Evolution by Natural Selection Worksheet

Name: ______Date: ______Period: ______

Unit 5 Corrective

Adapted from the University of California, Los Angeles Life Sciences 1 Demonstration Manual

Describe what is happening in figures 1-3. Is the population of mice different in figure 3 than in figure 1? Explain why.

Describe what is happening in figures 1-3.

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Is the population of mice different in figure 3 than in figure 1? Explain why.

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Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce. An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and reproduce. What characteristic of the mice is an adaptation that increased their fitness?

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The table below gives descriptions of four female mice that live in a beach area which is mostly tan sand with scattered plants. According to the definition given for fitness, which mouse would biologists consider the fittest? Explain why this mouse would be the fittest.

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Color of fur / Black / Tan / Tan and Black / Cream
Age at death / 2 months / 8 months / 4 months / 2 months
# pups produced by each female / 0 / 11 / 3 / 0
Running speed / 8 cm/sec. / 6 cm/sec. / 7 cm/sec. / 5 cm/sec.

If a mouse's fur color is generally similar to its mother’s color, what color fur would be most common among the pups?

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A characteristic which is influenced by genes and passed from parents to offspring is called heritable. Over many generations heritable adaptive characteristics become more common in a population. This process is called evolution by natural selection. Evolution by natural selection takes place over many, many generations.

Evolution by natural selection leads to adaptation within a population. The term evolution by natural selection does not refer to individuals changing, only to changes in the frequency of adaptive characteristics in the population as a whole. For example, for the mice that lived in the beach area with tan sand, none of the mice had a change in the color of their fur; however, due to natural selection, tan fur was more common for the pups than for the mother mice.

In summary, a heritable characteristic that helps an animal or plant to have more offspring which survive to reproduce will tend to become more common in a population as a result of evolution by natural selection.

Questions

1. Explain why a characteristic which helps an animal to live longer will generally tend to become more common in the population as a result of evolution by natural selection.

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Vocabulary Review: Define the following terms

1.stabilizing selection______

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2.directional selection ______

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3.disruptive selection ______

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Multiple Choice: Circle the correct answer for each of the questions below.

4.Starlings produce an average of five eggs in each clutch. If there are more than five, the parents cannot adequately feed the young. If there are fewer than five, predators may destroy the entire clutch. This is an example of

a.disruptive selection. b. stabilizing selection.

c. directional selection. d. none of the above.

5.The occurrence of large or small beak sizes among seed crackers in the absence of mediumsized beaks is an example of

a.directional selection. b. stabilizing selection.

c. disruptive selection. d. none of the above.

6.A scientist measures the circumference of acorns in a population of oak trees and discovers that the most common circumference is 2 cm. What would you expect the most common circumference(s) to be after 10 generations of stabilizing selection?

a.2 cm

b.greater than 2 cm or less than 2 cm

c.greater than 2 cm and less than 2 cm

d.can't tell from the information given

7.Refer to question 6, but this time answer what you would expect after 10 generations of disruptive selection.

a.2 cm

b.greater than 2 cm or less than 2 cm

c.greater than 2 cm and less than 2 cm

d.can't tell from the information given

8.Refer to question 6, but this time answer what you would expect after 10 generations of directional selection.

a.2 cm

b.greater than 2 cm or less than 2 cm

c.greater than 2 cm and less than 2 cm

d.can't tell from the information given

Short Answer: Answer the following questions in complete sentences.

9.What types of individuals in a population are represented by the two ends of a bell curve?

10.If a cow develops a preference for eating white four o’clock flowers and ignoring pink and red four o’clock flowers, what type of selection is being demonstrated? Sketch a graph of the curve with labeled axis to demonstrate the selection.

11.Label the three types of selection illustrated by the graphs below.

Interpreting Data: Use the following information to answer the questions below.

12.A population of birds, with various size beaks, eats seeds. Small seeds can be eaten by birds with small beaks. Larger, thicker seeds can only be eaten by birds with larger, thicker beaks. Suppose there is a shortage of small seeds but that there are still many large seeds.

a.Draw a new curve on the graph below to show how the distribution of beak sizes might change as a result of selection in this new environment.

Use the graph above to answer the following questions:

b.Which birds in this population have the highest fitness?

c.Explain how natural selection could lead to the change you predicted.

1. Vocabulary

distinguish between the terms in each of the following pairs.

a) taxonomy, binomial nomenclature

b) kingdom, species

c) phylum, genus

3.Why do biologists assign each organism a universally accepted name? Give an example of this.

4.Name Linneaus’ 7 taxonomic categories from SMALLEST to LARGEST

5.Explain why each of the following characteristics of a classification system is important:

a)It assigns a single, universally accepted name to each organism.

b)It places organisms into groups that are biologically related.

c)It divides organisms into small groups.

6.Matching

1. binomial nomenclature / a) ______devised a system of naming organisms that is still in use today.
2. taxonomy / b) Organisms are placed in ______, or classification groups.
3. Linneaus / c) The taxon that is larger than a genus and smaller than an order is a(n) ______.
4. taxa / d) In ______, an organism is given a 2‐part scientific name that give the organism’s genus and species.
5. family / e) The smallest taxon is the ______, which is made up of organisms that share similar characteristics and can breed with one another.
6. species / f) The science of naming organisms and putting them into classification groups is known as ______.

7.Complete the following table for at least 2 organisms (that aren’t in the notes!)

(common name)
Kingdom
Phylum
Class
Order
Family
Genus
Species

7.Name the 6 kingdoms and give an example of each (try to think of one on your own!)

Kingdom / Example

9.When classiying ofrganisms, orders are grouped togeterintoh

a) classesb) phyla c) families d) genera

10. A useful classification system does NOT

a) reveal revolutionary trends

b) show relationships

c) change the taxon of an organism based on new evidence

d)use different scientific names for the same organism

11. In the scientific name of an organism, the first part is the:

a) species identifier b) phyla c) genus d) subspecies

12. The species name of the lion is:

a) Pantheraleob pantheraleo )

c) Pantheraleod) Panthera Leo

13.Answer the following questions in relation to the tree provided.

14.What characteristics distinguish

a) protists from monerans

b) fungi from plants

c) plants from animals

15.a) what is the difference between eukaryotic and prokaryotic cells?

b) Which kingdoms are eukaryotic? Prokaryotic?

16. Explain the difference between the following. Give examples of each kind

a) Heterotrophs and autotrophs

b) Unicellular and multicellular organisms