The answer is d ...the number of organisms an ecosystem can support
<span>The most obvious change due to seasonal variation is the change from summer to winter. Some animals migrate to other parts of the world, such as migratory birds. Many animals in colder climates hibernate. In both cases, the absence of these animals leads to a gap in the ecosystem. In regions with highly seasonal rainfall, the low rainfall season can lead to low flows in rivers, and a reduction of certain habitats for some aquatic organisms, such as beaver or aquatic insects.</span>
Answer:
The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function.
Blood is the fuel that keeps you going! Oxygenated blood is brought to organs and tissues via the arteries, while veins bring deoxygenated blood back to the heart to be replenished. The point is, without the respiratory system your blood would be useless.
The circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles. Blood moves in and out of the lungs through the pulmonary arteries and veins that connect to the heart.