How do Organisms Compete and Survive in an Ecosystem


Chapter 6, lesson 1, pgs. 178, 179


1.    What do you think leads some kinds of animals to care for their young, while others do not?


Instinct controls animal behavior toward their young. Some animals, such as birds and mammals, have an instinct to care for and protect their young. Others, such as most fish, leave their young on their own.


2.    How does a population relate to a community?


A population refers to all the organisms of one kind in a given place; a community is made up of several populations living together and interacting.


3.    Why do organisms compete?


Each organism must meet its needs in order to survive, and sometimes there is not enough food, water, shelter, or space for all the organisms that need it.


4.    For which resources do plants compete?


They compete for space, water, sunlight, and nutrients in the soil.


5.    What do organisms compete for in an ecosystem?


They compete for food, water, shelter, and space.


Symbiosis, pg. 180


6.    Do organisms in a mutualistic relationship compete with each other? Explain your answer.


No they do not compete. Instead, they help each other meet their needs.


7.    How is symbiosis different from competition?


Symbiosis involves working together, but competition is a struggle with others for limited available resources.


8.    What are the three different kinds of symbiosis and their characteristics?


Mutualism both organisms benefit

Commensalism one organism benefits and the other is not harmed.

Parasitism one organism benefits and the other is harmed or even killed.


9.    How does symbiosis help organisms survive?


It helps them meet their needs, especially their need for food.


10.                       Why do many parasites eventually need a new host?


The parasites weaken or kill the hosts.


11.                       Why do viruses and bacteria spread easily in crowded places?


These parasites can easily find a new host (YOU) in a crowded place.



Pg. 181 Main Idea and Details question


Give examples of the three kinds of symbiosis.


Mutualism: rhino and bird; ants and aphids


Commensalism: remoras and sharks; barnacles and whales


Parasitism: bacteria and viruses that cause disease; tapeworms and roundworms in animals; mistletoe on trees


Pg. 182, Predator Prey Relationships


12.                       Should people try to keep predator prey relationships in balance?


Some people think it is a good idea to prevent populations from dying out in certain areas, while others believe that nature should achieve its own balance.


13.                       How can a change in the number of prey affect predators?


If the number of prey increases, predators can more easily meet their needs for food, and more of them will be able to survive and reproduce. If the number of prey decreases, predators must compete for food, and fewer will survive.


14.                       How can a change in the number of predators affect the prey?


An increase in predators could wipe out the prey. A decrease in predators could allow more prey to survive and reproduce, increasing their numbers.


15.                       How do predators help prey?


Predators keep the prey population in balance so that the prey population does not increase so much that all the food supply is eaten and some individuals begin to starve.


Pg. 182, Main Idea and Details Question


What symbiotic relationship is most like a predator prey relationship?

Parasitism is most like a predator prey relationship.


Pg. 183, Reading Review


Complete the following:


1.    A and B

2.    write a paragraph using at least four vocabulary terms

3.    draw conclusions

4.    skip 4

5.    Identify three populations living near you.

6.    select best response