf region, major extensor for jumping
    C. Head — used for jaw closure
    D. Abdomen — aids in breathing only
    Answer: B — Hindlimb — calf region, major extensor for jumping.
    Explanations:
    A: Incorrect — gastrocnemius is in hindlimb.
    B: Correct — large calf muscle important in extension of ankle and jump propulsion.
    C: Incorrect — not in head.
    D: Incorrect — not abdominal.

46. Which of the following bones supports the pelvic girdle laterally?
    A. Scapula
    B. Ilium
    C. Clavicle
    D. Sternum
    Answer: B — Ilium.
    Explanations:
    A: Incorrect — scapula is pectoral.
    B: Correct — ilium forms major lateral part of pelvic girdle connecting to sacrum/urostyle.
    C: Incorrect — clavicle part of pectoral girdle.
    D: Incorrect — sternum not main supporter.

47. The term “axial musculature” refers to muscles associated with:
    A. Limbs only
    B. Trunk and head (supporting axial skeleton)
    C. Only facial expressions
    D. Only digestive movements
    Answer: B — Trunk and head (supporting axial skeleton).
    Explanations:
    A: Incorrect — limb muscles are appendicular.
    B: Correct — axial muscles support the vertebral column and head.
    C: Incorrect — facial muscles are small subset but axial refers to trunk/head.
    D: Incorrect — many axial muscles contribute to functions including respiration, posture.

48. The frog’s tibiofibula is an example of:
    A. An unfused bone pair in body
    B. A bone formed by the fusion of tibia and fibula providing strength and lightness
    C. A cartilage rod used only in larvae
    D. A bone unique to mammals
    Answer: B — A bone formed by the fusion of tibia and fibula providing strength and lightness.
    Explanations:
    A: Incorrect — tibia and fibula are fused, not unfused.
    B: Correct — fusion creates a single sturdy bone (tibiofibula) aiding jumping.
    C: Incorrect — present in adults.
    D: Incorrect — many amphibians have this fusion; not a mammalian trait.

49. In frog locomotion, the role of pelvic girdle muscles is to:
    A. Propel forelimb during running
    B. Transmit and generate forces for hindlimb extension and jumping
    C. Pump blood through heart
    D. Move eyeballs for swallowing
    Answer: B — Transmit and generate forces for hindlimb extension and jumping.
    Explanations:
    A: Incorrect — pelvic girdle is hindlimb support.
    B: Correct — pelvic muscles anchor limb and generate power for jumps.
    C: Incorrect — heart pumps blood.
    D: Incorrect — eye movement not pelvic function.

50. Which of the following statements is correct regarding frog locomotor adaptations?
    A. Presence of long backbone with many free vertebrae increases flexibility for jumping
    B. Fusion of vertebrae into urostyle gives rigid support for transmitting jumping forces
    C. Forelimbs are longer than hindlimbs to push off ground
    D. Presence of heavy ribs to support trunk during landing
    Answer: B — Fusion of vertebrae into urostyle gives rigid support for transmitting jumping forces.
    Explanations:
    A: Incorrect — too many free vertebrae would reduce stiffness required for jumping.
    B: Correct — urostyle and fused elements stiffen posterior and aid in transmitting force.
    C: Incorrect — hindlimbs are longer for jumping.
    D: Incorrect — ribs are reduced/absent.

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