Honors Bio

What is the basic structure of a chloroplast?

A chloroplast has an outer membrane, stroma, grana, thylakoids, and lumen.

What is the function of the outer membrane of a chloroplast?

It protects everything inside the chloroplast.

The fluid inside the chloroplast where some reactions happen.

What is the stroma in a chloroplast?

What are grana in a chloroplast?

Stacks of thylakoids where light reactions occur.

What are thylakoids?

Disk-shaped structures inside the grana where light reactions happen.

What is the lumen in a thylakoid?

The inside of the thylakoid, important for the flow of H⁺ ions during ATP production.

What are the two main stages of photosynthesis?

Light reactions and the Calvin cycle.

Where do light reactions occur?

In the thylakoid membranes.

What are the inputs needed for light reactions?

Sunlight, H2O, ADP, and NADP⁺.

What are the products of light reactions?

ATP, NADPH, and O2.

What is the purpose of light reactions?

To turn light energy into high-energy molecules for the Calvin cycle.

What happens during the Calvin cycle?

CO2 is converted into glucose using ATP and NADPH.

Where does the Calvin cycle occur?

In the stroma.

What are the inputs needed for the Calvin cycle?

CO2, ATP, and NADPH.

What is the end product of the Calvin cycle?

Glucose (C6H12O6).

What is the role of chlorophyll in photosynthesis?

It absorbs sunlight and captures light energy.

What is the role of ATP and NADPH in photosynthesis?

They are energy carriers made in light reactions.

What is the significance of CO2 in photosynthesis?

It is the carbon source for glucose.

What is the source of electrons and oxygen in photosynthesis?

Water (H2O).

What are autotrophs?

Organisms that make their own food using energy from nonliving sources.

What are photoautotrophs?

Organisms that use sunlight to make food through photosynthesis.

What are chemoautotrophs?

Organisms that use chemicals to convert inorganic molecules into organic molecules.

What is the electromagnetic spectrum?

All the different types of light energy, ranging from high-energy, short wavelength to low-energy, long wavelength.

How do plants use light energy from the electromagnetic spectrum?

To cause chemical changes in molecules, powering photosynthesis.

What color light do chlorophyll absorb?

Red and blue light.

What color light do chlorophyll reflect?

Green light.

What is the mnemonic for the stages of photosynthesis?

Water, Sun, Split, Charge, Sugar!

What is the relationship between wavelength and energy?

Short wavelength corresponds to high energy, and long wavelength corresponds to low energy.

What happens to ADP and NADP⁺ after they are used in photosynthesis?

They are recycled back to the light reactions.

What is the byproduct of splitting water in light reactions?

Oxygen (O2).

What is the role of DNA in chloroplasts?

It contains the genetic material needed for chloroplast proteins and enzymes.

What is the visualization analogy for chloroplasts?

Think of a chloroplast as a solar-powered candy factory.

What protects the chloroplast?

Outer membrane

What controls traffic in the chloroplast?

Inner membrane

What is the function of the stroma?

Calvin cycle / sugar-making floor

What provides instructions for the chloroplast?

DNA

What are pigments?

Molecules in plants that absorb light energy for photosynthesis.

What do different pigments do?

Absorb different wavelengths of light.

What color do pigments reflect?

The color we see is the light not absorbed.

What is the main pigment for photosynthesis?

Chlorophyll a

What color light does chlorophyll a absorb?

Red and blue light.

What color does chlorophyll a reflect?

Green.

What is the role of chlorophyll b?

Accessory pigment that broadens range of light absorption.

What colors does chlorophyll b absorb?

Red and blue light.

What colors does chlorophyll b reflect?

Green.

What are accessory pigments?

Pigments that absorb other wavelengths that chlorophyll can't absorb.

What happens to accessory pigments in fall?

They become visible as chlorophyll breaks down.

What are examples of accessory pigments?

Carotenoids, Xanthophylls, Anthocyanins.

What is the mnemonic for chlorophylls?

Chlorophyll catches, Accessory assists, Fall colors persist.

What is the first step in photosynthesis?

Light-dependent reactions.

Where do light-dependent reactions occur?

Thylakoid membranes.

What is produced in light-dependent reactions?

ATP and NADPH.

What is the byproduct of light-dependent reactions?

Oxygen (O2).

What is the Calvin cycle?

Light-independent reactions that use ATP and NADPH to make sugars.

Where does the Calvin cycle take place?

In the stroma.

What does the Calvin cycle produce?

3-carbon sugars (G3P), which can be combined into glucose or starch.

