Unit 5 Evolution Study Guide KEY
Name
Be sure to refer to all notes and activities from this unit. Also be able to read an experimental scenario and pick out the following
parts: independent variable, dependent variable, constants and control
1. Be familiar with the progression of the events on the timescale from simple organisms to complex organisms. Put the following
groups of organisms in the correct evolutionary order according to the geologic time scale: Algae, jawed fish, mammals,
amphibians, bacteria
a. Bacteria, Algae, jawed fish, amphibians, mammals
2.
Define homologous structure. What is an example?
a. Homologous structure: structures that have similar characteristics but may or may not have similar functions;
examples: the forearms of vertebrates (see notes for detail)
3.
Define vestigial structure. What is an example?
a. Vestigial structure: structures that are diminished in size and or function; examples: wisdom teeth, the 5th (pinky)
toe, appendix, eyes of moles
4.
Define analogous structure. What is an example?
a. Analogous structures: structures with the same function in organisms that are not closely related; examples: the
wings of birds and the wings of insects, the thorns on a rosebush and the quills of a porcupine.
5.
Homologous and vestigial structures show that these organisms descended from a common ancestor. Explain this.
a. Suggests that descendants diverge (become different) as the distance from a common ancestor increases (as the
world gets older and things evolve over millions of years)
6.
Compare the embryological development of vertebrates and molecular comparisons.
a. Scientists look at how the embryos of different animals develop and compare and contrast similarities and
differences. They also compare the molecular make-up. The closer the patterns in DNA, and order and number of
amino acids, the more closely related the organisms are. (See notes for more detail)
7.
8.
The preserved remains of ancient organisms are fossils.
Describe Relative Dating v. Radiometric Dating.
a. Relative dating: comparative dating using rock layers (oldest layers at the bottom and younger layers toward the
top) does not assign an absolute number to the fossil.
b. Radiometric (radioactive) dating: assigns an absolute age to a fossil by using science and math (remember the halflife problems!)
9.
What type of information do both types of dating techniques tell you about the age of a fossil?
a. The fossil record is very incomplete but shows how organisms have changed over time. The age of fossils may not
be completely accurate, but it gives us a glimpse into the possibilities of what life on earth was like millions of years
ago.
10. Define half-life. Describe how half-lives are used to determine the age of fossils.
a. Half-life: the amount of time it takes for half of the radioactive atoms in a sample to decay. Scientists use half lifes
to determine an approximate age of a fossil based on the amount of an element remaining in the fossil (they
compare it to a living organism that may have been closely related)
11. This diagram shows that the chimp is more closely related to the mouse than it is to the pigeon. What would we expect to find
about the DNA of these organisms? Which organisms might have similar DNA?
The closer the organisms are to each other on the diagram, the more
Closely related they may be. For instance, the hagfish and perch are
More closely related than the salamander and mouse.
12. Define evolution.
a. a theory that the various types of animals and plants have their
origin in other preexisting types and that the distinguishable
differences are due to modifications in successive generations
13. Define adaptation.
a. Inherited characteristic that increases an organisms chance for survival
14. Define natural selection.
a. Those best adapted to their environment will survive and reproduce the most successfully (“Survival of the Fittest”)
15. How are mutations related to evolution?
a. Random mutations can cause new features that can better adapt an organism to survive.
16. What are the principles of natural selection? Be able to apply these principles to a real life situation. Know how the words
variation, overproduction, and natural selection fit into these steps.
a. Variation: can be inherited through DNA (example: light vs. dark moths of the same species)
b. Overproduction: when a species will produce more offspring than necessary to replace the parents, but the
population remains stable (Example: fish eggs, some will be eaten by predators but enough will survive to sustain
the population.
c. Each of these things contributes to the organism’s ability to survive in its environment. (Think of the Peppered Moth
Survey!)
17. In what order did birds, mammals, fish, reptiles, and amphibians evolve?
a. Fish, amphibians, reptiles, birds, mammals
18. External fertilization requires water. Which of the five main vertebrate groups use external fertilization?
a. Fish and Amphibians (rely on water)
19. Internal fertilization allowed reptiles to move onto land and increased the likelihood that fertilization will occur. What other
vertebrate groups, besides the reptile, use internal fertilization?
a. Birds and mammals
20. Unlike amphibians, reptiles have an egg that is shelled with membranes to protect the embryo. What is this type of egg called?
a. Amniotic Egg
21. Define ectothermic. Which of the five main vertebrate groups are ectothermic?
a. When an organism has to rely on its environment to regulate its body temperature (fish, amphibians, reptiles)
22. Animals who are endothermic control their own body temperature. To generate heat you must have a highly efficient respiratory
and circulatory system. Which two vertebrate classes show these characteristics?
a. Birds and mammals
23. What is the purpose of a placenta? List two mammals that DO NOT have a placenta.
a. Protects and nourishes the embryo
b. Duck billed platypus and the echidna are mammals that lay eggs
24. Mammal is to hair/fur as bird is to feathers.
25. List characteristics of each group of vertebrates (fertilization, reproductive cycle, endothermic or ectothermic, etc.)
a. See the Vertebrate Evolution Powerpoint on the website.
b. You can also check the textbook beginning on page 767
c. BRM 108-109
d. Vertebrate DLC