Which of these is a biotic factor of an aquarium ecosystem?

a: algae growing on the glass
b: gravel on the bottom of the aquarium
c: temperature of the water
d: amount of oxygen in the water

Aglow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion.

Which describes fat? a: a carbohydrate that produces energy b: a nucleic acid that directs cell function c: a lipid that stores energy d: a protein that speeds up a chemical reaction

What does the symbol (–hfus) indicate in a phase change?