Microbiology Study Guide: Metabolism, Nutrition, Growth, and Genetics

Q1. What is the name of the process in which larger molecules are broken down into smaller products to release energy?

Background

Topic: Microbial Metabolism

This question tests your understanding of metabolic pathways, specifically the distinction between anabolic and catabolic processes.

Key Terms:

• Anabolism: Building larger molecules from smaller ones (requires energy).

• Catabolism: Breaking down larger molecules into smaller ones (releases energy).

• Metabolism: All chemical reactions in a cell.

• Digestion: Physical and chemical breakdown of food (not always cellular).

Step-by-Step Guidance

1. Recall the definitions of anabolism and catabolism.

2. Identify which process releases energy by breaking down molecules.

3. Compare the answer choices to the definitions above.

Try solving on your own before revealing the answer!

Final Answer: Catabolism

Catabolism is the process where larger molecules are broken down into smaller products, releasing energy.

Q2. How do enzymes catalyze reactions?

Background

Topic: Enzyme Function

This question tests your understanding of how enzymes affect the activation energy of biochemical reactions.

Key Terms:

• Enzyme: Biological catalyst that speeds up reactions.

• Activation Energy: The minimum energy required to start a reaction.

• Catalysis: The process of speeding up a chemical reaction.

Step-by-Step Guidance

1. Recall what activation energy is and why it matters in reactions.

2. Think about how enzymes interact with substrates to affect activation energy.

3. Review the answer choices and identify which describes the effect enzymes have on activation energy.

Try solving on your own before revealing the answer!

Final Answer: By lowering activation energy needed to trigger a reaction

Enzymes lower the activation energy, making reactions proceed faster.

Q3. When electrons are transferred from donor molecules to acceptor molecules in a redox reaction, what happens to the donor molecule?

Background

Topic: Redox Reactions in Metabolism

This question tests your understanding of oxidation and reduction in metabolic pathways.

Key Terms:

• Redox Reaction: Transfer of electrons between molecules.

• Oxidation: Loss of electrons.

• Reduction: Gain of electrons.

Step-by-Step Guidance

1. Recall the definitions of oxidation and reduction.

2. Consider what happens to a molecule that donates electrons.

3. Match the answer choices to the correct definition.

Try solving on your own before revealing the answer!

Final Answer: It is oxidized.

The donor molecule loses electrons and is therefore oxidized.

Q4. The direct transfer of phosphate between substrates is called:

Background

Topic: ATP Generation Mechanisms

This question tests your knowledge of different phosphorylation methods in metabolism.

Key Terms:

• Substrate-level phosphorylation: Direct transfer of phosphate from one molecule to another.

• Oxidative phosphorylation: Uses electron transport chain.

• Photophosphorylation: Uses light energy.

Step-by-Step Guidance

1. Recall the definitions of each type of phosphorylation.

2. Identify which method involves direct transfer between substrates.

3. Compare answer choices to your definitions.

Try solving on your own before revealing the answer!

Final Answer: Substrate-level phosphorylation

Substrate-level phosphorylation is the direct transfer of phosphate between substrates.

Q5. A site on an enzyme other than the active site that can bind molecules and influence the shape of the active site is referred to as a(n) ________.

Background

Topic: Enzyme Regulation

This question tests your understanding of enzyme structure and regulation, specifically allosteric sites.

Key Terms:

• Active site: Where substrate binds.

• Allosteric site: Regulatory site that affects enzyme activity.

• Competitive inhibitor: Binds active site.

Step-by-Step Guidance

1. Recall the difference between active and allosteric sites.

2. Think about how binding at a site other than the active site can change enzyme activity.

3. Match the answer choices to the correct definition.

Try solving on your own before revealing the answer!

Final Answer: Allosteric site

The allosteric site is a regulatory site on an enzyme that can influence the active site.

Q6. Which cellular process results in the MOST ATP production?

Background

Topic: Cellular Respiration

This question tests your knowledge of the stages of cellular respiration and their ATP yields.

Key Terms:

• Electron Transport Chain (ETC): Produces most ATP.

• Glycolysis: Initial breakdown of glucose.

• Krebs Cycle: Further breakdown of products from glycolysis.

• Fermentation: Occurs without oxygen, less ATP.

