Explanation:
The DNA could be dried -through the process of lyophilization- or stored, as a precipitate of ethanol, in liquid nitrogen (temperatures below -80 degrees Celsius). The aim is to reduce water in the stored samples as much as possible because the water can be involved in natural hydrolytic reactions (depurination, depyrimidination, deamination, and hydrolytic cleavage) that could degrade the nucleic acids of the DNA.
If the DNA is stored while being used regularly it is not advisable to store it as a precipitate of ethanol. It should be stored in aqueous form but in a slightly alkaline pH of about 8.5 to prevent acid-catalysed degradation processes.
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Answer:
(A) True
Explanation:
The sun is producting the electromagnetic radiation which is the primary energy source on Earth and the driver of the entire climate system.
In general the sun is the source of energy that drives all life on Earth. This energy governs the weather, ocean currents and the hydrological cycles.
Without the continuous influx of sunlight and heat, life on Earth would cease to exist. The sun sets off the hydrological cycle, causing it to constantly evaporate into the atmosphere, from which it falls back to Earth.
Answer:
Phenotypic plasticity
Explanation:
Humans have evolved over thousands of years to adapt to various environmental changes. For example, when we are in an environment that requires certain level of adaptation our off spring often formalizes epigenetic traits that lows them to overcome small changes in the environment. Over time certain genes that are turned on may remain on and eventually the ones that are off remains off. This give rise to some genes that "don't work" after millions of years of such evolution we end up with a complex genome with more DNA than "working genes".
Answer:
b) Channel pumps
Explanation:
The channels are the transmembrane proteins that serve in the passive transport of substances down the concentration gradient. The channels can be gated or non-gated. The gated channels are opened and closed in response to certain stimuli such as electrical change.
For example, aquaporins are the gated water channels that transport the water across the plasma membrane. The process is driven by the osmotic gradient and does not use the energy of ATP.
Answer:
The correct answer is: geography and UV radiation.
Explanation:
Skin variation occurred thanks to evolution, and was driven as a consequence of the geographical location of different populations of humans.
The humans that lived in hot and sunny places, closer to the equator, where much more exposed to the sun's ultraviolet radiation. In order to survive the amount of UV lights that they were exposed to, new humans in those regions were being born with a darker skin tone, which was rich in melanin (a brown pigment that protects us from the sun radiation).
Contrary to these humans that lived in the tropical areas, the humans that populated the areas that were closer to the poles, developed much lighter skin as a result of lower amounts of melanin in their skin. Since sun exposure in the poles is very limited, humans needed to receive as much as they could for the production of Vitamin D, and thus, their skins got lighter and less protected.
