The structure of plasma membrane makes it selectively permeable allowing it to regulate the passage of substances into and out of the cell. Small nonpolar molecules can easily across the phospholipid bilayer of plasma membrane because it is hydrophobic. Polar molecules and ion cannot easily across the hydrophobic portion of plasma membrane because it is hydrophilic. Polar molecules and ions usually across the plasma membrane with the help of transport proteins.
oxygen can only hold two bonds with other elements.
A salt or ester of phosphoric acid, containing PO43− or a related anion or a group such as —OPO(OH)2.
Answer: C
Explanation: The two chromatids of a duplicated chromosome are held together at a region of DNA called the centromere. Centromeres are the attachment points for microtubules, which are responsible for the guiding the movement of chromosomes during mitosis and meiosis.
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