WorksheetsComplete Revision Question Bank
Total questions: 94
Worksheet time: 47mins
Which two climate variables primarily determine global biome distribution?
Temperature and precipitation
Latitude and altitude
Wind speed and barometric pressure
Solar radiation and cloud cover
Which biome typically has permafrost and very short summers?
Tundra
Temperate grassland
Tropical rainforest
Savanna
Which soil horizon is richest in organic matter and biological activity?
A horizon (topsoil)
O horizon (organic litter)
B horizon (subsoil)
C horizon (parent material)
What is the main role of the O horizon in soil?
Organic matter decomposition and nutrient input
Root storage and water uptake
Mineral accumulation from leaching
Bedrock formation
Tropical rainforests tend to have _____ net primary productivity compared to deserts and tundra.
Much higher
Similar
Slightly lower
Much lower
In the exponential growth model dN/dt=rN , what does r represent?
Intrinsic rate of increase
Carrying capacity
Net migration rate
Half-saturation constant
Which growth model includes carrying capacity K explicitly?
Logistic growth
Exponential growth
Geometric growth
Linear growth
On a logistic growth curve, the plateau at the top represents what?
Carrying capacity
Doubling time
Initial population size
Birth rate
Which phase of a bacterial growth curve corresponds to the plateau of the logistic curve?
Stationary phase
Lag phase
Log phase (exponential phase)
Death phase
If a bacterial population has a high r and a very short doubling time, which statement is true?
It can increase explosively when resources are abundant
It will always remain at carrying capacity
It cannot grow without predators
It grows only during the lag phase
Density-dependent factors are best described as factors that...
Increase in effect as population density increases
Act equally regardless of density
Only affect small populations
Are purely abiotic
Which of the following is a density-independent factor?
A severe hurricane
Competition for food
Disease transmission
Territoriality
In yeast fermentation, what ultimately limits the yeast population in the tank?
Accumulation of alcohol and depletion of nutrients
Lack of oxygen alone
Unlimited sugar supply
Predation by bacteria
Which statement best describes an r-selected species?
Many small offspring, short lifespan, high reproductive rate
Few large offspring, slow growth, late maturity
Extensive parental care with low fecundity
Stable population near carrying capacity
Which survivorship curve (Type I, II, III) is typical of humans and elephants?
Type I
Type II
Type III
Uniform survivorship
Which life-history trait combination is typical of a K-selected species?
Slow growth, late maturity, few large offspring
Early reproduction, many small offspring, fast growth
High dispersal, short generation time
High intrinsic rate of increase with minimal parental care
What is the main trade-off highlighted by life history strategies?
Energy for survival vs. reproduction
Temperature vs. rainfall
Predation vs. parasitism
Migration vs. hibernation
Intraspecific competition occurs between...
Individuals of the same species
Different trophic levels
Members of different species
Populations in different habitats
Which term describes indirect competition via depletion of a shared resource?
Exploitative competition
Interference competition
Mutualism
Commensalism
Producing bacteriocins to inhibit nearby conspecifics is an example of...
Interference competition
Exploitative competition
Facilitation
Neutralism
In scramble competition, resources are...
Shared so all get some but possibly insufficient
Taken by a single dominant competitor
Always partitioned evenly among species
Abundant and nonlimiting
The competitive exclusion principle states that...
Complete competitors cannot coexist indefinitely
Predators and prey always oscillate
Species diversity increases with area
Populations grow exponentially in ideal conditions
Which pair correctly matches the interaction type?
Interspecific competition – between different species
Intraspecific competition – between different species
Mutualism – both harmed
Commensalism – both benefit
Which is an example of a microbial structural adaptation?
Endospore formation in Bacillus
Flagellar rotation rate changes
Induction of operons
Increased mutation rate
What is the main advantage of thermophilic enzymes like Taq polymerase?
They remain stable and active at very high temperatures
They denature easily at moderate heat
They require cold conditions to function
They inhibit DNA replication
Biofilm formation gives microbes which key advantage?
Protection from stress and antibiotics
Increased individual motility
Immediate nutrient depletion
Reduced cell communication
Quorum sensing allows bacteria to...
Coordinate behavior based on population density
Respire anaerobically
Fix nitrogen
Store phosphorus
Ecological succession is best defined as...
Directional change in community structure over time
Random fluctuation in population size
Immediate replacement of species after disturbance
Seasonal migration of communities
Primary succession begins...
On bare substrate where no soil exists
In mature forests after selective logging
After minor disturbances within established soil
In agricultural fields left fallow
Which of the following is typical of secondary succession?
Soil and seed bank are already present
Begins on newly formed lava flows
Occurs where no organisms are present
Requires complete loss of all nutrients
During microbial succession in compost, which group tends to dominate at the hottest thermophilic stage?
Mesophilic fungi
Thermophilic bacteria (e.g., Bacillus and Thermus)
Nitrifying archaea
Actinomycetes
In the facilitation model of succession, early species...
