AP Biology Practice Quiz: Photosynthesis and Cellular Respiration

This equation correctly shows that carbon dioxide and water, using light energy, are converted into glucose and oxygen during photosynthesis. It summarizes the overall process accurately.

The mitochondrion is known as the powerhouse of the cell where cellular respiration occurs to convert nutrients into ATP. Other organelles have different functions in the cell.

Photosynthesis is divided into the light-dependent reactions and the Calvin cycle (light-independent reactions). The other options refer to processes that are part of cellular respiration or are unrelated to photosynthesis.

Chlorophyll is the primary pigment responsible for absorbing light energy in plants. While other pigments also absorb light, chlorophyll plays the central role in photosynthesis.

The Calvin cycle occurs in the stroma of the chloroplast, where the light-independent reactions take place. The thylakoid membranes are the site of the light-dependent reactions.

NADH is the primary electron carrier in cellular respiration, shuttling electrons to the electron transport chain for ATP production. Although FADH2 also carries electrons, NADH plays a more significant role.

The Krebs cycle takes place in the mitochondrial matrix, where it metabolizes pyruvate into electron carriers. This is a vital step in cellular respiration before the electron transport chain.

Water is split (photolysis) during the light-dependent reactions, yielding electrons, protons, and oxygen. This process is essential for replacing electrons lost by chlorophyll and for oxygen production.

ATP synthase uses the proton gradient created by the electron transport chain to convert ADP into ATP. This process is fundamental to energy production in the cell.

The Calvin cycle uses the energy from ATP and NADPH produced in the light-dependent reactions to fix CO2 into organic sugars. This process is key to converting light energy into chemical energy.

Oxidative phosphorylation, which occurs in the electron transport chain, produces the majority of ATP in cellular respiration. This process efficiently generates ATP compared to other steps.

Cytochrome c shuttles electrons between complexes in the electron transport chain, facilitating the production of ATP. Its role is critical to the efficiency of the process.

Light intensity is a key factor affecting the rate of photosynthesis as it influences the energy available for the light-dependent reactions. The other factors have lesser or indirect effects.

The thylakoid membranes, arranged in grana, provide a large surface area for the absorption of light, thus enhancing photosynthetic efficiency. This specialized structure is key to optimizing light capture.

Pyruvate is the end product of glycolysis and is subsequently converted into acetyl-CoA to enter the Krebs cycle. This link between glycolysis and the Krebs cycle is essential for cellular respiration.

Phosphofructokinase is a key regulatory enzyme in glycolysis that adjusts its activity based on the cell's ATP levels. This regulation ensures that glycolysis meets energy demands efficiently without wasting resources.

RuBisCO is essential for carbon fixation in the Calvin cycle, and a deficiency would lead to reduced incorporation of CO2 into organic molecules. This impairment would hinder the overall process of photosynthesis.

Chemiosmosis takes place in the mitochondria during cellular respiration, while photophosphorylation occurs in the chloroplasts during photosynthesis. They also use different sources of electrons, resulting in distinct processes.

Proper oxygen concentration ensures that electrons are transferred efficiently to oxygen, which is the final electron acceptor. This regulation helps prevent the formation of harmful reactive oxygen species.

Photosynthesis and cellular respiration are interconnected processes; photosynthesis generates oxygen and organic compounds for respiration, while respiration provides CO2 for the Calvin cycle. This synergy maintains the balance of gases and energy flow in ecosystems.