<span>Answer: occurs when the aortic and pulmonary valves backfill with blood</span>
The second heart sound,that is heard in normal hearts, is generated by the closing of the semilunar valves((the aortic valve and pulmonary valve). Before that, the first sound corresponds to the closing of the atrioventricular valves.
Answer:
Viruses and Bacteria
Explanation:
Bacteria are single-celled, prokaryotic microorganisms that exist in abundance in both living hosts and in all areas of the planet. By their nature, they can be either "good" or "bad" for the health of plants, humans, and other animals that come into contact with them. A virus is acellular (has no cell structure) and requires a living host to survive; it causes illness in its host, which causes an immune response. Bacteria are alive, while scientists are not yet sure if viruses are living or nonliving; in general, they are considered to be nonliving.
Infections caused by harmful bacteria can almost always be cured with antibiotics. While some viruses can be vaccinated against, most, such as HIV and the viruses which cause the common cold, are incurable, even if their symptoms can be treated, meaning the living host must have a strong enough immune system to survive the infection.
difficulty in transporting hormones and waste products
<h3>Answer:</h3>
The molecule produced is NADPH.
<h3>Explanation:</h3>
The molecule produced In biochemical reactions, NADP+ acts as a "hydride" acceptor.
The hydride is not H-, but its chemical equivalent, H++2e-
The hydrogen atom adds to the nicotinamide ring, converting the molecule to NADPH.
by adding two electrons and one proton to NADP plus is NADPH.
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