Biology - Photosynthesis, Carbon Cycle and Climate Change Test

How is the amount of CO2 released into the atmosphere affected by seasonal changes?

In summer, more leaves are present for photosynthesis, which takes CO2 out of the atmosphere. In winter, leaves are dead, resulting in no photosynthesis.

What are several pieces of evidence that our climate is changing?

Rising temperatures, melting ice caps and glaciers, extreme weather events, rising sea levels.

What are several causes of Global Warming?

Burning fossil fuels (cars), agriculture (livestock), factories (cement), deforestation.

What are several effects of Global Warming?

Impacts on farming, electricity and heating, ocean acidification, changes in wildlife activity.

What are some potential ways we can help slow the rate of global warming?

Drive less and use fuel-efficient or electric cars, use public transportation, turn off lights, lower heat/AC use, consume less meat and cheese, use alternative energy sources, buy less stuff.

What is the carbon cycle?

The process of moving carbon from inorganic to organic and back again.

How do photosynthesis and cellular respiration fit into the carbon cycle?

Photosynthesis uses CO₂ to build glucose; cellular respiration uses glucose and makes CO₂.

Where is carbon stored? What are the largest carbon reservoirs?

Carbon is stored in water, trees/plants, soil, Earth's crust, fossil fuels, and the atmosphere.

What is carbon flux?

A way carbon is exchanged.

Give examples of carbon flux.

Cellular respiration, decomposition, burning fossil fuels, photosynthesis.

Describe the Greenhouse Effect.

Gases in the atmosphere trap heat.

What gases cause the Greenhouse Effect?

CO₂, H₂O, methane.

What would happen without the Greenhouse Effect?

Earth would be too cold to support life.

Why is the Greenhouse Effect an issue today?

Too much gas means it's getting warmer.

What have been the recent trends in amounts of atmospheric CO₂?

CO₂ is increasing at a rapid rate.

Is the recent trend in atmospheric CO₂ different from the trend over the past two thousand years?

Yes, it began to differ around the time of the industrial revolution, approximately 258 years ago. It has worsened even more since around 1950.

How are Pika being affected by climate change?

Pika have a high metabolism and body temperature, making them sensitive to heat and cold. Warmer temperatures lead to less food and water, and less snow for insulation.

What is happening to the ice in the Arctic due to climate change?

The Arctic sea ice is decreasing.

How does having more Arctic ice help decrease global warming?

The ice reflects heat back to space; less ice means more absorption of light energy into oceans and land.

What is a dead zone?

A dead zone is an area with no fish and plant life due to high biological oxygen demand (BOD) and low dissolved oxygen (D.O.).

What causes eutrophication?

Eutrophication is caused by excess nitrogen from fertilizer runoff into water sources like lakes, rivers, and streams.

What happens to dissolved oxygen (D.O.) during eutrophication?

Dissolved oxygen decreases as BOD increases.

What happens to biological oxygen demand (B.O.D.) during eutrophication?

Biological oxygen demand increases due to the decomposition of organic matter.

What role do decomposers play in eutrophication?

Decomposers break down organic matter, consuming oxygen and contributing to low D.O. levels.

What are the two stages involved in photosynthesis?

Light-dependent and light-independent reactions

Where do the light-dependent reactions occur?

In the thylakoid membrane

Where do the light-independent reactions occur?

In the stroma

How are the light-dependent reactions and the light-independent reactions interconnected?

One's products are the other's reactants

What is the purpose of the light reactions?

To use energy from sunlight to produce ATP, NADPH, and oxygen

Where do electrons come from in the photosystems?

From H₂O in Photosystem II

Where do electrons go in the photosystems?

To NADP+ via the electron transport chain (ETC) in Photosystem I

What is the overall formula for photosynthesis?

6 CO₂ + 6H2O + light energy -> C6H12O6 + 6O₂

Is energy entering or being released by the process of photosynthesis?

Energy is entering.

What is a pigment?

Molecules that absorb a certain type of light energy.

What is the main pigment found in chloroplasts that is involved in photosynthesis?

Chlorophyll.

Why do we see plants as green?

The light reflects into a shade we perceive off the pigment, absorbing all wavelengths of light except green.

What happens in Photosystem II?

It absorbs energy, splits water into hydrogen ions and oxygen, and energizes electrons.

What is the function of both Photosystems?

They capture sunlight energy and use it to energize electrons in chlorophyll.

What occurs in the Electron Transport Chain?

High-energy electrons are transported, allowing for the active transport of hydrogen ions.

What happens to electrons after the Electron Transport Chain?

They are ultimately used to convert NADP+ into NADPH.

What is the role of ATP synthase?

H+ ions diffuse through it, driven by a concentration gradient, to produce ATP.

What is produced when water is split in Photosystem II?

Hydrogen ions and oxygen.

What do the energized electrons from Photosystem I produce?

NADPH.

What are the reactants of the light reactions?

H₂O, NADP+, ADP + P, H+

What are the products of the light reactions?

O₂, NADPH, ATP

Where is NADPH used?

In the light-independent reactions

Where is ATP used?

In the light-independent reactions

What is produced from water in the light reactions?

O₂

What are the three main steps of the Calvin Cycle?

1. Carbon fixation: CO₂ + RUBP forms PGA. 2. Energy investment: PGA → G3P, ATP donates phosphates, NADPH donates electrons. 3. Carbon recycling: G3P donates H and electrons back to RuBP.

What is the main purpose of the Calvin Cycle?

To turn carbon dioxide into glucose.

What is G3P from the Calvin Cycle ultimately used to build?

More G3P and glucose.

How many cycles does it take to make one glucose?

2 cycles.

What are the reactants of the Calvin Cycle?

CO2

What is produced from CO2 in the Calvin Cycle?

PGA

What is produced from PGA in the Calvin Cycle?

G3P

What is the final product that regenerates RuBP in the Calvin Cycle?

G3P

What does G3P convert back to in the Calvin Cycle?

RuBP