Answer:
e. None of these
Explanation:
The immune deficiency viruses (HIV) are retroviruses that use a reverse transcriptase (RT) enzyme to produce a single-stranded DNA (ssDNA) from an RNA template. The reverse transcription allows retroviruses to replicate their genetic material, which is integrated into the host's genome as a double-stranded linear DNA molecule in a similar way to the mechanism of insertion used by endogenous retrotransposons. The synthesis of DNA is started by cellular tRNAs (tRNA3Lys) that are packaged into the virion. After reverse transcription, the HIV DNA enters the nucleus of CD4 immune cells (also known as CD4+ T cells), and then it integrates into the genome to coopt the host's cell machinery for its own replication.
<span><span>All cells have a plasma membrane, ribosomes, cytoplasm, and DNA.
</span>Prokaryotic cells lack a nucleus and membrane-bound structures.
<span>Eukaryotic cells have a nucleus and membrane-bound structures called organelles.</span></span>
<span>Secondary succession is faster than primary succession because the soil is already there and the soil usually contains many seeds.</span>
Answer:
A) its elliptical orbit and tilt on its axis
Explanation:
Earth revolves around the sun in an elliptical path. Its axis is tilted to about 23.5° from the vertical.
These two factors determine the global climate on the Earth.
Due to elliptical orbit, the earth is sometimes closer to sun than the rest of the time. When it is closer the global temperature rises by 5 degrees. Due to the tilt of the Earth, seasons occur. The hemisphere which points towards the sun has summers where as which points away has winters.
Thus, the long-term climate change is effected by elliptical orbit and tilt of the axis.
