Answer:
React on cell surfaces, catalyze reactions.
Answer: A. the lens focuses light on the retina
The lens is composed of transparent, flexible tissue and is located directly behind the iris and the pupil. it is the secondary part of the eye after the cornea. by changing it's shape the lens changes the focal distance of the eye and focuses the light that passes through it and into the retina in order to create clear images of objects. it also works together with the cornea to refract, or bend light.
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D. Electrons because isotopes deal with electrons.
<h2>Answer </h2>
Lactic acid fermentation ocurrs in muscle cells when oxygen is in low supply
<u>Explanation</u>
The lactic acid fermentation in the muscles cell occurs when muscles work faster and it occurs due to the lack of supply of oxygen in the cell. The lactic acid fermentation is a type of aerobic respiration. The lactic acid formation is due to excessive exercise by individuals and oxygen which is essential for living, is less in the muscle which causes the feeling of burning in the muscles.