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which statement describes the condition of the heart at the point indicated in the electrocardiogram?

a. the atria are contracting and pushing blood into the bottom ventricles of the heart.

b. the valves of the aorta and pulmonary artery close, producing the first heartbeat.

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

Acquired mutations can result from radiation pollution toxins inheritence select all that apply

Answer ! in your opinion, what are the limiting factors that might affect the growth or diversity of our ecosystem? respond to this question in claim, evidence, reasoning format. 1. make your claim (i are the limiting factors that might affect the growth or diversity of our 2. follow the claim with 3 pieces of evidence. evidence may be taken from the reading, the videos, previous lessons, or googled answers. site sources, too. 3. use reasoning to explain why you chose your evidence.