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Multiple Choice
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
A
Phospholipids are completely unable to interact with water.
B
Phospholipids form a single sheet in water.
C
Phospholipids form a structure in which the hydrophobic portion faces outward.
D
They are triacylglycerols, which are commonly available in foods.
E
Phospholipids form a selectively permeable structure.
Verified step by step guidance
1
Understand the basic structure of phospholipids: Phospholipids consist of a hydrophilic (water-attracting) 'head' and two hydrophobic (water-repelling) 'tails'. This amphipathic nature is crucial for their function in biological membranes.
Recognize the arrangement of phospholipids in a membrane: In an aqueous environment, phospholipids arrange themselves into a bilayer, with hydrophilic heads facing the water on both sides and hydrophobic tails facing each other, away from the water.
Identify the role of phospholipids in membrane permeability: The bilayer structure creates a selectively permeable barrier, allowing certain molecules to pass through while blocking others, which is essential for maintaining cellular homeostasis.
Clarify the misconception about phospholipids interacting with water: While the hydrophobic tails avoid water, the hydrophilic heads interact with water, allowing the formation of the bilayer structure.
Differentiate phospholipids from triacylglycerols: Triacylglycerols are fats commonly found in foods and are not involved in forming biological membranes. Phospholipids, on the other hand, are key components of cell membranes due to their unique structural properties.