In ureotelic animals urea is formed by Ornithine cycle. Urea is formed in the liver where two molecules of ammonia combine with one molecule of CO₂ in presence of Ornithine, citrulline, arginine and enzyme arginase. This is called Ornithine cycle.

Correct Option: C

In ureotelic animals urea is formed by Ornithine cycle. Urea is formed in the liver where two molecules of ammonia combine with one molecule of CO₂ in presence of Ornithine, citrulline, arginine and enzyme arginase. This is called Ornithine cycle.

Terrestial animals have limited access to water. Hence they have to secrete hypertonic urine and conserve water. Choices (c) and (d) are characteristics of marine animals who need to overcome the problem of preventing entry of salts and loss of water. Choice (a) is characteristic of fresh water animals.

Correct Option: B

Terrestial animals have limited access to water. Hence they have to secrete hypertonic urine and conserve water. Choices (c) and (d) are characteristics of marine animals who need to overcome the problem of preventing entry of salts and loss of water. Choice (a) is characteristic of fresh water animals.

Hydra being a coelenterate, has blind sac body plan. It has only one mouth which serves as the opening for ingestion and waste elimination besides diffusion across body wall.

Correct Option: A

Hydra being a coelenterate, has blind sac body plan. It has only one mouth which serves as the opening for ingestion and waste elimination besides diffusion across body wall.

In uricotelic animals nitrogenous waste is eliminated in the form of uric acid. Ammonotelism is seen in aquatic animals wherein nitrogenous wastes is eliminated in the form of ammonia eg. Fishes, tadpole. Ureotelism is observed in human beings in which nitogenous waste is eliminated as urea.

Correct Option: C

In uricotelic animals nitrogenous waste is eliminated in the form of uric acid. Ammonotelism is seen in aquatic animals wherein nitrogenous wastes is eliminated in the form of ammonia eg. Fishes, tadpole. Ureotelism is observed in human beings in which nitogenous waste is eliminated as urea.

Solenocytes or flame cells or protonephridia are excretory organs in Platyhelminthes (Flatworms). They excrete ammonia. In Annelids excretory organ are nephridia. In Molluscs sac like kidneys are excretory organ. In a Echinodermata nitrogenous wastes are excreted through gills.

Correct Option: A

Solenocytes or flame cells or protonephridia are excretory organs in Platyhelminthes (Flatworms). They excrete ammonia. In Annelids excretory organ are nephridia. In Molluscs sac like kidneys are excretory organ. In a Echinodermata nitrogenous wastes are excreted through gills.