Valves ensure blood flows toward your heart. Vein valves work to bring the blood that flowed down via arteries back up to your heart.
True, the plasma membrane is selectively permeable and controls the various substances that are allowed into the cell and that are allowed to leave the cell.
Answer:
C. Carbon Dioxide
Explanation:
In a process called “photosynthesis,” plants use the energy in sunlight to convert CO2 and water to sugar and oxygen. The plants use the sugar for food—food that we use, too, when we eat plants or animals that have eaten plants — and they release the oxygen into the atmosphere.
Answer:
The right answer is 1 and 4
Explanation:
A hormone is a biologically active chemical substance, synthesized by a glandular cell secreted into the internal environment where it circulates, acting remotely and by blood on receptors specific to a target cell. It transmits a message in chemical form and therefore plays a role of messenger in the body.
The emitting organ thus acts at a distance on all of the target organs of the organism or of neighboring organisms of the same species, or even of symbiotic organisms whose receptors are activated in contact with specific hormones (lasting interactions).
