Part 5 — Respiratory System (Questions 101–125)

Q101.

The primary mode of respiration in frogs when they are on land is:
A. Cutaneous respiration
B. Buccopharyngeal respiration
C. Pulmonary respiration ✅
D. Gills

Explanation:

A. Cutaneous respiration: Occurs through skin, mainly in water, but not the primary mode on land.
B. Buccopharyngeal respiration: Occurs through the moist lining of buccopharyngeal cavity, supplementary only.
C. Pulmonary respiration (Correct): Lungs are the main organs used on land for respiration.
D. Gills: Present only in tadpole, not in adult frogs.

Q102.

In adult frogs, respiration through gills is:
A. Main source of respiration
B. Supplementary to lungs
C. Absent ✅
D. Same as buccal respiration

Explanation:

A. Main source of respiration: False, adults lack gills.
B. Supplementary to lungs: False, gills are not present in adults.
C. Absent (Correct): Gills are lost after metamorphosis.
D. Same as buccal respiration: False, gills and buccal respiration are different mechanisms.

Q103.

During hibernation, frogs respire mainly through:
A. Lungs
B. Buccopharyngeal cavity
C. Skin ✅
D. Gills

Explanation:

A. Lungs: Inactive during hibernation.
B. Buccopharyngeal cavity: Limited role, not main.
C. Skin (Correct): Cutaneous respiration is the only way during long periods of inactivity.
D. Gills: Absent in adults.

Q104.

Which of the following is NOT a respiratory organ in adult frogs?
A. Skin
B. Lungs
C. Buccopharyngeal cavity
D. Gills ✅

Explanation:

A. Skin: Functions in respiration.
B. Lungs: Main respiratory organ on land.
C. Buccopharyngeal cavity: Functions in respiration.
D. Gills (Correct): Absent in adults.

Q105.

The respiratory surface in cutaneous respiration is:
A. Lining of lungs
B. Lining of buccopharynx
C. Outer moist skin ✅
D. Alveoli

Explanation:

A. Lining of lungs: Pulmonary respiration.
B. Lining of buccopharynx: Buccopharyngeal respiration.
C. Outer moist skin (Correct): Gas exchange occurs across skin.
D. Alveoli: Not present in frogs (they have lung chambers).

Q106.

The buccopharyngeal respiration in frogs occurs when:
A. Glottis is open
B. Glottis is closed ✅
C. Nostrils are closed
D. Skin is dry

Explanation:

A. Glottis is open: Then air enters lungs.
B. Glottis is closed (Correct): Buccopharyngeal cavity surface exchanges gases directly with blood.
C. Nostrils are closed: Would block air entry.
D. Skin is dry: Prevents cutaneous respiration, not buccal.

Q107.

Pulmonary respiration in frogs is:
A. Diffusion through skin
B. Exchange of gases through buccal cavity
C. Ventilation of lungs by buccal pump ✅
D. Exchange of gases through gills

Explanation:

A. Diffusion through skin: Cutaneous respiration.
B. Exchange of gases through buccal cavity: Buccopharyngeal respiration.
C. Ventilation of lungs by buccal pump (Correct): Frogs use buccal cavity muscles to pump air into lungs.
D. Gills: Absent in adults.

Q108.

Which one of the following is essential for cutaneous respiration in frogs?
A. Moist skin ✅
B. Presence of lungs
C. Presence of alveoli
D. Dry skin

Explanation:

A. Moist skin (Correct): Essential for gas diffusion.
B. Presence of lungs: Not required for cutaneous respiration.
C. Presence of alveoli: Absent in frogs, not relevant.
D. Dry skin: Prevents gas exchange.

Q109.

Which of the following is FALSE regarding frog respiration?
A. Skin helps in respiration
B. Lungs are main respiratory organs on land
C. Buccopharyngeal respiration occurs when glottis is open ✅
D. Cutaneous respiration is important during hibernation

Explanation:

A. Skin helps in respiration: True.
B. Lungs are main respiratory organs on land: True.
C. Buccopharyngeal respiration occurs when glottis is open (Correct): False, it occurs when glottis is closed.
D. Cutaneous respiration during hibernation: True.

Q110.

The percentage contribution of cutaneous respiration in frogs is around:
A. 10%
B. 20%
C. 25% ✅
D. 50%

Explanation:

A. 10%: Too low.
B. 20%: Not accurate.
C. 25% (Correct): About one-fourth of total respiration occurs via skin.
D. 50%: Too high.

Q111.

In water, the main mode of respiration in adult frogs is:
A. Pulmonary
B. Buccopharyngeal
C. Cutaneous ✅
D. Gills

Explanation:

A. Pulmonary: Lungs are less efficient in water.
B. Buccopharyngeal: Minor role.
C. Cutaneous (Correct): Main method under water.
D. Gills: Absent in adults.

Q112.

During aestivation, frogs respire through:
A. Lungs
B. Gills
C. Buccopharyngeal cavity
D. Skin ✅

Explanation:

A. Lungs: Inactive.
B. Gills: Absent.
C. Buccopharyngeal cavity: Not effective during dormancy.
D. Skin (Correct): Cutaneous respiration is sole source.

Q113.

