Photosynthesis Overview and Stages

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Questions and Answers

What is the main product of the Calvin Cycle?

Oxygen

Carbon dioxide

Glucose (correct)

ATP

The Calvin Cycle occurs during the day time.

False (B)

What enzyme is responsible for joining carbon dioxide to RuBP in the Calvin Cycle?

Rubisco

Photorespiration occurs when there is insufficient ____.

CO2 Signup and view all the answers

Match the following plant types with their adaptations to limit photorespiration:

CAM plants = Open stomates at night C3 plants = Normal Calvin Cycle C4 plants = Spatial separation of steps Succulents = Store water to survive dry conditions Signup and view all the answers

What are the reactants of the light-dependent reactions of photosynthesis?

Light and water (C) Signup and view all the answers

ATP and NADPH are produced in the light-independent reactions of photosynthesis.

False (B) Signup and view all the answers

What are G3P molecules related to in the Calvin Cycle?

All of the above (D) Signup and view all the answers

Where does the light-dependent stage of photosynthesis occur?

Thylakoid membranes Signup and view all the answers

ATP is used in the Calvin Cycle to regenerate RuBP.

True (A) Signup and view all the answers

In CAM plants, when do stomates close to limit water loss?

During the day Signup and view all the answers

Water is split into hydrogen ions (H+) and ________ during the light-dependent stage.

Oxygen Signup and view all the answers

Match the following components of photosynthesis with their functions:

Chlorophyll = Absorbs light energy NADPH = Carries energy to the Calvin Cycle CO2 = Reactant in the Calvin Cycle Stomata = Site for gas exchange Signup and view all the answers

What is the primary purpose of the light-dependent reactions?

To generate ATP and NADPH (B) Signup and view all the answers

The Calvin Cycle occurs in the thylakoid membranes of the chloroplast.

False (B) Signup and view all the answers

What ion channels facilitate the movement of hydrogen ions (H+) during photosynthesis?

Ion channels Signup and view all the answers

Study Notes

Photosynthesis Overview

Photosynthesis is the process by which plants convert carbon dioxide and water into sugars, using sunlight as energy.
The overall equation for photosynthesis is: CO2 + H2O + Sunlight → C6H12O6 + O2 (Carbon dioxide + Water + Sunlight → Glucose + Oxygen)
The process occurs in chloroplasts, specifically within the thylakoid membranes and stroma.

Stages of Photosynthesis

Photosynthesis is divided into two main stages:
- Light-dependent reactions
- Light-independent reactions (Calvin cycle)

Light-Dependent Reactions

Location: Thylakoid membranes within chloroplasts.
Reactants: Sunlight and water
Process:
- Light energy is absorbed by chlorophyll.
- Water is split into hydrogen ions (H+) and oxygen.
- High-energy electrons are passed down an electron transport chain.
- This process creates ATP and NADPH, which are energy carriers.
- Oxygen is released as a byproduct.
Products: ATP, NADPH, and oxygen.

Light-Independent Reactions (Calvin Cycle)

Location: Stroma of chloroplasts.
Reactants: ATP, NADPH, and carbon dioxide.
Process:
- Carbon dioxide is "fixed" into an organic molecule (glucose).
- Energy from ATP and NADPH is used to convert 3-carbon molecules into a 6-carbon sugar, glucose.
Products: Glucose (sugar).

Factors Affecting Photosynthesis

CO2 Concentration: At low CO2 levels, the rate of photosynthesis is limited. More CO2 leads to a higher photosynthesis rate until a point, where it plateaus as CO2 is no longer the limiting factor.
Light Intensity: Increasing light intensity increases the rate of photosynthesis up to a certain point, after which it plateaus.
Temperature: Photosynthesis has an optimum temperature range. Temperatures above or below this range will negatively affect the rate of photosynthesis.

Limiting Factors

In a metabolic pathway, if one factor is low, the reaction is slowed. The factor closest to its minimum is the limiting factor.
Light intensity: Low light intensity slows ATP and NADPH production, rarely the limiting factor.
CO2 concentration: Low atmospheric CO2 is often the limiting factor.
Temperature: Low temperature slows enzyme-catalyzed reactions. High temperature can denature Rubisco, preventing carbon fixation.

Photosynthesis Adaptations in Plants

CAM plants: Plants in hot, dry environments have adaptations to reduce photorespiration, closing their stomata during the day to prevent water loss. They take in CO2 at night to store for use during the day, thus reducing competition with oxygen.

Summary of crucial information

Photosynthesis is fundamental to life on Earth.
It involves converting light energy into chemical energy in the form of sugars.
Two main stages (light-dependent & light-independent) work together.
Various environmental factors influence the rate of photosynthesis.

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Description

Explore the fascinating process of photosynthesis, where plants convert sunlight into energy. This quiz will cover the overall equation, the stages involved: light-dependent and light-independent reactions, and the specific processes happening in chloroplasts. Test your knowledge on the mechanisms that sustain life on Earth!