Test: Frog - 2 - NEET MCQ

The copulatory pads of the male frog are present on the first digit of the forelimbs. Frogs show sexual dimorphism and the presence of copulatory pads in male frogs is a distinguishing feature of the two sexes.

Topic in NCERT: Morphology

Line in NCERT: "Male frogs can be distinguished by the presence of sound producing vocal sacs and also a copulatory pad on the first digit of the fore limbs which are absent in female frogs."

Frogs are carnivorous. This means that their diet consists of food which is purely of animal origin. For this reason, the length of its intestine is reduced. Thus, frogs have a short alimentary canal.

Topic in NCERT: Anatomy: Digestive System

Line in NCERT: "The alimentary canal is short because frogs are carnivores and hence the length of intestine is reduced."

In frog, the cutaneous respiration is always carried out. During winter sleep and summer sleep it is the only method of respiration in frog.

Topic in NCERT: Anatomy : Respiration in Frogs

Line in NCERT: "In water, skin acts as aquatic respiratory organ (cutaneous respiration).Dissolved oxygen in the water is exchanged through the skin by diffusion. On land, the buccal cavity, skin and lungs act as the respiratory organs. The respiration by lungs is called pulmonary respiration."

RBCs of frog are nucleated, oval and biconvex and have haemoglobin (respiratory pigment).

Topic in NCERT:Anatomy: vascular system

Line in NCERT: "RBCs are nucleated and contain red coloured pigment namely haemoglobin."

Rana tigrina or frog possesses a bilobed tongue to capture food. It has webbed feet for the purpose of swimming in water. It also has a membranous tympanum to receive sound signals. It has moist, slippery skin.

Duodenum is the first part of the small intestine. Food ingested by the frog is churned with bile, pancreatic juices and hydrochloric acid in the stomach to form an acidic mixture called chyme. This is passed to the duodenum.

Line in NCERT: "Partially digested food called chyme is passed from stomach to the first part of the small intestine, the duodenum."

Pancreatic juice is first delivered from the pancreas to the common bile duct via the pancreatic duct. The common bile duct, which also receives bile from the gall bladder delivers its contents into the duodenum.

Line in NCERT: "The duodenum receives bile from gall bladder and pancreatic juices from the pancreas through a common bile duct."

Final digestion in frogs takes place in the intestine where pancreatic juices break down proteins and carbohydrates and bile break down fat. The undigested food moves to the rectum end exits through the cloaca.

Line in NCERT: "Final digestion takes place in the intestine."

The undigested food in frogs is passed out through the cloaca. The rectum lies before the cloaca. The undigested food is digested completely in the intestine and passed into the cloaca via the rectum.

Line in NCERT: "The undigested solid waste moves into the rectum and passes out through cloaca."

To determine the correct statements:

- Statement i is correct. The frog’s excretory system does consist of a pair of kidneys, ureters, cloaca, and urinary bladder.

- Statement ii is incorrect. Frogs primarily excrete urea, which classifies them as ureotelic animals, not ammonia.

- Statement iii is correct. The frog's brain is indeed divided into fore-brain, mid-brain, and hind-brain.

- Statement iv is incorrect. Frogs do not possess external ears; they have a tympanum for hearing which is not an external ear structure.

Thus, the correct statements are i and iii, making Option B the right choice.