Step-by-Step Guidance

1. Recall the ATP yield from each stage of cellular respiration.

2. Compare the answer choices based on their ATP production.

3. Identify which process produces the most ATP.

Try solving on your own before revealing the answer!

Final Answer: Electron Transport Chain

The electron transport chain produces the most ATP during cellular respiration.

Q7. Cellular Respiration results in the complete breakdown of _________ to _______ and __________.

Background

Topic: Cellular Respiration Products

This question tests your understanding of the reactants and products of cellular respiration.

Key Terms:

• Glucose: Main substrate for respiration.

• CO2 and H2O: Main products.

Step-by-Step Guidance

1. Recall the overall equation for cellular respiration.

2. Identify the starting molecule and the end products.

3. Match the answer choices to the correct equation.

Try solving on your own before revealing the answer!

Final Answer: Glucose; CO2 and water

Cellular respiration breaks down glucose into carbon dioxide and water.

Q8. What is the function of photosystems within cells?

Background

Topic: Photosynthesis

This question tests your understanding of the role of photosystems in light-dependent reactions.

Key Terms:

• Photosystem: Protein complex that absorbs light energy.

• ATP and NADPH: Energy carriers produced by photosystems.

Step-by-Step Guidance

1. Recall what photosystems do in the light-dependent reactions.

2. Identify the products of photosystem activity.

3. Match the answer choices to the correct function.

Try solving on your own before revealing the answer!

Final Answer: To absorb light energy and store it in the form of ATP and NADPH

Photosystems capture light energy and convert it to chemical energy.

Q9. The main result of the Calvin-Benson cycle, which is part of the light-independent reactions of photosynthesis, is:

Background

Topic: Photosynthesis - Calvin Cycle

This question tests your understanding of carbon fixation and the products of the Calvin cycle.

Key Terms:

• Calvin-Benson cycle: Light-independent reactions.

• Carbon fixation: Incorporation of CO2 into organic molecules.

Step-by-Step Guidance

1. Recall the purpose of the Calvin-Benson cycle.

2. Identify the main product of the cycle.

3. Compare answer choices to the function of the cycle.

Try solving on your own before revealing the answer!

Final Answer: Carbon fixation

The Calvin-Benson cycle fixes carbon dioxide into organic molecules.

Q10. What cellular process occurs in the absence of oxygen, oxidizes NADH to NAD+, and reduces cellular organic molecules?

Background

Topic: Anaerobic Metabolism

This question tests your understanding of fermentation and its role in regenerating NAD+.

Key Terms:

• Fermentation: Anaerobic process.

• NADH/NAD+: Electron carriers.

Step-by-Step Guidance

1. Recall which processes occur without oxygen.

2. Identify which process regenerates NAD+ by oxidizing NADH.

3. Match answer choices to the process described.

Try solving on your own before revealing the answer!

Final Answer: Fermentation

Fermentation occurs in the absence of oxygen and regenerates NAD+.

Q11. An organism that utilizes an inorganic source of carbon as its sole carbon source and light as its energy source is a:

Background

Topic: Microbial Nutrition

This question tests your understanding of nutritional classifications of microorganisms.

Key Terms:

• Photoautotroph: Uses light for energy and CO2 for carbon.

• Chemoautotroph: Uses chemicals for energy, CO2 for carbon.

• Photoheterotroph: Uses light for energy, organic carbon.

• Chemoheterotroph: Uses chemicals for energy, organic carbon.

Step-by-Step Guidance

1. Recall the definitions of autotroph and heterotroph.

2. Identify which organism uses light and inorganic carbon.

3. Match answer choices to the correct classification.

Try solving on your own before revealing the answer!

Final Answer: Photoautotroph

Photoautotrophs use light for energy and CO2 as their carbon source.

Q12. What type of microorganism would you find living in an arctic environment?

Background

Topic: Microbial Growth Conditions

This question tests your understanding of temperature classifications for microbes.

Key Terms:

• Psychrophile: Grows best at low temperatures.

• Mesophile: Grows best at moderate temperatures.

• Thermophile: Grows best at high temperatures.

• Barophile: Grows best under high pressure.

