Texas 7th grade science Biodiversity

1. TOPIC:
BIODIVERSITY
Essential Question: Explain
biodiversity and why it is important to
have a diverse ecosystems.

2. INSTRUCTIONS:
1. Take Cornell Notes
2. Stop & Answer slides ~ on a plain
sheet of notebook paper
3. Write the question & your answer.
(Your answer MUST be in
complete sentence.)
4. You MUST have a minimum of five
(5) sentences for each question.

3. Biodiversity
iodiversity refers to the number and variety of
species on Earth.
he number of known species on Earth is about
1.6 million, most of which are insects.
his is different from the actual number of
species on Earth, which may be closer to 13

4. Importance of Biodiversity
iodiversity provides:
 a variety of products and resources
 a livable planet for us and for all other species.
iodiversity helps:
 maintain the atmosphere
 keep the soil fertile

5. Loss of Biodiversity
e share the environment with other organisms in a
complex network.
ach species has a role or niche to play in its
ecosystem.
f one species disappears from an ecosystem, the
ecosystem changes.
eystone species are species that are so
important to the functioning of an
ecosystem that if they disappear, the
ecosystem falls apart.

6. An Example in Texas:
Black-tailed Prairie
lack-tailed prairie dogs once
Dogs
roamed the western mid-west.
Now cover less than 1% of their
original territory.
Digging aerates and promotes soil
formation.
Clip back brush maintaining the
short grass prairie.
Provide food and shelter for as
many as 170 different animals.

7. Main Threats to
Biodiversity
• Habitat loss
• Introduced species
• Population growth
• Pollution

8. he destruction of habitats is the number
Habitat Loss one cause of species extinction.

9. Stop & Answer
ow does habitat loss affect biodiversity in an
ecosystem?

10. Introduced Species
onnative or Exotic species that are not native to a
particular region.
ire ants from South America entered the U.S. through Mobile,
Alabama, probably in soil used for ships' ballasts. They were
accidentally introduced around the 1930's and have been
spreading ever since.

11. Stop & Answer:
ow do introduced species affect biodiversity in
an ecosystem?

12. Population Growth
here are 6 billion humans living on Earth.
arth’s population of human beings is increasing at a rate of about
222,000 people each day.
umans take up more space and deplete more resources than any
other species.

13. an be an oil spill, acid rain, trash or
Pollution insecticides that can cause reproductive
failure in fish, birds, and mammals (like
DDT).

14. Stop & Answer:
ow does pollution affect biodiversity in an
ecosystem?

15. Extinction
Extinction occurs when the last individual of a species dies.
an Marcos Gambusia, Texas, 1983
exas red wolf, Oklahoma, Texas, 1970

16. Mass Extinction
• the extinction of many species during a
relatively short period of time.
• often caused by a change in climate.
• Many scientists believe that we are living
in a mass extinction, and that by the year
2100, 25% or more of all species of plants
and animals that were on Earth in 1900
will have become extinct.

17. Stop & Answer:
ow will this mass extinction affect Earth?