<span>Phagocytosis and pincytosis </span>
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.
Fossils are physical evidence of preexisting organisms, either plant or animal. ... Fossils of any kind are useful in "reading the rock record," meaning they help us decipher the history of the earth. They can help us determine the geologic age and environment (the paleoenvironment) in which they were deposited.
1. Turn the water off when washing the dishes.
2. Turn the sink off when brushing your teeth instead of letting it run
3. Take a 2-5 minute shower (no longer)
4. Do not leave the water running when you use water
5. Do not fill up a cup of water that you will not drink, pour it in plants or put it in the fridge to stay cold
Photosynthesising primary producers require sunlight. Therefore, in the ocean, phytoplankton would be concentrated within the surface layers of the ocean where the sunlight penetrates. Phytoplankton support a wide range of marine life: zooplankton feed on phytoplankton, which in turn support fish and so on.
