Biology 8: Plant Needs and Photosynthesis

Plant Requirements

• Plants require water, small amounts of minerals, and carbon dioxide alongside sunlight to thrive.

Plant Contributions

• Plants provide essential food and oxygen to ecosystems.

Oxygen Release Mechanism

• During photosynthesis, plants split water molecules, using their components while releasing oxygen as a byproduct.

Photosynthesis Definition

• Photosynthesis is the process where certain organisms capture solar energy and convert it into chemical energy stored in carbohydrates.

Photosynthesis Formula

• The chemical equation for photosynthesis is 6CO2 + 6H2O --> C6H12O6 + 6O2.

Light Spectrum in Photosynthesis

• Photosynthesis primarily utilizes blue and red light wavelengths from the visible spectrum.

Location of Photosynthesis

• Photosynthesis occurs within chloroplasts in plant cells.

Role of Stomata

• Stomata are tiny openings on leaves that allow carbon dioxide to enter and water vapor to exit the plant.

Chloroplast Structure

• Chloroplasts contain a network of thylakoids surrounded by a fluid called stroma.

Stroma Function

• Stroma is the liquid in chloroplasts that hosts the Calvin cycle, where carbon dioxide and high-energy sugars are produced.

Pigments

• Compounds that absorb specific visible wavelengths of sunlight are referred to as pigments.

Primary Photosynthesis Pigment

• Chlorophyll a is the main pigment involved in plant photosynthesis.

Function of Chlorophyll a

• Chlorophyll a absorbs sunlight energy and transfers it to other molecules.

Light Reactions Overview

• In the light reactions, sunlight energizes electrons by stripping them from water, leading to their attachment to the mobile electron carrier NADP.

Calvin Cycle Overview

• The Calvin cycle is the stage where high-energy sugar is produced by combining electrons with carbon dioxide, occurring in the stroma.

Photosystems

• Photosystems are complexes of molecules within thylakoid membranes that capture solar energy and convert it into chemical energy.

Reaction Center

• The reaction center, consisting of specialized chlorophyll a molecules, converts absorbed solar energy into chemical energy.

Electron Transfer Process

• The process of electron transfer involves moving electrons uphill to the primary electron acceptor, then downhill through the electron transport chain, eventually reaching NADP.

Energy Transfer in Light Reactions

• Light reactions involve a series of redox reactions, where electrons are passed among carriers, oxidizing one while reducing another.