Lesson 4.1 - Biotic Limiting Factors

You learned much about abiotic limiting factors of a population.  Biotic means related to life.  So biotic limiting factors would be living things that affect the size of a population.  Can you think of any biotic limiting factors?  The first one to come to mind might  be predators.  There are many biotic limiting factors.  To learn more about biotic limiting factors read "Biotic Limiting Factors" on page 264 in your textbook.  Then look at the information presented in Figure 13.7 on pages 264 and 265.

Question 1. What are the three main biotic limiting factors that are discussed in the reading?

Question 2. Define parasitism.

Question 3. Name the two parasites described in Figure 13.7.

Question 4. The "Did You Know" discusses moose and ticks.  How many ticks can a single moose be host to?

Question 5. Define predation.

Question 6. Name the two predator-prey situations described in Figure 13.7.

Question 7. Interactions of biotic limiting factors are often complex.  How do parasites affect the predator-prey relationship?

Question 8. Define competition.

Question 9. Does competition only occur between individuals of the same species?



Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What are the three main biotic limiting factors that are discussed in the reading?

The three main biotic limiting factors discussed are parasitism, predation, and competition.

Question 2. Define parasitism.

Parasitism is defined as the relationship between the host and the parasite.  Parasites feed on the host, the host gets nothing in return.

Question 3. Name the two parasites described in Figure 13.7. 

The two parasites listed in Figure 13.7 are ticks and lice (louse is the singular of ticks).

Question 4. The "Did You Know" discusses moose and ticks.  How many ticks can a single moose be host to? 

The reading indicates that a single moose can be host to over 50 000 ticks.  There is a mistake in the reading about "ghost moose".  Moose can rub off their fur (not their skin as in the reading) because they are so itchy.  Moose fur is very dark, most moose appear black when they have healthy fur.  When they rub all the fur off an area, the white skin underneath is exposed and they appear white and hence are called ghost moose.

Question 5. Define predation.

Predation is defined as the killing and eating of another animal.

Question 6. Name the two predator-prey situations described in Figure 13.7.

Two predator-prey situations described in Figure 13.7 are the Canada lynx-snowshoe hare and the yellow warbler-caterpillar relationships.

Question 7. Interactions of biotic limiting factors are often complex.  How do parasites affect the predator-prey relationship? 

Parasites will weaken the host.  A weakened animal will more easily be killed by a predator since predators prey on the weak, the sick, and the old.  Note that predators will also prey on the very young animals since they are not developed enough to be able to run away.

Question 8. Define competition. 

Competition is defined as the competing for resources such as food, shelter, light, and water among organisms.

Question 9. Does competition only occur between individuals of the same species?

No, competition does not only occur between individuals of the same species.  Individuals from other species may need the same food, certainly will need the same water, possibly the same shelter and light.

 


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