University of Michigan
4 MAXE · 171 OIB
M
★ ★
UMICH Department of Ecology & Evolutionary Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
BIO 171 — Exam 4
E CO LO G Y, B I O D I V E RS I TY, B I O G E O C H E M I C A L CYC L E S & I N F E CT I O US D I S E A S E
INSTITUTION University of Michigan COURSE CODE BIO 171
PROGRAM Ecology & Evolutionary Biology ACADEMIC YEAR
EXAM TITLE BIO 171 Exam 4 — Ecology & TOTAL QUESTIONS 58 Questions
Global Change
COURSE TITLE Introductory Biology: Ecology & FORMAT Multiple Choice — Select the
Evolutionary Biology Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover biodiversity, community ecology, biogeochemical cycles, productivity, infectious
disease, and antibiotic resistance.
▸ Content is aligned with University of Michigan BIO 171 Exam 4 objectives.
▸ Correct answers and detailed rationales appear below each question.
, BIO 171 EXAM 4 — ECOLOGY, BIODIVERSITY, NUTRIENT
Questions 1 – 58
CYCLES & DISEASE
1. The variety of different types of life found on Earth is called:
A. Biodiversity
B. Species richness only
C. Ecosystem services
D. Primary productivity
CORRECT ANSWER A — Biodiversity
RATIONALE Per the source material, biodiversity is the variety of different types of life found
on Earth — encompassing genetic diversity, species diversity, and ecosystem
diversity. Species richness (option B) is one component of biodiversity. Ecosystem
services (option C) are benefits humans derive from ecosystems. Primary
productivity (option D) is the rate of organic matter production.
2. A physical factor that removes organisms from a community, characterized by intensity
and frequency, is called a:
A. Disturbance
B. Succession event
C. Limiting factor
D. Abiotic gradient
CORRECT ANSWER A — Disturbance
RATIONALE Per the source material, a disturbance is a physical factor that removes organisms
from a community, characterized by intensity (severity) and frequency (how often
it occurs). Examples include fires, floods, and storms. Succession (option B) is the
recovery process following disturbance. Limiting factors (option C) restrict
growth.
,3. The relative proportion of each species in a community is called:
A. Species richness
B. Species evenness
C. Biodiversity
D. Community structure
CORRECT ANSWER B — Species evenness
RATIONALE Per the source material, species evenness is the relative proportion of each
species within a community — it measures how equally individuals are
distributed among species. Species richness (option A) is the number of species
present. Biodiversity (option C) encompasses both richness and evenness.
4. A fecal transplant works by:
A. Restoring the microbial community so that C. difficile does not completely take over the
GI tract
B. Directly killing C. difficile with antibiotics
C. Removing all bacteria from the gut
D. Introducing genetically modified bacteria
CORRECT ANSWER A — Restoring the microbial community so C. difficile does not completely
take over the GI tract
RATIONALE Per the source material, fecal transplants restore the normal, diverse microbial
community in the gut. This prevents C. difficile — which often overgrows after
antibiotic treatment has depleted the normal microbiota — from dominating. The
transplanted microbiota competes with and suppresses C. difficile.
, 5. The latitudinal gradient of biodiversity states that:
A. The closer you are to the equator, the more biodiversity; biodiversity decreases when
moving toward the poles
B. Biodiversity is highest at the poles
C. Biodiversity is uniform across all latitudes
D. Biodiversity peaks at mid-latitudes
CORRECT ANSWER A — Closer to equator = more biodiversity; decreases toward poles
RATIONALE Per the source material, biodiversity follows a latitudinal gradient — it is highest
near the equator and decreases as you move toward the poles. This pattern is
observed across many taxonomic groups and is driven by factors including
climate stability, solar energy input, and evolutionary history.
6. The microbiome refers to:
A. The number of microbes that live on or in us
B. Only bacteria found in soil
C. Viruses that infect plants
D. The genetic material of a single species
CORRECT ANSWER A — The number of microbes that live on or in us
RATIONALE Per the source material, the microbiome is the collection of microbes (bacteria,
fungi, archaea, viruses) that live on and inside the human body. These microbial
communities play essential roles in digestion, immunity, and overall health. It is
not limited to soil bacteria (option B) or plant viruses (option C).
