HI i was wondering 1 what engineer choice you are going for and two if this is what you mean. study hard to to bed early and make class . (im saying this becasue i have done it before :])
Helps with oxygen and stuff
The cell theory consists of:
1. all living organisms are made up of cells
2. cells are the basic structural/organizational unit of all organisms
3. all cells come from pre-existing cells
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
