BIO 101 Final Exam Review | Questions & Correct
Answers with Detailed Rationales | New 2026–2027
Update
Ecology and Ecosystems
Which term best defines this organization: All the organisms/species living in a
particular area and the physical components with which the organism interact?
A) Population
B) Community
C) Ecosystem
D) Biome
Expert Rationale: An ecosystem encompasses both the biotic community (all
living organisms) and the abiotic physical components (such as soil, water, and
climate) with which they interact. A population refers to a single species, a
community refers only to living organisms, and a biome is a larger-scale
classification of ecosystems based on climate and vegetation.
I design an experiment to test whether or not fertilizer has an effect on the
growth of dandelions. My hypothesis is that dandelions in soil to which fertilizer
is added will produce more biomass. What is my independent variable in this
experiment?
A) Biomass production
B) Presence or absence of fertilizer
C) Type of soil used
D) Growth rate of dandelions
Expert Rationale: The independent variable is the factor that the researcher
manipulates. In this experiment, the researcher manipulates whether fertilizer is
present or absent. Biomass production is the dependent variable being measured.
,What is an example of Aposematism?
A) A bright red beetle sitting on a green leaf
B) A black and yellow stinging wasp that buzzes as it flies
C) A harmless hoverfly resembling a wasp
D) A moth blending with tree bark
Expert Rationale: Aposematism is a warning coloration that signals potential
danger to predators. Both a bright red beetle and a black-and-yellow stinging
wasp display warning coloration. A harmless hoverfly resembling a wasp is
Batesian mimicry, not aposematism.
Which model of natural selection is being exerted in the following scenario: In a
population of fish, adult body size is a variable trait (with a normal distribution).
The smallest adult fish are cannibalized by their cohorts and the largest adult
fish are visible to a bird predator and tend to be preyed upon frequently.
A) Directional selection
B) Stabilizing selection
C) Disruptive selection
D) Artificial selection
Expert Rationale: Stabilizing selection favors intermediate phenotypes and selects
against extreme phenotypes. Here, both the smallest and largest fish have
reduced fitness, favoring medium-sized fish. This maintains the average trait value
in the population.
Which mode of natural selection is being exerted in the following scenario: In a
population of plants, resistance to a type of fungal blight is a variable trait (with
a normal distribution). The blight kills 80% of the plants, leaving only the most
resistant to survive.
A) Stabilizing selection
B) Directional selection
,C) Disruptive selection
D) Sexual selection
Expert Rationale: Directional selection occurs when one extreme phenotype is
favored over others. The blight eliminates less resistant plants, shifting the
population toward greater resistance. This is a classic example of directional
selection.
Abiotic Factors and Biomes
Which abiotic factor(s) is/are responsible for the presence of different seasons
on our planet?
A) Distance from the sun
B) The Earth's tilt
C) Ocean currents
D) Atmospheric composition
Expert Rationale: The Earth's axial tilt (approximately 23.5 degrees) causes
different parts of the planet to receive varying amounts of solar radiation
throughout the year, creating seasons. Distance from the sun varies only slightly
and is not the primary cause of seasons.
Which biome is comprised of a productive area where rivers meet the ocean?
A) Wetland
B) Estuary
C) Coral reef
D) Lake
Expert Rationale: An estuary is a transition zone where freshwater from rivers
mixes with saltwater from the ocean. This mixing creates a highly productive
ecosystem with abundant nutrients, supporting diverse life forms.
Which key abiotic climate factor(s) distinguish terrestrial biomes?
, A) Sunlight and wind
B) Precipitation and temperature
C) Soil type and elevation
D) Humidity and latitude
Expert Rationale: Precipitation and temperature are the primary abiotic factors
that determine the distribution and characteristics of terrestrial biomes. These
factors influence vegetation types, which in turn define each biome.
Which biome does not include fire as a natural part of its cycle?
A) Savanna
B) Chaparral
C) Coniferous forest
D) Temperate grassland
Expert Rationale: While fire is a natural and important part of many biome cycles
(savannas, chaparral, grasslands), coniferous forests are not typically characterized
by fire as an essential part of their ecological cycle. Fires do occur but are not a
defining feature.
Species Interactions
Bark beetles feed under the bark of trees (bark beetles and trees)
A) Mutualism
B) Predation
C) Herbivory
D) Parasitism
Expert Rationale: Herbivory is the consumption of plant material by animals. Bark
beetles feeding on tree tissue (bark and underlying tissues) represents herbivory,
where the beetle benefits and the tree is harmed.