Step-by-Step Guidance

1. Recall the definitions of psychrophile, mesophile, thermophile, and barophile.

2. Identify which type thrives in cold environments.

3. Match answer choices to the correct classification.

Try solving on your own before revealing the answer!

Final Answer: Psychrophile

Psychrophiles are adapted to cold environments like the Arctic.

Q13. What happens if a cell is placed in a hypertonic solution?

Background

Topic: Osmosis and Cell Physiology

This question tests your understanding of how cells respond to different solute concentrations.

Key Terms:

• Hypertonic: Higher solute concentration outside the cell.

• Osmosis: Movement of water across a membrane.

Step-by-Step Guidance

1. Recall what happens to water movement in a hypertonic environment.

2. Consider the effect on cell volume.

3. Match answer choices to the correct outcome.

Try solving on your own before revealing the answer!

Final Answer: Water leaves the cell, causing it to shrink.

In a hypertonic solution, water moves out of the cell, leading to shrinkage.

Q14. During which phase of microbial growth are cells actively synthesizing enzymes to utilize novel nutrients?

Background

Topic: Microbial Growth Phases

This question tests your understanding of the phases of microbial growth and their characteristics.

Key Terms:

• Lag phase: Cells adapt and synthesize enzymes.

• Log phase: Rapid cell division.

• Stationary phase: Growth rate slows.

• Death phase: Cells die off.

Step-by-Step Guidance

1. Recall the characteristics of each growth phase.

2. Identify which phase involves enzyme synthesis for new nutrients.

3. Match answer choices to the correct phase.

Try solving on your own before revealing the answer!

Final Answer: Lag phase

During the lag phase, cells synthesize enzymes to adapt to new conditions.

Q15. Imagine that a certain bacterial species has a generation time of 30 minutes. If you started with a culture from 1 cell, how many would be present after 2 hours?

Background

Topic: Microbial Growth and Generation Time

This question tests your ability to calculate cell numbers based on generation time.

Key Formula:

$N = N_0 \times 2^n$

Where:

• $N$ = final number of cells

• $N_0$ = initial number of cells

• $n$ = number of generations

Step-by-Step Guidance

1. Identify the initial cell count ($N_0 = 1$).

2. Calculate the number of generations: $\text{Total time} \div \text{Generation time}$.

3. Set up the formula for final cell count.

4. Plug in the values for $N_0$ and $n$.

Try solving on your own before revealing the answer!

Final Answer: 16 cells

There are 4 generations in 2 hours (120 min / 30 min = 4), so $N = 1 \times 2^4 = 16$ cells.

Q16. Which statement regarding plasmids is INCORRECT?

Background

Topic: Microbial Genetics - Plasmids

This question tests your understanding of plasmid structure and function.

Key Terms:

• Plasmid: Small, circular DNA molecule.

• Chromosome: Larger, essential DNA molecule.

Step-by-Step Guidance

1. Recall the characteristics of plasmids.

2. Identify which statement does not match plasmid properties.

3. Compare answer choices to your knowledge of plasmids.

Try solving on your own before revealing the answer!

Final Answer: Plasmids are generally the same size as the chromosome.

Plasmids are much smaller than chromosomes.

Q17. Which of the following nitrogenous bases is not found in DNA?

Background

Topic: DNA Structure

This question tests your knowledge of the four bases in DNA.

Key Terms:

• Adenine, Thymine, Cytosine, Guanine: DNA bases.

• Uracil: RNA base.

Step-by-Step Guidance

1. Recall the four bases found in DNA.

2. Identify which base is unique to RNA.

3. Match answer choices to your knowledge.

Try solving on your own before revealing the answer!

Final Answer: Uracil

Uracil is found in RNA, not DNA.

Q18. Why is DNA replication said to be semiconservative?

Background

Topic: DNA Replication

This question tests your understanding of the mechanism of DNA replication.

Key Terms:

• Semiconservative: Each new DNA molecule has one old and one new strand.

Step-by-Step Guidance

1. Recall the process of DNA replication.

2. Identify what happens to the parent and daughter strands.

3. Match answer choices to the correct description.

Try solving on your own before revealing the answer!

Final Answer: Each daughter DNA molecule is composed of one parent strand and one daughter strand.

Semiconservative replication means each new DNA has one old and one new strand.

