Question

QUESTION 6

1. The ecological model of the relationships that form a network of complex interactions among organisms in a community from producers to decomposers is a(n):

   	A.	trophic pyramid
   	B.	dominance hierarchy
   	C.	ecosystem
   	D.	food web
   	E.	food chain

0.5 points   

QUESTION 7

1. Food webs are more stable than food chains.

   True

   False

0.5 points   

QUESTION 8

1. A keystone species is one that affects community structure in a disproportionate amount in relation to its abundance.

   True

   False

0.5 points   

QUESTION 9

1. In the absence of a keystone predator on the rocky intertidal, Robert Paine found that ____________ were competitively dominant to all other sessile organism.

   	A.	barnacles
   	B.	sea urchins
   	C.	mussels
   	D.	seastars
   	E.	kelp

0.5 points   

QUESTION 10

1. Elephants are not the most common species in African grasslands. The grasslands contain scattered woody plants, but they are kept in check by the uprooting activities of the elephants. Take away the elephants, and the grasslands convert to forests or to shrublands. The newly growing forests support fewer species than the previous grasslands. Elephants can be defined as what type of species in this community?

   	A.	redundant
   	B.	dominant
   	C.	keystone
   	D.	dominant and keystone
   	E.	none of the above

Answer 1

6- Trophic pyramid is basic structure of complex interaction among all living organisms in a community characterised by the manner in which food energy is transferred from one level to another level. The autotrophs are present at the bottom of the pyramid and others are heterotrophs dependent on autotrophs and other heterotrophs.

7- TRUE

food chain- it is a single network of food web starting from producers and ending with top level consumer. it ensures the transfer of food energy from one creature to another.

food web- is a cluster of food chains which are all interconnected

food webs are more stable because food web contains more diversity, food webs are connected to many consumers. for example, one producer is eaten by many consumers which are further eaten by many other consumers. In this way there is not extinction or over population of any one particular species.

8- TRUE

Keystone species have disproportionately huge impact on its natural environment in relation to its abundance.

9- SEASTARS

star fish is an important keystone predator in shallow intertidal marine ecosystem. it lives in the depth of the sea and eats almost everything and controls the ecosystem.

10- KEYSTONE

African elephants are considered to be key stone species as they control and maintain the density and composition of forest

Answer 2

The ecological model of the relationships that form a network of complex interactions among organisms in a community from producers to decomposers is a(n): food web.

Food webs are more stable than food chains. False.

A keystone species is one that affects community structure in a disproportionate amount in relation to its abundance. True.

In the absence of a keystone predator on the rocky intertidal, Robert Paine found that sea urchins were competitively dominant to all other sessile organism. B. Sea urchins.