Evaporation of water thrrough the Stoma
Answer:
D. toxins
Explanation:
<u>Toxins are not microorganisms</u>, in fact they are non-living substances/chemicals which can cause infection in our body. Toxins may be produced by microorganisms but they are themselves not microorganisms. Some of the examples of toxins produced by microorganisms are botulinum toxin A, tetanus toxin A, muscarine etc.
Other options can refer to potentially infectious type of microorganisms. Option A. talks about microbes, among microbes some are pathogenic. Option B. talks about pathogenic, as the name indicates will be infectious for sure.
Option C. talks about nonpathogenic, it may be non pathogenic at a time but later on it can be pathogenic. For example: some vaccines use inactivated microbes which are non pathogenic for generating antibodies in the body but later on in the human body when they get optimum conditions for growth they can turn pathogenic and start infecting our body.
The correct option is
a.True
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.
