<u>Answer:</u>
Geologists have sorted earth’s history into different geologic time scale. They just clubbed it into time scales by observing the major changes in the life forms that existed on the earth. Inferring to the fossils found in rocks the time scale was calculated.
First era single cell animals were formed then formed the complex animals.Then Mesozoic era where it is known as the era of dinosaurs. Then the evolution of different species of life during Cenozoic era. These major changes found through fossils helped them to form the GTS.
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.
The correct answers are:
B. Warmer air promotes more evaporation.
D. Humidity refers to the amount of water vapor in the air.
E. Areas with a lot of surface water have higher humidity than drier areas.
The humidity can simply be described as the amount of water vapor in the air. The humidity can vary, and it can be very high in certain place for the whole year, very low at other places for the whole year, or to be changing seasonally.
The areas that have a lot of surface water (the Amazon River Basin) tend to have higher humidity than the places that lack surface water (Sahara Desert). Also, the humidity depends a lot on the temperature of the air. The warmer the air is, the higher the humidity, and vice versa, the colder the air is, the lower the humidity.
