Biochemistry Answers

For the reaction: A + B = C + D, ∆Go ’= + 1kJ / mol. This reaction will proceed spontaneously in the right direction if: (select one) 

a. the concentration of A increases a hundredfold 

b. the concentration of both A and D decreases a hundredfold 

c. the concentration of B decreases a hundredfold 

d. the concentration of C increases a hundredfold 

e. the concentration of both A and D increases one hundredfold 

Which of the following statements about biological membranes are true? (select one or more) 

a. they are made up mainly of lipids and carbohydrates 

b. contain receptors for specific ligands (stimuli) 

c. they perform energy transformations in photosynthesis and oxidative phosphorylation 

d. are able to generate signals 

e. represent a boundary between the cell and the environment that exhibits selective permeability 

Which of the following statements does not express the meaning of metabolism? (select one) 

a. to convert nutrients taken from the environment into building blocks and precursors of biomolecules 

b. to extract chemical energy from substances obtained from the environment 

c. to synthesize biomolecules from their building blocks 

d. to degrade the biomolecules of the cell 

e. to establish a balance between substances outside the cell and biomolecules in the cell 

Arginine is a metabolite of: (select one) 

a. β-oxidation 

b. the ornithine cycle 

c. the glycolytic chain 

d. the Krebs cycle 

e. the glyoxalate cycle 

Which of the following statements about chemosmotic theory is true? (select one) 

a. electronic transfer in mitochondria is accompanied by asymmetric release of protons in the intermembrane space 

b. the influence of decoupling reagents is a consequence of their ability to transfer electrons across membranes 

c. oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrane 

d. electron transfer and ATP synthesis are inhibited by NADH 

e. membrane ATP synthase has no significant role in chemosmotic theory 

Phosphofructokinase 1 is regulated by: 

a. high [fructose 2,6 - phosphate] - activation 

b. high [ATP] - activation 

c. low [AMP] - activation 

d. high [ATP] and [citrate] - inhibition 

e. high [AMP] - activation 

Which of the reactions catalyzed by the listed enzymes does not produce ammonia? 

a. glutamate pyruvate amino transferase 

b. glutamate decarboxylase 

c. glutamine hydrolase 

d. aspartate deaminase 

e. glutamate dehydrogenase 

The main enzyme (though not the only one) of fatty acid biosynthesis under control is: (select one) 

a. β-hydroxy-β-methyl-glutaryl-CoA synthase 

b. private acid synthase 

c. citrate lyase 

d. acetyl-CoA carboxylase 

e. β-hydroxy-β-methyl-glutaryl-CoA lyase 

Which of the properties of an RNA indicate that it is a ribozyme? 

a. contains amino acids 

b. degraded by proteases 

c. shows substrate specificity 

d. exhibits catalytic action 

e. degraded by nucleases 

Phosphoenolpyruvate carboxykinase is important for metabolism for the following reasons: 

a. use cellular GTP 

b. forms oxaloacetate from phosphoenolpyruvate 

c. overcomes the irreversibility and pyruvate the kinase reaction 

d. stimulates the activity of pyruvate carboxylase 

e. synthesizes alanine in the liver