Answer:
The correct answer would be D.Alveolar sacs are surrounded by thin capillaries where gases can be exchanged.
Alveoli are tiny sacs which form the site of gas exchange in the lungs.
The features of alveoli which help in gas exchange are:
- They increase the surface area in the lungs thus, more space is available for gas exchange.
- They have very thin walls, as thin as the thickness of a single cell only.
- They are surrounded by a bunch of thin capillaries which exchange gases with alveoli.
Bacteria have been the very first organisms to live on Earth
The first one is C. Varying in shapes of forelimbs
The second one is B. Enable members of a phylum to survive and reproduce.
The third one is B. Deuterostome development
Answer: A.
Explanation: When a chlorine atom gains an electron, its outermost principal energy level achieves an octet. In this case, the ion has the same outermost shell as the original atom, but now that shell has eight electrons in it.
Muscle tissues signaling muscle tissues to contract.
