The best answer is B (semi permeable)
The cell membrane of a red blood cell is semi permeable membrane. This is a type of biological membrane that will allow certain molecules or ions to pass through while barring others.
Red blood cells have very thin membranes that allow oxygen diffuse through quickly. They are also permeable to water and osmosis across the membrane occurs very rapidly. In the body, they are bathed in isotonic plasma in which case water movement into the cell is equal to water movement out of the cell and so the cells remain intact.
Answer: A) Two atoms share electrons so they can fill their outer shells
Explanation: A covalent bond is a type of bond formed by sharing equal number of electrons between two non-metal atoms so that both of them can attain a stable octet or duplet structure of noble gases.
In covalent bonding, there is no loss or gain of electrons between atoms. For example, the formation of chlorine molecule, chlorine atom has seven electrons in its outermost shell, remaining one electron to attain an octet structure of noble gases. Two chlorine atoms share one pair of electron, each chlorine atom donating one electron to form a pair so that each atom in the chlorine molecule attains an octet structure..
The best answer is A
Saltwater fish are hypotonic to their surroundings. This means their blood has a higher water concentration than the surrounding sea water.
Due to the fact that there is more salt and less water outside their bodies, there is a tendency to take in salt and lose water.
To counter this, salt water fish drink a lot of the sea water and urinate very little. Special cells in the gills actively eliminate salt at the cost of extra energy and these fishes do not absorb any salt from the water they drink.
