Cell Transport Exam Questions Flashcards
(15 cards)
Explain the function of this ATP hydrolase.
hydrolyses ADP + Pi into ATP
which releases energy for active transport
The movement of Na+ out of the cell allows the absorption of glucose into the cell lining
the ileum.
Explain how.
maintains a concentration gradient for Na+
so sodium can move in by facilitated diffusion bringing glucose
Describe how amino acids join to form a polypeptide so there is always NH2 at one end and
COOH at the other end.
You may use a diagram in your answer.
One amine/NH2 group joins to a carboxyl/COOH group to form a
peptide bond;
(So in chain) there is a free amine/NH2 group at one end and a free
carboxyl/COOH group at the other
Describe and explain two features you would expect to find in a cell specialised for
absorption.
microvilli to increase surface area for absorption OR folded membrane to increase surface area for absoprtion
large number of carrier proteins for active transport
The student kept constant:
* the mass of fresh blueberries
* the volume of extraction solvent
* the time for the mixture to stand.
Name two other variables the student should have kept constant during this investigation.
temperature
concentration of ethanol
Use your knowledge of membrane structure to explain the results in the graph above.
Higher absorbance indicates more anthocyanin
OR
Higher absorbance indicates more membrane damage/permeability
OR
(G not zero because) some anthocyanin released when blueberries are crushed
OR
(G not zero because) some membrane damage when blueberries are crushed
Describe a method this student could use to prepare colour standards and use them to give
data for the total anthocyanin extracted.
More membrane damage/permeability results in more anthocyanin release
Accept ‘most’ for ‘more’.
(E and F greater than water because) phospholipids dissolve in ethanol;
(E greater than F because) acid denatures membrane proteins
Give two similarities in the movement of substances by diffusion and by osmosis.
both dont require energy from ATP
both move down a conc gradient high -> low
Explain the advantages of lipid droplet and micelle formation.
Droplets increase surface areas (for lipase / enzyme action);
so faster hydrolysis / digestion (of triglycerides / lipids);
Micelles carry fatty acids and glycerol / through the membrane
How is the golgi apparatus involved in absorption of
lipids.
Modifies / processes triglycerides;
Combines triglycerides with proteins;
forms vesicles
Sodium ions from salt (sodium chloride) are absorbed by cells lining the gut. Some of these
cells have membranes with a carrier protein called NHE3.
NHE3 actively transports one sodium ion into the cell in exchange for one proton (hydrogen
ion) out of the cell.
Use your knowledge of transport across cell membranes to suggest how NHE3 does this.
Co-transport;
Uses (hydrolysis of) ATP;
Sodium ion and proton bind to the protein;
Protein changes shape (to move sodium ion and / or proton across the membrane
High absorption of salt from the diet can result in a higher than normal concentration of salt
in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid
explain how
higher salt) results in low water potential of tissue fluid
less water returns to capillary by osmosis at venule end
Describe how an ATP molecule is formed from its component molecules.
adenine, ribose/pentose,
three phosphates
condensation reaction
ATP synthase
Using the graph above and the information provided, what can you conclude about amino
acid uptake by G cells and by H cells?
Amino acid uptake by) active transport;
Cyanide reduces/stops amino acid uptake;
ATP production stops on membrane
Use the graph above to calculate the percentage decrease in the rate of amino acid
absorption by H cells in 30 mmol dm–3 cyanide solution.
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