The water would freeze across the surface of the lake, blocking the dissolving of oxygen and nutrients. <span>Water is actually less dense when frozen, which is why ice cubes and ice bergs all float. This is also why you can ice skate on a lake if the ice gets thick enough on the surface. Many organisms that live in freezing lakes have special adaptations which help them survive.</span>
Answer:
The endosymbiotic theory
Explanation:
Protists are the multicellular organisms which possess characteristics of both the prokaryotes and eukaryotes.
The protist can derive nutrition by either heterotrophic mode or photoautotrophic mode. This variation could exist within the same genus and same species.
This variation could be explained with the endosymbiotic origin of the organisms as some species could engulf the photosynthetic bacteria whereas some could have engulfed the chemosynthetic bacteria.
This can be observed in the green and red algae which depend on a different mode of nutrition belonging to the same group.
Thus, the endosymbiotic theory is correct.
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