We are all familiar with the basics of viruses: These particles infect living cells and wreak havoc throughout the body. But viruses aren’t the only villains around causing chaos in living things. Other infectious agents called viroids and prions — …
The specific heat capacity (c) of a substance, commonly called its “specific heat,” is the quantity of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius (or 1 kelvin): C = q / …
No, friction cannot increase the mechanical energy of a body. Total Energy=KE+PE+WE; where WE are due to work done by the system against friction force. Thus, So that the more work done (i.e., more friction force all other things equal), …
The first plant fossils that show the presence of vascular tissue date to the Silurian period, about 430 million years ago. The simplest arrangement of conductive cells shows a pattern of xylem at the centre surrounded by phloem. Xylem is …
Enthalpy defines the sum of a system’s internal energy (U) and the mathematical product of its pressure (P) and volume (V): H = U + PV Enthalpy is also a state function. Enthalpy values for specific substances cannot be measured …
The most efficient heat engine cycle is the Carnot cycle, consisting of two isothermal processes and two adiabatic processes. The Carnot cycle is the most efficient heat engine cycle allowed by physical laws. When the second law of thermodynamics states …
The fossil plant Elkinsia polymorpha, a “seed fern” from the Devonian period—about 400 million years ago—is considered the earliest seed plant is known to date. Seed ferns produced their seeds along their branches, in structures called cupules that enclosed and …
If a process written as the sum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy changes of the various steps. Hess’s law is valid because enthalpy is a state function.
Root systems are mainly of two types. Dicots have a tap root system, while monocots have a fibrous root system. A taproot system has a main root that grows down vertically, and from which many smaller lateral roots arise. Dandelions …