PCR (polymerase chain reaction) is an excellent method of generating copies of target DNA. If a single piece of double stranded DNA (dsDNA) is put into a PCR machine, how many dsDNA segments will there be after 3 rounds?

After 3 rounds, 8 segments having 2 original strands on different segments will be present.

Explanation:

The polymerase chain reaction selectively and repeatedly copy the double stranded DNA (dsDNA) in the PCR machine.

1st round:

Single piece of double stranded DNA (dsDNA) unwinds in two seperate strands, before complementary nucleotides are synthesized to establish double helix.

2nd round:

The two dsDNA yields 4 segments before complementary nucleotides are synthesized

3rd round:

The four dsDNA yields 8 segments before complementary nucleotides are synthesized.

Therefore, at the end of 3 rounds, the two original strands will be present on the 8 different segments of copied DNA.

"d.) carbon dioxide and hydrogen sulfide"

the food storage products of chrysophytes are oils or the polysaccharide laminarin.   formerly classified as plants, the chrysophytes contain the photosynthetic pigments chlorophyll a and c all but the yellow-green algae also contain the carotenoid pigment fucoxanthin.