Part 1 — External Morphology, Integument & Locomotion (Questions 1–25)
Part 1 — External Morphology, Integument & Locomotion (Questions 1–25)
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Frog’s external body plan is divided into two main regions. These are:
A. Head and tail
B. Head and trunk
C. Head, thorax and abdomen
D. Head and abdomen
Answer: B — Head and trunk.
Explanations:
A: Incorrect — frogs lack a distinct tail in adults; “head and tail” is wrong.
B: Correct — adult frogs have a distinct head and trunk (trunk is often referred to as body or trunk region).
C: Incorrect — frogs do not have separate thorax and abdomen; those divisions are for higher vertebrates.
D: Incorrect — trunk (not specifically “abdomen”) is the correct paired region with head. -
The skin of a frog contributes to respiration because it is:
A. Thick and keratinised
B. Thin and richly vascularised
C. Covered with scales
D. Impermeable to gases
Answer: B — Thin and richly vascularised.
Explanations:
A: Incorrect — thick/keratinized skin would prevent gas exchange.
B: Correct — thin, moist, and richly supplied with blood vessels, allowing cutaneous respiration.
C: Incorrect — frogs do not have scales.
D: Incorrect — frog skin is permeable to gases, enabling cutaneous respiration. -
Which of the following structures helps a frog to produce sound during mating calls?
A. Vocal sacs
B. Tympanum
C. Nictitating membrane
D. Cloaca
Answer: A — Vocal sacs.
Explanations:
A: Correct — male frogs have vocal sacs that amplify mating calls.
B: Incorrect — tympanum is for hearing, not sound production.
C: Incorrect — nictitating membrane protects the eye.
D: Incorrect — cloaca is the common outlet for excretion/reproduction. -
The tympanum in a frog is:
A. A light-sensitive organ on skin
B. External ear structure (eardrum)
C. Part of the digestive system
D. A tactile organ on the snout
Answer: B — External ear structure (eardrum).
Explanations:
A: Incorrect — tympanum is not light-sensitive.
B: Correct — the external eardrum that transmits sound to inner ear.
C: Incorrect — not digestive.
D: Incorrect — not tactile; it’s auditory. -
Which structure protects the frog’s eyes while swimming?
A. Upper eyelid only
B. Tympanum
C. Nictitating membrane
D. Vocal sac
Answer: C — Nictitating membrane.
Explanations:
A: Incorrect — frogs have upper & lower eyelids; but protection in water is primarily by nictitating membrane.
B: Incorrect — tympanum is eardrum.
C: Correct — the transparent nictitating membrane moves across the eye to protect it and maintain visibility underwater.
D: Incorrect — vocal sac unrelated. -
Frogs are saltatory in their mode of locomotion. “Saltatory” means:
A. Swimming using fins
B. Jumping/hopping
C. Crawling on belly
D. Walking quadrupedally
Answer: B — Jumping/hopping.
Explanations:
A: Incorrect — swimming is natatorial.
B: Correct — saltatory = jumping; frogs are adapted for leaping.
C: Incorrect — that is serpentine/belly crawling.
D: Incorrect — not the usual term for frog locomotion. -
The forelimbs of frog are primarily used for:
A. Jumping propulsion
B. Landing and support during landing
C. Swimming with strong thrusts
D. Burrowing
Answer: B — Landing and support during landing.
Explanations:
A: Incorrect — hindlimbs provide major propulsion in jumping.
B: Correct — forelimbs absorb shock and support the body on landing.
C: Incorrect — hindlimbs are main propulsive swimming appendages.
D: Incorrect — not main function. -
The toe discs (pads) in tree frogs assist in:
A. Burrowing underground
B. Climbing smooth surfaces by adhesion
C. Digestion of hard prey
D. Respiration
Answer: B — Climbing smooth surfaces by adhesion.
Explanations:
A: Incorrect — toe pads aren’t for burrowing.
B: Correct — specialized adhesive pads help arboreal frogs adhere to surfaces.
C: Incorrect — no role in digestion.
D: Incorrect — not involved in respiration. -
Which of the following statements about frog skin glands is true?
A. Frogs lack skin glands
B. Mucous glands keep skin moist; granular glands may secrete toxins
C. Only mucous glands are present; no toxic secretion
D. Skin glands are for sound production
Answer: B — Mucous glands keep skin moist; granular glands may secrete toxins.
Explanations:
A: Incorrect — frogs have abundant skin glands.
