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:
It ensures that the two daughter molecules are exact copies of the parent molecule.
Explanation:
Answer:
Water will diffuse into the cell.
Explanation:
As the NaCl conentration in cell is greater then in water so water will diffuses into the cell and NaCl will move out of the cell
Answer:
A. decrease by half.
B. stay the same.
C. double.
Explanation:
Host-pathogen models resembels the host-parasite models and predator-prey which is used to evaluate the evolutionary strategies of pathogens.
The host-vector-pathogen system can be demonstarted as a change in the number of 4 types of people: healthy hosts, uninfected vectors, infected hosts, and infected vectors.
The threshold density should decrease by half, stay the same, or double, according to the standard host-pathogen model, if the combined death and recovery rate from a disease doubles, and the ability of the disease to spread from infected to uninfected persons.
Hence, the correct options are A. decrease by half, B. stay the same, and C. double.