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DO NOW: Answer the following question:
What is a population? What does it have to do with evolution?
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chicks. By 1974, the species had become extinct in New York, and captive
birds were released into the wild. By 2003, there were nearly 50 mated pairs.
However, the peregrine falcon is still an endangered species and the
population has limited genetic variation.
Which conclusion about the population can be drawn?
(1) This population can adapt easily to new environments.
(2) This population will have trouble adapting to new environments.
(3) This population has become immune to the pesticide DDE.
(4) This population will fill a new ecological niche.
Step 1. Rewrite the
question
Natural Selection
For a flower to share genetic information, an insect must carry its pollen
(which contains DNA) to another flower. If a bee lands on flowers of many
species, it may give most of the genetic information it picks up to species that
cannot use it. However, if a flower evolves so that only one moth can land on it,
it will always be able to pollinate other flowers of its species. This also helps
the moth, because it does not have to compete for food-in this case, few other
moth species have a foot-long tongue.
Darwin constructed his theory of evolution by carefully observing the beaks of
finches on the Galapagos Islands. Each finch species had a specially designed
beak that enabled it to eat a specific type of food, such as insects, berries,
small seeds, and large seeds. Each island had one species that could eat each
type of food, but no island had two species that could eat the same food.
Darwin concluded that each finch must be adapted to fulfill a particular
ecological function, which reduced competition for food.
KEY KNOWLEDGE:
Step 2. Predict your
answer
A niche is an ecological role.
Every animal has a niche, which includes the specific foods it can eat, places
where it can live, and behaviors for interacting with other organisms.
Competition between species may lead to increased fitness for an environment.
If two species need the same food or the same nesting areas, they will have
to compete. This causes fewer offspring to survive, but those offspring will be
well adapted to their environment and in turn their offspring will be fit.
However, if one species is very fit for a particular environment the other
species may become extinct.
Competition within a species may cause speciation.
If a population is competing for food and some of its members adapt to eat a
new kind of food, both groups will have a better chance of survival.
As each group evolves to be more fit for eating that kind of food, the single
species may genetically change so much that it becomes two species.
Large populations can adapt more easily to changes in the environment.
A large population is more likely to have genetic variety than a smaller
population. If an environmental change occurs, a few members may have
traits that allow them to survive. All of the members of a small population
may have the same unhelpful traits.
Step 3. Eliminate the
incorrect choices.
Step 4. Choose your
answer.
2. Based on the theory of natural selection, which statement explains why
some individuals are more likely to survive and reproduce than others living
in the same environment?
(1) Some individuals are better adapted to the environment than others.
(2) Some individuals produce fewer offspring than others.
(3) Useful traits acquired during an individual's lifetime may be passed on.
(4) Useful traits are not used by some individuals who have them.
Step 1. Rewrite the
question
Try it out: Follow the steps to answer the questions
1 During the 1960s, a pesticide called DDE was used widely in New
York. Peregrine falcons ate insects that had eaten the pesticide, and the
poison killed many falcons and prevented others from hatching healthy
Step 2. Predict your
1
Use and disuse Lamarck believed that if an organism did not use an organ
frequently, it would grow smaller and weaker, while organs used more
frequently would grow bigger and stronger. The organism would then pass
those traits to its offspring. We now know that use and disuse influence
which genes are expressed in an individual, but not which genes are passed
on to offspring.
answer
1 The concept of natural selection does not include the idea that
(1) individuals with favorable genes are more likely to reproduce
(2) populations produce more offspring than are expected to
survive to adulthood
(3) the use of structures in the body can change the genes that are
passed on
(4) individuals within a population have unique genes that cause
different traits
Step 1. Rewrite the
question
Step 3. Eliminate the
incorrect choices.
Step 4. Choose your
answer.
Evolution
Organisms on Earth today have evolved from very different organisms that
lived in the past. They will probably evolve into new species in the future.
Darwin's theory is used today to explain everything from antibiotic resistance,
to tail bones in human embryos, to moths with foot-long tongues. In the past,
the Regents Exam has also included questions about Lamarck's theory of
evolution, which has been disproved by experiments.
Step 2. Predict your
answer
Key Knowledge
Darwin In 1859, Charles Darwin published a book explaining his theory of
natural selection.
