Photosynthesis Flashcards

Flashcards about photosynthesis

What is photosynthesis?

The process by which plants, some bacteria, and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water.

What is the word equation for photosynthesis?

Carbon dioxide + water -> glucose + oxygen

What is the role of accessory pigments in photosynthesis?

It absorbs energy that chlorophyll a does not absorb.

From which wavelengths does chlorophyll a absorb energy?

Chlorophyll a absorbs energy from these wavelengths.

What are the two main components of all chlorophylls?

A lipid-soluble hydrocarbon tail and a flat hydrophilic head with a magnesium ion at its center.

What is the main function of stomata in land plants?

Allow gas to enter and leave the leaf.

What are thylakoids?

Flattened sacs/vesicles containing photosynthetic chemicals.

What are grana?

Stacks of thylakoids.

What is the stroma?

The areas between grana in the chloroplast.

What are the two main stages of photosynthesis?

Light-dependent reactions and light-independent reactions.

What does photoactivation of chlorophyll a result in?

The splitting of water molecules and the transfer of energy to ATP and NADPH.

What occurs during the light-dependent reactions?

Light energy is trapped by chlorophyll to make ATP & water is split into oxygen, hydrogen ions, and free electrons.

What happens during the light-independent reactions?

ATP and NADPH are used to make carbohydrates from carbon dioxide.

What is a photosystem composed of?

In whole chloroplasts, each chlorophyll molecule is associated with an electron acceptor and electron donor. These three molecules make up the core of a photosystem.

What are the two photosystems involved in the electron transfer system?

Photosystem II (PSII) and Photosystem I (PSI).

What is the electron transfer system?

Series of chemical reactions that carries two electrons to and fro across the thylakoid membrane.

What happens in the first photosystem (PSII) during non-cyclic phosphorylation?

Photoionisation of chlorophyll transfers excited electrons to an electron acceptor.

How does chemiosmosis contribute to ATP synthesis in photosynthesis?

Electrons passing through the transport chain provide energy to pump H+ ions from the stroma into the thylakoid compartment, creating an electrochemical gradient that drives ATP production.

What is cyclic phosphorylation?

Involves only Photosystem I, generating excited electrons which are transferred to the electron transport chain between PSII and PSI rather than to NADP+.

What is carbon fixation?

The incorporation of carbon dioxide into organic compounds.

What is the first step in the light-independent reactions?

Carbon dioxide combines with RuBP, forming an unstable six-carbon sugar that breaks down into two GP molecules.

What are the main factors affecting the rate of photosynthesis?

Light intensity, carbon dioxide concentration, and temperature.