Answer:D
Explanation: The pulmonary air sacs of birds only permit a unidirectional flow of air through the lungs. Unidirectional flow means that air is inhale and exhale through one trachea alternatively. This means the bird lungs only receive largely fresh air which has a high oxygen content during inhalation and do not receive fresh during exhalation. While air flow bidirectional in mammals.
Answer:
The salinity of water increases as you move from inland areas out towards to ocean.
Explanation:
Salinity refers to the concentration of salt in the water. The salinity of water increases as you move from inland areas out towards to ocean because the ocean has high salinity than the inland areas. That is it can be said that the ocean contains brackish water. Brackish water has more concentration of salt than freshwater.
Reproduction. I hope this helps!
<span>These are viroids. They are some of the smallest types of matter that have been shown to take on the properties of living beings. They have the ability to replicate, while not having many of the mechanisms that are commonly found in DNA and required for them to replicate.</span>