Competition When two species need the same limited resources, such as
food, water, or space, they will compete to get the resources.
Overproduction More offspring are produced than will survive to produce
offspring.
Genetic variation Species that reproduce sexually combine genes from both
parents to ensure that every offspring has unique genes.
Survival of the fittest Organisms that successfully compete for resources,
avoid predators, find food, and produce surviving offspring will be the ones
whose genes are passed on to the next generation. Those organisms who
cannot do all of those things successfully will not survive to produce more
offspring, and their genes will not be passed on.
Adaptive value Adaptive value is a measure of how fit an organism is, or
how good its genes are.
Lamarck Lamarck's theory has been disproved by experimental evidence.
Acquired characteristics Lamarck believed that if characteristics were
developed by an adult, they would be passed on to the offspring. For
example, if a mouse had its tail cut off, its offspring would also have shorter
tails.
Step 3. Eliminate the
incorrect choices.
Step 4. Choose your
answer.
2 Which condition is necessary for a new species to develop?
(1) The rainfall of the environment must change.
(2) Anatural disaster must disrupt the food web.
(3) The genes of the population must change.
(4) The organisms must move to a new location.
Step 1. Rewrite the
2
question
Step 3. Eliminate the
incorrect choices.
Step 2. Predict your
answer
Step 4. Choose your
answer.
Evidence for Evolution
As we discussed in Unit 4, theories are accepted when they can explain the
conclusions of many observations and experiments. The theory of evolution is
backed up by evidence from the past, structures in organisms living today, and
repeatable experiments.
Step 3. Eliminate the
incorrect choices.
Key Knowledge
Fossils In general, fossils in deeper rocks are older than fossils that are closer to the
surface. These fossils show very simple organisms, whereas fossils from newer rocks
show more complex organisms. This supports the idea that over time evolution has
resulted in more complex structures.
Similar structures Organisms that evolved from a common ancestor have similar
bone and organ structures. The more closely related the organisms are, the more
their structures usually have in common. For example, humans, whales, and
chimpanzees all share a common mammalian ancestor and similar bones for the
fingers of the hand.
Embryology Many organisms show stages of their evolutionary history during their
development as embryos. For example, human embryos grow and then lose gill slits
because they share a common ancestor with fish that had gills.
Location Organisms living in the same parts of the world often have similar traits. For
example, marsupials (animals with pouches like kangaroos and koalas) live only in
Australia. The common marsupial ancestor has evolved to fill many niches.
DNA All living organisms store their genetic information using the same four
nucleotides and express it as proteins with the same twenty amino acids. Organisms
that are closely related often have similar gene sequences. For example, most bases
in the human genes are the same as those in the chimpanzee genes, while many
more are different in whale genes.
Bacteria Not all evolution takes thousands of years. When bacteria are exposed to
an antibiotic, some populations can evolve in only a few days. Most of the bacteria
will die, but those who survive will produce offspring with the trait that made them
resistant to the antibiotic, resulting in a new gene frequency in the population.
Step 4. Choose your
answer.
3 Some frogs are white on the belly and bright green on the back. This gives
them a high adaptive value, because predators above them cannot distinguish
them from algae in the water, and predators below them cannot distinguish
them from the sky. If all of the ponds in a frog's habitat turn a muddy brown
color, the green color of the frogs will immediately
(1) have a lower adaptive value
(2) have a higher adaptive value
(3) have the same adaptive value
(4) genetically change to brown
Step 1. Rewrite the
question
Step 2. Predict your
answer
Try it out
1 Which statement below supports the theory of evolution?
(1) All fossils were formed at the same time, when a meteor crashed into the
earth.
(2) Characteristics acquired during an individual's lifetime are passed on to
offspring.
3
(3) Larger organisms always outcompete smaller organisms in an ecosystem.
(4) Some organisms have body structures that are not used, but were used by
their ancestors.
2 The limbs of two animals are shown below.
The similar shape, number, and placement of the bones in the limbs
indicates that these two animals have
(1) similar environments
(2) a common ancestor
(3) identical chromosomes
(4) similar hunting strategies
Evolutionary Trees
When a population of one species is divided into two different regions, each
new population will adapt to its new area. Over time, each population may
develop new traits until the two populations cannot interbreed successfully.