Inhibit later species
Have no effect on later species
Modify the environment to benefit later species
Replace later species only after catastrophes
Which two abiotic factors most strongly determine terrestrial biome distribution globally?
Temperature and soil pH
Temperature and precipitation
Sunlight intensity and wind speed
Altitude and salinity
Which biome is characterized by permafrost, low-growing vegetation, and very short growing seasons?
Tundra
Taiga (boreal forest)
Savanna
Temperate grassland
Which biome typically has the highest net primary productivity per unit area?
Desert
Temperate deciduous forest
Tropical rainforest
Tundra
Which soil horizon is known as topsoil, rich in organic matter and roots?
O horizon
A horizon
B horizon
C horizon
The O horizon of soil is mainly composed of what?
Clay and silt
Unweathered bedrock
Partially decomposed organic matter and litter
Dissolved minerals only
Which biome is dominated by grasses, has seasonal rainfall, and supports large grazing herbivores?
Savanna
Chaparral
Tundra
Boreal forest
In deserts, the main limiting factor for primary productivity is what?
Temperature
Nitrogen availability
Water
Sunlight
Which soil type is typically most fertile for agriculture in temperate regions?
Sandy soil
Clay soil
Loam
Peat
Tropical rainforests usually have nutrient-poor soils despite high productivity. True or False?
True
False
Boreal forests (taiga) are found mainly in low latitudes near the equator. True or False?
True
False
What is the exponential growth equation?
dN/dt=rN
dN/dt=rN(1−N/K)
Nt+1=λNt
dN/dt=0
In the logistic growth model, what does K represent?
Intrinsic rate of increase
Initial population size
Carrying capacity
Half-saturation constant
On a logistic growth curve, the maximum growth rate occurs at approximately what population size?
0
K
K/2
2K
Give one example of a density-dependent factor regulating population size.
Competition for food
Volcanic eruption
Hurricane landfall
Prolonged drought
Give one example of a density-independent factor regulating population size.
Competition for mates
Disease transmission between individuals
Severe drought
Territoriality
In population models, what does r refer to?
Carrying capacity
Per capita intrinsic rate of increase
Immigration rate
Number of births at time zero
If λ=1 in a geometric growth model, how is the population changing?
Growing exponentially
Declining
Stable (no change in size)
Oscillating
Which curve shape best represents exponential growth on a graph of N vs. time?
S-shaped curve
J-shaped curve
Linear increase
Inverted U-shaped curve
In a closed yeast culture, why does the population eventually stop growing?
Ambient temperature drops
Predators invade the culture
Nutrients are depleted and waste (e.g., alcohol) accumulates
Cells become larger and stop dividing
What may happen if a population overshoots its carrying capacity?
Sustained exponential growth continues
The population becomes stably higher than carrying capacity
A sudden crash or die-off may occur
Immediate recovery to the original size
The logistic model assumes per capita growth rate decreases as population size approaches K. True or False?
True
False
Density-dependent factors have the same effect regardless of population size. True or False?
True
False
Give one example of a human population or situation that might show logistic-like growth.
An island population with unlimited food and space
A developed country’s population stabilizing due to lower birth rates and resource limits
An introduced species experiencing unchecked growth in a new habitat
A community with frequent catastrophes causing repeated collapses
Distinguish exponential from logistic growth.
Exponential growth assumes unlimited resources and is J-shaped; logistic growth includes carrying capacity so growth slows as N approaches K, producing an S-shaped curve
Exponential growth assumes limited resources and is S-shaped; logistic growth assumes unlimited resources and is J-shaped
Both exponential and logistic growth are linear increases over time
Exponential and logistic growth are identical except for starting population size
Which trait combination is typical of r-selected species?
Few large offspring, late maturity, long lifespan
Many small offspring, early maturity, short lifespan
Slow growth, strong competitive ability, parental care
Low reproductive rate, high survivorship throughout life
Which trait combination is typical of K-selected species?
Many small offspring, early maturity, little parental care
Few large offspring, slow growth, late maturity, strong competitive ability
Explosive reproduction following disturbance, short lifespan
High juvenile mortality, little investment per offspring
Which survivorship curve type is typical of humans and elephants?
Type I
Type II
Type III
None of the above
Give an example of an organism that is strongly r-selected.
Dandelion
Oak tree
Elephant
Blue whale
Give an example of an organism that is strongly K-selected.
Elephant
Fruit fly
House mouse
E. coli bacterium
Life history traits reflect trade-offs between growth, reproduction, and survival. True or False?
True
False
r-selected species tend to dominate in disturbed or unpredictable environments. True or False?
True
False
K-selected species usually have high fecundity and almost no parental care. True or False?
True
False
What does trade-off mean in the context of life history?
Investment in one function reduces energy available for other functions
Simultaneous maximization of all functions
Increase in reproduction automatically increases survival
Trade-offs occur only in K-selected species
Give one life-history trait that differs between r- and K-selected species.
