Which of the following contributions to the theory of the conservation of energy is an observation of a biological system?
a. julius von mayer’s observation that vibration increases the temperature of water
b. james prescott joule’s observation that the potential energy of a weight can be converted into heat energy
c. hermann von helmholtz’s demonstrations that energy is converted but not created when animal muscles move
d. baron kelvin’s hypothesis that the melting point of ice decreases as pressure decreases

thymine. in rna, thymine is replace by uracil

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c