(A) To maintain balance of water and nutrients in the cell
Explanation:
According to the fluid mosaic model of the cell membrane to describe its structure proposed in 1972, the cell membrane possess components such as phospholipids, proteins and cholesterol. The phospholipid forms a bilayer in biological cell membranes.
The phospholipid bilayer is said to be AMPHIPATHIC i.e. they contain both hydrophobic (water-fearing) and hydrophilic (water-loving) regions. The phosphate head of the phospholipid is the hydrophilic region while the long fatty acid tails that face each other inwardly are the hydrophobic regions.
This amphipathic nature of the cell membrane is important to maintain the balance of water and nutrients in the cell because they control which substance can go in and out of the cell.
The cell membrane separates the intracellular environment from the extracellular environment outside of the cell. A phospholipid is composed of a phosphate group and a lipid. It is composed of a hydrophilic, polar phosphate head and two hydrophobic fatty acid tails.
The structure of the bilayer is such that the tails are shielded from contact with water, creating a selectively-permeable barrier which will be impermeable to most hydrophilic molecules.
So, the answer is A) To maintain balance of water and nutrients in the cell.
Exocytosis moves materials out of a cell. Endocytosis moves materials into a cell. Active transport uses carrier proteins. (not entirely sure about this one... check it out to be sure) Molecules move from an area of high concentration to an area of low concentration by passive transport.
The environment includes abiotic (nonliving) and biotic (living) factors. An ecosystem consists of all the biotic and abiotic factors in an area and their interactions
The answer would be D. Tropical Rainforest, this would be due to the abundance of rain which creates plenty of vegetation and then, more herbivores will live in the rainforest, and the more herbivores there are, the more carnivores will come to the rainforest. The canopy of the tall trees also provide shelter for countless of thousands of species of birds.
