Answer:
Hydrogen bonds make water molecules spread out when they freeze. This makes ice less dense than water and allows ice to float. If ice did not float then oceans and lakes would freeze from the bottom up, killing marine life by trapping organisms in the ice. When ice floats, it insulates the water below, keeping it at around 4 degrees C or 40F, which does not freeze and allows fish to survive the winter.
Explanation:
<span>When a testcross between f1 dihybrid flies produces
more offspring with both traits like those of one parent, or the other than
offspring with recombinant-type traits are produced means that the two genes are
link. The reason that linked genes are inherited together is that they are
located on the same chromosome.</span>
Answer;
-Analytical chemistry - composition.
Environmental - impact of chemicals
Explanation;
-Analytical chemistry involves the qualitative and quantitative determination of the chemical components of substances. In qualitative analysis all the atoms and molecules present are identified, with particular attention to trace elements. In quantitative analysis the exact weight of each constituent is obtained as well.
Environmental chemistry is the study of the chemical and biochemical phenomena that occur in the environment.It relies heavily on analytical chemistry and includes atmospheric, aquatic, and soil chemistry.
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.
