The monomer units of the carbohydrates vary in their total numbers extensively. Moreover, positions of the carbonyl groups along with the orientation of the hydroxyl groups also vary in the carbohydrates' monomers. The presence of any modification is also variable.
On the other hand, the nucleic acids have only 4 monomeric units. The linkages between the nucleic acid residues have less geometry than the glycosidic linkages.
The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Answer:
X is negative heterotropic modulator
Explanation:
In allosteric regulations, modulators are molecules that causes a change in the conformation of an enzyme, hence, resulting a change in enzyme activity. It can lead to a decrease or an increase of the enzyme. When a molecule decreases the enzyme activity it called a negative modulator, when it increases or activates the enzyme activity, it is called a positive modulator.
A positive or negative modulator can either be homotrophic (substrate acts as modulator) or heterotropic (another ligand acts as modulator).
In the example above, X is negative heterotropic modulator, because the modulator is different from the substrate and it also decreases the enzyme activity.
Answer:
sunlight
Explanation:
at the angle the earth is at, sunlight hits the equator almost directly, as well as the equator being closer to the sun.