CELL STRUCTURES AND FUNCTION
CELL STRUCTURE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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All materials can enter and leave the cell
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Certain things can enter while others cannot
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The cell manually sorts through all materials
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Only certain cells can interact with the cell.
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Detailed explanation-1: -Cell membranes serve as barriers and gatekeepers. They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly.
Detailed explanation-2: -The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids. Ions such as H+ or Na+ cannot.
Detailed explanation-3: -It is true that a membrane which allows only certain substances to pass through, but does not allow others to pass through it is called a selectively permeable membrane. For example, the plasma membrane of eukaryotic cells.
Detailed explanation-4: -Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions.
Detailed explanation-5: -The cell membrane is semipermeable (or selectively permeable). It is made of a phospholipid bilayer, along with other various lipids, proteins, and carbohydrates.