Ecosystems need producers because they are the start of the food chain.
Producers are consumed by first consumers, the second consumers and so on.
The answer is, different versions of the same gene are called alleles
Answer:
Because you body is introduced to the virus, it is familiar to it and can build up an immunity to the weakened form so when the actual virus invades, your body know what to do.
Explanation:
The answer is none of the above
