Where are the photoreceptors located inside a human eye?

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Which best explains how a heat pump can heat a room? cold air from the house is moved through pipes, where it absorbs thermal energy. warm air from outside is pushed into the house to replace the cold air. combustion warms the air when chemical energy is transferred to thermal energy. fuel is used to move a piston, which pushes warm air into the house.

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?