Light waves that have been emitted or reflected by an object enter the eye and first pass through the transparent layer called the where they are refracted. The light rays are then refracted again as they pass through the transparent

A. retina; cornea

B. lens, retina

C. comea, retina

D. cornea, lens

They both determine the exact age of rocks.

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.

Centriole.centrioles are present in animal cells but are usually absent in plant cells.

Leaves specifically the gas exchange between plants and the environment. while plants undergo photosynthesis, they also partake in cellular respiration. respiration is the process that happens in the leaves of plants.