The large number of areas covered by the chemical energetics can be explained by the different forms in which chemical energy can be released: heat and combustion work, electrical energy in electrochemistry, radiant energy in chemiluminescent systems.
The chemical energy provided by a reaction reflects the energy balance associated with the electronic modifications suffered by the species involved.
From an energy point of view, a chemical reaction between molecules can be schematized in two stages. The first requires a supply of energy and corresponds to the rupture of the bonds of the reactant molecules with release of the atoms which constitute them.
The second releases energy and concerns the creation, by recombination of these atoms, of new bonds entering the structure of the reaction molecules.
As a general rule, the energy released in the second stage is greater than the first. We are talking about exothermic reaction. The difference between these two energies (reaction enthalpy) measures the amount of chemical energy transferred to the external environment.
It is conceivable that this quantity translates, not only the number, but also the strength of the connections involved.
The correct answer is (d.) proteins. Higher organisms use nitrogen to make their protein. Food that is containing protein also involves nitrogen in it. Protein also has amino acids that contain nitrogen in it which is a necessary essential nutrient for the body.
In humans sperms can survive 3 -5 days within the female reproductive tract.
The ideal time of fertilization is around ovulation when the egg is in the fallopian tube. After travelling through the vaginal canal, the strongest sperm make it to the cervix. From here, the sperm must travel through the uterus and into one of the fallopian tubes.
Answer:
The Hay-flick Limit is a concept that helps to explain the mechanisms behind cellular aging. The concept states that a normal human cell can only replicate and divide forty to sixty times before it cannot divide anymore, and will break down by programmed cell death or apoptosis.
