Which of the following is true of environmental changes?
a. they cannot be caused by human activity.
b. they may affect several populations in an ecosystem.
c. they affect food chains, but not food webs.
d. they have no effect on living organisms in an ecosystem?

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work)

1. environmental factors, such as ph and temperature, can affect the function of an enzyme. a. true b. false 2. which of the following is an organic molecules (ex. vitamins) that an enzyme? a. coenzyme b. product c. active site d. substrate 3. how do enzymes effect the speed of a chemical reaction? a. they speed it up b. they slow it down c. they have no effect on the speed of a reaction 4. during a chemical reaction, an enzyme is used up so that it can only be used one time. a. true b. false 5. which of the following results from a chemical reaction that is catalyzed by an enzymes? a. active site b. product c. substrate d. coenzyme

Many plants can reproduce asexually. which of these is an example of asexual reproduction in a plant? a. pine cones forming on a tree b. cross-pollination in a tomato c. roots sprouting from a potato d. night-blooming jasmine flowers