University of Michigan
2 MAXE · 171 OIB
★ ★
M College of Literature, Science & the Arts — Department of Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
Bio 171 Exam 2
E CO SYST E M E CO LO G Y · P L A N T B I O LO G Y · T R O P H I C DY N A M I CS · B I O G E O C H E M I ST RY
INSTITUTION University of Michigan PROGRAM Bachelor of Science — Biology
COURSE CODE BIO 171 COURSE TITLE Introduction to Molecular &
Cellular Biology
ACADEMIC YEAR EXAM TITLE Bio 171 Exam 2
TOTAL QUESTIONS 35 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ This examination covers ecosystem ecology, plant biology, trophic dynamics, biogeochemical cycles,
and energy flow.
▸ Questions address primary productivity, food webs, nutrient cycling, plant vascular systems, and
ecosystem structure.
▸ Correct answers and explanatory rationales appear below each question for review purposes.
▸ All content reflects standard introductory biology curriculum for BIO 171 at the University of Michigan.
, SECTION I — ECOSYSTEM ECOLOGY & PLANT BIOLOGY Questions 1 – 35
1. Which term describes all living biomass above the soil including stems, stumps, branches,
bark, seeds, and foliage?
A. Below-ground biomass
B. Above-ground biomass
C. Net primary productivity
D. Gross primary productivity
CORRECT ANSWER B — Above-ground biomass
RATIONALE Above-ground biomass encompasses all living plant material visible above the
soil surface — stems, stumps, branches, bark, seeds, and foliage. It is a key metric
in ecosystem ecology, used to estimate carbon storage, forest productivity, and
the effects of land-use change. Below-ground biomass includes roots and other
subterranean plant structures. Biomass measurements are essential for
understanding carbon cycling and energy flow through ecosystems.
2. A food web is best defined as:
A. A single linear sequence of organisms through which energy flows
B. A community of organisms where there are several interrelated food chains
C. A diagram showing only the top predators in an ecosystem
D. A pyramid representing the biomass at each trophic level
CORRECT ANSWER B — A community of organisms where there are several interrelated food
chains
RATIONALE A food web represents the complex, interconnected network of feeding
relationships within an ecosystem. Unlike a single food chain (option A), which
follows one linear path of energy transfer, a food web shows multiple pathways —
most organisms consume and are consumed by multiple species. This
interconnectedness provides ecosystem stability; if one species declines,
predators can switch to alternative prey. Food webs more accurately depict the
complexity of real ecosystems than simple food chains.
, 3. Inorganic substances are characterized by:
A. Being formed from living things and containing carbon
B. Not being formed from living things or their remains and not containing carbon
C. Always containing nitrogen and phosphorus
D. Being produced exclusively through photosynthesis
CORRECT ANSWER B — Not being formed from living things or their remains and not
containing carbon
RATIONALE Inorganic compounds are typically not derived from living organisms and lack
carbon-hydrogen bonds. Examples include water (H2O), minerals, salts, and
atmospheric gases like nitrogen (N2) and carbon dioxide (CO2). Note that CO2,
while containing carbon, is classified as inorganic because it lacks C-H bonds.
Organic compounds, in contrast, contain carbon bonded to hydrogen and are
associated with living systems. This distinction is fundamental to
biogeochemistry and understanding nutrient cycling.
4. A tertiary consumer is best described as:
A. An herbivore that eats primary producers
B. A carnivore that eats secondary consumers
C. A decomposer that breaks down organic matter
D. A primary producer that captures energy from sunlight
CORRECT ANSWER B — A carnivore that eats secondary consumers
RATIONALE Trophic levels represent feeding positions in an ecosystem. Primary producers
(level 1) are autotrophs. Primary consumers (level 2) are herbivores eating
producers. Secondary consumers (level 3) are carnivores eating herbivores.
Tertiary consumers (level 4) are carnivores that eat secondary consumers — they
are top predators in many ecosystems, such as hawks eating snakes that eat mice.
Energy decreases at each successive trophic level (typically ~10% transfer
efficiency).
