It is the second sentence. Organs are made up of tissues. Tissues are made up of cells.
Answer:
DNA
Explanation:
Thymine is one of the four nucleobases that pairs with adenine to make up DNA, also called 5-methyluracil. It is replaced by uracil to make RNA molecules during transcription.
Theferore the unknown chemical analyzed was DNA because thymine is found in DNA and not in RNA molecules.
All the options are correct.
1. New ways to preserve and transport blood for blood transfusions were discovered.
2. Blood transfusion safety was improved.
3. Scientists discovered that elements of blood could be separated by centrifuge.
4. Scientists discovered that plasma could be preserved by freezing.
Karl Landsteiner
Karl Landsteiner was the man who discovered some of the human blood types in 1900 and 1901 at the University of Vienna.