The cell membrane protects the cell and keeps bad things like viruses from getting in the cell.<span>It consists of the lipid bilayer with embedded proteins.</span>
A phenomenon, in the scientific context, is an observable event that can range from a seasonal hazard to a technological issue. For a scientist, a phenomenon is an observable event.
A. Abrasion
Reason - cause by scraps on rough surface which breaks skin on outer layer.
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.
ITS TWO WE R LEARNING ABOUT IT RN
