Q: A sample of farm soil weighing 1 gram contains approximately 2.5 billion bacteria. If a scientist collects 10 grams of soil, how many bacteria would be present, assuming uniform distribution?

$$2.5 \times 10^9$ \times 10 = 2.5 \times 10$$^{10}$$ bacteria

Question 1

Which of the following statements best describes a key difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus enclosed by a nuclear membrane, while prokaryotic cells lack a nucleus.

Question 2

Which metabolic strategy is used by prokaryotes that obtain energy from inorganic molecules and synthesize their own food?

Accepted Answer

Chemoautotrophy

Question 3

A scientist discovers a microorganism living in a hot spring with water temperatures near boiling. Which domain is this organism most likely to belong to?

Accepted Answer

Domain Archaea

Question 4

Which of the following is NOT a characteristic of most bacteria?

Accepted Answer

They divide by mitosis.

Question 5

Cyanobacteria played a crucial role in Earth's history by:

Accepted Answer

Creating the first oxygen-rich atmosphere through photosynthesis.

Question 6

Which of the following best explains why Archaea are often found in extreme environments?

Accepted Answer

They possess unique membrane lipids that are branched and can withstand harsh conditions.

Question 7

Methanogens are a type of Archaea that produce methane. Which chemical reaction do they use to generate methane?

Accepted Answer

$$CO_2 + 4H_2$$ \rightarrow $$CH_4 + 2H_2O$$

Question 8

Which of the following bacterial shapes is correctly matched with its description?

Accepted Answer

Spirillum — Helical-shaped

Question 9

A farmer wants to improve soil fertility by increasing the amount of nitrogen available to plants. Which type of bacteria should he encourage in his soil?

Accepted Answer

Nitrogen-fixing bacteria

Question 10

Which of the following is a real-world application of bacteria in biotechnology?

Accepted Answer

Production of antibiotics such as streptomycin

Question 11

Which process do prokaryotes use to reproduce?

Accepted Answer

Binary fission

Question 12

Which of the following statements about biofilms is correct?

Accepted Answer

Biofilms are communities of bacteria that adhere to surfaces and are often more resistant to antibiotics.

Question 13

Which of the following is a major ecological role of bacteria?

Accepted Answer

Decomposition of organic matter

Question 14

A sample of farm soil weighing 1 gram contains approximately 2.5 billion bacteria. If a scientist collects 10 grams of soil, how many bacteria would be present, assuming uniform distribution?

Accepted Answer

$$2.5 	imes 10^9$ 	imes 10 = 2.5 	imes 10$$^{10}$$ bacteria

Question 15

Which of the following is true about the genetic material in most bacteria?

Accepted Answer

It consists of a single circular chromosome and is haploid.

Question 16

Which of the following is a correct match between a type of extremophile and its preferred environment?

Accepted Answer

Halophilic Archaea — High salt concentrations

Question 17

Which of the following is a plausible consequence if bacteria were suddenly removed from all ecosystems?

Accepted Answer

Decomposition of organic matter would slow dramatically, disrupting nutrient cycles.

Question 18

Which of the following best describes the role of bacteria in food production?

Accepted Answer

Bacteria are essential for making foods like yogurt, pickles, and cheese.

Question 19

Which of the following is an example of bioremediation using bacteria?

Accepted Answer

Using bacteria to remove pollutants from water, air, and soil

Question 20

Which of the following is a common misconception about prokaryotes?

Accepted Answer

All prokaryotes are harmful to humans.

Prokaryotes: Diversity, Structure, and Importance

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