AP Biology Unit 3 Hunt

How do enzymes work?

Enzymes lower activation energy, converting reactants into products more efficiently

How can scientists increase enzyme reaction rates?

By increasing temperature, enzyme concentration, or substrate concentration

What slows down enzymatic reactions? Name 3 factors

Low temperature, pH imbalance, inhibitors

What is denaturation, and what causes it?

Denaturation is the loss of an enzyme’s shape due to high temperature or extreme pH

Compare the first and second laws of thermodynamics

The first law states energy cannot be created/destroyed (e.g., ATP formation); the second law states energy disperses/disorganizes (e.g., heat loss)

Compare catabolic and anabolic reactions

Catabolic breaks down molecules to release energy; anabolic builds molecules, requiring energy

Compare endergonic and exergonic reactions

Endergonic absorbs energy (e.g., photosynthesis); exergonic releases energy (e.g., cellular respiration)

Identify if the following are endergonic or exergonic: Building ATP

Endergonic

Identify if the following are endergonic or exergonic: Breaking down ATP

Exergonic

How is ATP made?

Through cellular respiration or photosynthesis

What happens in the light dependent reactions?

Light starts the reaction, producing ATP and NADPH in the thylakoid membrane

What happens in the light independent reactions?

CO2 is used to form glucose in the stroma

What is the overall photosynthesis reaction?

6CO2 + 6H2O + light → C6H12O6 + 6O2

Which organisms perform photosynthesis?

Plants, algae, and some bacteria

How are Photosystems II and I different?

Photosystem II absorbs shorter wavelengths; Photosystem I prefers longer wavelengths

What happens in glycolysis?

Glucose is split into pyruvate, producing ATP in the cytoplasm

Describe the Kreb’s Cycle

Acetyl CoA is oxidized to produce ATP, NADH, and FADH2 in the mitochondria

What occurs in oxidative phosphorylation?

ATP is formed as electrons are transferred in the mitochondrial membrane

What happens if oxygen is absent?

Anaerobic respiration; in animals, it leads to lactic acid fermentation; in yeast, alcohol fermentation

Compare ectotherms and endotherms with examples

Ectotherms rely on external heat (e.g., reptiles); endotherms generate internal heat (e.g., mammals)

What is photosynthesis?

Photosynthesis is the process by which plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen

Where does photosynthesis occur in a plant cell?

Photosynthesis occurs in the chloroplasts of plant cells

What are the two main stages of photosynthesis?

The two main stages are the light

What occurs during the Calvin Cycle?

The Calvin Cycle uses CO2, ATP, and NADPH to produce glucose

Where does the Calvin Cycle take place?

It takes place in the stroma of the chloroplast

What is carbon fixation in the Calvin Cycle?

Carbon fixation is the process of converting CO2 into an organic molecule (glucose) during the Calvin Cycle

What is the overall equation for photosynthesis?

6CO2 + 6H2O + light → C6H12O6 + 6O2

What are photosystems, and what are their roles in photosynthesis?

Photosystems I and II are protein complexes in the thylakoid membrane that capture light energy to drive electron transport

What role does water play in photosynthesis?

Water is split during the light

What colors of light do chlorophyll and accessory pigments absorb?

Chlorophyll absorbs blue and red light; accessory pigments absorb other wavelengths such as green, yellow, and orange

What is the purpose of NADPH in photosynthesis?

NADPH carries high

What is cellular respiration?

Cellular respiration is a process by which cells break down glucose and other molecules to produce ATP, releasing energy

Where does cellular respiration occur in eukaryotic cells?

Cellular respiration occurs in the mitochondria

What are the three main stages of cellular respiration?

The three main stages are glycolysis, the Krebs Cycle, and oxidative phosphorylation (electron transport chain)

What is glycolysis, and where does it occur?

Glycolysis is the first stage of cellular respiration, breaking down glucose into pyruvate in the cytoplasm

What are the products of glycolysis?

The products are 2 ATP, 2 NADH, and 2 pyruvate molecules

What happens to pyruvate after glycolysis if oxygen is present?

Pyruvate enters the mitochondria and is converted to Acetyl

What happens to pyruvate in the absence of oxygen?

Pyruvate undergoes fermentation, producing lactic acid in animals or ethanol and CO2 in yeast

What is the Krebs Cycle, and where does it occur?

The Krebs Cycle (Citric Acid Cycle) is a series of reactions in the mitochondrial matrix that produces ATP, NADH, FADH2, and CO2

What are the reactants and products of the Krebs Cycle?

