* not completed

. Which of the following statements about the lipid constituents of membranes is correct?

Lateral movement of membrane lipids is catalysed by special proteins. correct incorrect

The inner and outer halves of the lipid bilayer are identical. correct incorrect

Lateral movement of membrane lipids occurs rapidly within the plane of the bilayer. correct incorrect

Transverse movement of membrane lipids within the bilayer is unrestricted. correct incorrect

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. Which of the following statements about membrane fluidity is correct?

Membrane fluidity is increased when there is a high proportion of trans unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer. correct incorrect

Membrane fluidity is decreased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer. correct incorrect

Membrane fluidity is increased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer. correct incorrect

Membrane fluidity is increased when there is a high proportion of saturated fatty acids in the glycerophosphate molecules that make up the bilayer. correct incorrect

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. Which of the following statements about membrane proteins is not correct?

Integral membrane proteins have ends rich in hydrophilic amino acids. correct incorrect

Integral membrane proteins are anchored to the lipid bilayer by ionic bonds. correct incorrect

Transmembrane porins have hydrophilic amino acids that point inwards in the -barrels. correct incorrect

Integral membrane proteins have transmembrane domains rich in hydrophobic amino acids. correct incorrect

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. Which of the following statements about the functions of cell membranes is not correct?

Cell membranes maintain the shape of cells. correct incorrect

Cell membranes retain the contents of cells. correct incorrect

Cell membranes are impermeable to most molecules. correct incorrect

Cell membranes are permeable to most inorganic ions. correct incorrect

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. Which of the following statements about the mechanism of the Na⁺/K⁺ pump is correct?

The Na⁺/K⁺ ATPase uses energy to pump Na⁺ outside the cell and K⁺ inside. correct incorrect

The Na⁺/K⁺ ATPase uses energy to pump Na⁺ inside the cell and K⁺ outside. correct incorrect

The Na⁺/K⁺ ATPase uses energy to bind both Na⁺ and K⁺ in turn. correct incorrect

The phosphorylation of the Na⁺/K⁺ ATPase does not change its conformation. correct incorrect

* not completed

. Which is an important function of cholesterol in cell membranes?

It increases the fluidity of the membrane at 37⁰ C. correct incorrect

It acts as a fluidity barrier in bacterial membranes. correct incorrect

It stabilises the structure of mammalian membranes. correct incorrect

It allows polar substances to pass through the membrane.
correct incorrect

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. 07) What is the undesirable effect of dietary trans fatty acids?

They insert into cell membranes and affect the fluidity. correct incorrect

They increase the levels of low density lipoprotein in the blood. correct incorrect

They decrease circulating triacylglycerols. correct incorrect

They compete with polyunsaturated fatty acids for eicosanoid synthesis. correct incorrect

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. 08) Which of the following statements about the mechanism of the Na+ /K+ ATPase pump is correct?

In the Na+ /K+ ATPase pump Na+ is pumped into the cell when the protein is dephosphorylated. correct incorrect

In the Na+ /K+ ATPase pump Na+ is pumped out of the cell when the protein is phosphorylated. correct incorrect

Cardiac glycosides inhibit the Na+ /K+ ATPase pump by preventing its phosphorylation by ATP. correct incorrect

In the Na+ /K+ ATPase pump Na+ is pumped into the cell when the protein is phosphorylated. correct incorrect

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. 09) Which of the following statements about the transport of substances through a cell membrane is correct?

Small polar molecules can diffuse through a cell membrane along a concentration gradient. correct incorrect

Small polar molecules require specific transport systems for passage across a membrane. correct incorrect

Small polar molecules cannot be transported through a cell membrane against a concentration gradient. correct incorrect

Small inorganic ions can diffuse through a cell membrane along a concentration gradient. correct incorrect

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. 10) Which of the following statements about ATP-binding cassette (ABC) proteins is incorrect?

A number of genetic diseases are associated with deficiencies in ATP-binding cassette (ABC) proteins. correct incorrect

ATP-binding cassette (ABC) proteins have ATP-binding transmembrane domains. correct incorrect

The multidrug resistance protein (MDR protein) is an ATP-binding cassette (ABC) protein. correct incorrect

ATP-binding cassette (ABC) proteins have ATP-binding cytoplasmic domains. correct incorrect

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. Which of the following is not a constituent of cell membranes?

triacylglycerol correct incorrect

Phosphatidyl ethanolamine correct incorrect

cholesterol correct incorrect

lecithin correct incorrect

* not completed

. The sodium/glucose transport system in the intestine is an example of which type of transport process?

Active transport. correct incorrect

Facilitated diffusion. correct incorrect

Secondary active transport. correct incorrect

Antiport. correct incorrect

* not completed

. What is the function of the protein spectrin?

It forms ion gated channels across cell membranes. correct incorrect

It is involved in sodium/calcium antiport systems. correct incorrect

It preserves the shape and flexibility of the erythrocyte membrane. correct incorrect

It stabilises phospholipids found in the fluid mosaic structure of plasma membranes. correct incorrect