BIOL 180 EXAM QUESTIONS AND VERIFIED
ANSWERS
What is the most important difference between species richness and species diversity?
- Answers - Species diversity takes species number AND relative frequency into
account.
What is the key difference between primary productivity and net primary productivity? -
Answers - Net primary productivity represents just the energy used to build biomass.
"Diversity leads to stability." This slogan claims that ecosystems with a large number of
species present are more stable than ecosystems with a low number of species. Which
of the following lines of evidence support this claim? - Answers - As the number of plant
species increases, resistance and resilience increases
What is biomass? - Answers - total organic matter, usually measured per plant or per
square meter
Why would a sampling effect lead to higher productivity in an experimental plot? -
Answers - If a few highly productive species are present in a community, biomass
production will be a function of whether or not they are present.
What is a functional group? - Answers - Species that use resources or allocate
resources in a similar way
In biological communities, what is "resistance?" - Answers - degree of change during
and after a disturbance
In biological communities, what is "resilience?" - Answers - ability to "bounce back" after
a disturbance, to the pre-disturbance conditiion
What is a "natural experiment?" - Answers - an unplanned/unmanipulated change in
environmental conditions that can be exploited to answer a question
What is the difference between climate and weather? - Answers - Climate consists of
long-term conditions; weather consists of short-term conditions.
What causes the Earth's seasons? - Answers - The Earth is tilted on its axis; when the
northern hemisphere is tilted towards the Sun, it warms and we're in summer. When it's
tilted away, that's winter.
, When warm air rises and cools, what happens? - Answers - The air expands and cools,
and water condenses into droplets and falls. Rain!
Why does it rain so much in the Olympic Peninsula? (This is a peninsula west of
Seattle, home of the Olympic mountains.) - Answers - Warm, wet air from the Pacific is
pushed up as it passes over the mountains. The air expands and cools, and the
moisture falls as rain.
Why is it so dry in Eastern Washington, on the other side of the Cascade mountains
from Seattle? - Answers - Air coming from over the Pacific Ocean loses its water as it
climbs up the Cascades, casting a rain shadow on the east side of the mountains.
Almost every liquid gets less dense as it warms. Water gets MORE dense as it warms
from 0C to 4C. Why is this bizarre aspect of water so important? - Answers - When the
frozen (or nearly frozen) surface of a lake warms, the water sinks, which pushes
nutrient-rich water up from the depths.
Deep oceans do not have a high concentration of fish. Why might that be? - Answers -
Light does not penetrate down into the deep ocean, so there are very few primary
producers (plants), so there's little for fish to eat.
Why does the highly productive fishery off the coast of Peru occasionally have
extremely bad years? - Answers - In El Niño years, the trade winds—which drive an
upwelling of nutrients—decrease.
The resource use efficiency hypothesis is an explanation for why productivity increases
when plant species diversity increases. Which of these predictions follows from this
hypothesis? - Answers - There should be a strong positive relationship between the
number of functional groups in an experimental plot and biomass.
The sampling effect hypothesis is an explanation for why productivity increases when
plant species diversity increases. Which of these predictions follows from this
hypothesis? - Answers - If a certain "big-producer" is present, then biomass in a plot is
high. If the big producer is absent, biomass is low.
The presence of nitrogen-fixing plants should benefit nearby individuals of other
species, because nitrogen is a key nutrient--it is usually in very short supply. But
nitrogen--fixing bacteria live inside tight nodules in the host plant's roots, and the host
plant has to provide the bacteria with large quantities of sugar. Which of the following
statements is correct? - Answers - Nitrogen will only become available to other, nearby
plants when the nodules or the nitrogen-fixing plant itself dies.
Some plants make large seeds (eg coconut palms), while some make numerous seeds
(eg sunflowers). Why isn't there a plant that makes numerous, large seeds? - Answers -
A plant has limited resources to invest in seed production. If it makes many seeds, they
must be relatively small. If it makes large seeds, they must be relatively few.
