Answer:
c) labeled DNA ... DNA
Explanation:
Hersey and Chase prepared two separate virus samples and infected the host cell, <em>E. coli</em>, that was present into different culture media. One of them contained a radioactive isotope of phosphorus (³²P) and the other contained a radioactive isotope of sulfur (³⁵S). After a division cycle in bacteria, all the viruses recently formed had one of the two isotopes depending on the culture media in which infected bacteria had grown. Viruses coming from bacteria incubated with ³²P had radioactive DNA whereas viruses coming from bacteria incubated with ³⁵S had radioactive proteins. This was due to the differences between the structures of the DNA and proteins: DNA contains phosphorus, but not sulfur and the proteins contain sulfur in cysteine and methionine, but not phosphorus.
After incubation, the cells were centrifugated to separate any extracellular viral material. Hersey and Chase found out that ³⁵S remained outside of the bacterial cells, in the empty capsids, and that ³²P had entered the cells and was present in the new viruses formed. They concluded that the genetic material was DNA and not the proteins.
Answer:
Over time, many species gradually adapted to a more oxygen-rich enviroment, allowing them to survive in shallow water and on land.
Answer:
d mutations and competition
Desalination is the process. It is used to covert salt water into pure water, or fresh.
Plants use sunlight, soil, and water to grow. Animals use leaves, branches, trees, or soil for shelter and other living things for food. These are examples of interactions of biotic and abiotic elements in ecosystems. In a pond, the plants, soil, and water create suitable habitat for many different birds, insects, and fish. Other animals, such as bears, eat fish and berries. Feeding interactions give living things the nutrients they need to survive.