Chapter 7 Final Study Guide

1. The light reactions take place in the region of the chlorplast call the_____, while the Calvin cylcle takes place in the ______.

The light reactions of photosynthesis occur in the thylakoid region of the chloroplast. This is where light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH. The Calvin cycle, on the other hand, takes place in the stroma of the chloroplast. In this stage, ATP and NADPH produced during the light reactions are used to convert carbon dioxide into glucose through a series of enzyme-mediated reactions.

Explanation

The light reactions of photosynthesis occur in the thylakoid region of the chloroplast. This is where light energy is absorbed by chlorophyll and converted into chemical energy in the form of ATP and NADPH. The Calvin cycle, on the other hand, takes place in the stroma of the chloroplast. In this stage, ATP and NADPH produced during the light reactions are used to convert carbon dioxide into glucose through a series of enzyme-mediated reactions.

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2. When light strikes cholorphyll molecules, they lose electrons, which are ultimately replaced by splitting a molecule of_____.

When light strikes chlorophyll molecules, they undergo a process called photosynthesis. During this process, the chlorophyll molecules lose electrons, which are ultimately replaced by splitting a molecule of water (H2O). This splitting of water molecules releases oxygen and provides the electrons needed for the chlorophyll molecules to carry out photosynthesis and produce energy in the form of ATP.

Explanation

When light strikes chlorophyll molecules, they undergo a process called photosynthesis. During this process, the chlorophyll molecules lose electrons, which are ultimately replaced by splitting a molecule of water (H2O). This splitting of water molecules releases oxygen and provides the electrons needed for the chlorophyll molecules to carry out photosynthesis and produce energy in the form of ATP.

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3. The combustion of fossil fuels may be contributing to global warming mainly by raising atmospheric concentrations of_____.

The combustion of fossil fuels releases carbon dioxide (CO2) into the atmosphere. CO2 is a greenhouse gas that traps heat in the Earth's atmosphere, contributing to the greenhouse effect and global warming. As the concentration of CO2 increases in the atmosphere, more heat is trapped, leading to rising temperatures and climate change. Therefore, the combustion of fossil fuels, such as coal, oil, and natural gas, is a significant contributor to global warming through the release of CO2.

Explanation

The combustion of fossil fuels releases carbon dioxide (CO2) into the atmosphere. CO2 is a greenhouse gas that traps heat in the Earth's atmosphere, contributing to the greenhouse effect and global warming. As the concentration of CO2 increases in the atmosphere, more heat is trapped, leading to rising temperatures and climate change. Therefore, the combustion of fossil fuels, such as coal, oil, and natural gas, is a significant contributor to global warming through the release of CO2.

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4. Which of the following are produced by reactions tha take place in the thylakoids and are consumed by reactions in the stroma?

CO2 and H2O

NADP+ and ADP

ATP and NADPH

Glucose and O2

ATP and NADPH are produced by reactions that take place in the thylakoids during the light-dependent reactions of photosynthesis. These molecules are then consumed by reactions in the stroma during the light-independent reactions (Calvin cycle) to convert carbon dioxide into glucose. CO2 and H2O are reactants in the light-independent reactions, while NADP+ and ADP are not directly involved in the production or consumption of molecules in the thylakoids and stroma.

Explanation

ATP and NADPH are produced by reactions that take place in the thylakoids during the light-dependent reactions of photosynthesis. These molecules are then consumed by reactions in the stroma during the light-independent reactions (Calvin cycle) to convert carbon dioxide into glucose. CO2 and H2O are reactants in the light-independent reactions, while NADP+ and ADP are not directly involved in the production or consumption of molecules in the thylakoids and stroma.

5. Of the following metabolic processes, which one is common to photosynthesis and cellular respiration?

Reactions that convert light energy to chemical energy

Reactions that split H2O molecules and release O2

Reactions that store energy by pumping H+ across membranes

Reactions that convert CO2 to sugar

The correct answer is "reactions that store energy by pumping H+ across membranes." This metabolic process, known as chemiosmosis, occurs in both photosynthesis and cellular respiration. In photosynthesis, H+ ions are pumped across the thylakoid membrane during the light-dependent reactions, creating a proton gradient that is used to produce ATP. In cellular respiration, H+ ions are pumped across the inner mitochondrial membrane during the electron transport chain, creating a proton gradient that is used to produce ATP.

Explanation

The correct answer is "reactions that store energy by pumping H+ across membranes." This metabolic process, known as chemiosmosis, occurs in both photosynthesis and cellular respiration. In photosynthesis, H+ ions are pumped across the thylakoid membrane during the light-dependent reactions, creating a proton gradient that is used to produce ATP. In cellular respiration, H+ ions are pumped across the inner mitochondrial membrane during the electron transport chain, creating a proton gradient that is used to produce ATP.