Photosynthesis and Cellular Respiration (Exam 2)

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Questions and Answers

What is the main function of photosynthesis in plants?

To convert sunlight into thermal energy

To synthesize carbohydrates from carbon dioxide and water (correct)

To break down glucose into water and carbon dioxide

To absorb oxygen and release carbon dioxide

Which of the following organisms is capable of photosynthesis?

Mammals

Cyanobacteria (correct)

Bacteria

Fungi

What is produced as a byproduct of photosynthesis?

Oxygen (correct)

Carbon Dioxide

Nitrogen

Glucose

Where does the process of photosynthesis primarily occur within plant cells?

Chloroplasts Signup and view all the answers

Which of the following statements about cellular respiration is true?

It converts chemical energy from carbohydrates into ATP Signup and view all the answers

Which component of photosynthesis primarily captures light energy?

Chlorophyll Signup and view all the answers

In photosynthesis, the light-dependent reactions take place in which structure?

Thylakoids Signup and view all the answers

What is the primary purpose of stomata in plant leaves?

To exchange gases Signup and view all the answers

What are the primary sources of methane emissions?

Decomposition in landfills, coal production, and agriculture Signup and view all the answers

Which greenhouse gas is primarily associated with agriculture and fertilizers?

Nitrous oxide Signup and view all the answers

Which evidence suggests a significant rise in global temperatures?

10 of the warmest years on record have occurred in the last 15 years Signup and view all the answers

What is one major contributor to increased ocean acidity since the industrial revolution?

Increased fossil fuel combustion Signup and view all the answers

Which statement accurately reflects the sources of carbon dioxide emissions?

Electricity generation from fossil fuels and transportation are the greatest contributors. Signup and view all the answers

What is the primary role of ATP and NADPH in the Calvin Cycle?

To energize carbon molecules to form G3P Signup and view all the answers

Which molecule exits the Calvin Cycle after formation?

G3P Signup and view all the answers

Which process occurs in the stroma of the chloroplast?

Calvin Cycle Signup and view all the answers

Which substance is generated as a byproduct of the light-dependent reactions?

Oxygen Signup and view all the answers

What is the function of the enzyme Rubisco in the Calvin Cycle?

To catalyze the reaction between CO2 and RuBP Signup and view all the answers

What happens to excess sugars produced in the Calvin Cycle?

They are stored as starch Signup and view all the answers

Which wavelengths of light do plants primarily absorb?

Red and blue light Signup and view all the answers

Which of the following enters the plant through the stomata?

Carbon dioxide Signup and view all the answers

What type of energy is light energy characterized as?

Kinetic energy Signup and view all the answers

Which pigment primarily absorbs red and blue-violet wavelengths of light?

Chlorophyll a Signup and view all the answers

What happens to chlorophyll in deciduous trees during the fall?

It breaks down and conserves. Signup and view all the answers

In photosynthesis, where do light reactions take place?

In the thylakoid membrane Signup and view all the answers

What role do stomata play in photosynthesis?

They open for gas exchange. Signup and view all the answers

What is the primary function of NADP+ in photosynthesis?

To act as the final electron acceptor Signup and view all the answers

What molecule combines with three molecules of atmospheric carbon during the Calvin Cycle?

RuBP Signup and view all the answers

What happens to protons (H+) during the light reactions of photosynthesis?

They accumulate in the thylakoid space. Signup and view all the answers

Which regions accounted for the majority of global carbon dioxide emissions in 2012?

U.S., Europe, and Asia Signup and view all the answers

What is the primary purpose of carbon sequestration?

To remove and store atmospheric carbon dioxide Signup and view all the answers

Which of the following best defines a carbon sink?

An entity that absorbs more carbon dioxide than it releases Signup and view all the answers

Why are carbon dioxide emissions increasing in developing nations?

Because of industrial growth and population increases Signup and view all the answers

What method is commonly associated with enhancing carbon capture?

Injecting carbon dioxide into coal beds Signup and view all the answers

Study Notes

Photosynthesis

Photosynthesis is the process by which plants use sunlight to synthesize foods from carbon dioxide and water.
Photosynthesis requires chlorophyll (green pigment) and generates oxygen as a byproduct.
Photosynthesis involves the conversion of light energy to chemical energy.
Photosynthesis has the following chemical equation:
- 6H2O + 6CO2 → C6H12O6 + 6O2
- Water + Carbon Dioxide → Glucose + Oxygen

Cellular Respiration

Cellular Respiration is the aerobic harvesting of energy.
Aerobic means that cellular respiration requires oxygen.
Cellular Respiration involves the conversion of chemical energy to usable energy (ATP).
Cellular Respiration has the following chemical equation:
- C6H12O6 + 6O2 → 6H2O + 6CO2 + 36ATP + Heat
- Glucose + Oxygen → Water + Carbon Dioxide + ATP + Heat

Organism Photosynthesis

Phytoplankton, cyanobacteria, protists, kelp, flowering plants, conifers, ferns, and mosses can all photosynthesize.

