The link between prokaryotes and multicellular eukaryotes is ......... .

In which of the following unicellular organisms is a large macronucleus found for nutritional functions and a smaller micronucleus for reproductive functions?

The contractile vacuole is absent in $......$.

The presence of cilia, an oral groove, and food vacuoles, and the absence of chloroplasts in a unicellular organism indicate that the organism carries on

$A$: Holophytic protistans are important phytoplanktons and they contribute $80\%$ of the total photosynthesis.
$R$: They lack chemosynthetic nutrition and utilize non-sulphur organic compounds as the source of electron and proton in carbon assimilation.

Explain the characteristic features of the group Chrysophytes and provide examples.