Homeostasis and osmoregulation - class-XII

Most vertebrates are osmoregulators, but Myxine (hagfish) are osmoconformers, and sharks are osmoconformers that maintain internal osmolarity near that of seawater using urea. Since both A and B are correct examples of non-osmoregulating vertebrates, D is the correct choice.

Osmoconformers are organisms that allow their internal body fluid osmolarity to match that of their external environment. They do not expend energy to maintain a different osmotic concentration.

Hormones provide the best feedback mechanism. There are positive feedback mechanism in which the hormone stimulates the production of itself example estrogen before ovulation.

Homeostasis is the process of maintaining a constant and stable internal environment by an organism. This term was first described in 1865 by Claude Bernard and coined by Walter Bradford Cannon in 1930. The word is derived from Greek where 'home' means 'similar' and 'stasis' means 'stable'. So, the correct answer is "Walter Cannon'.

Homeostasis is the tendency to resist change in order to maintain a stable, and constant internal environment. The internal environment should be contains the optimum concentration of gases, nutrients, ions, and water, has an optimal temperature, and has an optimal pressure for the health of the cells. For example, the concentration of various ions in the blood must be kept steady, along with pH and the concentration of glucose. Maintenance of homeostasis usually involves negative feedback loops. These loops act to oppose the stimulus. Its works on first, high temperature will be detected by sensors—primarily nerve cells with endings in the skin and brain—and relayed to a temperature-regulatory control center in brain. The control center will process the information and activate effectors—such as the sweat glands—whose job is to oppose the stimulus by bringing body temperature down.

• Homeostasis is the tendency towards a relatively stable equilibrium between interdependent elements maintained by the physiological process.
  
• In the body, some systems support  homeostasis, like the nervous and endocrine system

Vasoconstriction occurs in superficial blood vessels of warm-blood vessels of warm-blooded animals when their ambient environment is cold, this process diverts the flow of heated blood to the center of the animal, preventing the loss of heat

Homeostasis is a self-regulating system inside living organisms that keep conditions like pH, temperature, osmolarity constant. This system is self-regulatory in the sense that keeping a stable internal environment requires constant adjustments as conditions change and these adjustments are all automatically made without conscious effort or external effort from anywhere. 

A. Evolution is a change in the inheritable characteristics of species over successive generations.

Homeostasis is a phenomenon of maintaining an equilibrium of internal environment despite constantly changing external environment. Various body systems are involved in performing the function of homeostasis. Circulatory system maintains homeostasis by continuous and controlled movement of blood that reaches every cell in the body. Nutrients pass from capillary blood into fluids surrounding the cells and waste products are removed.

Homeostasis is maintaining constant conditions inside living organisms. These might be in terms of maintenance of pH, temperature, osmolarity etc. Organisms achieve homeostasis by various adaptations. This can be understood with the example of temperature regulation in different organisms-

Some organisms show behavioral adaptations to cope with variations in their environment. A rhino covering itself in mud to keep cool and desert lizard basking in Sun to keep warm are examples of behavioral ,means of homeostasis.