D. all of the above
as they are all, evergreen, short and contain flammable oils
Answer:
D: 4.6 x 
Explanation:
4.6 x 10^{9} = 4,600,000,000
Earth is approximately, 4.6 billion = 4,600,000,000 = 4.6 x 10^{9}
Answer:
1. Ends of the respiratory branches are called alveoli.
2. C. To control blood flow to different areas of the body depending on activities
Explanation:
1. The trachea divides into left and right primary bronchi which in turn divide multiple times upon entering the lungs and make the bronchial tree.
The final branches of the bronchial tree are the terminal bronchioles that lead to alveoli. The alveoli are the balloon-shaped structures and serve as the site of gas exchange between the blood and inhaled air.
2. The opening and closing of sphincters of capillary beds regulate the direction of blood flow. The opening of sphincters allows the blood to flow into associated branches of capillary beds while closed sphincters direct the blood from arterioles to venules via thoroughfare channel.
This local change in blood flow is responsible for the autoregulation of blood flow to different tissues to match their respective metabolic demands. For example, during physical activity, more blood is directed to skeletal and cardiac muscles.
Rather, each myelin sheath insulates the axon over a single long section and, in general, each axon comprises multiple long myelinated sections separated from each other by short myelin sheath-gaps called nodes of Ranvier. ... In the CNS, axons carry electrical signals from one nerve cell body to another.
