Answer:
It happens in the diastolic phase of the cardiac cycle
Explanation:
During the diastolic phase of the cardiac cycle, blood is allowed to enter the heart when it relaxes after a contraction.
Approximately one systole (contraction phase) that lasts 300 milliseconds and a diastole of 500 milliseconds.
Answer: HIV & related viruses such as HTLV possess unusual virally encoded reverse transcriptase enzyme.
Reverse transcriptase is an enzyme which synthesizes a complementary DNA or cDNA from a RNA template strand. The process of reverse transcription is used by the retroviruses for replicating their genome and proliferating within the host genome. The HIV uses reverse transcriptase to infect humans. Without the reverse transcriptase enzyme the genome of the virus cannot incorporate into the host cell and will fail to replicate. HTLV or human T-lymphotropic virus or HTLV also uses the same mechanism with the enzyme reverse transcriptase.
Microscopes allowed scientists to observe Prokaryotic cells which make up Bacteria and Archaea. These cells are small and contain no membrane- bound organelles. It allowed them to observe Eukaryotic cells with a nucleus and membrane-bound organelles that perform different life functions.
Answer:
I think it's the second one
Answer:
tundra, Antarctic tundra, and alpine tundra
Explanation:
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