Biology: Cellular Respiration, Photosynthesis, Mitosis & Meiosis

What does aerobic mean?

Requires oxygen.

What does anaerobic mean?

Does not require oxygen.

What is glycolysis?

The process of splitting glucose into two pyruvate molecules.

Where does glycolysis occur?

Cytoplasm (cytosol).

Does glycolysis require oxygen?

No.

What is the net ATP produced from glycolysis?

2 ATP per glucose.

What are the reactants of glycolysis?

Glucose, 2 ATP, 2 NAD+, and 4 ADP + phosphate.

What are the products of glycolysis?

2 pyruvate, 2 NADH, and net 2 ATP.

Do prokaryotes perform glycolysis?

Yes.

What are the three fates of pyruvate?

Aerobic respiration, lactic acid fermentation, or alcoholic fermentation.

What is fermentation?

Anaerobic process that regenerates NAD+ so glycolysis can continue.

Does fermentation require oxygen?

No.

Does fermentation produce much ATP?

No, it relies on glycolysis for 2 net ATP.

What is lactic acid fermentation?

Converts pyruvate into lactate and regenerates NAD+.

Where does lactic acid fermentation occur?

Muscle cells and certain bacteria.

What is alcoholic fermentation?

Converts pyruvate into ethanol and CO2 while regenerating NAD+.

Where does alcoholic fermentation occur?

Yeast and some microorganisms.

What is the evolutionary importance of fermentation?

Allows organisms to produce ATP without oxygen.

Why is glycolysis evidence of common ancestry?

It occurs in nearly all organisms and is an ancient conserved pathway.

What does fermentation regenerate?

NAD+.

What is NAD+?

An electron carrier that accepts electrons and becomes NADH.

What is NADH?

The reduced form of NAD+ that carries high-energy electrons.

What is Acetyl CoA synthesis?

Converts pyruvate into acetyl CoA before the Krebs cycle.

What are the reactants of Acetyl CoA synthesis?

Pyruvate, NAD+, and coenzyme A.

What are the products of Acetyl CoA synthesis?

Acetyl CoA, NADH, and CO2.

What happens to CoA after Acetyl CoA synthesis?

It is released and recycled.

Where does Acetyl CoA synthesis occur?

Mitochondrial matrix in eukaryotes.

What is the Krebs cycle?

A series of reactions that break down acetyl CoA and transfer energy to electron carriers.

What is another name for the Krebs cycle?

Citric acid cycle.

What are the reactants of the Krebs cycle?

Acetyl CoA, NAD+, FAD, and ADP + phosphate.

What are the products of the Krebs cycle?

CO2, NADH, FADH2, ATP, and regenerated oxaloacetate.

Why is it called the Krebs cycle?

Oxaloacetate is regenerated and combines with another acetyl CoA.

What is the role of citric acid in the Krebs cycle?

Citric acid forms when acetyl CoA combines with oxaloacetate.

What is the net ATP produced from the Krebs cycle?

2 ATP per glucose.

Where does the Krebs cycle occur?

Mitochondrial matrix.

Why are mitochondria folded?

Folds increase surface area for the electron transport chain and ATP production.

What are cristae?

Folds of the inner mitochondrial membrane.

What is ATP synthase?

Enzyme that produces ATP from ADP and phosphate using energy from H+ flow.

What is chemiosmosis?

Movement of H+ down its electrochemical gradient through ATP synthase.

In which direction do H+ flow through ATP synthase?

Down its concentration/electrochemical gradient.

What powers ATP synthase?

The energy released as H+ flows down its gradient.

What are the electron carriers in cellular respiration?

NADH and FADH2.

What is the electron transport chain (ETC)?

A series of protein complexes that transfer electrons and pump H+.

Where does the mitochondrial ETC occur?

Inner mitochondrial membrane.

How many major respiratory complexes are in the ETC?

Four.

Which ETC complexes pump H+?

Complexes I, III, and IV.

Does the ETC use ATP to pump H+?

No.

What powers proton pumps in the ETC?

Energy released by energized electrons from NADH and FADH2.

What type of transport is used in the ETC?

Active transport.

What is the final electron acceptor in cellular respiration?

Oxygen.

What happens to oxygen in cellular respiration?

