Question

Acoelomate animals with flame cells are
A. Platyhelminthes
B. Annelida
C. Aschelminthes
D. Arthropoda

Answer 1

Hint: A flame cell is specialized in excretory function. This cell is found in simple fresh-water invertebrates which include flatworms, rotifers, and etc. These are the simplest animals or organisms which have a dedicated excretory system. The group of flame cells forms a bundle, and these bundles are called protonephridia.

Complete answer: They function like kidneys. Many invertebrates such as flatworms use a nephridium as their excretory organ. At the end of each blind tubule, the nephridium is present which is a ciliated flame cell. As the fluid passes down the tubule, solutes are reabsorbed and returned to the body fluids. Nephridium loops and widens into the bladder. The bladder drains the waste to the outside of the body through the nephridiopore.
-The annelid excretory system is made up of long tubular organs called nephridia. Each nephridium has an opening called a nephrostome. This nephrostome takes in body fluids from the coelom and exits the waste through an exit pore called the nephridiopore. This nephridiopore is present on the body wall of the worm.
-The excretory system aschelminthes contains gland cells or of canals or sometimes both of them. In Ascaris, the excretory system shape represents the ‘H’ shape. The excretory system canals and giant cells called renette cells. Ammonia is the main excretory matter. Sometimes Ascaris also excretes urea.
-Arthropods excrete by means of Malpighian tubules, projections of the digestive tract that help conserve water. Terrestrial forms excrete nitrogen as uric acid, as do birds. Their waste is dry waste. These have an open circulatory system and sexes are separated.
Hence, the correct answer is Option A.

Note: The nephridium (plural nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidney. Nephridia remove metabolic wastes from an animal's body. Nephridia come in two basic categories: metanephridia and protonephridia.