Answer:
Adaptive immune responses are triggered by activation of antigen-specific T cells that produce antibodies against foreign antigens such as, for example, harmful viruses. These immune responses are useful to eliminate dangerous molecules from the body. In a normal immune reaction, the antibodies produced by T-cells target antigen molecules in order to be subsequently absorbed by phagocytic macrophage cells.
Autoimmune diseases are triggered by the response of the adaptive immune system against self-antigen molecules. Since the immune system can not eliminate antigens from the own body, this immune reaction generates an excessive inflammatory response, and it may lead to the damage of tissues and organs.
Darwin’s Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources. This illustration shows the beak shapes for four species of ground finch: 1. Geospiza magnirostris (the large ground finch), 2. G. fortis (the medium ground finch), 3. G. parvula (the small tree finch), and 4. Certhidea olivacea (the green-warbler finch) the Grants measured beak sizes in the much-reduced population, they found that the average bill size was larger. This was clear evidence for natural selection of bill size caused by the availability of seeds. The Grants had studied the inheritance of bill sizes and knew that the surviving large-billed birds would tend to produce offspring with larger bills, so the selection would lead to evolution of bill size. Subsequent studies by the Grants have demonstrated selection on and evolution of bill size in this species in response to other changing conditions on the island. The evolution has occurred both to larger bills, as in this case, and to smaller bills when large seeds became rare.
To detect predators by using the large size and flexible positioning of the external ears to channel sound waves into the ear canal.
<h3>What is thermoregulation ?</h3>
Mammals regulate their body temperature carefully and independently of their environment through a process called thermoregulation. A method of maintaining a constant internal temperature necessary for survival is temperature regulation.
- Poikilothermy and homeothermy are the two main reactions to changing environmental temperatures (TA) that animals display.
- Progesterone tends to promote heat conservation and higher body temperatures, whilst estradiol tends to increase heat dissipation, and both hormones have an impact on thermoregulation both centrally and peripherally.
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