It accepts electrons and H+ to form water.

What is the H+ gradient?

An accumulation of H+ in the intermembrane space.

How does the H+ gradient produce ATP?

H+ flows through ATP synthase, powering ADP + phosphate to form ATP.

What is the dam analogy for ATP synthase?

Stored water represents the H+ gradient; flowing water turns a turbine like ATP synthase.

How much ATP is produced from the ETC alone?

Approximately 26-28 ATP per glucose.

What is the total ATP produced from cellular respiration?

Approximately 30-32 ATP per glucose in eukaryotes.

What happens to glucose carbons during respiration?

They are released as CO2.

Are glucose carbons used in the ETC?

No.

Where do electrons in NADH and FADH2 come from?

They originate from glucose and are transferred during metabolic reactions.

Which stages release CO2?

Acetyl CoA synthesis and the Krebs cycle.

What happens to CO2 produced during respiration?

It leaves the cell and can be transported to the lungs and exhaled in animals.

What is the difference between NAD+ and NADH?

NAD+ is oxidized and accepts electrons; NADH is reduced and carries electrons.

What is the role of energized electrons in the ETC?

Their energy powers proton pumps as electrons move through the complexes.

What is the role of H+ in the ETC?

H+ creates a gradient that powers ATP synthase.

What is the overall purpose of cellular respiration?

Breaks down glucose to produce ATP.

What is photosynthesis?

Process that converts light energy into chemical energy stored in sugars.

Does photosynthesis occur in human cells?

No.

What organelle is responsible for photosynthesis?

Chloroplast.

Where does photosynthesis occur?

Chloroplasts in plants and algae.

What are the reactants of photosynthesis?

CO2, water, and light energy.

What are the products of photosynthesis?

Glucose (or sugars) and oxygen.

What is chlorophyll?

Green pigment that absorbs light energy.

Why do plants appear green?

Chlorophyll reflects and transmits much of the green light.

Is green light effective for photosynthesis?

Less effective than red and blue because much green light is reflected or transmitted.

What are accessory pigments?

Pigments that absorb additional wavelengths of light and transfer energy to chlorophyll.

What are carotenoids?

Yellow and orange pigments that absorb light and help protect against excess light.

What are anthocyanins?

Red, purple, or blue pigments that can protect plant tissues and help absorb or filter light.

What are thylakoids?

Flattened membrane sacs inside chloroplasts where light reactions occur.

Why are thylakoids folded and stacked?

Increase surface area for photosystems and electron transport.

What are light reactions?

Use light energy to split water and produce ATP, NADPH, and oxygen.

Where do light reactions occur?

Thylakoid membrane.

What are the products of light reactions?

ATP, NADPH, and O2.

What is a photosystem?

A group of pigments and proteins that captures light energy.

What is the relationship between chlorophyll and photosystems?

Chlorophyll is a pigment found within photosystems.

What is Photosystem II?

Uses light energy to excite electrons and replaces them by splitting water.

What is Photosystem II responsible for?

Uses light energy to excite electrons and replaces them by splitting water.

What is the function of Photosystem I?

Uses light energy to re-energize electrons to help produce NADPH.

What does water splitting produce in photosynthesis?

Electrons, H+ ions, and oxygen.

What is the source of electrons in photosynthesis?

Water.

What is the final electron acceptor in the light reactions?

NADP+, which becomes NADPH.

What is NADPH?

An electron carrier that provides reducing power for the Calvin cycle.

How is the photosynthesis ETC similar to respiration ETC?

Both transfer electrons, pump H+, and use ATP synthase.

What is the main difference between the two ETCs?

Photosynthesis uses light energy and water; respiration uses electrons from food and oxygen as the final acceptor.

Does photosynthesis use glucose as fuel?

No, it uses light energy to make chemical energy.

What happens to ATP from light reactions?

It is used in the Calvin cycle.

What does the Calvin cycle use to produce G3P?

CO2, ATP, and NADPH.

Where does the Calvin cycle occur?

Chloroplast stroma.

Does the Calvin cycle require light directly?

No, but it depends on ATP and NADPH from the light reactions.

What are the reactants of the Calvin cycle?

CO2, ATP, and NADPH.

What are the products of the Calvin cycle?

G3P, ADP, and NADP+.