I believe the answer is During<span> prophase
</span>The nucleus during mitosis. Micrographs illustrating the progressive stages ofmitosis<span> in a plant cell. </span>During<span> prophase, the chromosomes condense, the </span>nucleolus<span>disappears, and the </span>nuclear envelope<span> breaks down. At metaphase, the condensed chromosomes </span>
<span>B. tiny structures in the cell that carry out the cell's activities</span>
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.
Intrasexual selection
Intrasexual Selection is when
members of the same sex within a species contend emulously with each other in
order to acquire chances to mate with others such as the male against male
competition for females. This type of selection often involves posturing and
fighting. Species or individuals suitable for intrasexual selection will possess
developed better weapons than their competitors.
