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.
Answer:
D. Swamp
Explanation:
The photograph shows an ecosystem that is saturated by water. The plant species shown in the photograph are mostly trees and wooden species. These are characteristics of a swamp ecosystem. A swamp ecosystem is a wetland characterized by trees and wooden species. Therefore, the photograph shows a swamp ecosystem.
A relatively large molecule that has an electrical charge associated with it, regardless if it is full charge or partial. Would require facilitated diffusion to enter a cell.
Eg - complex sugars, or disaccharides - fructose, or amino acids, ions - Na + or Ca +.
Answer:
C
Explanation:
There was no C and D on yours but here is a picture of my son's exam.
i think its a hidden virus i hope this helps
