Download Name: Date: Concept Check Questions Chapter 8 (orange) or 6

Name: ________________________________________ Date: _______________________
Concept Check Questions
Chapter 8 (orange) or 6 (green)
An Introduction to Metabolism
8.1 An organism’s metabolism transforms matter and energy, subject to the laws of
thermodynamics
1. How does the second law of thermodynamics help explain the diffusion of a substance
across a membrane?
2. What is the relationship between energy and work?
3. Describe the forms of energy found in an apple as it grows on a tree, then falls and is
digested by someone who eats it.
8.2 The free energy change of a reaction tells us whether the reaction occurs spontaneously
1. Cellular respiration uses glucose, which has a high level of free energy, and releases CO2
and water, which have low levels of free energy. Is respiration spontaneous or not? Is it
exergonic or endergonic? What happens to the energy released from glucose?
2. A key process in metabolism is the transfer of H+ ions across a membrane to create a
concentration gradient. In some conditions, H+ ions flow back across the membrane and
come to equal concentrations on each side. In which conditions can the H+ ions perform
work in this system?
8.3 ATP powers cellular work by coupling exergonic reactions to endergonic reactions
1. In most cases, how does ATP transfer energy from exergonic to endergonic processes in
the cell?
2. Which of the following groups had more free energy: glutamic acid + ammonia + ATP,
or glutamine + ADP + Pi? Explain.
8.4 Enzymes speed up metabolic reactions by lowering energy barriers
1. Many spontaneous reactions occur very slowly. Why don’t all spontaneous reactions
occur instantaneously?
2. Describe why enzymes act only on very specific substrates.
3. Malonate is a competitive inhibitor for the enzyme succinate dehydrogenase. Describe
how malonate would prevent the enzyme from acting on its normal substrate succinate.
8.5 Regulation of enzyme activity helps control metabolism
1. How can an activator and an inhibitor have different effects on an allosterically regulated
enzyme?