Answer:
Explanation:
In a lake, oxygenic phototrophs produce new organic material as well as O₂. If primary production rates are very high, the resultant excessive organic matter production can lead to bottom-water O₂ depletion from respiration and the development of anoxic conditions. This in turn stimulates anaerobic metabolisms, including anaerobic respirations and fermentations.
Organic matter that is not consumed in surface layers sinks to the depths and is decomposed by anaerobes.
<span>A. The nebula contracts and shrinks instead of expanding
</span><span>Nebula is the cloud of interstellar dust and gas that forms a star. It is collborately shaped during colliding and collapsing of the interstellar mediums this is influenced by the gravitational attraction of the atoms and particles in the entites. Hence, there are three types of nebular namely, are classical nebula, diffuse nebula, planetary nebular and supernova remnants.</span>
I think they are effected by the sun and rotation of the earth. If that helps?
