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Science 7
Unit A Interactions and Ecosystems
3.0 Changes can be observed and monitored in ecosystems
3.1 Investigating the Distribution of Living Things in an Environment
Read pages 50 and 51 and answer the following questions:
1. It is believed that the Tyrannosaurus rex died about
_______ millions years ago by a dramatic,
_____________ change in its ecosystem. The “great
auk” died around the year ___________, and its’ death
was caused by _____________________ by the
Europeans.
2. Ecosystems are always changing: some changes are natural changes,
like ____________ or _______________ that can cause massive,
long-term changes to ecosystems. Sometimes the changes are caused
by ___________ activity, like building dams and clearing
______________.
3. Think about our schoolyard here at Delburne School. List some
changes you have noticed in the years you have been here.
____________________________
________________________
____________________________
_________________________
Have these changes been “natural” changes, or have they been caused
by human impact?
________________________________________________________
4. To help with counting, scientists estimate the _______________ of
living things in an area by a technique called _________________.
This technique is used when it is too ______________ to count each
living thing. Page 52 has a “mathLink” section that talks about a
specific kind of sample. A staked out area that is to be studied is
called a ______________, and can be square, rectangular or
_______________ in shape. Studying the area inside is called
_____________ _______________.
Science 7
Unit A Interactions and Ecosystems
3.2 Interactions and Changes Occur in Ecosystems
Read pages 55 – 60 and answer the following questions
5. Imbalances in ecosystems may create problems in that ecosystem.
Sometimes, human _____________ has caused imbalance. For
example, humans in the past have destroyed wetland ecosystems by
draining them to be replaced by _________________ and
__________________. Others were ______________ by pollution.
We now recognize the importance of wetlands, and many steps have
been taken to _____________ and preserve them.
6. The infoBIT on page 56 talks about the importance of
dragonflies as indicators of problems in a wetland
ecosystem. If dragonflies disappear from a pond, what
should we be concerned about?
__________________________
7. Everything changes, including ecosystems. Some ways that changes
can occur are through ___________________,
_______________________, predation and weather.
Bioinvasion
8. Remember, “bio” means “life”, or “living”. Think of what the word
“invasion” means. Do you think you have a little understanding of
what “bioinvasion” might mean? _________ Many plants and
animals that we might think are common to Canada have
actually come from _______________ else.
______________ settlers brought many of these with them
from their home countries. Scientists call this species
introduction __________________. Some of these species that
were brought here were stronger than the native species (species
that were here already), or they had no natural ______________.
Therefore, the new species could quickly ________________.
9. European starlings are an example of bioinvasion. They were put into
New York’s ______________________ and now number over
200 _____________ in North America. They cause
problems in _____________ fields and are hazards at
_________________. They compete with
__________________, woodpeckers and __________________ for
nesting sites.
10.Zebra mussels were first noticed in our Great Lakes in 1988. They
probably came over on ships from ______________. House sparrows
were also released in ___________________’s Central Park over 100
years ago. They complete for food and ________________ sites with
many native birds. And more than ____________ of Canada’s plant
species are not native.
Competition
11.All living things compete with all other living things in
their community for resources like ___________,
water, and __________ to live. There is only so much
of each resource, so all living things are always trying to get
enough to meet their ___________. Now tell me, what
happens if a living thing cannot compete and meet their needs?
______________________________
Predation
12.Predation occurs when an animal ________ other animals for
________. Hunted organisms are called the ______. What are the
ones doing the hunting called? ________________. The interactions
of these two (predator and prey) can affect an ecosystem. If there are
too many predators, the __________ population will _________.
This may then increase _______________ for food among predators’
populations. If so, one or more will either _________ or
___________ to a new location. If there are not enough predators, the
_________ population will ___________, creating competition for
food among the __________ species. Therefore, one or more will
either die out or move to a new ______________.
Weather
13.Good weather will help ecosystems grow, but poor weather conditions
can cause plant populations growth to __________ or _________.
Natural ____________ also change ecosystems, like bad storms,
____________ and lightning.
14.Answer the Check and Reflect questions on page 60, #1 and 2