I believe it is the nitrogen base. Adenine pairs with Thymine, and Cytosine pairs with Guanine.
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Parasites benefit their hosts is the true statement. Parasitism is a symbiotic relationship in which one organism (the parasite) benefits from another organism and this other organism is harmed by the parasite.
The others aren't true because:
- the organism that is harmed doesn'y adapt and evolve it still is vulnerable
- it is a fact that parasites change from hosts
- phoresy is an association between two species in which one transports the other. This does not include killing the host (is possible, but it is not a condition under which you can call something a phoresy).
Answer:
Explanation:
Considering the atmosphere of the primitive earth to have contained water vapor, carbon dioxide, carbon monoxide, methane, and ammonia and/or nitrogen, then in the presence of an energy source, such as sunlight or lightning, a number of small molecules like hydrogen cyanide, HCN, are formed.
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