BIO EXAM 3

Organisms that use light energy to produce organic molecules from CO₂ are called: (A) Heterotrophs (B) Photoautotrophs (C) Decomposers (D) Parasites

B. Photoautotrophs

Which of the following organisms can perform photosynthesis? (A) Plants (B) Algae (C) Cyanobacteria (D) All of the above

D. All of the above

Photosynthesis in plant cells occurs in the: (A) Nucleus (B) Chloroplast (C) Mitochondria (D) Ribosome

B. Chloroplast

The light-dependent reactions occur in the: (A) Stroma (B) Cytoplasm (C) Thylakoid membrane (D) Cell membrane

C. Thylakoid membrane

The Calvin cycle occurs in the: (A) Thylakoid membrane (B) Cytosol (C) Stroma (D) Mitochondrial matrix

C. Stroma

Chlorophyll appears green because it: (A) Absorbs green light (B) Reflects green light (C) Absorbs all light equally (D) Reflects red light

B. Reflects green light

The main purpose of photosynthesis is to: (A) Produce oxygen only (B) Convert light energy into chemical energy (C) Produce heat (D) Break down glucose

B. Convert light energy into chemical energy

The overall equation of photosynthesis uses which inputs? (A) CO₂ and oxygen (B) Water and oxygen (C) CO₂, water, and light (D) Glucose and oxygen

C. CO₂, water, and light

One of the products of photosynthesis is: (A) Nitrogen (B) Oxygen (C) Ammonia (D) Methane

B. Oxygen

ATP in photosynthesis serves as: (A) Structural molecule (B) Storage protein (C) Energy carrier (D) Pigment

C. Energy carrier

NADPH functions primarily as: (A) DNA molecule (B) Electron carrier (C) Sugar molecule (D) Pigment

B. Electron carrier

Light energy is absorbed in packets called: (A) Protons (B) Photons (C) Neutrons (D) Molecules

B. Photons

Which photosystem acts first in the light reactions? (A) Photosystem I (B) Photosystem II (C) Calvin cycle (D) ATP synthase

B. Photosystem II

During light reactions, water molecules are split to produce: (A) Nitrogen (B) Carbon dioxide (C) Oxygen (D) Glucose

C. Oxygen

The light reactions produce which molecules for the Calvin cycle? (A) ATP and NADPH (B) Glucose and oxygen (C) CO₂ and water (D) RuBP and G3P

A. ATP and NADPH

The Calvin cycle fixes which molecule? (A) Oxygen (B) Carbon dioxide (C) Nitrogen (D) Hydrogen

B. Carbon dioxide

The enzyme responsible for carbon fixation is: (A) ATP synthase (B) RuBisCO (C) DNA polymerase (D) Catalase

B. RuBisCO

The main sugar product of the Calvin cycle is: (A) Glucose (B) Sucrose (C) G3P (D) Fructose

C. G3P

Which stage of the Calvin cycle regenerates RuBP? (A) Fixation (B) Reduction (C) Regeneration (D) Oxidation

C. Regeneration

RuBP is best described as: (A) A 5-carbon molecule (B) A 6-carbon molecule (C) A pigment (D) A protein

A. A 5-carbon molecule

The Calvin cycle requires which molecules produced in the light reactions? (A) ATP and NADPH (B) Oxygen and CO₂ (C) Water and oxygen (D) Glucose and starch

A. ATP and NADPH

Which factor can limit the rate of photosynthesis? (A) Light intensity (B) CO₂ concentration (C) Temperature (D) All of the above

D. All of the above

Photorespiration occurs when RuBisCO binds: (A) Carbon dioxide (B) Oxygen (C) Nitrogen (D) Hydrogen

B. Oxygen

Photorespiration generally: (A) Increases efficiency (B) Decreases efficiency (C) Has no effect (D) Stops photosynthesis

B. Decreases efficiency

C4 plants reduce photorespiration by: (A) Using more oxygen (B) Concentrating CO₂ near RuBisCO (C) Stopping photosynthesis (D) Closing stomata permanently

B. Concentrating CO₂ near RuBisCO

In C4 plants, CO₂ is first fixed into: (A) 3-carbon molecule (B) 4-carbon molecule (C) 5-carbon molecule (D) 6-carbon molecule

B. 4-carbon molecule

CAM plants open their stomata mainly: (A) During the day (B) At night (C) At noon (D) Never

B. At night

CAM photosynthesis is common in: (A) Aquatic plants (B) Desert plants (C) Forest trees (D) Algae

B. Desert plants

CAM plants store CO₂ during the night as: (A) Sugars (B) Organic acids (C) Proteins (D) Lipids

B. Organic acids

Oxygenic photosynthesis produces: (A) Nitrogen gas (B) Oxygen gas (C) Carbon monoxide (D) Methane

B. Oxygen gas

Accessory pigments help plants by: (A) Producing oxygen (B) Absorbing additional wavelengths of light (C) Breaking down glucose (D) Producing ATP directly

B. Absorbing additional wavelengths of light

The main source of oxygen released during photosynthesis is: (A) CO₂ (B) H₂O (C) Glucose (D) ATP

B. H₂O

Which structure contains chlorophyll? (A) Ribosome (B) Thylakoid (C) Golgi apparatus (D) Lysosome

B. Thylakoid

Photosynthesis provides energy for most ecosystems because it: (A) Creates oxygen only (B) Produces chemical energy stored in carbohydrates (C) Destroys carbon dioxide (D) Produces proteins

B. Produces chemical energy stored in carbohydrates

Most organisms on Earth depend on photosynthesis: (A) Directly or indirectly (B) Only indirectly (C) Only plants (D) Only animals

A. Directly or indirectly

The main goal of cellular respiration is to: (A) Produce oxygen (B) Produce ATP (C) Produce carbon dioxide (D) Produce water

