International AS Biology Cell Membrane Structure Assessment

What was a key finding that helped falsify the Davson-Danielli Model through freeze-etched electron micrographs?

• Proteins were found only on the outer surface

• Proteins were discovered throughout the membrane

• Phospholipids were arranged randomly

• The membrane had no proteins

In the Singer-Nicolson Fluid Mosaic Model, how are proteins arranged in the membrane?

• Only on the outer surface

• Only on the inner surface

• Embedded throughout the membrane in various ways

• In a single uniform layer

What characteristic of membrane proteins was revealed through biochemical extraction techniques?

• They are all the same size

• They are completely hydrophilic

• They are flat and structural

• They are globular and varied in size

What did the fluorescent antibody tagging experiment of 1972 demonstrate?

• Proteins were fixed in place

• Membrane proteins could move freely

• Proteins were only on cell surfaces

• The membrane was rigid

Which component forms the primary barrier of the cell membrane?

• Cholesterol

• Integral proteins

• Phospholipids

• Peripheral proteins

What is the defining characteristic of phospholipids in the cell membrane?

• They are completely hydrophobic

• They are completely hydrophilic

• They are amphipathic

• They are neutral

What is the composition of phospholipid tails?

• Phosphate groups

• Hydrocarbon chains

• Protein strands

• Cholesterol molecules

Which type of membrane protein is not embedded in the membrane?

• Peripheral proteins

• Transmembrane proteins

• Integral proteins

• Transport proteins

What is the role of cholesterol in the cell membrane?

• It provides protein attachment sites

• It increases membrane fluidity

• It blocks all substance movement

• It creates membrane pores

What property allows integral proteins to be embedded in the membrane?

• Complete hydrophilia

• Partial hydrophobicity

• Complete neutrality

• Negative charge