The portion of the membrane that faces the lumen is called the apical membrane.
Membrane is the lipid bilayer that surrounds the cell on its outer surface. The membrane serves various functions like: protection, cell shape and integrity and regulate the traffic of molecules across the membrane. It is semi-permeable in nature.
Lumen is the hollow portion present inside any organ or tube like the artery or intestine. It is a Latin word that means 'an opening'. The lumen of different organs served various purposes. However, the major function is the transport of substances like air, nutrients, waste materials, immune cells, hormones, etc.
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Answer:
It's impossible to predict the phenotype of the offspring by only observing the parents because DNA from their grandparents can affect the offspring as well.
Explanation:
DNA is combined from the parents to create offspring. When that offspring reproduces their children not only possess DNA from their parents but from their grandparents as well. Mixing together two separate DNA's from two different family trees can result in rare genetic mutations which results in the offspring looking different from their parents but showing resemblance to their grandparents. This is why you have to look at the phenotypes of more then just the two parents because there are more possibilities, including what their grandparents looked like.
I believe it is a 2:1 ratio of hydrogen to oxygen, because the way i learned was that carbon hydrogen and oxygen have a ratio of 1:2:1, respectively.