Natural selection is a central concept of evolution. Natural selection is the process where organisms with favorable traits are more likely to reproduce. In doing so, they pass on these traits to the next generation. Over this time this process allows organisms to adapt to their environment.
Answer:
Explanation:
Increased nitrogen level in ocean water can lead to excessive growth of aquatic plants in the ocean which in turn leads to high oxygen (dissolved oxygen) uptake by these plants when they decompose. The overgrowth of these plants also prevent light penetration in the ocean water. All these can affect other aquatic organisms particularly those that depend on these dissolved oxygen and/or light penetration (such as fish and crustaceans).
Answer:
third option should be correct
Explanation:
Answer: B. pressure changes in the thorax
Explanation:
The veins are the blood vessels which returns the deoxygenated blood from all the tissues and cells of the body back to the heart. The ventricular systole, venous valves, activity of the skeletal muscles and neural control over venoconstriction all influence the movement of the blood in the venous.
The pressure changes in the thorax occurs due to inspiration and expiration. During the process of inspiration, the diaphragm below the lungs contracts and moves downward while the muscles of the ribs pulls downward. When the size of the thoracic cavity increase the air pressure inside the cavity decreases and vice-versa. The pressure inside the thoracic cavity is not related with the movement of the venous blood as it regulates the exchange of the gases not the blood.