The lungs of frogs are:
A. Simple sac-like structures with inner folds ✅
B. Highly branched alveolated structures
C. Absent in adults
D. Filled with water

Explanation:

A. Sac-like with folds (Correct): True, lungs are simple sacs with septa.
B. Highly alveolated: Alveoli are mammalian features.
C. Absent in adults: False, lungs are main organs on land.
D. Filled with water: False, lungs contain air.

Q114.

The buccopharyngeal cavity remains moist due to:
A. Sweat glands
B. Salivary glands
C. Mucous secretions ✅
D. Cutaneous secretions

Explanation:

A. Sweat glands: Absent in frogs.
B. Salivary glands: Absent in frogs.
C. Mucous secretions (Correct): Buccal lining secretes mucus to keep moist.
D. Cutaneous secretions: Skin, not buccal cavity.

Q115.

Respiration in tadpoles takes place by:
A. Lungs
B. Gills ✅
C. Skin
D. Buccopharyngeal cavity

Explanation:

A. Lungs: Develop after metamorphosis.
B. Gills (Correct): Tadpoles are aquatic and respire with gills.
C. Skin: Some cutaneous respiration occurs, but not main.
D. Buccopharyngeal cavity: Not well developed in larvae.

Q116.

The respiratory pigment in frog blood is:
A. Hemocyanin
B. Hemoglobin ✅
C. Myoglobin
D. Chlorocruorin

Explanation:

A. Hemocyanin: Found in arthropods and molluscs.
B. Hemoglobin (Correct): Pigment in frog RBCs.
C. Myoglobin: Found in muscles.
D. Chlorocruorin: Found in some annelids.

Q117.

Which of the following respiratory processes is possible both in water and on land in frogs?
A. Buccopharyngeal respiration
B. Cutaneous respiration ✅
C. Pulmonary respiration
D. Gill respiration

Explanation:

A. Buccopharyngeal: Occurs only on land.
B. Cutaneous (Correct): Works both in water and land.
C. Pulmonary: Only on land.
D. Gills: Only in tadpoles, not adults.

Q118.

The rate of buccopharyngeal respiration is:
A. Faster than pulmonary respiration ✅
B. Slower than pulmonary respiration
C. Same as pulmonary respiration
D. Absent

Explanation:

A. Faster (Correct): Buccopharyngeal respiration is continuous and rapid.
B. Slower: Incorrect.
C. Same: False.
D. Absent: False, it is important.

Q119.

Respiration in frogs is an example of:
A. Obligatory cutaneous respiration
B. Obligatory pulmonary respiration
C. Amphibious respiration ✅
D. Gill-only respiration

Explanation:

A. Obligatory cutaneous: Not only skin.
B. Obligatory pulmonary: Not only lungs.
C. Amphibious respiration (Correct): Frogs use multiple organs depending on environment.
D. Gill-only: Only in tadpoles.

Q120.

The lungs of frog open into buccal cavity through:
A. Glottis ✅
B. Bronchi
C. Trachea
D. Larynx

Explanation:

A. Glottis (Correct): Opening into lungs.
B. Bronchi: Absent in frogs.
C. Trachea: Absent in frogs.
D. Larynx: Absent in frogs.

Q121.

Which one of the following statements is TRUE for frog respiration?
A. Lungs are richly alveolated
B. Frog cannot respire in water
C. Buccopharyngeal respiration occurs only when glottis is closed ✅
D. Frog has permanent gills

Explanation:

A. Lungs richly alveolated: False, simple sac-like lungs.
B. Cannot respire in water: False, cutaneous respiration occurs.
C. Buccopharyngeal respiration occurs when glottis is closed (Correct).
D. Permanent gills: Only tadpoles have gills.

Q122.

Respiration during prolonged diving in water in frogs occurs through:
A. Lungs
B. Skin ✅
C. Buccal cavity
D. Gills

Explanation:

A. Lungs: Not functional underwater.
B. Skin (Correct): Cutaneous respiration in water.
C. Buccal cavity: Air is absent in cavity.
D. Gills: Absent in adults.

Q123.

Which respiratory method does not require muscular effort in frogs?
A. Pulmonary respiration
B. Cutaneous respiration ✅
C. Buccopharyngeal respiration
D. None

Explanation:

A. Pulmonary: Requires buccal pumping.
B. Cutaneous (Correct): Passive diffusion, no muscles.
C. Buccopharyngeal: Requires buccal movements.
D. None: Incorrect.

Q124.

What structural adaptation allows cutaneous respiration in frogs?
A. Presence of alveoli
B. Rich capillary network beneath skin ✅
C. Sweat glands
D. Trachea

Explanation:

A. Alveoli: Not present in frogs.
B. Capillary network (Correct): Ensures diffusion of gases.
C. Sweat glands: Absent in frogs.
D. Trachea: Absent.

Q125.

The glottis in frog is located at the:
A. Roof of buccopharynx ✅
B. Floor of buccopharynx
C. In lungs
D. In nasal chamber

Explanation:

A. Roof of buccopharynx (Correct): Glottis opens into lungs.
B. Floor of buccopharynx: False.
C. In lungs: False, glottis is before lungs.
D. In nasal chamber: False.

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Part 5 — Respiratory System (Questions 101–125)