Frogs reproduce by external fertilisation. The female frog ovulates in the water and releases its gametes. The sperm released from the male frog fertilizes to form zygote which turns into a well-developed egg. So, the correct answer is option B.

Bidder's canal is present in male frogs. Vasa-efferentia opens into the Bidder's canal and the Bidder's canal is connected to longitudinal collecting tubules by means of a number of transverse collecting ducts and helps in the passing of the sperms. So, the correct answer is option B.

In all terrestrial vertebrates except the placental mammals, the genital ducts and excretory ducts, open into the cloaca. In mammals, however, the cloaca becomes separate into a dorsal part, which conveys the faeces and a ventral part, which receives excretory and genital products. The sperm cells from seminiferous tubules pass into Bidder's canal through vasa efferentia. The Bidder's canal runs along the length of each kidney near its inner side. Thus, vasa efferentia conduct mature sperm from testis to the ureter.

Eggs laid by female frogs are protected by Gelatinous material that prevents desiccation of the developing embryo.

Tympanum is a membrane of the eardrum. It has a three chambered heart made of muscle tissues. The body of the frog is divisible into head and trunk. The head is in a triangular shape. The lungs is present in the trunk of the body.

Tadpole larva has a rudimentary mouth which is not highly developed. Thus frog tadpole is a herbivore, feeding on relatively simpler food found available in the aquatic systems, such as Zooplanktons. Upon growth, tadpole larva undergoes metamorphosis where the mouth and internal organs will be rearranged to develop an adult carnivorous lifestyle.

The oviducts present in amphibians are simple tubes which are lined with glands that produce mucus and jelly. Oviducts in male frogs are vestigial oviducts as they have no specific function and no role in reproduction. However, in female, oviduct responds to ovarian or female sex hormones by enlarging and acquiring a lumen. Oviducts carries egg to the cloaca. This posterior opening is the common exit for intestinal, urinary and reproductive tracts. The oviduct of the female is known as the rudimentary oviduct or Mullerian duct. This duct has no lumen and is very much reduced in size. Due to small size, it is difficult to locate these ducts. 

• The larva of Herdmania shows retrogressive metamorphosis in which the larva looses the characters of chordates and attains the form of a invertebrate.
• The tadpole larva of Frog shows fish like characters like gills, gill slits and lateral line organs. This indicates that amphibians evolved from fish like ancestors.
• Gingko is a primitive gymnosperm. Presence of flagellated sperms in Gingko like in Pteridophytes suggest that gymnosperms have evolved from Pteridophytes.

In male frogs, each testis is located on the anterio-ventral margin of the kidney. From each testis, ten to twelve vasa efferentia emerge and enter the kidney to open into the Bidder's canal. The Bidder's canal helps in the transfer of sperms via the vasa efferentia. Vasa efferentia open into the Bidder's canal and the Bidder's canal is connected to longitudinal collecting tubules by means of a number of transverse collecting tubes and these longitudinal collecting tubules open into the ureter. Finally, they open into the urinogenital duct that emerges from the kidneys. So, the correct answer is option C.

Frog reproduces in water. They are oviparous and they lay eggs in water which is fertilised outside the body of the frog. In order to make sure that the sperm reaches the eggs, the male and female get into a mating posture called amplexus. so, the correct answer is option A.

Vocal sacs are prominent in a male frog. It is composed of flexible skin which easily expands or contracts to change the frequency of sound waves and helps in amplification. The sound produced is a call for mating. The presence or development of the vocal sac is one way of externally determining the sex of a frog in many species. The vocal sac is open to the mouth cavity of the frog, with two slits on either side of the tongue. To call, the frog inflates its lungs and shuts its nose and mouth. So, the correct answer is option A.

In indirect development, an animal's birth form is different from the adult form. The embryo hatches from the egg in the larval form. The larva undergoes a drastic metamorphosis in order to achieve its adult stage. Frog, the adult form is completely different from the tadpole, its birth form. Hence, frog undergoes indirect development.
So, the correct answer is option B.

Males croak louder especially during the night in the breeding season. Males croak to the sound of vacuums, running water, loud noises, to attract females for mating and protect their territory from other male frogs. So, the correct answer is option D.

• Frogs are the amphibians and they are indulged in external fertilization. They are oviparous and they lay eggs. A male frog sheds millions of sperm and female sheds 2,000 to 3,000 eggs at a time in the water. 

When a sperm enters the cytoplasm of the oocyte, there is a cortical reaction, which prevents other sperms from fertilising that egg. The oocyte now (after sperm enters the oocyte) undergoes second meiotic division producing haploid ovum and releases a polar body.
So, the correct answer is option C.

