Chapter 1: Humans and the Microbial World

Question 1

What are the three major groups of microorganisms?

Answer 1

• prokaryotes
• eukaryotes
• acellular microbes

Question 2

What are prokaryotes? (2)

Answer 2

• bacteria (and archaea)
• have one single xme

Question 3

What are eukaryotes?

Answer 3

• Algae
• Fungi
• Protozoa

Question 4

What are acellular microbes?

Answer 4

• Viruses (DNA and RNA types)

Question 5

Order the following from smallest to largest: virus, bacteria, microeukaryotes

Answer 5

1. viruses
2. bacteria
3. microeukaryotes (protozoa)

Question 6

Viruses are very small. What size?

Answer 6

20 nm (0.000002 mm)

Question 7

Some protozoa (Eukaryotes) are very large. What size?

Answer 7

• 5 mm

Question 8

The best studied microorganism is bacteria. What is their size?

Answer 8

• 1 micrometer, or 0.001 mm

Question 9

What are the major entities living in the biosphere?

Answer 9

• VIRUSES

Question 10

Why are microbes important to the environment? (4)

Answer 10

• some produce oxygen
• Fix nitrogen for use by plants
• important members of the food chain
• breakdown and recycle organic wastes

Question 11

Why are microbes important for industries?

Answer 11

• used by industry to produce beer, wine, pickles, cheese, etc.
• pharmaceuticals use it to make antibiotics
• genetically engineered to produce therapeutic substances like insulin
• Play a role in human immunity - normal microbiota

Question 12

How can microbes degrade explosives?

Answer 12

• Trinitrotoluene, or TNT, contaminates the soil in areas where ammunition is kept
• Bacteria named Clostridium bifermentans can break down this contaminant

Question 13

What is bioremediation? (2)

Answer 13

• the biological degrading processes for the treatment of contaminated soils, groundwater, or sediments
• relies of microorganisms like bacteria and/or fungi to use the contaminants as a food source to degrade the contaminant
  essentially using microbes to degrade organic pollutants

Question 14

Why is bioremediation beneficial?

Answer 14

• the most economic remedial techniques for treating most organic fuel based contaminants like coal tars, petroleum, etc.

Question 15

How can bacteria help with oil spills? (5)

Answer 15

• natural microbes in the ocean feed on hydrocarbons in oil
• oil contains hydrocarbons (made of H and C)
• oxygen is needed for the reaction, but can be sparse at great ocean depths
• so the microbes break apart the hydrocarbons and combine them with oxygen to create water and CO2
• not all of the oil can be consumed, but the leftovers can be easily dispersed by currents and wind

Question 16

Why is adding fertilizer not good for helping bacteria clean up oil spills? (2)

Answer 16

• fertilizer increases the size and number of microbes so they can eat more oil
• too much fertilizer can cause algae blooms that starve the ecosystem of light and oxygen

Question 17

How are bacteria used to make chocolate? (3)

Answer 17

• chocolate comes from the seeds of the cacao tree
• the seeds come in pods and the only way to retrieve the seeds are to ferment them with yeasts and lactobacilli and acetobacter
• The lactobacillus secretes an acid to help break apart the pod

Question 18

How can microbes make plastics? (2)

Answer 18

• Alcaligenes eutrophus is a useful bacterium that makes plastics
• strong hopes of using these bacteria and their plastics for medical purposes

Question 19

How can bacteria fade jeans? (2)

Answer 19

• Alkalothermophilic Thermomonospora produces enzyme cellulase
• when you mix cellulase with denim cloth, it reduces the hairiness and makes it softer and lighter

Question 20

How can bacteria act as insecticides? (2)

Answer 20

• used and studied as biocontrol agents to help control diseases in important crops
• can control pests