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This results in greater top-down control because consumed plant matter is quickly released back into the system as labile organic waste. [ 15 ] [ 27 ] In terrestrial ecosystems, primary producers are less nutritionally dense and are more likely to contain defense structures. [ 22 ]
Natural convection is a flow whose motion is caused by some parts of a fluid being heavier than other parts. In most cases this leads to natural circulation: the ability of a fluid in a system to circulate continuously under gravity, with transfer of heat energy. The driving force for natural convection is gravity.
The energy remaining after respiration is considered the net primary production. In general, gross production refers to the energy contained within an organism before respiration and net production the energy after respiration. The terms can be used to describe energy transfer in both autotrophs and heterotrophs.
The convection heat transfer mode comprises two mechanism. In addition to energy transfer due to specific molecular motion , energy is transferred by bulk, or macroscopic, motion of the fluid. This motion is associated with the fact that, at any instant, large numbers of molecules are moving collectively or as aggregates.
Energy intake is measured by the amount of calories consumed from food and fluids. [1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus, [1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.
The second case is when natural convection acts in the opposite way of the forced convection. Consider a fan forcing air upward over a cold plate. [5] In this case, the buoyant force of the cold air naturally causes it to fall, but the air being forced upward opposes this natural motion.
Internal energy is a principal property of the thermodynamic state, while heat and work are modes of energy transfer by which a process may change this state. A change of internal energy of a system may be achieved by any combination of heat added or removed and work performed on or by the system.
Heat transfer is the natural process of moving energy to or from a system, other than by work or the transfer of matter. In a diathermal system, the internal energy can only be changed by the transfer of energy as heat: Δ U s y s t e m = Q . {\displaystyle \Delta U_{\rm {system}}=Q.}