In frog, from the outer smooth convex posterior side of each kidney arises a mesonephric or wolffian duct or ureter which passes backwards to open into the dorsal side of cloaca. In the males, the ureter dilates just posterior to the kidney to form a vesicula seminalis. Its function is to store sperms. 

In frogs, males frogs can be distinguished by the presence of to attract a mate, the male frog croaks from a shallow puddle, sending out ripples that invite not just female frogs, but also hungry bats. Male túngara frogs croak from shallow puddles to attract mates. Male frogs grow pads on their forelegs that help them to grasp the females in an embrace known as amplexus.

Female frogs listen to the croaking of male frogs, and this helps them choose the most suitable ones for mating. Another reason for which male frogs croak is to claim territory. By croaking loudly at night, a male frog warns other males that a particular part of a territory is already occupied.

In female frog, on each side of the ovary there is a long much coiled whitish glandular tube called oviduct or Mullerian duct. At the anterior end of each oviduct there is an oviducal funnel with a wide aperture called ostium.. The posterior part of the oviduct dilates to form a thin walled ciliated ovisac , where the ova are stored and agglutinated. So, the correct answer is 'Ova'.

Nephron of frog is short, it lacks Henle's loop because water conservation is not important in amphibians who reside near water. Whereas for other animals the loop of henle present in the nephron helps in water conservation. So, the correct answer is 'Frog'.

Metamorphism is a hormonal effect influenced by hormones. The metamorphism in frogs is under the control of thyroxine which is produced by the thyroid gland. Frogs live in water bodies with rich iodine content to produce thyroxine.The deficiency in iodine would result in a retarded growth.

Female frogs lay up to 4,000 eggs at a time, which are immediately fertilized by the male. Frogs become sexually mature around four years of age. They emerge from hibernation from February to March to seek out breeding grounds. Females lay their eggs in shallow water. It takes about 40 days for tadpoles to emerge from the eggs.

The truncus arteriosus is formed of a basal thick-walled conus arteriosus and a distal thin-walled ventral aorta. Its conus arteriosus part which is next to the ventricle is known as pylangium and the distal ventral part as synangium. Pylangium is a short tubular structure, while synangium is simply formed by the union of the basal parts of the arteries.

The egg of the frog is mesolecithal as moderate amount of yolk is present. As the yolk is concentrated in the lower part of the egg and the cytoplasm in the upper part, these eggs are moderately telolecithal. 

In the frog, each kidney is composed of several structural and functional units called uriniferous tubule or nephrons. Two ureters emerge from the kidneys in the male frogs. The ureters act as a urinogenital duct which opens into the cloaca. The thin-walled urinary bladder is present ventral to the rectum which opens in the cloaca.

In the male frog, the final digestion takes place in the intestine. Digested food is absorbed by the numerous finger-like folds in the inner wall of the intestine called villi and microvilli. The undigested solid waste moves into the rectum and passes out through cloaca. Hence the urinogenital duct of the male frog opens into the cloaca.

Fertilization in frog is external. The female releases her eggs from her body into water. Then, the male releases his sperm to fertilize them.

In frogs, the vitellin membrane and an adhesive jelly coating, also known as tertiary egg membrane, surround the eggs. When passing from the oviduct, it is added to the egg. This jelly enables the egg to be easily trained. The capable sperm readily fertilizes the egg as it has the location of the jelly receptor. The frog egg on the animal pole has yolk on the vegetable pole and nucleus.

The female frog secretes jelly like substance that covers the egg. This coating is an oviducal secretion, that is secretion of the oviduct, that helps the eggs clump together, stay afloat and prevent being eaten away by predators.

In almost all frogs, egg fertilization happens outside the female's body instead of inside. The female releases her eggs and the male releases his sperm at the same time. In order to make sure that the sperm reach the eggs, the male and female get into a mating posture called amplexus. The male climbs onto the female's back and clasps his forelegs around her middle. 

In frog growth and metamorphosis are controlled by hormones synthesized by endocrine glands near the front of the body. Neurosecretory cells in an insect's brain secrete a hormone, the prothoracicotropic hormone that activates prothoracic glands, which secrete a second hormone, usually ecdysone, that induces ecdysis. PTTH also stimulates the corpora allata, a retrocerebral organ, to produce a juvenile hormone, which prevents the development of adult characteristics during ecdysis.

The frog egg is surrounded by an albuminous layer by an oviduct which later it comes into a uterus. The oviduct is a long coiled duct with the thick wall that is not connected with kidneys.  It consists some glands which secrete albumen that hardens ova. After the ovulation, the cilia of the oviducal funnel draws the coelomic fluid with ova which moves into the middle region with the help of cilia.