Why might chloroplasts be able to live outside of their host algal cells

Elysia chlorotic is a bizarre-looking creature that lives in the Atlantic Ocean off the coast of North America. It is
a green, leaf-shaped sea slug. Mary Rumpho-Kennedy, a professor at the University of Maine,studiedthis odd
creature and discovered that E. chloroticaacquires chloroplasts from the algae that it consumes. These
chloroplasts are stored in the cells that line the slug’s gut, allowing the slug to live off of the photosynthetic
products of the chloroplasts and not eat for extended periods of time.
Questions:
1) Why might chloroplasts be able to live outside of their host algal cells for extended periods of time in the gut
of E.chlorotica?
2) Most organelles that are endosymbiotic in origin are no longer capable of living outside of their host because
they lack all of the genes necessary for autonomous life. Where are they getting these gene products from
when living inside their host cells?
3)What might be true about the genome of E. chlorotica that allows it to maintain algal chloroplasts inside its
body?