Struggle Areas

10% Rule of Energy

Only about 10% of energy is passed from one trophic level to the next; the rest is lost as metabolic heat.

Pyramid of Energy

An ecological pyramid showing energy flow; it can NEVER be inverted or upside-down.

Biomagnification

The increase in concentration of a toxin (like DDT) as it moves up a food chain, harming top-level predators most.

Denitrification

The process by which soil bacteria convert nitrates back into nitrogen gas (N2), releasing it into the atmosphere.

Nitrification

The process where soil bacteria convert toxic ammonia into nitrates (NO3-), the form of nitrogen plants can actually use.

Oligotrophic Lake

A deep, clear lake with low nutrient levels, low plant productivity, but high oxygen levels.

Eutrophic Lake

A shallow, murky lake with high nutrient levels, excessive plant/algae growth, and low oxygen levels.

Lamarck's Theory

The disproven evolutionary theory of "use and disuse" and the inheritance of acquired characteristics (e.g., giraffes stretching necks).

Natural Selection

The process where the environment selects for individuals with heritable traits best suited for survival and reproduction.

Photolysis

The splitting of water molecules by light during the light-dependent reactions to supply electrons, releasing oxygen gas.

Light-Dependent Reactions

Occur in the thylakoid membrane; uses light and water to produce ATP, NADPH, and oxygen.

Calvin Cycle (Light-Independent)

Occurs in the stroma; uses carbon dioxide, ATP, and NADPH to synthesize glucose.

Glycolysis

The anaerobic breakdown of glucose into 2 pyruvate molecules; occurs in the cytoplasm and yields a net of 2 ATP.

Krebs Cycle (Citric Acid Cycle)

Occurs in the mitochondrial matrix; oxidizes pyruvate derivatives to produce carbon dioxide, ATP, NADH, and FADH2.

Electron Transport Chain (Respiration)

Occurs on the inner mitochondrial membrane (cristae); uses NADH and FADH2 to create a proton gradient and produce massive amounts of ATP.

Lactic Acid Fermentation

The anaerobic pathway in human muscle cells when oxygen is depleted; converts pyruvate to lactic acid, causing fatigue.

Amylase

An enzyme in saliva and pancreatic juice that initiates carbohydrate digestion by breaking starch down into maltose.

Pepsin

An enzyme in the stomach activated by HCl that breaks down proteins into smaller polypeptides.

Villi and Microvilli

Finger-like projections in the small intestine that massively increase surface area for nutrient absorption into the blood/lacteals.

Alveoli

The tiny, grape-like air sacs in the lungs where gas exchange (oxygen and carbon dioxide) occurs across capillaries.

Negative Feedback Mechanism

A primary homeostatic mechanism where the body detects a change and activates mechanisms to reverse or counteract that change.

Nephron

The functional filtering unit of the kidney that regulates blood volume, blood pressure, and eliminates metabolic waste.

Aldosterone

A hormone secreted by the adrenal cortex that acts on nephrons to increase sodium reabsorption, which increases blood volume and pressure.

1. Thylakoid Membrane

The exact structural location inside the chloroplast where the Light-Dependent reactions take place.

2. Photoactivation

Light strikes Photosystem II, exciting electrons which leave the reaction center and enter the Electron Transport Chain (ETC).

3. Photolysis (Water Splitting)

Light energy splits H2O into oxygen gas (released as waste), protons (H+ ions), and electrons to replace those lost by Photosystem II.

4. Proton Gradient Setup

As excited electrons move down the ETC, their energy is used to pump H+ ions into the thylakoid lumen, creating a high concentration gradient.

5. Chemiosmosis (Photosynthesis)

H+ ions rush down their gradient back into the stroma through ATP Synthase, driving the phosphorylation of ADP to create ATP.

6. NADPH Formation

Electrons reach Photosystem I, are re-energized by light, and are passed to NADP+ along with an H+ ion to form the electron carrier NADPH.

7. The Stroma

The fluid-filled space surrounding the thylakoids where the Light-Independent reactions (Calvin Cycle) take place.

8. Carbon Fixation (Calvin 1)

Carbon dioxide (CO2) from the atmosphere is attached to a 5-carbon molecule (RuBP) by the enzyme Rubisco, forming unstable 6-carbon compounds.

9. Reduction Phase (Calvin 2)

ATP and NADPH from the light reactions are used to convert the carbon compounds into energy-rich G3P (PGAL) molecules.

10. Glucose Synthesis

Two molecules of G3P (PGAL) exit the Calvin Cycle and combine to form one 6-carbon glucose ($C_6H_{12}O_6$) molecule.

11. RuBP Regeneration (Calvin 3)

The remaining G3P molecules use additional ATP to regenerate RuBP, allowing the cycle to continue fixedly turning.

1. Glycolysis Location

Occurs strictly in the cytoplasm of the cell and operates under both aerobic and anaerobic conditions.

2. Glycolysis Process

One 6-carbon glucose is broken down into two 3-carbon pyruvate molecules, yielding a net of 2 ATP and 2 NADH.

3. The Link Reaction

Pyruvate enters the mitochondrial matrix, loses a carbon as CO2, and binds with Coenzyme A to form Acetyl-CoA, producing 1 NADH per pyruvate.

4. Krebs Cycle Location

Takes place entirely within the fluid mitochondrial matrix.

5. Krebs Cycle Process

Acetyl-CoA combines with a 4-carbon starting molecule. As the cycle turns twice per glucose, it releases CO2 and produces 2 ATP, 6 NADH, and 2 FADH2.

6. Cristae (Inner Membrane)

The folded inner membrane of the mitochondrion where the oxidative Electron Transport Chain is embedded.

7. Electron Delivery (Respiration)

NADH and FADH2 deposit their high-energy electrons into the ETC proteins, reverting back to NAD+ and FAD to be reused.

8. Proton Pumping

The energy from the moving electrons is used by ETC proteins to pump H+ ions out of the matrix and into the intermembrane space.

9. Oxygen's Role (Final Acceptor)

Oxygen gas ($O_2$) acts as the final electron acceptor at the end of the ETC, binding with H+ ions to form water ($H_2O$) as a byproduct.

10. Chemiosmosis (Respiration)

The massive H+ gradient drives ions back into the matrix through ATP Synthase, generating roughly 32 to 34 ATP molecules.

Type A+

Has A antigens and Rh factor on red blood cells; Can receive from A+, A-, O+, O-; Can donate to A+, AB+

Type A-

Has A antigens but lacks Rh factor on red blood cells; Can receive from A-, O-; Can donate to A+, A-, AB+, AB-

Type B+

Has B antigens and Rh factor on red blood cells; Can receive from B+, B-, O+, O-; Can donate to B+, AB+

Type B-

Has B antigens but lacks Rh factor on red blood cells; Can receive from B-, O-; Can donate to B+, B-, AB+, AB-

Type AB+

Has A and B antigens, and Rh factor (Universal Recipient); Can receive from all blood types; Can donate to AB+ only

Type AB-

Has A and B antigens but lacks Rh factor; Can receive from A-, B-, AB-, O-; Can donate to AB+, AB-

Type O+

Lacks A and B antigens but has Rh factor; Can receive from O+, O-; Can donate to A+, B+, AB+, O+

Type O-

Lacks A, B, and Rh antigens (Universal Donor); Can receive from O- only; Can donate to all blood types

Antigen

A protein or carbohydrate on the surface of a red blood cell that triggers an immune response

Antibody

A protein in the blood plasma that targets and attacks foreign antigens

Rh Factor

An inherited protein found on the surface of red blood cells that determines if a blood type is positive or negative