Tag: respiration in living organisms

In animals, three main types of respiratory systems exist: respiration through the skin, respiration through the gills or respiration through internal air structures. Respiration through the skin, as in the Hydra, involves the passing of molecules into and out of the body via diffusion. Aquatic animals use gills, which are structures composed of tissues and blood vessels that extend from the body, for their respiration needs. Most terrestrial animals use internal air structures, such as lungs or tracheae, to respire. Cockroach, snail and earthworm has blood. 

Animal P always breathes through gills - fish; animal Q breathes both through moist skin and lungs - frog; animal R breathes only through its moist skin - earthworm; animal S breathes through its cell membrane - amoeba. Oxygen diffuses in and carbon dioxide diffuses out of its cell membrane.

In frogs the process of respiration takes place through three respiratory surfaces - skin, lungs and lining of the mouth. However, when submerged in water, the frog respires through its cutaneous membranes on the skin as it is quite permeable to water and contains a large network of blood vessels. The cutaneous membrane allows the respiratory gases to readily diffuse directly. Even when out of water, mucus glands present in the skin help in the cutaneous respiration.

Respiration of aquatic animals is a process wherein they obtain the oxygen from the water. The large aquatic animals have well developed gills which helps them in their respiratory function. 

Double trachea is a type of the respiratory tract found in penguins, spoonbills, petrels, dugongs and sea lions shows a high bifurcation of the trachea with fused primary bronchi and intra tracheal septum.

Earthworms have no special respiratory organs. Gases are exchanged through the moist skin and capillaries, where the oxygen is picked up by the hemoglobin dissolved in the blood plasma and carbon dioxide is released.
The basic respiratory system of insects consists of a series of rigid tubes, called as tracheae.
In most of the fishes, the respiration takes place through gills.
The birds have lungs, air sacs and a syrinx and their respiration requires two cycles to move a volume of air.
Therefore, the correct answer is option A.

Respiration in frogs is both through lungs and skin. However, during hibernation, frogs make use of the skin to breathe. However, there are exceptions such as the wood frog which stops to breathe completely during its hibernating period. During hibernation most of these amphibians receive their necessary oxygen through their skin referred to as cutaneous gas exchange. Their skins soaks in the oxygen required by their bodies require.

Freshwater fish lives in rivers and lakes where the salinity levels are less than 0.05%. The freshwater species differ physiologically from salt water fish in that their gills are modified to diffuse dissolved gasses while retaining the salts present in the body fluids. Further, their scales reduce water diffusion through the skin and also have well developed kidneys that can reclaim salts from body fluids before excretion. Through this process, they get rid of water and acquire salt.

The mucus glands present in the skin of the frog helps to absorb dissolved oxygen from the air. However, the frogs have three respiratory surfaces and exchange of gases with the surroundings through the skin is a continuous process.
Therefore, the correct answer is option D.

Water naturally seeks a chemical balance, or equilibrium. That means water flows from areas of higher water concentration to areas of lower water concentration to equalize the system. Water concentration inside a fish is higher than in the ocean itself because the ocean is so salty. As a result, most saltwater fish constantly lose water through their gills and skin. Because the fish is losing water, it must drink a lot to stay hydrated-but salty seawater is the only water around. To get rid of excess salt, the fish's kidneys pump lots of salt into its urine.