It can change multiple times depending on the studying being shown
Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
part 1: inconsistent
part 2: not uniformly available
hope this helps.
Answer:
chitin
Explanation:
chitin is a complex carbohydrates, similar to cellulose, that makes up organic structure, such as the cell walls of fungi and exoskeletons of insects and other arthropods.
Answer: Here are three reasons if they don't help just tell me.
1. Changes in water temperature can affect the environments where fish, shellfish, and other marine species live. As climate change causes the oceans to become warmer year-round, populations of some species may adapt by shifting toward cooler areas. Oceans are becoming more acidic. 2. Oceans are becoming more acidic. The acidity of seawater is increasing as a direct result of increasing carbon dioxide levels in the air from human activities, like burning fossil fuels. Concentrations of carbon dioxide are higher than in the last 800,000 years. Carbon dioxide dissolves in water, changing seawater chemistry and decreasing pH (making seawater more acidic). The ocean’s increased acidity results in thinner shells and more shellfish die as they become easier for predators to eat. 3. More severe storms and precipitation can pollute coastal waters. Warmer oceans increase the amount of water that evaporates into the air. When more moisture-laden air moves over land or converges into a storm system, it can produce more intense precipitation—for example, heavier rainstorms. Heavy rain in coastal areas can lead to increases in runoff and flooding, impairing water quality as pollutants on land wash into water bodies. Some coastal areas, such as the Gulf of Mexico and the Chesapeake Bay, are already experiencing “dead zones” – areas where water is depleted of oxygen because of pollution from agricultural fertilizers, delivered by runoff. The phrase “dead zone” comes from the lack of life – including fish – in these waters.
