Biologists Estimate That There Are Tens of Millions of Species

question 58

Multiple Choice

Biologists estimate that there are tens of millions of species on Earth.How many have been described?

• A) 18,000
• B) 90,000
• C) 180,000
• D) 1.8 million
• E) 9 million

---

Definitions:

Cardiac Arrest

A sudden loss of heart function, breathing, and consciousness, typically resulting from an electrical disturbance in the heart.

Bundle Of His

A collection of heart muscle cells specialized for electrical conduction that transmits electrical impulses from the atrioventricular node to the ventricles of the heart.

AV Bundle

The atrioventricular bundle, or Bundle of His, is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node to the point of the apex of the fascicular branches.

Bicuspid Valve

The heart valve located between the left atrium and left ventricle that controls blood flow and consists of two flaps; also known as the mitral valve.