Answer:
B. Glucagon
Explanation:
Glucagon is a pancreatic hormone, secreted by the alpha cells of islets of Langerhans. Whenever the blood glucose level falls, glucagon is released to increase the blood glucose levels. This function of glucagon is quite opposite to the function of insulin and hence both are antagonistic hormones. Insulin reduces the blood glucose where as glucagon increases the blood glucose.
Glucoagon is large polypeptide of 29 amino acids. Since it helps in increasing the blood glucose homeostatic levels it is called as hyperglycemic hormone. It does so by stimulating certain processes such as:
- Stimulating Glycogenolysis i.e breakdown of glycogen to release more glucose from liver.
- Stimulating Gluconeogenesis i.e. synthesis of glucose from non-carbohydrate sources like proteins.
- Glucagon inhibits the process of glycogenesis i.e. synthesis of glycogen, the storage form of glucose.
Plasma membrane is a part of the cell made of a lipid bilayer and an embedded protein layer. It protects the cell from the surroundings and also controls the materials leaving or entering the cell. The membrane is semipermeable and therefore allows certain materials to enter or leave the cell. In this case, the plasma membrane may prevent unlimited flow of water into or out of the cell.
Answer:
The first and 2nd pictures basically capture what they look like.
D. Predators
Predators keep populations of other species in check. This was pretty clearly demonstrated in Yellowstone National Park after the wolves were eradicated there. The deer populations increased to the point that the aspen trees nearly disappeared due to the saplings' being eaten by deer. Since the reintroduction of wolves to the park, the aspen trees have begun to flourish once again.