B: Correct — mucous glands maintain moisture; granular (poison) glands produce defensive secretions.
C: Incorrect — granular glands often produce toxic substances.
D: Incorrect — glands do not produce sound. -
The skeleton part unique to frogs that aids in jumping is:
A. Sternum
B. Urostyle
C. Ribs
D. Pectoral girdle
Answer: B — Urostyle.
Explanations:
A: Incorrect — sternum present but not unique jumper adaptation.
B: Correct — the urostyle (fused posterior vertebrae) provides stiffness to trunk aiding jumping.
C: Incorrect — ribs are reduced/absent in frogs.
D: Incorrect — pectoral girdle supports forelimbs, not unique for jumping. -
The external opening of the nostrils of frog that leads into the buccal cavity are called:
A. Choanae (internal nostrils)
B. External nares
C. Glottis
D. Eustachian openings
Answer: B — External nares.
Explanations:
A: Incorrect — choanae are internal nostrils (connect buccal cavity to nasal chamber).
B: Correct — external nares are the external nostril openings.
C: Incorrect — glottis is the opening to larynx/trachea.
D: Incorrect — Eustachian openings connect middle ear to buccal cavity. -
The dorsal part of frog’s trunk is called:
A. Ventrum
B. Dorsum
C. Gular region
D. Cloacal region
Answer: B — Dorsum.
Explanations:
A: Incorrect — ventrum = belly (ventral).
B: Correct — dorsum = back (upper surface).
C: Incorrect — gular is throat area.
D: Incorrect — cloacal is posterior outlet region. -
Which of the following help in respiration when frog is at rest?
A. Buccal pumping and cutaneous respiration
B. Only pulmonary ventilation with diaphragm
C. Only active thoracic expansion by ribs
D. Cloacal ventilation only
Answer: A — Buccal pumping and cutaneous respiration.
Explanations:
A: Correct — frogs use buccal pumping to ventilate lungs and rely on skin (cutaneous) respiration at rest.
B: Incorrect — frogs lack diaphragm; pulmonary ventilation is via buccal pumping.
C: Incorrect — ribs are not involved in ventilatory movements.
D: Incorrect — cloaca contributes little to respiration relative to buccal/cutaneous methods. -
The webbing between the toes of a frog aids primarily in:
A. Climbing trees
B. Swimming efficiency
C. Prey capture on land
D. Vocalization
Answer: B — Swimming efficiency.
Explanations:
A: Incorrect — webbing is not for climbing.
B: Correct — webbed hind feet increase surface area for swimming.
C: Incorrect — not used for prey capture.
D: Incorrect — no role in sound production. -
Which of the following is true about frog’s eyes?
A. They are located on the ventral side
B. They have a horizontal pupil and bulging position aiding wide vision
C. They do not have eyelids
D. They are immovable and cannot aid swallowing
Answer: B — Horizontal pupil and bulging position aiding wide vision.
Explanations:
A: Incorrect — eyes are dorsal/anterolateral, not ventral.
B: Correct — prominent, bulging eyes with horizontal pupils give wide field of view.
C: Incorrect — frogs have eyelids including nictitating membrane.
D: Incorrect — the eyeballs help push food into the oesophagus during swallowing. -
The presence of a cloaca in frogs indicates:
A. Separate openings for excretion and reproduction
B. Single common chamber receiving digestive, urinary and reproductive tracts
C. No urinary system present
D. Only digestive functions
Answer: B — Single common chamber receiving digestive, urinary and reproductive tracts.
Explanations:
A: Incorrect — cloaca is a single common opening, not separate.
B: Correct — cloaca is common terminal chamber for digestive, urinary and reproductive ducts.
C: Incorrect — urinary system is present (paired kidneys).
D: Incorrect — cloaca serves multiple systems, not only digestion. -
Which statement best describes sexual dimorphism in many frog species?
A. Females always have vocal sacs
B. Males may have vocal sacs and nuptial pads during breeding season
C. Only females have nuptial pads
D. There is no dimorphism; males and females identical
Answer: B — Males may have vocal sacs and nuptial pads during breeding season.
Explanations:
A: Incorrect — vocal sacs typically in males.
B: Correct — males exhibit vocal sacs for calling and nuptial pads on thumbs to hold female during amplexus.
C: Incorrect — nuptial pads are male breeding adaptations.
