Alien Invasion Worksheet

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Alien Invasion Worksheet Answer Key

Directions: As you read the article, answer the following questions. Use complete sentences for full credit.

1. How do alien plants threaten native plants and animals?

They move into areas and push out the native plants.
They diminish the diversity of plants so animal diversity also decreases.
They can increase soil erosion.
They out compete the natives.

2. What is a common name for "invasive aliens"?

They are also called "weeds".

3. What two characteristics do alien plant species have that allow them to spread quickly?

They reproduce rapidly
They have no natural pests or predators.

4. Define weed.

A weed is any plant that you do not want.

5. How are foreign plants introduced to local areas?

They can be intentionally brought in for crops or as ornamental plants.
Crop seeds may be contaminated.
They can be accidentally imported on ships or other vehicles.

6. How do park managers fight the alien plant species? Decide if it is a mechanical, chemical or biological control method and place an X in the appropriate column.

Method	Mechanical	Chemical	Biological
fire	_____X_____	__________	__________
herbicides	__________	____X______	__________
imported pests	__________	__________	_____X_____
shading	_____X_____	__________	__________
moving	_____X_____	__________	__________
biological control	__________	__________	_____X_____
weed-eating boat	_____X_____	__________	__________

7. Define biological control.

Insects, animals, or microbes that attack undesirable plants.

8. Why do park managers worry about using biological control methods?

The pest or predator might be a bigger problem than the original invader.

Extra Credit:

Find 5 words that you did not know from the article. Write the sentence each was used in and underline the new word. On the back of this page, use each word in your own sentence.