Biology Laboratory Manual, 6/e

Darrell S. Vodopich, Baylor University
Randy Moore, University of Minnesota--Minneapolis

Exercise 20 - Community Succession

Choose the one answer that best answers the question.


1	What includes all the organisms that live and interact in the same area at the same time?
		A)	community
		B)	population
		C)	genus
		D)	species


2	What is the term for a series of communities that change an environment to allow for the growth of new communities?
		A)	allelopathy
		B)	interspecific competition
		C)	community succession
		D)	intraspecific competiton


3	How is milk treated in order to prevent the growth of pathogenic bacteria?
		A)	heating the milk
		B)	rapidly cooling the milk
		C)	irradiating the milk
		D)	heating the milk and then cooling it rapidly


4	What is the first step in the community succession of bacteria in milk?
		A)	Pseudomonas and Achrombacter digest the butterfat, giving the milk a putrid smell.
		B)	Lactobacillus and Streptococcus ferment lactose to lactic acid and acetic acid.
		C)	Fungi metabolize the acids into non-acidic compounds.
		D)	Bacillus metabolizes proteins into ammonia products.


5	Under what conditions do fungi begin to play a role in milk succession?
		A)	when the pH becomes basic
		B)	when the pH becomes acidic
		C)	when ammonia has been produced
		D)	when the milk has been refrigerated


6	What effect does Lactobacillus have on the community?
		A)	digests butterfat
		B)	ferments lactose to lactic acid and acetic acid, lowering the pH
		C)	metabolizes the acids into non-acidic compounds
		D)	metabolizes proteins into ammonia products, raising the pH

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