The answer would be D. The definition of a homologous structure is an organ or body part that appears in different animals and is similar in structure and location, but doesn't necessarily share the same purpose. The birds and rabbits have similar bones in their forelimbs, but one uses them to run and other uses them to fly.
Answer:
Pancreas secrets two hormones called insulin and glucagon which helps in maintaining the glucose level in the blood.
Explanation:
Pancreas secrets a hormone called as insulin, which helps the cell in absorbing the glucose by reducing the blood sugar and providing glucose for energy. On falling of the sugar level pancreas releases a hormone called glucagon. This glucagon informs the pancreas about the presence of low sugar in blood, after which it releases the stored glucose, and helps in raising the blood sugar level. Alpha cell of pancreas produces glucagon.
Answer:
Blood clothing is an example of positive feedback.
This type of feedback mechanism is useful to the body because it multiplies the factor that intervenes in clotting accelerating the process.
If a toxin affects the molecules that signal for platelets the feedback will not be effective enough to produce clotting and the body will keep bleeding.
Explanation:
Blood clotting is an example of positive feedback due to the fact that when the vascular endothelium is damaged platelets will go to this area and activate themselves once they are in contact with the collagen fibers of the damaged structure. When the platelets are activated they will release the contents that is stored in their granules. One of the contents is a Gq-linked protein receptor cascade, that will increase the concentration of calcium in the platelets. Calcium activates protein kinase C, which, in turn, activates phospholipase A2 (PLA2). PLA2 will modifies an integrin membrane increasing its affinity to bind fibrinogen. The activated platelets change their shape , and the fibrinogen cross-links with the integrin membrane aiding in the aggregation of adjacent platelets. After this the coagulation cascade takes place. there are two pathways the extrinsic and the extrinsic one.
The extrinsic pathway will be activated due to tissular factor released by the platelets and the intrinsic pathway will be activated due to endothelial collagen. The final product of both pathways is factor x.
Factor x will transform prothrombin into thrombin will activate the conversion of fibrinogen into fibrin. Thrombin will form a net of fibrin that will the clot.
A cascade reaction is useful because every component of the cascade are related making a quick reaction once that one of then is activated and can activate other or more factors.
If a toxin affects the molecules that signals for platelets, platelets will not go to the damaged area and in consequence there will not be thrombin and fibrin to form the clot together with platelets.
Secondary succession has soil when primary doesn't
I don't know if this helps Sorry if it doesn't I tried
