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:
there are two types of cell one eukaryotic cell that have true nucleus (genetic material enclosed in membrane) and membrane bounded organelles and other is prokaryotic cell that donot have have true nucleus (genetic material dispersed in cytoplasm) and membrane bounded organelles.
similarities between PC and EC is that both contains cell membrane, ribosomes (not a membrane bounded organelle) .
examples of PC are bacteria , paramecium,fungi etc
examples of EC are plant and animal cells
there are two names for cell membrane i.e plasmalemma, cell surface membrane,
selectively permeable or semipermeable means cell only allows those material to pass through its cell membrane which it needs.this cell'ability is important because to protection against the poisonous substance and to maintain cell needs .
Answer:
its function is to absorb light
Number 1 is B and number 2 is C.
