Chapter 5:

Expert Question Answers

1. Fossils - shows how some species have changed over time.

2. Homologous Structures - Body parts are similar in related animals so there must be a common ancestor.

3. Vestigial Structures - There are structures present in modern day organisms but are not even used, so they may have been used by a common ancestor.

4. Molecular Biology - Similar species of organisms have more common DNA than do organisms that are more different!

5. Fetal Similarities - The unborn offspring of many species resemble each other, suggesting a common ancestor.

1. What are the five pieces of evidence for evolution? Describe how each one proves evolution.

• Charles Darwin is a scientist who developed “The Theory of Natural Selection”.

• He went to the Galapagos Islands to study many diverse plants and animals and learn how they were successful in the environment that they inhabited.

2. Who is Charles Darwin? Describe why he traveled to the Galapagos Islands?

1. Overproduction and Variation – There are many offspring and they are all different.

2. Competition - A natural environment does not have enough resources (food, water, shelter, space, and mates) to keep all offspring alive. Only the organism with a variation that makes them better adapted to the environment will survive.

3. Survival of the Fittest – the offspring best suited to the environment will survive.

4. Successful Reproduction- Individuals who adapt to their environment are more likely to survive and reproduce and pass on the successful traits to offspring.

3. List and explain the 4 steps of natural selection.

1. Overproduction and variation – lots of baby sharks are born. Some have sharp teeth, some have dull.

2. Competition - The sharks with dull teeth can’t attack pray and eat as well as sharks with sharp teeth and will die.

3. Survival of the fittest - The sharks with sharp teeth will survive.4. Successful Reproduction – the sharks that survive pass their sharp

teeth on to their offspring.

4. Using the four steps of natural selection, describe how sharks have sharp teeth.

• When over time, 2 populations become so different that they can no longer interbreed.

5. What is speciation?

1. Separation - portion of the population becomes isolated.

2. Adaptation- as the environment changes, so may the population living there change and evolve separately to form separate species.

3. Division- over hundreds to thousands of generations, the 2 groups became so different that they were no longer the same species and could no longer interbreed.  

6. Describe the three steps of speciation.

1. Canyon Forms

2. Mountain Range

7. What are 4 things that could cause speciation?

3. Volcano

4. Tsunami 

1. Food

2. Water

8. What are 4 things that species compete for? 3. Shelter

4. Mates

They may develop the following:• New digestive system • Smaller heads with quick reflexes• Softer bite• Long and skinny tongue

Darwin’s Theory of Natural Selection would come into play.1. Overproduction and variation – lots of baby lizards are born.

Some inherit the traits above & some don’t.2. Competition – there isn’t enough food to go around.3. Survival of the fittest- Lizards that do not inherit the traits above

will die. 4. Successful Reproduction - The lizards with the traits above will

survive, reproduce, and pass their sharp teeth on to their offspring.

9. Describe what would happen to lizards where they could only eat bugs. How would these new conditions affect the species?

They may develop the following:• New digestive system • Larger heads• Harder bite • Short and thick tongue

Darwin’s Theory of Natural Selection would come into play.1. Overproduction and variation– lots of baby lizards are born.

Some inherit the traits above & some don’t.2. Competition – There isn’t enough food for everyone.3. SOTF - Lizards that do not inherit the traits above will die. 4. Successful Reproduction - The lizards with the traits above will

survive, reproduce, and pass their sharp teeth on to their offspring.

Describe what would happen to lizards that could only eat plants. How would these new conditions affect the species?