What is the mnemonic for energy conversion in photosynthesis?

Sun → Spark → Sugar.

What happens during the light absorption step?

Light energy is captured by thylakoid pigments.

What is the function of ATP and NADPH?

Temporary energy storage.

What is stored as long-term energy in plants?

Glucose and starch.

What is the mnemonic for light reactions?

Light Sparks Sweetness.

What is the role of photosystems in photosynthesis?

Capture light energy and excite electrons.

What happens in Photosystem II?

Splits water and starts the electron transport chain.

What happens in Photosystem I?

Re-energizes electrons and reduces NADP+ to NADPH.

What is the mnemonic for the flow of light reactions?

Water splits at PS II → electrons pass → PS I charges → NADPH made.

What captures sunlight in the chloroplast?

Solar panels (photosystems) on the thylakoid membranes.

What is the purpose of the electron transport chain?

Move electrons across the thylakoid membrane to generate ATP.

What is the Electron Transport Chain (ETC)?

A series of proteins (Pq, Pc, Fd) that move electrons across the thylakoid membrane.

What happens in Step 1 of the light reactions?

Photosystem II absorbs light, excites electrons, splits water into H⁺, O₂, and electrons.

What is produced as a byproduct of water splitting in PS II?

O₂ is released.

What is the role of Pq in the ETC?

Pq (plastoquinone) carries electrons from PS II to the cytochrome complex.

What does Pc do in the electron transport chain?

Pc (plastocyanin) carries electrons from the cytochrome complex to PS I.

What is the function of Fd in the light reactions?

Fd (ferredoxin) carries electrons from PS I to NADP⁺ reductase.

What is the outcome of the electron flow from PS II to PS I?

It pumps H⁺ into the lumen, creating a gradient that drives ATP synthesis.

What happens in Step 3 of the light reactions?

Photosystem I absorbs light, re-excites electrons, and reduces NADP⁺ to NADPH.

What is the significance of NADPH in photosynthesis?

NADPH carries high-energy electrons to the Calvin Cycle.

What is the proton gradient in the thylakoid lumen used for?

It drives ATP synthesis through ATP synthase.

How is ATP produced in the light reactions?

H⁺ flows down the gradient through ATP synthase, converting ADP + P into ATP.

What are the products of the light reactions?

ATP, NADPH, and O₂.

What does the Calvin Cycle use from the light reactions?

ATP and NADPH to convert CO₂ into glucose.

What is the process of ATP synthesis in the thylakoid?

Chemiosmosis.

What is the mnemonic for the light reactions?

"Water splits at PS II → electrons pass the protein belt → PS I charges them → NADPH made, ATP pumped!"

What is the role of NADP⁺ reductase?

It reduces NADP⁺ to NADPH using electrons and protons.

What happens to electrons after they are re-energized in PS I?

They are used to reduce NADP⁺ to NADPH.

What is the overall flow of electrons in the light reactions?

H2O → PS II → ETC → PS I → NADP⁺ → NADPH.

What is the energy source for the Calvin Cycle?

ATP and NADPH produced in the light reactions.

What is a memory trick for the light reactions?

"Light charges ATP/NADPH batteries → Calvin cycle bakes sugar."

What is the role of water in the light reactions?

Water provides electrons and protons (H⁺) for the reactions.

What does the accumulation of H⁺ in the thylakoid lumen create?

A proton gradient.

What is the final product of the Calvin Cycle?

Glucose.

How does ATP synthase function?

It converts mechanical energy from H⁺ flow into ATP.

What is the significance of the light reactions in photosynthesis?

They convert light energy into chemical energy (ATP and NADPH) for the Calvin Cycle.

What is the first step in the light reactions?

Photosystem II absorbs light and excites electrons.

What happens to the H⁺ ions during the light reactions?

They are pumped into the thylakoid lumen, contributing to the proton gradient.

What is the purpose of the proton motive force?

To drive ATP synthesis through ATP synthase.

What is the relationship between the light reactions and the Calvin Cycle?

The light reactions produce ATP and NADPH, which are used in the Calvin Cycle to synthesize glucose.

What is the role of Photosystem I (PS I)?

PS I provides a second energy boost to electrons, allowing for the reduction of NADP⁺ to NADPH.

What is the reaction catalyzed by NADP⁺ Reductase?

NADP⁺ + H⁺ + e⁻ → NADPH.

What is the purpose of NADPH in the Calvin Cycle?

NADPH carries high-energy electrons and protons to convert CO2 into glucose.

What is the first step in the light reaction flow?

PS II absorbs light and excites electrons.