Alveolar walls are thin to enable the quick passage of oxygen in and out of the lungs. The lungs works hand-in-hand with the heart and also is responsible in converting blood that's de-oxygenated into an oxygenated blood that is usable by the organ systems of the body. The alveolar walls are also designed to have thin membranes so that it can expand and constrict quickly allowing us to breather properly.
<h2>Answer:</h2>
Paramecium is the single celled organism (unicellular).
<h3>Explanation:</h3>
- An organism which contain only one cell is known as unicellular organism.
- Paramecium is the unicellular parasite. It can move and digest food.
- In its structure there are food vacuoles for the digestion of food.
- Paramecium is the eukaryotic organism because it has a well organised cell with distinct nuclear membrane.
- It belongs to kingdom protista.
Answer:
Warm air is cooling quickly.
Explanation:
Hot air rises and cool air sinks.