D: Incorrect — sexual dimorphism is present in many species. -
The frog’s hindlimbs are modified for jumping because they have:
A. Short and weak femur and tibiofibula
B. Long ilium, long hindlimbs and fused bones for strength and extension
C. Numerous tail vertebrae to propel leaps
D. Extra ribs for leverage
Answer: B — Long ilium, long hindlimbs and fused bones for strength and extension.
Explanations:
A: Incorrect — hindlimbs are long and powerful, not short/weak.
B: Correct — adaptations include elongated hindlimbs, long pelvic elements (ilium), fusion of tibia & fibula (tibiofibula) for strong leaping.
C: Incorrect — adult frogs lack tails.
D: Incorrect — ribs are reduced and not involved in jumping. -
Which statement about frog’s head is correct?
A. The frog has a distinct neck separating head and trunk
B. The skull is light and mostly without teeth in the lower jaw (some have maxillary & vomerine teeth)
C. Frogs have teeth on lower jaw only
D. Frogs have gill slits on head region as adults
Answer: B — The skull is light and mostly without teeth in the lower jaw (some have maxillary & vomerine teeth).
Explanations:
A: Incorrect — no distinct neck in frogs.
B: Correct — frog skull is light; most have maxillary and vomerine teeth but lower jaw usually toothless.
C: Incorrect — lower jaw typically lacks teeth.
D: Incorrect — external gills are present in tadpoles, not adult frogs. -
The function of the upper and lower eyelids in frog includes:
A. Protection and vision; lower eyelid is transparent
B. Protection; nictitating membrane provides additional protection and moisture
C. No function; vestigial
D. Hearing enhancement
Answer: B — Protection; nictitating membrane provides additional protection and moisture.
Explanations:
A: Incorrect — lower eyelid is not transparent; nictitating membrane is semi-transparent.
B: Correct — eyelids protect the eye; nictitating membrane keeps eye moist and protected underwater.
C: Incorrect — eyelids are functional.
D: Incorrect — eyelids do not enhance hearing. -
The frog’s skin coloration and pigmentation primarily function for:
A. Photosynthesis
B. Camouflage and sometimes warning (aposematism)
C. Sound production
D. Excretory filtration
Answer: B — Camouflage and sometimes warning (aposematism).
Explanations:
A: Incorrect — animals do not photosynthesize.
B: Correct — coloration conceals frog from predators or warns if toxic.
C: Incorrect — coloration not for sound.
D: Incorrect — pigmentation not for excretion. -
The frog’s forelimb digits are usually:
A. Webbed and long for swimming
B. Short and unwebbed for landing and handling prey
C. Clawed for digging
D. Fused into a single digit
Answer: B — Short and unwebbed for landing and handling prey.
Explanations:
A: Incorrect — webbing is prominent on hindlimbs, not forelimbs.
B: Correct — forelimb digits are short, unwebbed and help in landing and holding prey.
C: Incorrect — claws are absent.
D: Incorrect — digits are separate. -
The external opening for the ear in frog is called:
A. External nares
B. Tympanic membrane (tympanum)
C. Lateral line canal
D. Spiral valve
Answer: B — Tympanic membrane (tympanum).
Explanations:
A: Incorrect — external nares are nostrils.
B: Correct — tympanum is external eardrum; visible as a circular disc behind the eye.
C: Incorrect — lateral line present in aquatic larvae, not adult frog ear.
D: Incorrect — spiral valve is intestinal structure in some fishes. -
Which of the following is true about frog larvae (tadpole) compared to adult frog?
A. Tadpoles have lungs and limbs similar to adults
B. Tadpoles are primarily herbivorous and aquatic with gills for respiration
C. Tadpoles are terrestrial from hatching
D. Tadpoles have external ear openings like adults
Answer: B — Tadpoles are primarily herbivorous and aquatic with gills for respiration.
Explanations:
A: Incorrect — tadpoles have gills and tail; limbs develop later.
B: Correct — tadpoles are aquatic, usually herbivorous, and respire through gills and skin.
C: Incorrect — tadpoles live in water.
D: Incorrect — tympanum and ear openings develop during metamorphosis. -
The ventral surface (belly) of a frog is called:
A. Dorsum
B. Ventrum
C. Nape
D. Urosternum
Answer: B — Ventrum.
Explanations:
A: Incorrect — dorsum = back.
B: Correct — ventrum denotes belly/underside.
C: Incorrect — nape is back of neck (not distinct in frogs).
D: Incorrect — urosternum not a standard term for belly.