Module 5: Section 1A

Question 1

Microbes in the ocean

Answer 1

• Form the base of the food chain
• Major players in controlling the health of the marine ecosystem

Question 2

Bioluminescence of marine microbes

Answer 2

• This communication system is used to manipulate the behaviour of host organisms
• Can facilitate searching for pray, finding mates, deter predators, or help camouflage the host via bioluminescence

Question 3

Marine Viruses and Coral Reefs

Answer 3

Marine viruses (phages and eukaryotic viruses) help maintain ocean health by lysing hosts and “shunting” organic matter into the benthic compartment, recycling nutrients for microbes and coral around reefs

Question 4

Microbes and Plants

Answer 4

• Plants have normal microbial flora, mostly around their roots, that can protect against pathogens and sometimes benefit growth
• Many are commensals with no known effect, while others like nitrogen-fixing bacteria have a direct positive impact on the plant

Question 5

Rhizosphere

Answer 5

Narrow region of soil that is directly influenced by root secretions and associated soil microorganisms

Question 6

Aboveground plant parts

Answer 6

Induction of resistance in below ground plant parts spreads to above ground parts and vice versa

Question 7

Plant roots

Answer 7

Root exudates and other rhizodeposits stimulate and/or inhibit various microbes

Question 8

Pathogenic microbes

Answer 8

Damage the plant through infection or production of phytotoxic compounds

Question 9

Beneficial microbes

Answer 9

Either promote plant growth directly or protect the plant by inhibiting deleterious microbes or through induced systemic resistance

Question 10

Kudzu Bug

Answer 10

• Kudzu bugs acquire their symbiont Ishikawaella capsulata by feeding on capsules containing the microbes after birth; if capsules are missing, nymphs search for them
• This shows that animal behavior can shape how symbionts are acquired

Question 11

Green Iguana

Answer 11

Juvenile green iguanas eat soil or feces to modify their gut microbiota for their diet, showing that animals can adjust their microbiota at different life stages

Question 12

Bobtail Squid

Answer 12

The bobtail squid hosts Vibrio fischeri and ejects these bioluminescent bacteria daily, showing that animals can actively regulate their symbiont populations

Question 13

Fruit Fly

Answer 13

In fruit flies, diet-specific gut microbiota influence mating preferences, suggesting that microbes can drive speciation

Question 14

Mosquito

Answer 14

Human skin microbes influence how attractive a person is to mosquitoes, meaning differences in skin microbiota could affect disease transmission and spread

Question 15

Mouse

Answer 15

In mice, the probiotic Lactobacillus rhamnosus reduces anxiety levels, showing that gut bacteria can influence mood and behavior