The Beginning of the Cambrian Period Marks an Important Event

question 99

Multiple Choice

The beginning of the Cambrian period marks an important event in animal evolution - the appearance of organisms with ________.

• A) wings
• B) cells
• C) hard parts
• D) vertebrae
• E) none of the above

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Definitions:

Capillaries

The smallest blood vessels in the body's circulatory system, facilitating the exchange of water, oxygen, carbon dioxide, and other nutrients between blood and tissues.

Pulse

The rhythmic throbbing of the arteries as blood is propelled through them, typically palpable at body sites where arteries are close to the skin surface.

Diastole

Relaxation of the heart chambers, during which they fill with blood; usually refers to ventricular relaxation.

Ejection of Blood

is the process during which the heart pumps blood out of the ventricles into the aorta and pulmonary artery during systole.