Evolution Directed Reading
Name
Key
(Lessons 4.3, 6.1, 6.2, 6.3)
Mutations
Read Chapter 4 Lesson 3 and answer the following questions.
Page 119
1. Define mutation. Any change in the DNA of a gene or a chromosome
2. How can mutations affect an organism (Key Question)? Mutations can cause a cell to
produce an incorrect protein during synthesis. As a result, the organism’s trait
may be different from what it normally would be.
3. What types of mutations are possible?
a.
b.
c.
d.
Addition of a base pair
Deletion of a base pair
Substitution of a base pair
When chromosomes don’t separate correctly and a cell ends up with the
wrong number of chromosomes.
Page 120
4. Mutations introduce changes to an organism. Mutations can be harmful, helpful, or neither
harmful or helpful.
5. When is a mutation harmful?
If it reduces the organism’s chances for survival and reproduction
6. When is a mutation helpful?
If it increases an organism’s chances for survival and reproduction
7. Drug resistance is a beneficial mutation in bacteria, but how can it be harmful for humans?
People with the disease caused by the bacteria won’t be helped by certain drugs
taken for treatment.
Page 121
8. There are more than 100 types of cancer.
9. Cancer is a disease in which cells grow and divide
uncontrollably,
parts of the body around them.
10. Which factors work together in determining if a person gets cancer?
damaging
the
Inherited traits, substances in the environment (cigarettes, UV light, high sugar
high fat diets)
Page 122
11. Scientists think that cancer begins when something damages a portion of the DNA in a
chromosome. The damage causes a mutation.
12. Cancer begins when mutations disrupt the normal cell cycle, causing the cells to divide in an
uncontrollable way.
13. As a cell divides over and over, more and more abnormal cells are produced. In time these
cells form a tumor.
14.How does cancer spread? Some cancerous cells break away from the tumor and
move to the bloodstream which moves the cells to other parts of the body.
Page 123
15.If you were a cancer researcher working on a cure, would you want to design a drug that would
speed up or slow down the cell cycle? Why? Slow it down. Cancer cells divide too often
and grow too large.
16. What are some of the things you can do to reduce your risk of getting cancer? Eat healthy,
exercise, don’t smoke, don’t get too much sun, reduce exposure to toxins
(pesticides, etc.)
Darwin’s Theory
Read Chapter 6 Lesson 1 and answer the following questions.
Page 167
1. Darwin was amazed by the diversity of living things that he saw during the voyage. He
wondered why they were so different from what he saw in England.
2. What do today’s scientists know about diversity? How many organisms have been identified?
Organisms are even more diverse than Darwin thought. Scientists have identified
more than 1.6 million species.
3. Define species. A group of similar organisms that can mate with each other to
produce fertile offspring
4. Define fossil. The preserved remains or traces of an organism that lived in the past.
5. Darwin was puzzled by some fossils. He saw fossils that resembled the bones of living sloths,
but were much larger.
Page 168
6. Darwin discovered many similarities between Galapagos organisms and those found in South
America.
7. He also noted important differences between the organisms.
8. Darwin thought species could change and even produce new species over time.
Page 169
9. What did the government official in the islands explain to Darwin? He could tell which island
a tortoise came from just by looking at its shell
10. Darwin learned that the different birds were all finches. Darwin concluded that the finch
species were all related to a single ancestor species that came from the mainland.
11.Define adaptation. a trait that increases an organism’s ability to survive and
reproduce
Page 170
12. Darwin became convinced that organisms change over time.
13. This process of change is called evolution.
14. Darwin hypothesized that species change over many generations and become better
adapted to new conditions.
15.Define scientific theory. A well-tested concept that explains a wide range of
observations.
Page 171
16.Explain artificial selection. Only the organisms with a desired characteristic, such as
color, are bred. By repeatedly only allowing organisms with the desired trait to
reproduce, the species can be altered. This occurs very rapidly as compared to
evolution
17. Darwin thought that a process similar to artificial selection might happen in nature.
Page 172-173
18.
Natural
Selection is the process by which individuals that are better adapted to their environment
are more likely to survive and reproduce more than other members of the same species.
19. Darwin’s identified factors that affect the process of natural selection. Please summarize these factors
below.
Overproduction – species produce far more offspring that can survive.
Resources are limited.
b. Variation – organisms within a species show slight difference from one
another such as: speed, color, etc.
c. Competition –members of the species will compete with one another for
the limited resources.
a.
d. Selection(Successful Reproduction)- those individuals who happen to be
better adapted to the environment are more likely to survive and
reproduce. Their offspring are likely to inherit those beneficial
adaptations.
20. Darwin proposed that, over a long time, natural selection can lead to change. Helpful variations
may accumulate in a species while unfavorable ones may disappear.
Page 174
21. A change in the environment can affect an organism’s ability to survive and therefore lead to
natural selection.
22. Darwin couldn’t explain where variations in species came from, but scientists later figured out the
mystery. Where do variations in species come from?
Variations can result from changes in genes and the shuffling of different forms
of a gene when the egg and sperm join.
23. A variation is any (similarity/difference) between individuals of the same species.
Evidence of Evolution
Read Chapter 6 Lesson 2 and answer the following questions.
Page 177
1. The fossil record provides clues about how and when new species evolved and how
organisms are related.
2. Similarities in early development suggest that species are related and share a common
ancestor.
Page 178
3. Similarities, like presence of a backbone, provides evidence that many animal groups share a
common ancestor.
4. Similar structures that related species inherit from a common ancestor are known as
homologous structures.
5. The fossils show that the ancestors of today’s whales had legs and walked on land.
Page 179
6. Why do some species have similar body structures and developmental patterns? Species
inherited many of the same genes from a common ancestor
7. The more similar the DNA sequences, the more closely related the species are.
8. DNA evidence has confirmed conclusions based on fossils, embryos, and body structure.
Rate of Change
Read Chapter 6 Lesson 3 and answer the following questions.
Page 180
1. How do new species form? New species can form when a group of individuals
remains isolated from the rest of its species long enough to evolve different traits
that prevent reproduction.
2. Isolation occurs when some members of a species become cut off from the rest of the species
which can happen when a natural barrier, such as a river, separates group members.
Page 181
3. What separates the Kaibab and Abert squirrel species? Grand Canyon
Page 182-183
4. What are the 2 patterns that scientists have developed to describe the pace of evolution?
a. gradualism
b. punctuated equilibrium
5. Gradualism involves small changes that add up to major changes over a long period of time.
6. Define punctuated equilibrium. Species evolve during short periods of rapid change
and then don’t change much for a long period of time
7. Why are fossils of intermediate life forms likely to be rare if the pattern of punctuated
equilibrium explains how evolution occurs? Evolution would occur rapidly over a short
period of time, so the chances of intermediate fossils forming is reduced