Download File

Name: _______________________________________Sec: ___________Date: _________________________________
Lab 23: Evidence for Evolution
Objective: In this lab, students will be able to identify and interpret the different types of evidence involved in proving
the theory of evolution. They will also examine schools of thought that originally existed before this evidence was
discovered.
Introduction: The theory of evolution is an idea that all living things on earth share a common ancestor. Over time, this
original ancestor began to mutate so much that they eventually became brand new species. When the theory of
evolution was first brought to the attention of the public, many people did not believe in it. It was not until many, many
years after scientific works were published that people started to take the idea seriously. As we know in science class,
many scientific ideas are first dismissed but it is the evidence that turns people into believers. In this lab we are going to
look at some pretty convincing pieces of evidence in order to determine if evolution is in fact a valid theory.
Comprehension Questions:
1. Define Evolution: _________________________________________________________________________________
2. How do scientists turn theories into fact? ______________________________________________________________
__________________________________________________________________________________________________
ACTIVITY 1: FOSSILS
Due to the extensive fossil record that scientists have today. It is easy to look at the bones of the organisms that exist
today, as well as the organisms that were alive millions of years ago. Scientists have spent a long time analyzing all of the
remains to determine relationships between individual species. As they continued to examine the remains ,they realized
that many seemingly different species had characteristics in common. Today, the entire fossil record has be created and
scientists have created a detailed map following the evolution of organisms from the beginning of time to the present.
Comprehension Questions:
1. What did the fossil record help scientists to determine? __________________________________________________
__________________________________________________________________________________________________
2. Using the pictures of fossils provided by Shannon, create an evolutionary tree. Determine which fossil has something
in common with every other fossil and grow from there. You will be determining the evolution of organisms just as the
scientists did. When you have completed your tree show it to Shannon and draw it in the space below.
ACTIVITY 2: HOMOLOGOUS STRUCTURES
Homologous structures is another strong piece of evidence that supports the theory of evolution. Homologous
structures are structures that are similar in different species but do not necessarily perform the same function. As we
have learned this year, structures determine function in organisms. Well, several organisms that exist today have a very
similar structure in their “arms” but minor differences cause them to perform different functions. Scientists cannot
ignore the fact that seemingly different organisms have very similar bones. Take a look at the example below.
Comprehension Questions:
1. Define homologous structures: ______________________________________________________________________
2. Identify the structure and function of each other organism’s body parts above:
ORGANISM
Whale
BODY PART
FUNCTION
Frog
Horse
Lion
Human
Bat
Bird
3. If each of the body parts above perform completely different functions, why do scientists think that they are so similar
in bone structure?
ACTIVITY 3: VESTIGIAL STRUCTURES
Vestigial structures are structures present in organisms that have either reduced in size or even sometimes, they no
longer exist at all. An example in humans is the appendix. A long time ago, the appendix was much larger because it
helped early humans to digest foods like twigs and berries. Nowadays, humans don’t really eat such types of food
anymore, and so there is no need for an appendix anymore. The size of the appendix has therefore greatly decreased
over time.
Comprehension Questions:
1. Define Vestigial Structures: __________________________________________________________________________
2. Look at the picture below, determine what part of the whale is a vestigial structure. ____________________________
3. What is a possible reason why these whales might have those bones? _______________________________________
__________________________________________________________________________________________________
ACTIVITY 4: EMBRYOLOGY
Scientists have been studying the development of many different species in order to determine relationships between
organisms in the study of embryology. They have found that many species start out exactly the same during
development. Below are some images of different species during development.
Comprehension Questions:
1. Define Embryology: ___________________________
_____________________________________________
2. List some of the similarities in development that you
notice between the different types of species.
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
What evidence does this image provide to the theory of evolution. Why do scientists find it reliable?
_____________________ ____________________________________________________________________________
__________________________________________________________________________________________________
ACTIVITY 5: DNA
Just as we studied the DNA of the different plant species in our NYS Biodiversity Lab, scientists study the DNA of
different species all the time in order to determine relationships between organisms. As we know from our last lab, we
cannot rely on structural characteristics alone, the DNA evidence is always going to be the most reliable of all of the
evidence addressed in today’s lab. DNA sequences contribute to such molecular evidence as enzymes, hormones, and
pigments present in organisms. If organism have the same proteins, then they must have similar DNA sequences.
Comprehension Questions:
Look at the diagram above. Based on the amino acid sequence, determine what the evolution tree between these five
organisms would look like and draw it below.
CONCLUSION: If you had to defend evolution in a court of law. Write an opening argument that provides the jury with
the necessary information needed to support the theory of evolution as discovered in this lab. Write it below.