Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
The ovaries produce the egg cells, called the ova or oocytes. The oocytes are then transported to the fallopian tube where fertilization by a sperm may occur. The fertilized egg then moves to the uterus, where the uterine lining has thickened in response to the normal hormones of the reproductive cycle.
Answer : B is the heaviest puppy amongst all.
Explanation : There are three comparisons shown in the figure, out of which B is assumed to be heaviest amongst all on the basis of following assumptions.
When weighing A and C puppy, A was found to have lighter weight than C. So, in this case C is the heavier puppy.
In second case, when C and D are weighed, both are found to be equal in weight.
Then last comparison was with B and D puppies where, D was observed to be of light weight and B proved to be the heaviest.
Therefore, the conclusion is that B is the heaviest puppy in comparison with rest others.
An intrusion is the action of intruding or intruding. I hope I helped a little!! :-)
ATP is used in cellular activity in living organisms as a source of energy.
