A food wed is about who eat who like for example I think the human are on the top of the food chain because no one eat him
Answer:
C
Explanation:
When two species share a common niche, then one is bound to exclude the other. This is due to the stiff competition for resources. The species with a slight advantage in acquiring the resources will edge out the other species from the environment. This has been demonstrated by George Gauss using two Paramecium species grown in the same media in the lab. <em> P. aurelia</em> outcompetes <em>P. caudatum</em>
Answer:
a. + glucose, + lactose = On
b. - glucose, - lactose = Off
c. + glucose, - lactose = Off
d. - glucose, + lactose = On
Explanation:
Lac operon has both types of control, repressible and inducible.
Whenever glucose level is low in the cell, an enzyme known as adenylyl cyclase raises the level of cAMP which forms a dimer with CRP protein and they both act as activator of lac operon and cause expression.
Apart from this, when lactose is present in the cell, β-galactosidase enzyme metabolizes lactose to form allolactose which causes allosteric repulsion in the lac repressor and causes its removal from the operator. As soon as repressor is removed lac operon gets activated.
In wild type lac operons, the expression of lac operon occurs when glucose level is low in the cell and lactose is present but in this mutant presence or absence of glucose will not make a difference because CRP will bind Plac promoter independent of cAMP level i.e. activator CRP will work even in high glucose concentration. If lactose is present then lac operon will always express so in option 'a & d' lac operon will express but in option 'b & c' it will not express.
Answer: A.They contain plants that purify water.
