Download Watch this video about human evolution below

Grade 9 Semester 2 Exam Review Practice Questions:
Unit 4: Evolution
Watch this video about natural selection below, then answer the questions:
1. http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_4.html
2. In your own words describe what natural selection and “survival of the fittest” means.
Natural Selection Means:
Organisms with more advantageous traits leave more offspring than organisms with other traits, causing
populations to change over time.
Survival of the fittest means:
Organisms that have more advantageous traits which help them survive in their environment are more likely
to survive than organisms with other traits.
These organisms with the more advantageous traits I
considered more fit than other organisms
3. Identify three things that are needed for evolution via natural selection to occur.
i.
.Natural variation
ii.
.Inheritance of this variation
iii.
.Difference in reproductive success & a struggle to survive.
I.
Identify the idea that each scientist(s) contributed to our understanding of evolution.
Scientist
Idea
Lamarck
Like Darwin, Lamark believed that organism changed over time, but he believed that an
organism could drastically change within a lifetime due to their needs and pass these drastic
changes to their offspring.
Darwin
Like Lamark, Darwin believed that organism changed over time, but he believed organisms
could NOT change within a lifetime. He believed that within a population there was an
immense amount of variation of traits, and some traits where more favorable than others;
Organisms with these favorable traits were more likely to survive and reproduce and pass
these traits to their offspring, and as a result, over many generations the population would
change to be more adapted to their environment.
4. What is variation and why is it important?
Variation is:
In any population of organisms individuals have many different traits that show differences (example: hair
color, foot size)
It is important because:
Some traits will be more advantageous than others; Organisms with these advantageous traits are more likely to
survive and reproduce and pass these traits to their offspring, and as a result, over many generations the population
would change to be more adapted to their environment. This is evolution through natural selection.
5. Give a scientific explanation for why the finches have different shaped beaks.
Each different shape bird beak is an adaptation that allows
each bird to eat different food (i.e. different types of seeds,
insects, flower nectar). Birds that have beaks that allowed
them to get enough food to survive and reproduce passed
this beak adaptation off to their offspring. Over time beak
shapes become better adapted to get food from their
environment. Birds with different beak sizes/ shapes may
have become reproductively isolated and over time they
evolved into separate species.
6. DDT is an insecticide that was first used in the 1940s to kill mosquitoes and stop the spread of malaria. At
first the DDT was very affective. However, over a period of time, people began to notice that the DDT was
becoming less and less effective. A possible explanation was that the insect population was becoming
resistant to DDT. Explain how resistance may have evolved.
 Within an insect population there is natural variation.

Because of this Natural Variation some insects will be resistant to the DDT insecticide.

In areas where the insecticide is being used, insects that are resistant to the DDT insecticide are
more likely to survive and reproduce, and pass this DDT resistant gene to their offspring.

Overtime insects with the DDT resistance gene will be very abundant and DDT will be less
effective at killing insect populations.
7. Watch this video about evidence for evolution then answer the questions below:
http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_3.html
8. Examine the diagram below, and then explain how the fin of a whale and the arm of other mammals are
scientific evidence of evolution.
 Each appendage (arm, fin, wing, paw) have the
same bones, joints, tendon and ligaments but
they are adapted for a difference habits.
 The fact that they have all the bone structure
suggests that they all evolved from a common
ancestor.
 Over a very long period of time this common
ancestor diverge into different species.
 Each species occupyed a special & different
habitat.
 Each habitat had different natural selection
pressure, which selected for difference
adaptations.
9. Complete the following table by describing how each
of the following is evidence for evolution.
Fossils

Fossils show how organisms have changed over time

Fossils show intermediated species (example: Australopithecus fossils show
features of both modern humans and African apes)

