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.
The mouth is the beginning of the digestive tract; and, in fact, digestive starts here when taking the first bite of food
The term "ferrying its newly-gained energy with it" means that the fluid carries the energy it acquired as it rises during convection.
Convection is a mode of heat transfer in which energy is transferred by the bulk movement of particles from one point to another. During convection, a fluid is heated and its particles acquire energy, These energetic particles now move upwards and are replaced by less dense fluid at a lower energy.
The term ferrying its newly-gained energy with it, implies that the heated particles carry the energy they have gained with them as they rise during convection.
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Answer:
It provides a defined order to the succession of organisms.
Explanation: Relative dating of rocks involves the relative or comparative determination of age with reference to past events. There are several principles involved in carrying out relative dating. Some of these principles are:1. Principle of inclusion2. Principle of inclusion 3. Principle of fossil and fauna succession The Principle of fossil and fauna succession postulates that fossil and fauna succeeds one another in a definite pattern. It is this defined order that we use to achieve relative dating of rocks. Plant and animal remains constitutes the fauna and fossils used in dating the rocks. When we find a particular fossil in a rock, we can place that rock in its appropriate geological time. We can even go further by correlating rock types using their fossil contents.