Question
European flycatchers feed caterpillars to their hatchlings. Graph 1 shows the average dates of hatching and fledging (leaving the nest), and the biomass of the caterpillars between early May (when flycatcher young hatch) and June (when fledging of young occurs).
Based on the data, scientists claim that the reproductive behavior of European flycatchers is influenced by the availability of energy sources. Which of the following statements best justifies this claim?
A. Young European flycatchers hatch from eggs when caterpillar biomass is available for the young birds to consume and convert into energy for growth.
B. European flycatcher hatchlings begin to need energy to leave the nest only after the caterpillars have turned into pupae.
C. Female European flycatchers require energy to lay eggs, so they lay their eggs when the caterpillar biomass is maximal.
D. The energy requirements for hatching European flycatchers and caterpillars are proportional to each other.
▶️Answer/Explanation
Ans: A
The date of European flycatchers hatching matches the date when the peak biomass of caterpillars is available, ensuring better odds of survival for young flycatchers.
Question
A researcher claims that the incorporation of carbon dioxide into organic molecules during photosynthesis does not violate the second law of thermodynamics.
Which of the following statements best helps justify the researcher’s claim?
A. Organisms contain enzymes that lower the activation energies of specific chemical reactions.
B. An ecosystem is formed by the interaction of a community of organisms with their surrounding environment.
C. Photosynthetic organisms use the organic molecules produced during photosynthesis for growth and repair.
D. The total system that includes photosynthetic organisms and the Sun becomes less ordered over time.
▶️Answer/Explanation
Ans: D
Because the total system that includes photosynthetic organisms and the Sun becomes less ordered over time, the incorporation of carbon dioxide molecules into organic molecules that occurs during photosynthesis does not violate the second law of thermodynamics.
Question
Brown fat is a type of fat tissue found in hibernating mammals. Inside the mitochondria of these fat tissue cells, these mammals have an uncoupling protein embedded in the inner mitochondrial membrane. This uncoupling protein allows hydrogen ions to leak from the intermembrane space back into the mitochondrial matrix. Figure 1 shows details of the processes in the inner mitochondrial membrane.
Which of the following statements provides reasoning that supports the claim that brown fatty tissue keeps an animal warm?
A. The uncoupling protein in this tissue increases the production of ATP and causes more body heat to be produced to warm the animal.
B. The uncoupling protein in this tissue reduces the proton gradient across the membrane and thus produces heat to warm the animal without ATP production.
C. The uncoupling protein in this tissue causes an increase in the proton gradient, which causes more ATP to be produced that helps to warm the animal.
D. The uncoupling protein in this tissue reduces the production of ATP and creates an increase in the proton gradient that allows more heat energy to be produced to warm the animal.
▶️Answer/Explanation
Ans: B
The uncoupling protein causes a reduction in the proton gradient across the inner mitochondrial membrane because protons constantly leak into the matrix. Heat energy is released as the protons move, but less ATP is made because of the decreased concentration of hydrogen ions available to move across ATP synthase.
Question
A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (\(P_i\)) is essential to cellular function.
Which of the following statements best helps justify the researcher’s claim?
A. ADP is a small molecule that some cells release into their environment as a way of communicating with other cells.
B. ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.
C. Inorganic phosphate (\(P_i\)) is a substance that cells typically acquire from their environment.
D. ATP synthase is a mitochondrial enzyme that catalyzes the conversion of ADP and \(P_i\) to ATP.
▶️Answer/Explanation
Ans: B
Many cellular processes necessary for maintaining the internal organization of the cell are coupled with the hydrolysis of ATP. Without a supply of ATP, these activities will stop and the cells will die.
Question
A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair.
Which of the following observations best helps justify the researcher’s claim?
A. Light-capturing pigment molecules in green plants absorb red, blue, and violet light but reflect green light.
B. The energy of a photon of light is proportional to its frequency and inversely proportional to its wavelength.
C. As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.
D. Captured energy is stored in the molecular bonds of organic molecules, including simple sugars and starch.
▶️Answer/Explanation
Ans: C
During photosynthesis, some of the captured light energy is lost to the environment in the form of heat energy. As a result, only some of the captured light energy is converted to chemical energy and stored for later use in growth and repair.