Ms. McKinley


Site Map

About Me


Lesson Plans

Antibiotic Resistance:
Case Study



UNIT 7: Evolution and Natural Selection

What you should know:

The Earth formed about 4.5 billion years ago according to evidence obtained by radiometric dating. Today, new species roam the Earth that have been influenced by the extinction of past species. The first vertebrates to invade dry land were amphibians. When many reptile species became extint this enabled birds and mammals to become the dominant vertebrates on land. The continents have been slowly, and continuosly moving on the Earth. This has contributed to the geographic distribution of some species.

Charles Darwin was a scientist who became famous for his work with evolution. From his travels and studies he concluded that animals on the coast of South America that resembled those on the nearby islands evolved differences after separating from a common ancestor. Darwin proposed that natural selection favors individuals that are best able to survive and reproduce in a given environment.

The fossil record, comparitive anatomy and molecular structures are all evidence of evoluton. Fossils are evidence of orderly change when they are arranged by age. Differences in amino acid sequences and DNA sequences are greater between species that are more distantly related than between species that are more closely related. The presence of homolgous structures and vestigial structures suggests that all vertebrates share a common ancestor. Most scientists believe that evolution is a slow, gradual process referred to as gradualism. Others think that speciation occurs rapidly between periods of little of no change. This is referred to as punctuated equilibrium.

Natural selection favors the survival of individuals that have traits that enable them to survive and reproduce in a given environment. These individuals pass their traits on to their offspring, and the population evolves. The changing of a species that results in its being better suited to its environment is called adaptation. When a species becomes geographically isolated the two populations may diverge into two new species as they adapt differently to their environments. Once new species have formed, they will become reproductively isolated to keep them from breeding with one another.

How you make sense of things:

Initial EPE before lab

Observations you make
in your daily life:
Patterns you notice:
Explanations for the patterns:

Husky dogs look very similar to wolves.

Penguins have wings but they can not fly.

Cheetahs can run up to 60 mph to catch their prey.

Doctor prescribes antibiotic when you have strep, an ear infection, sinus infection.

I go to the doctor and expect an antibiotic to feel better.

I forgot to take the last couple of doses of my antibiotic because I felt all better.

Mom uses antibacterial cleansers when cleaning.

When I had pneumonia the doctor prescribed me a second antibiotic after the first one did not completely get rid of the pneumonia.



Sometimes when I took prescribed antibiotics they did not make me feel any better

People go to the doctor to feel better and doctors intern prescribe them antibiotics

Sometimes antibiotics are wrongly given to those who have viral infections

Antibacterial cleansers say that they kill 99.9% of germs

Cheetahs that are the fastest have the best chance of catching their prey. Over time the fastest cheetahs have survived and reproduced.

When you do not finish your prescriptions the most resistant bacteria survive and reproduce.



Goal EPE after lab

Observations you make
during lab:
Patterns you notice
in the data:
Explanations for the patterns:

Birdies Activity
The spoon picks up many beans. The fork picks up fewer beans. The chopsticks and knife pick up very few beans.

A Fishy Twist on Adaptations

Peppered Moth Survey
With newspaper as the background, many white paper disks were caught, and few newspaper disks were caught.

With white paper as the background, few white paper disks were caught, and many newspaper disks were caught.

TB Case Study
Many people are dying in Russian prisons from TB.

The drugs that used to cure the TB are no longer working.

Birdies Activity
The spoon picks up more beans than the other utensils.

A Fishy Twist on Adaptations
Fish have certain adaptations that are useful for various things.

Peppered Moth Survey
When the paper disk blends into the background it is not caught as often as if it stands out.

TB Case Study
The more often bacteria like TB are exposed to antibiotics, the more chances they have to evolve resistance to our drugs.

Birdies Activity
The spoon represents the beak of a bird and it is the best shape for picking up beans, so it survived to reproduce while the other utensils went extinct.

A Fishy Twist on Adaptations
Fish have adapted to their environments by evolving various features that make them more successful in their given habitat.

Peppered Moth Survey
Coloration affects predation on moths. Moth coloration changes through natural selection to camoflague the moth from predators based on the background.

TB Case Study
The evolution of antibiotic resistance - Overuse and abuse of antibiotics and antibacterial cleansers give rise to resistant bacteria through the process of natural selection. The resistant strains of bacteria survive when exposed to antibiotics and the following generations have more and more of the resistant bacteria.

What you should be able to do:

1. Explain how extinction removes genes from the gene pool.
2. Summarize the major concepts of natural selection (differential survival and reproduction of chance inherited variants, depending on environmental conditions).
3. Describe how natural selection provides a mechanism for evolution.
4. Explain how a new species or variety may originate through the evolutionary process of natural selection
5. Explain how natural selection leads to organisms that are well suited for the environment (differential survival and reproduction of chance inherited variants, depending upon environmental conditions).
6. Explain, using examples, how the fossil record, comparative anatomy, and other evidence may support the theory of evolution.
7. Describe species as reproductively distinct groups of organisms that can be classified based on morphological, behavioral, and molecular similarities.
8. Trace the relationship between environmental changes and changes in the gene pool, such as genetic drift and isolation of subpopulations.
9. Interpret a cladogram or phylogenetic tree showing evolutionary relationsips among organisms.
10. Explain how natural selection acts on individuals, but it is populations that evolve. Relate genetic mutations and genetic variety produced by sexual reproduction to diversity within a given population.
11. Describe the role of geographic isolation in speciation.