B. Produce ATP

Cellular respiration extracts energy mainly from: (A) Water (B) Glucose (C) Oxygen (D) Nitrogen

B. Glucose

In aerobic respiration, the final electron acceptor is: (A) Carbon dioxide (B) Oxygen (C) NADH (D) Glucose

B. Oxygen

The first stage of cellular respiration is: (A) Citric acid cycle (B) Glycolysis (C) Fermentation (D) Electron transport chain

B. Glycolysis

Glycolysis occurs in the: (A) Cytosol (B) Mitochondrial matrix (C) Inner membrane (D) Nucleus

A. Cytosol

Glycolysis breaks down glucose into: (A) 2 pyruvate molecules (B) 1 acetyl-CoA (C) 3 lactate molecules (D) 4 CO₂ molecules

A. 2 pyruvate molecules

Glycolysis produces which electron carrier? (A) NADH (B) NADPH (C) ATP synthase (D) Oxygen

A. NADH

Glycolysis is considered anaerobic because it: (A) Produces oxygen (B) Requires oxygen (C) Does not require oxygen (D) Occurs in mitochondria

C. Does not require oxygen

When oxygen is unavailable, cells may perform: (A) Photosynthesis (B) Fermentation (C) Oxidation (D) Glycogenesis

B. Fermentation

The main purpose of fermentation is to: (A) Produce oxygen (B) Regenerate NAD⁺ (C) Produce glucose (D) Stop glycolysis

B. Regenerate NAD⁺

Lactic acid fermentation converts pyruvate into: (A) Ethanol (B) Lactate (C) Glucose (D) Acetyl-CoA

B. Lactate

Alcohol fermentation produces: (A) Lactate and CO₂ (B) Ethanol and CO₂ (C) Oxygen and water (D) ATP only

B. Ethanol and CO₂

Alcohol fermentation is commonly performed by: (A) Bacteria (B) Yeast (C) Plants (D) Animals

B. Yeast

In bread making, fermentation causes dough to rise because of: (A) Oxygen release (B) CO₂ production (C) ATP production (D) Water evaporation

B. CO₂ production

During baking, ethanol in bread dough: (A) Remains in bread (B) Converts to sugar (C) Evaporates (D) Turns into oxygen

C. Evaporates

Pyruvate oxidation occurs in the: (A) Cytosol (B) Mitochondrial matrix (C) Thylakoid (D) Nucleus

B. Mitochondrial matrix

Pyruvate is converted into: (A) Acetyl-CoA (B) Lactate (C) Glucose (D) NADPH

A. Acetyl-CoA

The citric acid cycle occurs in the: (A) Cytosol (B) Mitochondrial matrix (C) Chloroplast (D) Ribosome

B. Mitochondrial matrix

The citric acid cycle produces which electron carriers? (A) NADH and FADH₂ (B) ATP and ADP (C) Oxygen and water (D) Glucose and starch

A. NADH and FADH₂

For each acetyl-CoA entering the citric acid cycle, how many CO₂ molecules are released? (A) 1 (B) 2 (C) 3 (D) 4

B. 2

Which process produces the most ATP in cellular respiration? (A) Glycolysis (B) Citric acid cycle (C) Oxidative phosphorylation (D) Fermentation

C. Oxidative phosphorylation

The electron transport chain is located in the: (A) Outer mitochondrial membrane (B) Inner mitochondrial membrane (C) Cytosol (D) Nucleus

B. Inner mitochondrial membrane

Electron carriers donate electrons to the: (A) Calvin cycle (B) Electron transport chain (C) Glycolysis (D) Fermentation

B. Electron transport chain

The movement of electrons in the ETC helps create a: (A) Sugar gradient (B) Proton gradient (C) Oxygen gradient (D) Carbon gradient

B. Proton gradient

ATP synthase uses the proton gradient to: (A) Destroy ATP (B) Produce ATP (C) Produce glucose (D) Produce oxygen

B. Produce ATP

The proton gradient forms across the: (A) Outer membrane (B) Inner mitochondrial membrane (C) Cytosol (D) Nuclear membrane

B. Inner mitochondrial membrane

Oxygen combines with electrons and protons to form: (A) Carbon dioxide (B) Water (C) Glucose (D) Lactate

B. Water

If oxygen is absent, the electron transport chain: (A) Speeds up (B) Stops functioning properly (C) Produces more ATP (D) Produces glucose

B. Stops functioning properly

NADH produces more ATP than FADH₂ because: (A) It enters the ETC earlier (B) It contains more oxygen (C) It produces glucose (D) It blocks respiration

A. It enters the ETC earlier

The citric acid cycle is considered amphibolic because it: (A) Produces oxygen (B) Supports both catabolism and anabolism (C) Stops respiration (D) Produces only ATP

B. Supports both catabolism and anabolism

Lipids enter cellular respiration mainly as: (A) Pyruvate (B) Acetyl-CoA (C) Glucose (D) Oxygen

B. Acetyl-CoA

Proteins enter respiration after: (A) Photosynthesis (B) Deamination (C) Fermentation (D) Glycolysis

B. Deamination

Cellular respiration must be regulated because: (A) Cells must match ATP production with demand (B) Cells produce too much oxygen (C) Cells produce too much glucose (D) Cells cannot store ATP

A. Cells must match ATP production with demand

High ATP levels generally: (A) Speed up glycolysis (B) Slow down glycolysis (C) Stop photosynthesis (D) Increase fermentation

B. Slow down glycolysis

The citric acid cycle is part of a larger network of metabolic pathways because: (A) It is isolated (B) It connects carbohydrate, fat, and protein metabolism (C) It produces only glucose (D) It occurs outside cells

B. It connects carbohydrate, fat, and protein metabolism