Answer:
C. At least five mass-extinction events have occurred during the last 500 million years.
Explanation:
- The history of mass extinct is related to the five mass extinctions that are caused over by the 350 million years n which many species have disappeared in there short geologic time.
- A massive extinction is caused in the Permian Triassic extinction event i.e about 250 mn years ago which on an estimate has killed 90% of the species.
- The Cretaceous–Paleogene extinction event that occurred over 66 million years ago is known to have wiped out the dinosaurs and many other species.
Answer: D) Pulmonary and aortic valves.
Explanation
There are two main heartbeats from a healthy heart.
The first beat is called the S1 or the lub, and it occurs when the atrioventricular valves (comprising the mitral and tricuspid valves) close.
The second beat is called the S2 or the dub, and it occurs when the semilunar valves (comprising the aortic and pulmonary valves) close.
Listening for heart beats is an essential part of cardiac auscultation.
Yeah yeah you know where I can get it and I have to get my
The system that controls and coordinates
the body through hormones is the <span>endocrine system.</span>
<span>Endocrine system produces hormones and then these hormones
transmit the messages to various cells within the body. Hormones have great
importance in our body system and even our body is functioning due to hormones.
If hormones are disturbed it can lead to
many diseases.</span>
Limiting factors determine the carrying capacity Hope this helps :)
