Tag: biology

A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. The gills are present in fishes cartilaginous fishes as well as bony fishes, in aquatic organisms such as prawns and mussels.
Therefore, the correct answer is option A.

Fish and some amphibians respire primarily with gills. Gills are projection of the skin. Gills are comprised of highly vascular structures, with their outer surfaces thrown into thin folds or narrow filaments to increase the surface area for the exchange of oxygen between the water and the blood. These gill structures develop entirely from the pharyngeal arch complex. Blood is supplied through the aortic arches that pass through each pharyngeal arch. The aortic arches branch to form the afferent branchial arteries and the capillary network in the gills. Oxygenated blood comes from the gills through efferent branchial arteries which supply the dorsal aorta, the vessel which is the primary supply of oxygenated blood to the body. Gills are not the projections of fins, alimentary canal and nostrils in fish. Thus, option A is correct.

A gill is a respiratory organ found in many aquatic organisms that extract dissolved oxygen from water and excretes carbon dioxide.complex or more active aquatic organisms usually require a gill or gills for respiration.  Gills has neither terrestrial nor pulmonary respiration because terrestrial respiration refers to respiration on land and pulmonary respiration refers to respiration facilitated by lungs. Hence, respiration by gills is neither terrestrial nor pulmonary.

The principle of counter current exchange can be illustrated using fish gills. In the gills, oxygen diffuses from an area of high concentration, the water, into an area of lower concentration, the fish’s bloodstream. First, consider what would happen under same or concurrent exchange. If oxygen-rich water and oxygen-deficient blood flow in the same direction, diffusion occurs into the bloodstream until equilibrium is reached. Thus, the maximum amount of oxygen that can enter the blood at any given time is only 50% of the total oxygen. On the other hand, if oxygen-rich water and oxygen-deficient blood flow in opposite directions, oxygen diffusion is continuous. This is because even though the oxygen concentration may decrease, the amount of oxygen in the water is always slightly greater than that in the blood, allowing diffusion to continue, and equilibrium to be avoided. In this case, the maximum amount of oxygen that can enter the blood is 90%, much greater than the amount which entered via concurrent exchange. 

A gill is a respiratory organ found in large aquatic organisms that extract dissolved oxygen from water and excretes carbon dioxide.
Tracheae is the cartilaginous tube descending from the larynx to the bronchi and carrying air to the lungs as in insects.
Malpighian tubules are involved in excretion (not respiration).
Book lungs is the respiration organ used for atmospheric gas exchange that is found in many arachnids.
Therefore, the correct answer is option C.

During the tadpole stage of the amphibian life cycle, most respire by means of autonomous external or internal gills. They do not usually have arms or legs until the transition to adulthood, and typically have a large, flattened tail with which they swim by lateral undulation, similar to most fish. As a tadpole matures, it most commonly metamorphosizes by gradually growing limbs (usually the back legs first, followed by the front legs) and then (most commonly in the case of frogs) outwardly absorbing its tail by apoptosis. Lungs develop around the time of leg development and tadpoles late in development will often be found near the surface of the water, where they breathe air. Tadpole does not respire through skin and air  bladder. 

Most fish exchange gases using gills on either side of the pharynx (throat). Gills are tissues which consist of cloth and fabric structures called as filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids and ammonia. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx. Some fish, like sharks and lampreys, possess multiple gill openings. However, bony fish have a single gill opening on each side. This opening is hidden beneath a protective bony cover called an operculum. Fish do not have lungs and do not absorb oxygen through mouth or tail. 

Although frogs have lungs, they perform much of their respiration through their skin, bypassing their lungs completely. Their moist skin is specially designed with tiny blood vessels near the surface to help diffuse oxygen in and carbon dioxide out, even when the frogs are hibernating or underwater. When a frog breathes through his skin, it's called as cutaneous gas exchange. This means he's exchanging oxygen for carbon dioxide, similar to the way your lungs exchange the gases. The gases pass through the skin by diffusion. Frog breathes through lungs when on land. Fish and earthworms can not breath through lungs as they dont have.