Reactants: Acetyl

What is the purpose of NADH and FADH2 in cellular respiration?

NADH and FADH2 carry high

What is oxidative phosphorylation?

Oxidative phosphorylation is the final stage of cellular respiration, where electrons from NADH and FADH2 are transferred through the electron transport chain, creating ATP

Where does oxidative phosphorylation occur?

It occurs in the inner mitochondrial membrane

How does the electron transport chain produce ATP?

The chain uses energy from electrons to pump protons across the membrane, creating a gradient that drives ATP synthase to generate ATP

What is the role of oxygen in cellular respiration?

Oxygen is the final electron acceptor in the electron transport chain, forming water as a byproduct

What is the overall equation for cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

How are photosynthesis and cellular respiration related?

Photosynthesis produces glucose and oxygen used in cellular respiration, while cellular respiration produces CO2 and water used in photosynthesis

This organelle uses photons to carry out electron transfer and subsequent carbohydrate production

Chloroplast

What is the balanced formula for respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

This is the most efficient type of cellular respiration that includes both substrate level and oxidative phosphorylation

Aerobic Respiration

Identify this molecule

ATP

What are the products of anaerobic respiration in plants/animals?

2 ATP, Ethanol/Lactic Acid

Name the 3 stages in the complete oxidation of glucose

Glycolysis, Krebs Cycle, Electron Transport Chain

Give an example of an ion that uses an ATP pump

Na+, K+, H+

How many ATP are produced by substrate level phosphorylation (NOT ETC)?

4 (2 in glycolysis + 2 in Krebs)

This is the reactant that allows the Krebs Cycle to begin (the product of pyruvate oxidation)

Acetyl CoA

What are 2 products of Photosystem II?

Oxygen (O2), H+ or ATP

Where does the Calvin Cycle take place?

The stroma of the chloroplast

How many ATP are produced by oxidative phosphorylation?

28 to 34

This is the final electron acceptor in the electron transport chain during respiration

Oxygen (O2)

Where do light

dependent reactions take place?

Name the two molecules that donate ions to the electron transport chain in the mitochondria

NADH, FADH2

What is the reactant of the transition reaction (between glycolysis and Krebs)?

Pyruvic acid

What are the 3 reactants of the light

independent reactions?

What does chlorophyll do in the photosynthetic process?

Absorbs/captures light (photons), receives electrons from water, transfers electrons

If there is an increase in NADPH at the end of photosystem I, what happens?

The cyclic pathway begins

Explain how temperature can affect enzymatic activity

Increased temperature can increase collisions and thus enzymatic rates; too much heat leads to denaturation, causing the enzyme to change shape and stop working. Decreased temperature reduces collisions and decreases enzymatic rates

Which part of aerobic respiration produces the greatest amount of ATP energy?

The electron transport chain

What is the balanced equation for photosynthesis?

6CO2 + 6H2O + sunlight → C6H12O6 + 6O2

What process converts pyruvate to lactic acid?

Anaerobic respiration (specifically lactic acid fermentation)

Chemiosmosis refers to…

Movement of H+ ions down the concentration gradient through ATP synthase

How much NADH does one round of the Krebs Cycle produce?

6

Which respiration process is least efficient?

Fermentation (anaerobic respiration)

Location of glycolysis

Cytosol/cytoplasm outside the mitochondria

The organelle responsible for ATP production

Mitochondria

What effect does a lack of oxygen have on glycolysis?

None

What happens during competitive inhibition?

Another chemical competes for the enzyme’s active site, decreasing enzymatic efficacy

During what part of photosynthesis is water split? What is it split into?

Photosystem II; split into H+, O2, and electrons

What type of reaction is the following: ATP + H2O → ADP + Pi + chemical energy

Hydrolysis, catabolic, exergonic

What is it called when an enzyme’s shape changes due to a chemical attaching to it away from the active site?

Allosteric inhibition/non

Why is the energy of an endothermic reaction always more than its exothermic counterpart?

Some energy is lost to heat

Dehydration synthesis is what type of reaction?

Anabolic, endergonic

What are the 2 steps of the light

dependent reaction (in order)?

When electrons and hydrogens are added to a molecule, what has happened to the molecule?

It has been reduced

When a molecule loses electrons, we say it has been _____

Oxidized

A molecule that stabilizes the active form of an enzyme

Activator (coenzyme or cofactor)