Number and size of offspring differ: r-selected produce many small offspring, K-selected produce fewer larger offspring with more parental care
Both produce the same number of offspring but differ only in habitat
r-selected invest heavily in parental care, K-selected invest none
Only K-selected species reproduce sexually
Intraspecific competition occurs between which individuals?
Individuals of the same species
Individuals of different species
Predators and their prey
Individuals from different ecosystems
In exploitative competition, how do individuals compete?
Indirectly by consuming and depleting a shared resource
Directly by aggression and blocking access
By cooperating to share resources
By mutualistic exchange of nutrients
In interference competition, how do individuals compete?
Directly by blocking or aggressively defending access to resources
Indirectly via depletion of a shared resource
By avoiding resources altogether
By increasing resource production
What does the competitive exclusion principle state?
Complete competitors cannot coexist indefinitely; one will be excluded
Species with identical niches always coexist
Competition always leads to mutualism
Predators exclude prey from all habitats
Producing antibiotics that inhibit neighboring bacteria is an example of what type of interaction?
Amensalism
Mutualism
Commensalism
Facilitation
What does niche differentiation (resource partitioning) allow species to do?
Coexist by using different resources or conditions
Increase direct interference competition
Occupy identical niches without change
Go extinct more rapidly
Competition can occur for light, space, nutrients, mates, and other resources. True or False?
True
False
Intraspecific competition is usually stronger than interspecific because individuals are ecologically very similar. Often true or false?
True
False
Briefly distinguish exploitative from interference competition.
Exploitative is indirect via depletion of a shared resource; interference is direct, blocking access through aggression or other mechanisms
Exploitative is direct aggression; interference is indirect resource use
Exploitative and interference are identical processes
Interference occurs only among different species; exploitative only within the same species
Endospore formation in Bacillus mainly helps bacteria survive what?
Extreme conditions such as heat, dryness, and nutrient limitation
Abundant nutrients
Low cell density
Lack of oxygen in all environments
Which adaptation is typical of thermophilic enzymes?
They remain stable and active at very high temperatures
They denature at moderate temperatures
They function only at very low temperatures
They are inactive in hot environments
What key advantage do biofilms provide to microbes?
Protection from stress, antibiotics, and host immune responses
Immediate cell death
Enhanced photosynthesis in all microbes
Elimination of competition
What does quorum sensing allow bacteria to do?
Coordinate gene expression and behavior based on cell density
Perform photosynthesis in the dark
Move randomly without signals
Form spores only in radiation
Name one common biofilm habitat.
Teeth (dental plaque)
Sterile distilled water in a sealed flask
Vacuum of outer space
Dry desert sand with no moisture
Biofilms can make infections more difficult to treat with antibiotics. True or False?
True
False
Extremophiles survive only in mild environments. True or False?
True
False
Give one example of a microbial structural adaptation and the challenge it addresses.
Endospores enable survival in heat and dryness
Thick cell walls help resist osmotic stress
Capsules increase light absorption to support photosynthesis
Plasmids directly reduce environmental salinity
Why is Taq polymerase useful in PCR?
It is heat-stable and remains active during the high temperatures used to denature DNA in PCR
It binds RNA at low temperatures
It denatures DNA so primers can anneal without heating
It requires freezing conditions to function
What is ecological succession?
Directional change in community composition and structure over time
Random seasonal fluctuations with no directional trend
Instantaneous genetic change within individuals
Inevitable loss of biodiversity regardless of conditions
Primary succession begins under what conditions?
On bare substrate where no soil or organic matter exists
After a disturbance where soil remains
In mature forests only
Only in deep ocean vents
Secondary succession occurs under what conditions?
After a disturbance where soil and some organisms or seed bank remain
On newly formed lava with no soil
Only when predators are removed
During undisturbed climax conditions
In the facilitation model of succession, what do early species do?
Modify the environment to make it more suitable for later species
Exclude all later species via competition
Leave the environment unchanged
Reduce resource availability for all species
During microbial succession in compost, which group often dominates during the hottest thermophilic phase?
Thermophilic bacteria
Mesophilic fungi
Cold-adapted algae
Anaerobic archaea only
As succession proceeds towards a climax community, what happens to structural complexity and often diversity?
Both usually increase
Both usually decrease
Complexity increases while diversity decreases
Complexity decreases while diversity increases
Pioneer species are usually stress-tolerant and can colonize harsh environments. True or False?
True
False
Disturbance can reset succession and create a mosaic of patches at different stages. True or False?
True
False
What is the main difference between primary and secondary succession?
Primary begins without soil, whereas secondary begins where soil and some life remain after disturbance.
Primary begins after minor disturbance, whereas secondary begins on brand-new land formed by lava.
Primary relies on an existing seed bank, whereas secondary occurs only in aquatic ecosystems.
Primary is always faster than secondary, whereas secondary is slower in all cases.
Give one real-world example of secondary succession.
Vegetation regrows after a forest fire.
Plant communities reestablish on abandoned agricultural fields.
New communities establish on fresh lava flows that create brand-new land.
Lichens colonize bare rock following glacier retreat.