Answers with Detailed Rationales | New 2026–2027
Update
Ecology and Ecosystems
Which term best defines this organization: All the organisms/species living in a
particular area and the physical components with which the organism interact?
A) Population
B) Community
C) Ecosystem
D) Biome
Expert Rationale: An ecosystem encompasses both the biotic community (all
living organisms) and the abiotic physical components (such as soil, water, and
climate) with which they interact. A population refers to a single species, a
community refers only to living organisms, and a biome is a larger-scale
classification of ecosystems based on climate and vegetation.
I design an experiment to test whether or not fertilizer has an effect on the
growth of dandelions. My hypothesis is that dandelions in soil to which fertilizer
is added will produce more biomass. What is my independent variable in this
experiment?
A) Biomass production
B) Presence or absence of fertilizer
C) Type of soil used
D) Growth rate of dandelions
Expert Rationale: The independent variable is the factor that the researcher
manipulates. In this experiment, the researcher manipulates whether fertilizer is
present or absent. Biomass production is the dependent variable being measured.
,What is an example of Aposematism?
A) A bright red beetle sitting on a green leaf
B) A black and yellow stinging wasp that buzzes as it flies
C) A harmless hoverfly resembling a wasp
D) A moth blending with tree bark
Expert Rationale: Aposematism is a warning coloration that signals potential
danger to predators. Both a bright red beetle and a black-and-yellow stinging
wasp display warning coloration. A harmless hoverfly resembling a wasp is
Batesian mimicry, not aposematism.
Which model of natural selection is being exerted in the following scenario: In a
population of fish, adult body size is a variable trait (with a normal distribution).
The smallest adult fish are cannibalized by their cohorts and the largest adult
fish are visible to a bird predator and tend to be preyed upon frequently.
A) Directional selection
B) Stabilizing selection
C) Disruptive selection
D) Artificial selection
Expert Rationale: Stabilizing selection favors intermediate phenotypes and selects
against extreme phenotypes. Here, both the smallest and largest fish have
reduced fitness, favoring medium-sized fish. This maintains the average trait value
in the population.
Which mode of natural selection is being exerted in the following scenario: In a
population of plants, resistance to a type of fungal blight is a variable trait (with
a normal distribution). The blight kills 80% of the plants, leaving only the most
resistant to survive.
A) Stabilizing selection
B) Directional selection
,C) Disruptive selection
D) Sexual selection
Expert Rationale: Directional selection occurs when one extreme phenotype is
favored over others. The blight eliminates less resistant plants, shifting the
population toward greater resistance. This is a classic example of directional
selection.
Abiotic Factors and Biomes
Which abiotic factor(s) is/are responsible for the presence of different seasons
on our planet?
A) Distance from the sun
B) The Earth's tilt
C) Ocean currents
D) Atmospheric composition
Expert Rationale: The Earth's axial tilt (approximately 23.5 degrees) causes
different parts of the planet to receive varying amounts of solar radiation
throughout the year, creating seasons. Distance from the sun varies only slightly
and is not the primary cause of seasons.
Which biome is comprised of a productive area where rivers meet the ocean?
A) Wetland
B) Estuary
C) Coral reef
D) Lake
Expert Rationale: An estuary is a transition zone where freshwater from rivers
mixes with saltwater from the ocean. This mixing creates a highly productive
ecosystem with abundant nutrients, supporting diverse life forms.
Which key abiotic climate factor(s) distinguish terrestrial biomes?
, A) Sunlight and wind
B) Precipitation and temperature
C) Soil type and elevation
D) Humidity and latitude
Expert Rationale: Precipitation and temperature are the primary abiotic factors
that determine the distribution and characteristics of terrestrial biomes. These
factors influence vegetation types, which in turn define each biome.
Which biome does not include fire as a natural part of its cycle?
A) Savanna
B) Chaparral
C) Coniferous forest
D) Temperate grassland
Expert Rationale: While fire is a natural and important part of many biome cycles
(savannas, chaparral, grasslands), coniferous forests are not typically characterized
by fire as an essential part of their ecological cycle. Fires do occur but are not a
defining feature.
Species Interactions
Bark beetles feed under the bark of trees (bark beetles and trees)
A) Mutualism
B) Predation
C) Herbivory
D) Parasitism
Expert Rationale: Herbivory is the consumption of plant material by animals. Bark
beetles feeding on tree tissue (bark and underlying tissues) represents herbivory,
where the beetle benefits and the tree is harmed.
