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WorksheetsEcological Succession and Speciation
Total questions: 20
Worksheet time: 3600secs
Grassland ecosystems in Texas have evolved to depend on periodic fires to return nutrients to the soil and
encourage plant reproduction. Humans have prevented fires in many of these grassland areas, resulting in plant
and animal communities with little diversity. Wildlife biologists often recommend purposefully starting fires called
prescribed burns, which are monitored and controlled, in grassland ecosystems every 3 to 4 years. These
biologists observe greater diversity in plant and animal life in the years following a prescribed burn.
What natural processes are the biologists attempting to imitate?
Biomagnification
Succession
Population bottleneck
Species Extinction
Which of the following biological processes would most likely increase species diversity in the ecosystem?
Plants release a toxic substance into the soil to compete with other species in the area.
The populations of herbivores increases exponentially while plant populations decreases.
Bacteria present in the soil convert atmospheric nitrogen to nitrates used by plants.
A species from a distant ecosystem establishes a population and outcompetes native species.
Why are ecosystems that undergo secondary succession more likely to reach equilibrium faster than ecosystems
that undergo primary succession?
The beginning soil quality in an ecosystem undergoing secondary succession allows for pioneer species
that generate more biomass.
The lichens present during secondary succession break down hard rock material at a faster rate than
primary succession.
Secondary succession usually occurs in ecosystems with warmer climates which allows biological
process to occur quickly.
Ecosystems never reach equilibrium after primary succession because secondary succession always
occurs after primary succession.
Hydrothermal vents form deep in the ocean when iron-rich magma is released from openings on the seafloor.
These vents spew extremely hot water (400°C) mixed with methane and sulfur. Bacteria that thrive in this hostile
environment form the base of a food chain that leads to colonization by tube worms, mussels, and many other life
-forms. When a hydrothermal vent becomes inactive and cold, the bacterial community that lives in the hot fluid
methane and sulfur dies out. Which organisms most likely succeed the original community in this ecosystem?
Cold-tolerant bacteria that feed on sulfur and iron in the vents
Giant kelp that use sulfur in photosynthesis
Fish that do not need oxygen for cellular respiration
Ocean mammals that tolerate cold and act as top predators in the food chain
During secondary succession, which of these best describes why decomposing pioneer plants give way to larger,
more complex plants species, such as hardwood trees?
Increased amounts of sunlight are able to reach the ground while the pioneer species are decomposing.
Increased soil temperatures from decomposing pioneer species help tree seeds germinate more quickly.
Increased amounts of decomposing pioneer species remove nutrients that tree seedlings need to grow
and mature.
Increased amounts of soil nutrients from decomposing pioneer species allow plants with more extensive root
systems to become established.
During ecological succession, how does the growth of young hardwoods affect the organisms living in an
ecosystem?
Grasses and low shrubs are unable to obtain the amount of light they need to survive, so there are
small numbers of them.
The trees provide shelter and food for a variety of mammals, insects, and birds.
In autumn, falling leaves provide a source of energy for decomposers such as fungi.
All of the above
In 2011, fires in Bastrop County, Texas were the most destructive wildfires in Texas history. The fire spread
through the Loblolly pine trees and scorched nearly 5,700 acres of Bastrop State Park. The majority of the
Houston toad’s habitat was lost, and the Lost Pines Forest was heavily affected. The table below details
descriptions of changes in the population and diversity of species in the Lost Pines Forest. According to the information and table above, which of the following lists the correct order of the ecological succession in the Lost Pines Forest?
I, II, III, IV
II, III, I, IV
IV, I, II, III
III, II, IV, I
The diagram above shows the process of ecological succession after wild fire. Which
of the following is correct?
I. It usually takes more than 100 years to reach to a stable ecosystem after a natural
disaster such as wild fire and flood has occurred.
II. During the stage IV, many populations change, and each new population changes
the environment, making it more suitable for next coming species.
III. During the stage I, grasses and weeds are growing fast in the ecosystem because the species can grow better under the condition of little amount of sunlight than any tree plants.
IV. During stage V there is the least amount of Biodiversity
I only
I and II only
II, III, and IV only
I, II, and III only
Which statement best describes the differences in species diversity between an ecosystem beginning the process
of primary succession and one beginning the process of secondary succession?
Species diversity is much greater in the ecosystem undergoing primary succession because that
ecosystem is experiencing a longer period with a lack of competition for space.
No differences in species diversity exist because both ecosystems initially lack living organisms.
Species diversity is much greater in the ecosystem undergoing primary succession because the lack of
soil provides a greater area for organisms to claim niches.
Species diversity is greater in the ecosystem undergoing secondary succession because the soil already
contains seeds and spores of various species.
The information shown in the graph suggests that the changes in the forest community were caused by
tree-leaf replacement after a storm
repeated habitat destruction due to human activity
decreased species diversity after a fire
one community of plants replacing the previous community
What explanation best fits the data found in the graph?