At this point, they are no longer the same species. This process is called
speciation. Speciation occurs because of genetic drift, or changes in the
frequency at which genes appear in a population.
Evolutionary trees are graphic organizers that illustrate the relationships
between groups of organisms. They may be made based on evidence from
bone structure, embryology, location, and DNA. However, DNA testing is
considered to be the best way of finding out how closely two organisms are
related.
1 The leopard pictured below is named Panthera pardus.
To which of the following animals is it most closely related?
(1) Domestic cat (Felis silvestris)
(2) Lion (Panthera leo) ~
(3) Cheetah (Acinonyxjubatus)
(4) Leopard (Leopardus pardalis)
Step 1. Rewrite the
question
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The History of Life
Fossils or imprints preserved in rocks give scientists a good idea of how life
evolved on Earth. You should have an idea of what order life evolved in, but do
not try to memorize everything on this page. The most important dates are for
the first unicellular (one-celled) organisms and those for the first multicellular
(many-celled) organisms. All dates included below are approximate. Mya
stands for, "millions of years ago."
4600 mya Formation of the Earth
3800 mya First rocks harden, first oceans form, no oxygen in atmosphere
3500 mya Unicellular organisms
2500 mya Oxygen released by blue-green algae as waste
7500 mya Organelles in unicellular organisms
7200 mya Sexual reproduction
1000 mya Multicellular organisms
545 mya First organisms with hard outer shells (exoskeletons)
500 mya First fish with internal bones
430 mya First plants and fungi on land
420 mya First land animals (probably similar to insects, scorpions, or centipedes)
370 mya First amphibians and plants with roots
300 mya First reptiles
220 mya First mammals
50 mya First monkeys
0.5 mya First humans
Step 2. Predict your
answer
Step 3. Eliminate the
incorrect choices.
Step 4. Choose your
answer.
2 Species A, B, C, and D are four species of moths. Species A and B have
similar coloration. Species A and C have the same feeding patterns. The
enzymes in species A and Care very similar, and the enzymes in species
B and D are very similar.
Draw an evolutionary tree that shows the relationships between moth
species A, B, C, and D.
Step 1. Rewrite the
question
Independent Practice:
1 During which time interval did unicellular organisms appear on Earth?
Step 2. Answer what
they ask
(1) A to B
(2) B to C
(3) C to D
(4) D to E
2 Amphibians are animals that reproduce by external fertilization in the water
and have gills for the first part of their lives. Later in life, they grow legs and
replace their gills with lungs so that they can live on land.
Name one type of organism that evolved before amphibians and one type of
organism that evolved after amphibians. [2]
Step 3. Revise your
answer
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1 The diagram below shows how a species of flower underwent speciation.
(1) Species A is more fit than species B.
(2) Species A and B can mate with each other.
(3) Species A can mutate faster than species B.
(4) Species A is genetically identical to species B.
A biological process is summarized by the equation below:
carbon dioxide + water → glucose + oxygen + water
This process occurs in the
(1) choroplasts
(2) cell membranes
(3) ribosomes
(4) mitochondria
For questions 7 through 9 use the diagram below that shows the evolution of
some species in the horse family and your knowledge of biology.
Which statement about this evolutionary tree is correct?
(1) Species A became extinct.
(2) Species B evolved from species C.
(3) Species E is the ancestor of species D.
(4) Species Band C can interbreed successfully.
1 Which term is explained correctly in the chart below?
List the characteristics that the park ranger used to group these birds.
2 Darwin published a book called On the Origin of the Species by Natural
Selection in 1895.
One of the concepts explained in this book was
(1) the loss of biodiversity due to human actions
(2) why different organisms have similar structures
(3) strategies for selective breeding for better crops
(4) how ecological succession proceeds on
3 Which statement best demonstrates that a rapid biological adaptation has
taken place?
(1) Cockroaches have not altered for hundreds of years.
(2) Bird habitats have been lost due to deforestation.
(3) Fossils of some ancestors of modern humans had larger skulls.
(4) Certain weeds have become resistant to pesticides.
4 Strawberries in the wild are small and sour. Domestic strawberries are large
and sweet.
