Answer:
Nucleus
Explanation:
It is enclosed by a nuclear membrane perforated by numerous pores. It regulates the activities of the rest of the cell. It contains chromosomes which carry the hereditary materials. One or more densely staining bodies called nucleoli is present in the nucleus. It is site for synthesis of ribosomes
Answer:
A. Glucose:
As lactose is absent will follow the glucose metabolism, so the lac repressor will hold tightly with the operator which leads to the prevention of transcription as RNA polymerase can not bind to promoter so no lactose metabolism.
B. lactose:
In the case or wild mutant lactose metabolism will occur as lactose is present, allolactose binds to the lac repressor thus the operator and promoter are free so transcription starts. The same result will be in all test except in the case of a mutant repressor.
C. glucose and lactose:
In this case, diauxic growth will occur. This growth takes place when two sugars are present in the media. The preferred sugar will be consumed first That is glucose. Then a lag phase will come which will be followed by the second sugar metabolism that is lactose. the given two cases :
Lactose will be metabolized first, as operator site mutation prevents repressor protein binding and thus will lead to the constitutive synthesis of lac operon in test B.
The same thing will happen, as in this case also, constitutive synthesis of lac operon will happen in test C.
Cultures grown in the presence of both glucose and lactose are metabolizing lactose. In the test (b) and (c) will be responsible due to constitutive synthesis of lac operon will happen.
Natural changed to the ecosystem relate to environmental shock that occur naturally. Natural changes include floods, volcanic activity, hurricanes, etc. They can be destructive, but they also have advantages. Floods have the contribution of nutrients to the soil which was lacking. It can also relocate fishes and organisms living in bodies of water which improves the ecosystem.
Answer:sponge
Explanation:
Collar cells have a sticky funnel-shaped collar and a hair-like whip that is called the flagellum. A cell called an amebocyte takes the food picked up by a collar cell to other cells within the sponge. Collar cells are also called choanocytes
