Answer:
D. The two students who have two fragments have one restriction site in this region.
Explanation:
The DNA samples from the cheek cells were subjected to digestion with a restriction enzyme. This enzyme is an endonuclease and cuts the DNA at a specific sequence only. This sequence is called a restriction site. If the restriction site is not present in the sample DNA, the restriction enzyme cannot cut it. The presence of one restriction site in the sample DNA would cut it into two DNA fragments.
Similarly, the presence of two restriction sites in each DNA molecule would obtain a total of three DNA fragments per DNA molecule.
Meiosis in reproductive organs (testes and ovary) produce gametes. Each human cell including reproductive cells contains 23 pair of chromosomes. Meiosis separates the two chromosomes from each pair thus, each gamete receives only one copy of each chromosome. Therefore, each gamete has 23 new chromosomes, one from each of the 23 pairs. During meiosis, exchange of chromosome segment between copies of a pair of chromosomes. The exchange of chromosome segments creates new combinations of genes which enhances genetic variability within a species.
Hydrochloric acid is found in the stomach