ANSWERS
What is the most important difference between species richness and species diversity?
- Answers - Species diversity takes species number AND relative frequency into
account.
What is the key difference between primary productivity and net primary productivity? -
Answers - Net primary productivity represents just the energy used to build biomass.
"Diversity leads to stability." This slogan claims that ecosystems with a large number of
species present are more stable than ecosystems with a low number of species. Which
of the following lines of evidence support this claim? - Answers - As the number of plant
species increases, resistance and resilience increases
What is biomass? - Answers - total organic matter, usually measured per plant or per
square meter
Why would a sampling effect lead to higher productivity in an experimental plot? -
Answers - If a few highly productive species are present in a community, biomass
production will be a function of whether or not they are present.
What is a functional group? - Answers - Species that use resources or allocate
resources in a similar way
In biological communities, what is "resistance?" - Answers - degree of change during
and after a disturbance
In biological communities, what is "resilience?" - Answers - ability to "bounce back" after
a disturbance, to the pre-disturbance conditiion
What is a "natural experiment?" - Answers - an unplanned/unmanipulated change in
environmental conditions that can be exploited to answer a question
What is the difference between climate and weather? - Answers - Climate consists of
long-term conditions; weather consists of short-term conditions.
What causes the Earth's seasons? - Answers - The Earth is tilted on its axis; when the
northern hemisphere is tilted towards the Sun, it warms and we're in summer. When it's
tilted away, that's winter.
, When warm air rises and cools, what happens? - Answers - The air expands and cools,
and water condenses into droplets and falls. Rain!
Why does it rain so much in the Olympic Peninsula? (This is a peninsula west of
Seattle, home of the Olympic mountains.) - Answers - Warm, wet air from the Pacific is
pushed up as it passes over the mountains. The air expands and cools, and the
moisture falls as rain.
Why is it so dry in Eastern Washington, on the other side of the Cascade mountains
from Seattle? - Answers - Air coming from over the Pacific Ocean loses its water as it
climbs up the Cascades, casting a rain shadow on the east side of the mountains.
Almost every liquid gets less dense as it warms. Water gets MORE dense as it warms
from 0C to 4C. Why is this bizarre aspect of water so important? - Answers - When the
frozen (or nearly frozen) surface of a lake warms, the water sinks, which pushes
nutrient-rich water up from the depths.
Deep oceans do not have a high concentration of fish. Why might that be? - Answers -
Light does not penetrate down into the deep ocean, so there are very few primary
producers (plants), so there's little for fish to eat.
Why does the highly productive fishery off the coast of Peru occasionally have
extremely bad years? - Answers - In El Niño years, the trade winds—which drive an
upwelling of nutrients—decrease.
The resource use efficiency hypothesis is an explanation for why productivity increases
when plant species diversity increases. Which of these predictions follows from this
hypothesis? - Answers - There should be a strong positive relationship between the
number of functional groups in an experimental plot and biomass.
The sampling effect hypothesis is an explanation for why productivity increases when
plant species diversity increases. Which of these predictions follows from this
hypothesis? - Answers - If a certain "big-producer" is present, then biomass in a plot is
high. If the big producer is absent, biomass is low.
The presence of nitrogen-fixing plants should benefit nearby individuals of other
species, because nitrogen is a key nutrient--it is usually in very short supply. But
nitrogen--fixing bacteria live inside tight nodules in the host plant's roots, and the host
plant has to provide the bacteria with large quantities of sugar. Which of the following
statements is correct? - Answers - Nitrogen will only become available to other, nearby
plants when the nodules or the nitrogen-fixing plant itself dies.
Some plants make large seeds (eg coconut palms), while some make numerous seeds
(eg sunflowers). Why isn't there a plant that makes numerous, large seeds? - Answers -
A plant has limited resources to invest in seed production. If it makes many seeds, they
must be relatively small. If it makes large seeds, they must be relatively few.