4 MAXE · 171 OIB
M
★ ★
UMICH Department of Ecology & Evolutionary Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
BIO 171 — Exam 4
E CO LO G Y, B I O D I V E RS I TY, B I O G E O C H E M I C A L CYC L E S & I N F E CT I O US D I S E A S E
INSTITUTION University of Michigan COURSE CODE BIO 171
PROGRAM Ecology & Evolutionary Biology ACADEMIC YEAR
EXAM TITLE BIO 171 Exam 4 — Ecology & TOTAL QUESTIONS 58 Questions
Global Change
COURSE TITLE Introductory Biology: Ecology & FORMAT Multiple Choice — Select the
Evolutionary Biology Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Questions cover biodiversity, community ecology, biogeochemical cycles, productivity, infectious
disease, and antibiotic resistance.
▸ Content is aligned with University of Michigan BIO 171 Exam 4 objectives.
▸ Correct answers and detailed rationales appear below each question.
, BIO 171 EXAM 4 — ECOLOGY, BIODIVERSITY, NUTRIENT
Questions 1 – 58
CYCLES & DISEASE
1. The variety of different types of life found on Earth is called:
A. Biodiversity
B. Species richness only
C. Ecosystem services
D. Primary productivity
CORRECT ANSWER A — Biodiversity
RATIONALE Per the source material, biodiversity is the variety of different types of life found
on Earth — encompassing genetic diversity, species diversity, and ecosystem
diversity. Species richness (option B) is one component of biodiversity. Ecosystem
services (option C) are benefits humans derive from ecosystems. Primary
productivity (option D) is the rate of organic matter production.
2. A physical factor that removes organisms from a community, characterized by intensity
and frequency, is called a:
A. Disturbance
B. Succession event
C. Limiting factor
D. Abiotic gradient
CORRECT ANSWER A — Disturbance
RATIONALE Per the source material, a disturbance is a physical factor that removes organisms
from a community, characterized by intensity (severity) and frequency (how often
it occurs). Examples include fires, floods, and storms. Succession (option B) is the
recovery process following disturbance. Limiting factors (option C) restrict
growth.
,3. The relative proportion of each species in a community is called:
A. Species richness
B. Species evenness
C. Biodiversity
D. Community structure
CORRECT ANSWER B — Species evenness
RATIONALE Per the source material, species evenness is the relative proportion of each
species within a community — it measures how equally individuals are
distributed among species. Species richness (option A) is the number of species
present. Biodiversity (option C) encompasses both richness and evenness.
4. A fecal transplant works by:
A. Restoring the microbial community so that C. difficile does not completely take over the
GI tract
B. Directly killing C. difficile with antibiotics
C. Removing all bacteria from the gut
D. Introducing genetically modified bacteria
CORRECT ANSWER A — Restoring the microbial community so C. difficile does not completely
take over the GI tract
RATIONALE Per the source material, fecal transplants restore the normal, diverse microbial
community in the gut. This prevents C. difficile — which often overgrows after
antibiotic treatment has depleted the normal microbiota — from dominating. The
transplanted microbiota competes with and suppresses C. difficile.
, 5. The latitudinal gradient of biodiversity states that:
A. The closer you are to the equator, the more biodiversity; biodiversity decreases when
moving toward the poles
B. Biodiversity is highest at the poles
C. Biodiversity is uniform across all latitudes
D. Biodiversity peaks at mid-latitudes
CORRECT ANSWER A — Closer to equator = more biodiversity; decreases toward poles
RATIONALE Per the source material, biodiversity follows a latitudinal gradient — it is highest
near the equator and decreases as you move toward the poles. This pattern is
observed across many taxonomic groups and is driven by factors including
climate stability, solar energy input, and evolutionary history.
6. The microbiome refers to:
A. The number of microbes that live on or in us
B. Only bacteria found in soil
C. Viruses that infect plants
D. The genetic material of a single species
CORRECT ANSWER A — The number of microbes that live on or in us
RATIONALE Per the source material, the microbiome is the collection of microbes (bacteria,
fungi, archaea, viruses) that live on and inside the human body. These microbial
communities play essential roles in digestion, immunity, and overall health. It is
not limited to soil bacteria (option B) or plant viruses (option C).
