Which of the following statements explain why red blood cells
(rbcs) are highly specialized for oxygen transport?
(1) rbcs contain hemoglobin.
(2) rbcs lack a nucleus.
(3) rbcs have many mitochondria and thus generate atp aerobically.
(4) the biconcave shape of rbcs provides a large surface area for the inward and outward diffusion of gas molecules.
(5) rbcs can carry up to four oxygen molecules for each hemoglobin molecule.

(a) 1, 2, 3, and 5 (b) 1, 2, 4, and 5 (c) 2, 3, 4, and 5

(d) 1,3, and 5 (e) 2, 4, and 5

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."