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Before viruses can reproduce, they must infect a host cell.
Viruses need a way to enter the body before they can infect a host cell.
Plants release oxygen into the atmosphere during photosynthesis while respiration by plants and animals and the decomposition and decay of dead organisms releases carbon dioxide into the atmosphere. These three produce maintain a cycle in which plants and animals depend on and benefit from each other.
Answer:
scientific theory is the answer
A scientist would use, C. Weather Balloon.
Answer:
Index fossils
Explanation:
The index fossils are the fossils that come in very handy for the geologists when it comes to identifying or dating rock samples or other fossils. The reason for this is that the index fossils have already been dated. They are fossils that are very commonly found, wide dispersed, are easy to be identified, and are limited to only a certain geological period. These characteristics make them an excellent indicator for the dating of the rock layers in which they are found, or the fossils found in the same layers with them, without conducting further examinations.