Site of Photosynthesis

Stomata are pores on the leaf where gas exchange occurs.
Chloroplasts are organelles in plants and algae where photosynthesis occurs.
Thylakoids are membranes within the chloroplasts that are the location of photosynthetic pigments.
Stroma is the fluid inside chloroplasts where the Calvin cycle takes place.

Exergonic and Endergonic Reactions

Cellular respiration is exergonic, meaning it releases energy.
Photosynthesis is endergonic, meaning it requires energy.

Light Energy

Light energy is a type of kinetic energy made up of tiny packets of energy called photons.
The wavelength of the photon determines the energy level.
Shorter wavelength = more energy.
Longer wavelength = less energy.

Photosynthetic Pigments

Pigments are molecules that absorb and reflect certain wavelengths of light.
Photosynthetic pigments in plants include:
- Chlorophyll a: absorbs red and blue-violet wavelengths.
- Chlorophyll b: absorbs blue and red-orange wavelengths.
- Carotenoids: absorbs blue-violet and blue-green wavelengths.

Changing Seasons - Changing Leaves

Deciduous trees break down and conserve chlorophyll a and b during the fall months.
Carotenoids in leaves reflect red, yellow, and orange wavelengths of light.

Role of Stomata

Stomata open and close to regulate gas exchange.
When stomata open, water, oxygen, and carbon dioxide can pass through.
When stomata close, water, oxygen, and carbon dioxide can not pass through.

Two Stages of Photosynthesis

Photosynthesis occurs in two stages:
- Light reactions
- Calvin cycle

Light Reactions

Light reactions occur in the thylakoid membrane
In Photosystem II, energy from photons excite electrons in chlorophyll, which are then replaced by splitting water molecules.
Falling electrons power the electron transport chain and ATP production.
Energy from photons excite electrons again in Photosystem I, which are then released to NADP+ to power the Calvin cycle.

Photosystems

Antenna pigments: chlorophyll molecules that gather light energy to transfer to the reaction center.
Reaction center: specialized chlorophyll molecule that loses an electron when it’s excited to a higher energy level.
Primary electron acceptor: molecule that receives the excited electron from the reaction center.

Summary of Light Reactions

Electrons excited in Photosystem II power membrane proteins that pump hydrogen ions (H+) into the thylakoid space.
Hydrogen ions (protons) move down their concentration gradient through ATP synthase, which forms ATP.
Electrons excited in Photosystem I are captured by NADP+ and transported to the Calvin cycle.

Calvin Cycle

The Calvin cycle occurs in the stroma.
Rubisco combines three molecules of atmospheric carbon with three molecules of RuBP.
Three 6-carbon molecules break down into six 3-carbon molecules (3-PGA).
ATP and NADPH from light reactions energize 3-PGA molecules forming six molecules of G3P.
One molecule of G3P exits the Calvin Cycle.
ATP is used to convert the remaining G3P molecules into three molecules of RuBP.

Outputs of the Calvin Cycle

Sugars are used in mitochondria to produce ATP.
G3P is used for plant growth, starch storage, and cellulose production.
Excess sugars can be stored as starch.

Summary of Photosynthesis

Light dependent reactions: Water donates electrons to Photosystem II in the thylakoid meme, which are then excited by light energy and used to make ATP. The electron gets excited again in Photosystem I before being passed to NADP+ to make NADPH. ATP and NADPH move to the Calvin Cycle.
Calvin Cycle: Rubisco in the stroma combines atmospheric CO2 with an existing carbon molecule, which is then transformed by ATP and NADPH from the light reactions to make G3P. G3P goes on to make glucose, starch, and cellulose.

Carbon Dioxide and Global Warming

Atmospheric CO2 has increased above 300 ppm for the first time in recorded history.
The global temperature is rising, with 10 of the warmest years on record occurring in the last 15 years.
Oceans are warming and becoming more acidic, and sea levels are rising.
Ice sheets in Greenland and Antarctica are shrinking.

Sources of Carbon Dioxide

Electricity: the burning of fossil fuels to produce electricity.
Transportation: the combustion of fossil fuels in vehicles.
Industry: the burning of fossil fuels to produce energy and heat.

Carbon Dioxide Capture and Sequestration

Carbon sequestration is the removal and storage of atmospheric carbon dioxide in oceans, terrestrial environments, or geologic formations.
Carbon sinks absorb more carbon dioxide than they release.

Evidence for Climate Change

Sea level rise: Global sea levels rose by about 6.7 inches in the last century.
Global temperature rise: 10 of the warmest years on record have occurred in the last 15 years.
Warming oceans: Oceans have warmed by 0.3°F since 1969.
Shrinking ice sheets: Greenland and Antarctica ice sheets declined by more than 30 cubic miles between 2002-2005.
Ocean acidification: The acidity of oceans' surfaces has increased by 30% since the Industrial Revolution.

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Description

Explore the vital processes of photosynthesis and cellular respiration. Learn how organisms convert sunlight into energy and how they utilize that energy for growth and survival. This quiz covers key equations and examples of organisms involved in these processes.