Bio Exam 3 Flash Cards

Energy

The ability to do work.

Kinetic energy

Energy of motion.

Potential energy

Stored energy.

Entropy

Measure of disorder.

Free energy

Usable energy for work.

Electron transport chain

Series of proteins that transfer electrons to make ATP.

ATP

Main energy molecule in cells.

Enzyme

Protein that speeds up chemical reactions.

Ribozymes

RNA molecules that act as enzymes.

Substrate

The molecule an enzyme acts on.

Active site

Part of an enzyme where the substrate binds.

Activation energy

Energy needed to start a reaction.

Cofactors

Helpers (ions or molecules) for enzymes.

Half-life

Time for half of a substance to break down.

Autophagy

Process where cells break down their own parts for recycling.

First law of thermodynamics

Energy cannot be created or destroyed, only transferred.

Second law of thermodynamics

Energy transfer increases disorder (entropy).

Endergonic reaction

A chemical reaction that absorbs energy.

Exergonic reaction

A chemical reaction that releases energy.

Oxidation-reduction (redox) reactions

Transfer of electrons; oxidation loses electrons, reduction gains electrons.

Free energy equation (H = G + TS)

H = total energy, G = free energy, T = temperature, S = entropy.

Enzyme properties

Reusable; forms enzyme-substrate complex to speed up reactions.

Noncompetitive inhibition

Inhibition where the inhibitor binds elsewhere, changing the enzyme's shape.

Competitive inhibition

Inhibition where the inhibitor blocks the active site.

Catabolic pathways

Pathways that break molecules down.

Anabolic pathways

Pathways that build molecules up.

Substrate-level phosphorylation

Direct transfer of phosphate to make ATP.

Chemiosmosis

Using a proton gradient to make ATP.

Photosynthesis

Process where plants make food using light.

Biosphere

All living things on Earth.

Heterotroph

Organism that eats others for food.

Autotroph

Organism that makes its own food.

Photoautotroph

Organism that uses light to make food, such as plants and algae.

Pigments

Molecules that absorb light.

Accessory pigments

Extra pigments that help absorb more light.

Stomata

Openings on leaves for gas exchange.

Chloroplasts

Organelles where photosynthesis happens.

Thylakoids

Flattened sacs in chloroplasts where light reactions occur.

Granum

Stack of thylakoids.

Stroma

Fluid in chloroplast where the Calvin cycle happens.

Photons

Light particles.

Ground state

Low-energy state of electrons.

Excited state

High-energy state of electrons after absorbing light.

Photosystem

Protein-pigment complex that captures light.

Rubisco

Enzyme that fixes CO₂ in the Calvin cycle.

Photorespiration

Wasteful process where rubisco binds oxygen instead of CO₂.

Chemical equation of photosynthesis

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.

Two stages of photosynthesis

Light reactions and Calvin cycle.

Main photosynthetic pigment

Chlorophyll a.

Where photosynthesis occurs

In the chloroplasts.

Byproducts of light reactions

ATP, NADPH, O₂.

Photosystem II

Absorbs light, splits water, releases O₂.

Noncyclic electron flow

Produces ATP & NADPH.

Cyclic electron flow

Produces only ATP.

Carbon fixation

Process where Rubisco fixes CO₂.

C4 plants

Plants that store carbon differently to reduce water loss.

CAM plants

Plants that open stomata at night to save water.