Q19. The DNA fragments that constitute the lagging strand during DNA replication are called:

Background

Topic: DNA Replication - Lagging Strand

This question tests your knowledge of Okazaki fragments.

Key Terms:

• Okazaki fragments: Short DNA segments on the lagging strand.

Step-by-Step Guidance

1. Recall how the lagging strand is synthesized.

2. Identify the name of the fragments produced.

3. Match answer choices to the correct term.

Try solving on your own before revealing the answer!

Final Answer: Okazaki fragments

Okazaki fragments are short DNA pieces on the lagging strand.

Q20. Which of the following is part of the central dogma of genetics?

Background

Topic: Central Dogma

This question tests your understanding of the flow of genetic information.

Key Terms:

• Transcription: DNA to RNA.

• Translation: RNA to protein.

Step-by-Step Guidance

1. Recall the steps of the central dogma.

2. Identify which answer choice correctly describes the process.

3. Match answer choices to the central dogma.

Try solving on your own before revealing the answer!

Final Answer: DNA is transcribed to RNA, which is then translated to form polypeptides.

This is the central dogma: DNA → RNA → protein.

Q21. What term best describes the process of copying DNA to RNA?

Background

Topic: Transcription

This question tests your understanding of the process of gene expression.

Key Terms:

• Transcription: DNA to RNA.

• Translation: RNA to protein.

• Replication: DNA to DNA.

Step-by-Step Guidance

1. Recall the definitions of transcription, translation, and replication.

2. Identify which process copies DNA to RNA.

3. Match answer choices to the correct process.

Try solving on your own before revealing the answer!

Final Answer: Transcription

Transcription is the process of copying DNA to RNA.

Q22. What type of DNA repair typically follows up replication to correct errors?

Background

Topic: DNA Repair Mechanisms

This question tests your understanding of mismatch repair and other DNA repair processes.

Key Terms:

• Mismatch repair: Corrects errors after replication.

• Light repair: Fixes UV damage.

• SOS response: Emergency repair.

• Dark repair: Fixes UV damage without light.

Step-by-Step Guidance

1. Recall which repair mechanism corrects replication errors.

2. Identify the process that scans for mismatches.

3. Match answer choices to the correct repair mechanism.

Try solving on your own before revealing the answer!

Final Answer: Mismatch repair

Mismatch repair corrects errors that occur during DNA replication.

Q23. What type of horizontal gene transfer requires physical contact between donor and recipient cells?

Background

Topic: Horizontal Gene Transfer

This question tests your understanding of conjugation, transduction, and transformation.

Key Terms:

• Conjugation: Requires cell-to-cell contact.

• Transduction: Uses viruses.

• Transformation: Uptake of naked DNA.

Step-by-Step Guidance

1. Recall the mechanisms of horizontal gene transfer.

2. Identify which process involves direct contact.

3. Match answer choices to the correct mechanism.

Try solving on your own before revealing the answer!

Final Answer: Conjugation

Conjugation requires physical contact between cells.

Q24. Which event causes a nonsense mutation?

Background

Topic: Mutation Types

This question tests your understanding of how mutations affect protein synthesis.

Key Terms:

• Nonsense mutation: Changes a codon to a stop codon.

• Missense mutation: Changes amino acid.

• Silent mutation: No change in amino acid.

Step-by-Step Guidance

1. Recall what a nonsense mutation is.

2. Identify which event creates a stop codon.

3. Match answer choices to the correct event.

Try solving on your own before revealing the answer!

Final Answer: An amino acid codon is changed into a stop codon.

Nonsense mutations create premature stop codons.

Q25. If the operator sequence were deleted from the lac operon, which of the following would result?

Background

Topic: Gene Regulation - Lac Operon

This question tests your understanding of operon structure and function.

Key Terms:

• Operator: DNA sequence where repressor binds.

• Lac operon: Regulates lactose metabolism.

Step-by-Step Guidance

1. Recall the function of the operator in the lac operon.

2. Consider what happens if the operator is missing.

3. Match answer choices to the expected outcome.

Try solving on your own before revealing the answer!

Final Answer: Transcription would remain active in the absence of lactose.

Without the operator, the repressor cannot bind, so transcription is always active.