2 MAXE · 171 OIB
★ ★
M College of Literature, Science & the Arts — Department of Biology
EST. 1817
ARTES · SCIENTIA · VERITAS
Bio 171 Exam 2
E CO SYST E M E CO LO G Y · P L A N T B I O LO G Y · T R O P H I C DY N A M I CS · B I O G E O C H E M I ST RY
INSTITUTION University of Michigan PROGRAM Bachelor of Science — Biology
COURSE CODE BIO 171 COURSE TITLE Introduction to Molecular &
Cellular Biology
ACADEMIC YEAR EXAM TITLE Bio 171 Exam 2
TOTAL QUESTIONS 35 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ This examination covers ecosystem ecology, plant biology, trophic dynamics, biogeochemical cycles,
and energy flow.
▸ Questions address primary productivity, food webs, nutrient cycling, plant vascular systems, and
ecosystem structure.
▸ Correct answers and explanatory rationales appear below each question for review purposes.
▸ All content reflects standard introductory biology curriculum for BIO 171 at the University of Michigan.
, SECTION I — ECOSYSTEM ECOLOGY & PLANT BIOLOGY Questions 1 – 35
1. Which term describes all living biomass above the soil including stems, stumps, branches,
bark, seeds, and foliage?
A. Below-ground biomass
B. Above-ground biomass
C. Net primary productivity
D. Gross primary productivity
CORRECT ANSWER B — Above-ground biomass
RATIONALE Above-ground biomass encompasses all living plant material visible above the
soil surface — stems, stumps, branches, bark, seeds, and foliage. It is a key metric
in ecosystem ecology, used to estimate carbon storage, forest productivity, and
the effects of land-use change. Below-ground biomass includes roots and other
subterranean plant structures. Biomass measurements are essential for
understanding carbon cycling and energy flow through ecosystems.
2. A food web is best defined as:
A. A single linear sequence of organisms through which energy flows
B. A community of organisms where there are several interrelated food chains
C. A diagram showing only the top predators in an ecosystem
D. A pyramid representing the biomass at each trophic level
CORRECT ANSWER B — A community of organisms where there are several interrelated food
chains
RATIONALE A food web represents the complex, interconnected network of feeding
relationships within an ecosystem. Unlike a single food chain (option A), which
follows one linear path of energy transfer, a food web shows multiple pathways —
most organisms consume and are consumed by multiple species. This
interconnectedness provides ecosystem stability; if one species declines,
predators can switch to alternative prey. Food webs more accurately depict the
complexity of real ecosystems than simple food chains.
, 3. Inorganic substances are characterized by:
A. Being formed from living things and containing carbon
B. Not being formed from living things or their remains and not containing carbon
C. Always containing nitrogen and phosphorus
D. Being produced exclusively through photosynthesis
CORRECT ANSWER B — Not being formed from living things or their remains and not
containing carbon
RATIONALE Inorganic compounds are typically not derived from living organisms and lack
carbon-hydrogen bonds. Examples include water (H2O), minerals, salts, and
atmospheric gases like nitrogen (N2) and carbon dioxide (CO2). Note that CO2,
while containing carbon, is classified as inorganic because it lacks C-H bonds.
Organic compounds, in contrast, contain carbon bonded to hydrogen and are
associated with living systems. This distinction is fundamental to
biogeochemistry and understanding nutrient cycling.
4. A tertiary consumer is best described as:
A. An herbivore that eats primary producers
B. A carnivore that eats secondary consumers
C. A decomposer that breaks down organic matter
D. A primary producer that captures energy from sunlight
CORRECT ANSWER B — A carnivore that eats secondary consumers
RATIONALE Trophic levels represent feeding positions in an ecosystem. Primary producers
(level 1) are autotrophs. Primary consumers (level 2) are herbivores eating
producers. Secondary consumers (level 3) are carnivores eating herbivores.
Tertiary consumers (level 4) are carnivores that eat secondary consumers — they
are top predators in many ecosystems, such as hawks eating snakes that eat mice.
Energy decreases at each successive trophic level (typically ~10% transfer
efficiency).
