Chapter Exam

Chapter 6: Microbial Nutrition and Growth — Online MCQ Test

Q: Which organisms derive their carbon source from carbon dioxide?

Answer: A. Autotrophs — Autotrophs are organisms that utilize inorganic carbon in the form of CO2 as their primary carbon source.

Q: The phase in bacterial growth where the rate of growth is equal to the rate of death is called:

Answer: C. Stationary phase — In the stationary phase, nutrient depletion and waste accumulation balance the growth rate, leading to no net population change.

Q: What happens to the microbial cell membrane at extremely low temperatures?

Answer: B. It solidifies and prevents transport — At low temperatures, membrane lipids solidify, reducing fluidity and hindering nutrient transport into the cell.

MICROBIOLOGY · CLASS 11th · Tamil Nadu State Board

Practice Chapter 6: Microbial Nutrition and Growth with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 11th MICROBIOLOGY. This chapter covers: Exploring cellular metabolism this chapter details nutritional categories autotrophs heterotrophs microbial growth phases batch and continuous culture. Students examine environment.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 6: Microbial Nutrition and Growth — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 11th MICROBIOLOGY — Chapter 6: Microbial Nutrition and Growth, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which organisms derive their carbon source from carbon dioxide?

A. Autotrophs ✓
B. Heterotrophs
C. Chemoorganotrophs
D. Parasites

Answer: A. Autotrophs
Autotrophs are organisms that utilize inorganic carbon in the form of CO2 as their primary carbon source.

The phase in bacterial growth where the rate of growth is equal to the rate of death is called:

A. Lag phase
B. Log phase
C. Stationary phase ✓
D. Decline phase

Answer: C. Stationary phase
In the stationary phase, nutrient depletion and waste accumulation balance the growth rate, leading to no net population change.

What happens to the microbial cell membrane at extremely low temperatures?

A. It becomes too fluid
B. It solidifies and prevents transport ✓
C. It ruptures due to ice crystals
D. It increases enzyme activity

Answer: B. It solidifies and prevents transport
At low temperatures, membrane lipids solidify, reducing fluidity and hindering nutrient transport into the cell.

Why is the lag phase longer in old or damaged bacterial cultures?

A. Cells are dividing too rapidly
B. Cells need time to synthesize new enzymes for nutrient utilization ✓
C. The culture is already in the decline phase
D. Oxygen is not required in the lag phase

Answer: B. Cells need time to synthesize new enzymes for nutrient utilization
When inoculated into new media, aged cells must repair damage and adapt their enzymatic machinery before synthesis and division occur.

A chemostat differs from a batch culture because in a chemostat:

A. The population eventually dies
B. The dilution rate is controlled to maintain steady-state growth ✓
C. Waste products accumulate in the medium
D. It is used primarily for clinical diagnosis

Answer: B. The dilution rate is controlled to maintain steady-state growth
A chemostat allows for the precise control of the growth rate by balancing the inflow of media with the outflow of culture volume.