Test: Frog (NCERT) - NEET MCQ

The medulla oblongata passes out through the foramen magnum and continues into the spinal cord, which is enclosed in the vertebral column. Vasa efferentia are 10 -12 in number that arises from testes. Ovaries are situated near the kidneys and there is no functional connection with the kidneys.
Frog secretes urea and hence is ureotelic and not uricotelic.

The human body has 12 pairs of cranial nerves. The first two cranial nerves, the olfactory and optic nerves, originate from the cerebrum. The remaining 10 nerves originate from the brain stem. 

In frog, the hind limbs end in five digits and they are larger and muscular than fore limbs that end in four digits.

In water, frogs respire through skin (cutaneous respiration). When on land, buccal cavity, skin and lungs, all act as respiratory organs. The respiration by lungs is known as pulmonary respiration. Lungs are a pair of elongated pink hollow structures found in the thorax. During aestivation and hibernation, gaseous, exchange takes place through skin.

In female frog, ovaries are irregular shaped, tubulated structures attached to the kidneys with the help a membrane called mesnverium The ovaries has no internal connection with kidneys. In male frog, there are present 10-12 fine tubes called vasa efferentia that connect the testes to the kidneys on each side. They open into the anterior part of Bidder's canal. In frog, there are ten percent of canial nerves. RBCs are nucleated and  contained the coloured pigment namely himoglobin.

Frogs have three main modes of respiration

• Respiration through skin: Frogs can absorb oxygen directly through their moist skin, especially when underwater.
• Respiration through mouth: Also known as buccal respiration, where they take in oxygen through the lining of their mouth.
• Respiration through lungs: Frogs use their lungs to breathe air, especially when they are on land.

Frogs do not use a trachea for respiration. Hence, the correct answer is

A: respiration through trachea

The nictitating membrane in frogs serves primarily to protect their eyes underwater. Here's why:

• Acts like a transparent or translucent third eyelid.
• Provides a layer of protection from debris and predators while swimming.
• Maintains moisture on the eye surface while allowing frogs to see clearly underwater. 

Therefore, the correct answer is:
B: Protects eyes underwater

In frog, there is present a cylindrical testis near each kidney, being suspended by mesorchium. There arise several then vasa efferntia from each testis that emerges through mesorchium and join the uriniferous tubules of the posterior part of the kidney to open into the Bidder's canal which in turn open into the ureter.

Bidder's canal found in the kidney of frog and as urinogenital canal opening into ureter. It helps in excretion. 

P. The male frog has a special organ on the throat called (i) 'vocal sac'.
Q. (ii) 'Tympanic' membrane is a part of the ear and serves to receive sound waves.
R. Dermis of the frog contains sac-like (iii) 'mucous' glands.
S. Tongue of frog is (iv) 'bilobed'
T. (v) 'Pulmonary' respiration takes place in lungs on land.
So, the correct answer is '(i)- vocal sac; (ii)- Tympanic; (iii)- mucous; (iv)- bilobed; (v)- Pulmonary'.