Frog - NEET Biology Class 11 Free MCQ Test with solutions

Correct option: A

• Liver is the largest gland and produces bile, so it corresponds to II.
• Gall bladder stores the bile produced by the liver, so it corresponds to I.
• Pancreas (exocrine part) secretes digestive enzymes into the intestine, so it corresponds to III.
• Rectum is the terminal part of the alimentary canal and opens into the cloaca, so it corresponds to IV.

Matching: A- II, B- I, C- III, D- IV

The correct answer is Option A - A: A-II, B-III, C-I

Forebrain (prosencephalon) contains the olfactory lobes, cerebral hemispheres and diencephalon; these structures mediate smell, higher neural integration and relay/visceral regulatory functions.

Midbrain (mesencephalon) comprises the optic lobes, which are the main centres for visual processing in the frog.

Hindbrain (rhombencephalon) includes the cerebellum and medulla oblongata, responsible respectively for coordination of movement and autonomic/reflex control.

Therefore, the grouping given in the stated option correctly matches each brain division with its components.

Topic in NCERT: Nervous system

Line in NCERT: "forebrain includes olfactory lobes, paired cerebral hemispheres and unpaired diencephalon. the midbrain is characterised by a pair of optic lobes. hind-brain consists of cerebellum and medulla oblongata."

Answer: Option A - statements A, B, C and D are correct; E is incorrect.

A. The testes in male frogs are paired, yellowish and ovoid and lie attached to the dorsal surface of the kidneys, so statement A is correct.

B. Fine ducts called vasa efferentia carry sperm from the testes into the kidney region and open into Bidder's canal, which then communicates with the ureter; the ureter functions as a common urinogenital duct, so statement B is correct.

C. Bidder's canal is a short median canal that receives the vasa efferentia and opens into the ureter, thereby connecting the vasa efferentia to the ureter; statement C is correct.

D. The cloaca is a common chamber that receives the terminal openings of the digestive, urinary and reproductive systems and opens to the exterior; statement D is correct.

E. Male frogs do not have a well-developed internal copulatory organ; fertilization is external. Males may have a nuptial (copulatory) pad for holding the female during amplexus, but this is not a copulatory organ, so statement E is incorrect.

The correct answer is Option C - Statement I is correct but Statement II is incorrect

Statement I is correct because the heart of the frog is three-chambered, consisting of two auricles (atria) and one ventricle. The right auricle receives deoxygenated blood from the body and the left auricle receives oxygenated blood from the lungs and skin.

Statement II is incorrect because the ventricle does not have a complete anatomical septum; therefore it cannot produce a complete separation of oxygenated and deoxygenated blood. Blood from both auricles enters the single ventricle and partial mixing occurs.

Mixing is reduced but not eliminated by internal structures: the ventricular trabeculae and the spiral valve in the conus arteriosus help to direct blood so that relatively more oxygenated blood goes to the systemic circulation and more deoxygenated blood goes to the pulmocutaneous circulation, producing a functional (not complete) separation.

Thus, Statement I is true and Statement II is false; this makes Option C the correct choice.

Topic in NCERT: Heart anatomy

Line in NCERT: "the heart is a muscular structure situated in the upper part of the body cavity. it has three chambers, two atria and one ventricle."

The correct answer is Option A - A, B, C and E only

Statement A is correct because the mucous glands keep the skin moist, and a moist surface is necessary for gases to dissolve and diffuse across the skin.

Statement B is correct because a rich supply of blood capillaries beneath the skin carries absorbed oxygen into the body and removes carbon dioxide, maintaining a concentration gradient for diffusion.

Statement C is correct because the skin is thin and highly vascularized, which reduces diffusion distance and increases the area available for gas exchange.

Statement D is incorrect because scales are absent in frogs and, if present, would reduce skin permeability and impede cutaneous respiration.

Statement E is correct because dissolved oxygen in the thin film of moisture on the skin diffuses passively through the epidermis into underlying capillaries, enabling gas exchange.

Therefore, A, B, C and E are correct and D is incorrect.