<span>Gene experssion are influenced by enviroment. the best example is skin color in case of human for e.g if person with fair color or white complexion goes to africa or any part where sun exposure is more his or her color gets dark .the darking of skin is due to melanin production. see here person is same only difference is in enviromental condition due to which gene which are responsible for the production of melanin are produced.
I hope u understood it</span>
There was no life on Earth for the first billion years because the atmosphere was not suitable for life. Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air.
The Cell Membrane<span>. All living cells and many of the tiny organelles internal to cells are bounded by thin </span>membranes<span>. These </span>membranes<span> are </span>composed<span> primarily of phospholipids and proteins and are typically described as phospholipid bi-layers.
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Answer;
-Allele frequency change
In single-gene traits, natural selection can lead to allele frequency change.
Explanation;
-Allele frequencies can change over time within a single population, and frequently differ between populations. This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift.
-Random forces lead to genetic drift. Sometimes, there can be random fluctuations in the numbers of alleles in a population. These changes in relative allele frequency, called genetic drift, can either increase or decrease by chance over time.