Light-colored oysters have a hard time opening their shells to get needed nutrients and oxygen. Over
time, the oysters with light-colored shells evolved to have dark-colored shells so that they would be able
to get the resources they need to survive.
Oysters with light-colored shells could blend into the rocks in the shallows of a river, while the dark-colored oysters would blend into the shadows. This camouflage allowed the light and dark-colored oysters to survive and pass on their traits, while the intermediate colored oysters become prey.
Light and dark-colored oysters are much smaller than oysters with the intermediate shell color. This makes them more likely to be eaten by predators before they can reproduce. Over time, the light and dark-colored shells became less common while the intermediate shell color became more common.
Oysters with light and dark-colored shells are better at blending in with their surroundings, so individual oysters with an intermediate shell color began expressing either light-colored or dark-colored genes so they could hide from predators.
White-tailed deer are seasonal breeders. Female white-tailed deer begin their reproductive cycle in the fall. Rising
testosterone levels in male white-tailed deer cause them to start their breeding season around the same time.
Offspring are born the following spring and summer. What is the most likely explanation for white-tailed deer having a seasonal breeding cycle instead of a monthly breeding cycle like many domesticated animals?
Habitat isolation. Male and female deer come into contact with each other only in the fall.
Habitat isolation. Large predators are not found in deer habitats during the spring and summer months.
Temporal isolation. Giving birth only in the spring and summer ensures that offspring are born when food is most available.
Temporal isolation. Deer give birth in the spring and summer in order to avoid being pregnant during the hot summer
months.
Which of the following best explains why a finite supply of environmental resources is important to differential
reproductive success?
Limited resources create selection pressures for survival on the population.
Variations within a population allow for differential reproductive success.
Some members of a population survive competition but never reproduce.
Natural selection does not occur when the environment limits the supply of resources.
Abdopus aculeatus, an octopus from Indonesia, will guard a single female for up to 10 days during their mating
period. The large male octopus will display dark stripes. Smaller males will hide their masculine stripe and
camouflage themselves. This is an example of sympatric speciation through behavioral isolation. What adaptation in the behavior of the larger male octopus increases its reproductive
success?
The smaller male octopus is unable to reproduce successfully due to his size. The smaller octopus will not pass on his genes and eventually only large octopuses will be produced.
The smaller male octopus can endure the 10 day mating period better than the larger male octopus due
to the need of the larger octopus to feed more often.
The dark stripes of the large male are considered unattractive to the females. The females only allow
other female octopuses around during the mating period.
The small male octopus goes unnoticed by the large male giving the impression it is a female and is
allowed to approach potential mates.
The green frog (Lithobates clamitans clamitans) is found in many parts of the United States. The table contains
some information about this frog. Each population of frogs has different breeding seasons based on their location. This is an example of sympatric speciation through temporal isolation. Given enough time each population will evolve into a unique species. Why does the ability to lay 1,000 to 5,000 eggs increase the fitness of the species L. clamitans clamitans?
It increases opportunities for offspring to compete for limited resources.
It increases the probability that some offspring will survive long enough to reproduce.
It increases the probability that moving water will promote gene flow from one population to another.
It increases the chance of the recombination of alleles, leading to genetic drift in the population.
Which of the following is an example of Allopatric speciation?
female birds choosing a mate based on the male's song
female birds choosing a mate based on the male's feather colors.
two populations of the same bird species separated by a mountain.
two populations of the same bird species separated by their favorite food source.
An estuary collects sediments from the ocean and rivers that feed into it. The sediments swirl around and then
settle to form a mudflat. Eel grass is then established on the mudflat. The ecosystem changes over time and
ultimately develops into a salt marsh that contains mangrove trees.
Which of the following is likely NOT involved in this example of ecological succession?
The rotting remains of plants add to the fertility of the soil.
The soil becomes so fertile that eel grass is replaced by other plant species.
The roots from plants help stabilize the sediment, keeping it in place.
The concentration of salt becomes so high that all plant life is destroyed.
Which of the following is a place where primary succession will occur?
A mountain where wild fire burnt most trees and grasses
A mountain where volcanism destroyed all plants and animals
An area where flood sweptaway plants
A sand dune formed in a desert or a coastal area
What are the pioneer species in primary vs secondary succession
p - lichens
s - grass
p - lichens
s - shrubs
p - grass
s - shrubs
p - grass
s - lichens
After the Chernobyl Nuclear Disaster (which occurred in the country of Ukraine in 1986), Scotch pine trees in the
surrounding environment died and this area became known as the Red Forest due to the red brown color of the
dead pine trees. Some plants and animals were also killed by the acute, high doses of nuclear radiation. This area,
however, quickly repopulated with surviving animals, grasses, wildflowers, and eventually trees from the
neighboring low-dose and clean areas. The new population of trees are more selective with who they mate with based on the color red. This is an example of ?
Allopatric Speciation
Geographic isolation
Temporal isolation
Sympatric Isolation