The domestic strawberries have these characteristics because of
(1) selective breeding (3) cell division
(2) cloning (4) natural selection
5 Which statement below gives the best explanation for the following graph?
7 Name one common ancestor of H and I. [1]
8 Name one species that is extinct and give one possible explanation for its
extinction. [2]
9 Name three methods that scientists could have used to determine where
each species belongs on this tree. [3]
6
(3) Natural selection can be caused by environmental changes.
(4) Natural selection has been disproved through experiments and
observations.
Which species has the best chance of surviving changes in its environment?
(1) a species that reproduces sexually
(2) a species with few genetic variations
(3) a species with a long life expectancy
(4) a species that competes with similar species
La Nina is a temporary climate change, which causes ocean waters to remain
cool when they would otherwise be warm. This change interferes with food
webs and weather patterns. Which event is most likely to arise from La
Nina?
(1) The food webs in the ecosystem would remain unaltered.
(2) Simple species would be replaced by more complex species.
(3) The mutation rate would increase among individuals in some populations.
(4) The number of individuals in some populations would change
temporarily.
A population of insects has 75%green individuals and 25%brown
individuals. For several summers, droughts occur in the area and the grass
remains brown for most of the year. After this period, the population of
insects is 30%green and 70%brown. This is an example of
(1) use and disuse
(2) overpopulation
(3) natural selection
(4) fossil evidence
For questions 7 through 8 use the passage below and your knowledge of
biology.
In the 1860s, English gentlemen brought wild rabbits to southern Australia to
shoot for entertainment. Because they had no natural predators, the rabbits
covered the continent by 1910.They caused deforestation, erosion, and
desertification. They also caused two species of burrowing mammals to
become extinct. Poisoning the rabbits killed native species, and hunting
caused the rabbits to invade new habitats. In 1950, the virus myxomatosis,
which only affects rabbits, reduced the population from 600 million to 100
million. The virus has been applied several times, but rabbits are still a threat
to Australia's ecosystems. Many rabbits have become resistant to
myxomatosis.
7 Rabbits are herbivores, which means they eat only plants and not other
animals. Explain how the rabbits caused two species of burrowing mammals
to become extinct. [1]
10 Zebra mussels are clamlike animals that were accidentally transported
from Europe in the 1980s. By 1990, they had spread throughout the Great
Lakes and the Hudson River.
Because they consume large amounts of phytoplankton, the microorganisms
that carry out photosynthesis in the water, the oxygen levels in the Great
Lakes are dropping. In addition, zebra mussels can consume large amounts of
certain toxic chemicals from the lakes without being harmed. This can be
deadly to the birds and fish that eat the zebra mussels.
Freshwater clams are a native species that lives in the Great Lakes and
Hudson Bay and feeds on phytoplankton. Explain how zebra mussels have
affected the freshwater clam population. Your explanation must include:
• the effect of decreased oxygen levels [1]
• the relationship between zebra mussels and freshwater clams [1]
• two possible results that this relationship could have on freshwater clams [1
The diagram below shows the evolutionary relationships between the
dinosaur Thecodontosaurus antiquus (TA) and three other dinosaurs (A, B,
and C). Based on the diagram, which statement is true?
(1) Dinosaur A is only related to Dinosaur B.
(2) Dinosaur Cis only related to Dinosaur B.
(3) Dinosaur B is more closely related to Thecodontosaurus antiquus than to
Dinosaur A.
(4) Dinosaur A is more closely related to Dinosaur C than to
Thecodontosaurus antiquus.
Which statement is the best description of natural selection?
(1) Natural selection does not contribute to the evolution ofthe species.
(2) Natural selection causes mutations in genetic material.
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8 Explain how the rabbits became resistant to the virus myxomatosis. You
must include and circle the following terms in your explanation: [4]
• overproduction
• survival of the fittest
• variation
• adaptive value
Name two adaptations that allowed animals to live on land instead of in the
water.
A biologist obtained a large container of seawater and boiled the water to kill
any organisms living in it.
The biologist then placed two species of plankton, Species X and Species Y,
in the container. During the first week, Species X decreased while Species Y
increased. During the second week, Species X died and Species Y decreased.
During the third week, Species Y died. Give two possible explanations for
these observations. [2]
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