Fossils show that many organisms that use to exist have gone extinct.
Geographic
distribution of
organisms
Shows that closely related species tend to be found closer together, suggesting
that they evolved in one place and then spread out .
DNA
DNA of related species have similar base (ATGT) sequences suggesting they
evolved froma common ancestor
Homologies
Similar body structures…and arrangement of bones . This suggests that the limbs
were inherited from a common ancestor and then modified through natural
selection.
Vestigial
Structures
None functioning organs (example: human appendix) that has no function anymore
but once had a function in an ancestor species (example: human appendix was
used in primate ancestor to help with digestion of tough plant material.
Embryos
Related species go through a similar embryonic development.
10. What are two sources of genetic variation?
Sexual Reproduction = genetic shuffling
Genetic mutation == small changes in DNA on chromosomes
11. How do changes lead to a new species?
Population become geographically isolated and reproductively isolated from one another. IF they
are living in a different environments there will be different natural selection pressures on them and
over time they can become different species.
12. What is speciation?
When two populations can no longer breed and have fertile offspring.
13. List and describe the three isolation mechanisms that can lead to a new species.
a. Geographic barriers between population (ie. Rivers, islands, mountain
ranges)
b. Temporal Barrier between populations (i.e. organisms mating seasons occurs
during a different time)
c. Behavioral Barriers between populations (ie. Organisms have different
courtship behaviors.
ii. What is Geographic Isolation?
Some feature that separates a population from each other. Example: Mountain ranges, rivers,
canyons, islands,
iii.Triarthus was a trilobite that lived on Earth about 500 million years ago. The diagrams below
show its structure, viewed from above and below. The structure was discovered by
studying fossils of Triarthus.
a. Outline the evidence for evolution provided by fossils.

Fossils show how organisms have changed over time

Fossils show intermediated species (example: Australopithecus fossils show features of
both modern humans and African apes)

Fossils show that many organisms that use to exist have gone extinct.
b. Some trilobites swam in clear, shallow water and had very large eyes. Suggest how species with
large eyes could evolve from species with smaller eyes. In your explanation be sure to mention
the following vocabulary words:

a. Adaptation
b. Natural Variation
c. Inheritance
d. Difference in Reproductive Success.
e.
Within an trilobite population there is natural variation.

Because of this Natural Variation some triolobites will have different sizes of eyes.

If it is advantageous to have bigger eyes. For example it helps the trilobites escape predators or locate
prey. Then trilobites with bigger eyes are more likely to survive and reproduce, and pass this big eye
gene to their offspring.

Overtime trilobites will have bigger eyes. Tis is evolution via natural selection.
Go to the below website & review coevolution:
http://evolution.berkeley.edu/evosite/evo101/IIIFCoevolution.shtml
Watch the video about Co-evolution between microbes & human evolution:
http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_6.html
iv.
Define Coevolution:
The term coevolution is used to describe cases where two (or more) species reciprocally affect each other’s evolution. So for
example, an evolutionary change in the morphology of a plant, might affect the morphology of an herbivore that eats the plant,
which in turn might affect the evolution of the plant, which might affect the evolution of the herbivore...and so on.
Coevolution is likely to happen when different species have close ecological interactions with one another. These ecological
relationships include:
1. Predator/prey and parasite/host
2. Competitive species
3. Mutualistic species
v.
Using an example, explain how two living organisms can coevolve?
Poisonous Salamander (prey) and garder snake (predator)– as the salamander gets more
poisonous the garder snake gets more of a resistance to the poison. The salamander gets
more poisonous to escape predation from the snake; the snake gets more of a resistance to
maintain food source (salamander). Both are affecting each others evolution.
Evolutionary Trees
1.
Based on the below phylogeny, humans are most closely related to which
organism(s)? How do you know?
Human are the most closely related to chimpanzees and bonobos
 Human and chimps/ bonobos share two common ancestors, while gorillas and humans only share one
 One of the ancestors Humans share with chimps and bonobos is more recent than
The one humans share with gorillas
2. Which of the letters in the below tree corresponds to the most recent ancestor of the mushroom and a sponge?
D is the most recent ancestor of the sponge and mushroom
3.
Correct answer is C because Green Alga shares two ancestors with with red algae but three common ancestors
with moss.
T/F: According to the diagram below, gorillas are more closely related to humans than they are to
orangutans. (Hint: think about most recent common ancestor)
True…….Gorillas and humans share two common ancestors……and orangutans and gorillas only share one
common ancestor.
Human Evolution:
Instruction: Watch this video about human evolution below, then answer the questions:
http://www.becominghuman.org/node/interactive-documentary
1. Define Bipedalism
Bipedalism is a form of locomotion where an organism moves by means of its two
rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is
known as a biped (pron.: /ˈbaɪpɛd/), meaning "two feet" (from the Latin bi for "two"
and ped for "foot").
2. What characteristics do humans share with other primates?
a. Flattened noses
b. Reduced sense of smell
c. Grasping hands/ opposable thumbs
d. Flexible shoulder joints
3. How are hominids different from other primates?
Hominids are designed to walk upright on two legs/ they are bipedal
4. What species was the famous fossil “Lucy”?
Australopithecus afrarensis
5. Identify two Homo species that went extinct.
a. Homo erectus
b. Homo hablis
c. Homo neanderthalensis