Chapter 26

Question 1

Ecosystem

Answer 1

consists of populations of species plus their habitat or environment

Question 2

population

Answer 2

is a group of individuals of one species living in a common location

Question 3

niche

Answer 3

within an ecosystem, each population of organisms fills this
set of traits that enable living and enable living and interacting with others

Question 4

assimilation

Answer 4

converts carbon from CO2 into biomass

Question 5

dissimilation

Answer 5

breaks down biomass

Question 6

physical factors limit microbial growth

Answer 6

oxygen, salinity, pH

Question 7

biochemical oxygen demand (BOD)

Answer 7

is the amount of O2 removed from the water through aerobic respiration.
BOD goes up when the number of heterotrophic microbes increases, due to
Increase in organic compounds (sewage)
Increase in other nutrients (nitrates)

Question 8

eutrophic

Answer 8

lakes (excessive nutrients present) have increased BOD

Question 9

algal bloom

Answer 9

In a eutrophic lake, the nutrients support growth of algae and bacteria to high densities
Algal blooms increasingly threaten our water supplies worldwide.
Fertilizer runoff can cause algal blooms.
Algal blooms are associated with climate change.

Question 10

Microbes in marine environments

Answer 10

Oceans are two-thirds of Earth with variations in depth.
Coastal ecosystems-high concentration of nutrients
Heterotrophs, photoautotrophs
Deep ocean ecosystems

Question 11

lithotrophic

Answer 11

bacteria at thermal vents support life in the deep ocean

Question 12

dead zones

Answer 12

fish and invertebrates can’t survive

Question 13

mutualism

Answer 13

a relationship where species require each other for survival

Question 14

synergism

Answer 14

a relationship where species grow better when together but can grow independently

Question 15

commensalism

Answer 15

an interaction that benefits one partner species without harm to the other

Question 16

amensalism

Answer 16

an interaction that harms one partner nonspecifically, without harming the other

Question 17

parasitism

Answer 17

a relationship that benefits one member and causes harm to the other

Question 18

gut microbes are being seen as an “organ” that influences the function of other body systems

Answer 18

immune system
endocrine system
nervous system

Question 19

zoonotic

Answer 19

parasites may cause human diseases
Zoonotic diseases are infectious diseases of animals that can “cross over” into humans.
Animals are reservoirs; humans are typically dead-end hosts.
Rarely humans may become reservoirs of zoonotic diseases and person-to-person transmission occurs.
Example: H5N1 (avian) influenza

Question 20

fermentation

Answer 20

Microbes turn sugars into acids and/or alcohol during glycolysis/fermentation.
Uses of fermentation
Food preservation
Acid, alcohol and ammonia produced by microbes
Improves digestibility of fibrous foods
Increases levels of some nutrients in food, such as vitamins (B12)
Improves food flavor by adding esters and sulfur compounds

Question 21

alcoholic fermentation

Answer 21

yeasts ferment sugars to ethyl alcohol

Question 22

enzymatic processes

Answer 22

naturally break down complex organic compounds to simpler ones

Question 23

chemical reactions with the environment

Answer 23

such as oxidation reactions

Question 24

microbial contamination

Answer 24

of food and their growth produces metabolites that contribute to food spoilage

Question 25

dehydration and freeze-drying

Answer 25

physical methods of food preservation
removal of water prevents microbial growth

Question 26

refrigeration and freezing

Answer 26

food preservation
refrigeration temp. slows microbial growth
freezing halts growth of most microbes, which might grow again when food is thawed

Question 27

controlled or modified atmosphere

Answer 27

food preservation
food packed in low O2 or high CO2 limits growth and prevents abiotic oxidation

Question 28

pasteurization

Answer 28

food preservation
short-term heat treatment decreases microbe number but does not affect food quality or texture

Question 29

canning

Answer 29

food preservation
cooking food under pressure destroys the majority of microbial forms, including endospores, without harming food quality

Question 30

food irradiation

Answer 30

food preservation
food is exposed to ionizing radiation , which sterilizes food and improves shelf life
unknown effects of radiation on food chemistry
hazards to workers involved in the irradiation process

Question 31

acids

Answer 31

food preservation
lowering the pH of a food through fermentation or addition of acids

Question 32

other organic compounds with antimicrobial activity

Answer 32

food preservation
cinnamon, cloves, and other plant-based compounds inhibit microbial growth

Question 33

inorganic compounds

Answer 33

food preservation
salts, phosphate, nitrites, sulfite inhibit aerobic respiration
may have harmful effects on humans (toxicity, allergy)

Question 34

wastewater

Answer 34

Human society contributes organic wastes (human sewage, industrial effluents) to the water cycle.
Introduction of these compounds into an ecosystem disrupts the ecological balance, leading to eutrophication and dead zones.

Question 35

wastewater treatment

Answer 35

remove organic carbon and nitrogen from water before it returns to aquatic systems and the oceans.