Answer:
A. Scientists discovered chromosomes and DNA.
Explanation:
Mendel's ideas were based on patterns of inheritance in plants. Although he identified these patterns, at the time, we did not know what the hereditary material was. This means Mendel couldn't uncover the mechanism of why he was seeing the patterns he was.
When scientists discovered chromosomes and DNA, they were able to see how Mendel's observations made sense in the context of DNA and chromosomes.
Answer:
Because the vaccine is an antigen from living, weakened or killed microorganisms that activate the immune system and the body produces protective antibodies.
The health effects of drinking contaminated water can range from no physical impact to severe illness or even death. Some of the effects of drinking contaminated water can be immediate, or not noticed for many years. These include gastrointestinal and stomach illnesses like: nausea.