Lesson 5.1: What Threatens Biodiversity?

Biodiversity describes the number and variety of living things in an area.  Millions of years ago, animals such as dinosaurs existed, but they do not exist today.  Also, many species that existed a hundred years ago are now extinct or in danger of extinction.  What causes extinctions? 

Extinctions can be caused by events such as meteorites hitting Earth and causing large changes in climate or by man hunting certain species until none is left.  Farming practices, mining operations, and power generation can also cause extinctions by destroying too much of the habitat that certain species need to survive. 

Read What Threatens Biodiversity? on page 286 of your textbook. Then, answer the following questions.

 

Question 1. Answer Reading Check on page 286 of your textbook.

Question 2. Answer Check Your Understanding questions 1, 2, and 3a to 3d from page 287 of your textbook.

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. Answer Reading Check on page 286 of your textbook.

The extinction of a species is its elimination from Earth.

Question 2. Answer Check Your Understanding questions 1, 2, and 3a to 3d from page 287 of your textbook.

1.    Extinction can occur due to normal circumstances such as an Ice Age that could make it too cold for many plants and animals to survive.

2.    An extinct species no longer exists, such as the dinosaurs.  An at-risk species exists in such small numbers that it could become extinct.  An example of this is the black-footed ferret.

3a.    The biodiversity will decrease because, instead of having many types of food for many different species, only a single type of food is available.

3b.    The biodiversity will decrease because the habitat of many species is destroyed and the soil may change in composition.

3c.    The biodiversity will decrease because much vegetation will be crushed and destroyed.

3d.    The biodiversity will decrease because the habitat of many species is destroyed.

 


Now, do Assignment 14E.  Page forward to access it.