Answer:
I am pretty sure that the answer is A.
Explanation:
Protein kinases regulate the cell cycle by giving the "go-ahead" or "stop" signal at checkpoints in the cycle. A mutation/disruption in the protein kinases can result in it not doing its job properly. As a result, it can give the 'go-ahead' signal to all cells (mutated or not) to continue through the cell cycle. A distrupted kinase will infleunce the enviornment for a cancer cell as the cancer cell can continue to divide continuously.
I do not think the answer is D because G-couped receptirs are not involed in the regulation of the cell cycle. Additionally, I do not think the answer is C since the production of cAMP (a secondary messgenger amplifies transduction signals; this doesn't have anything to do with cancer?) Finally, between A and B I know that a direct result of cancer is due to a distruption in either protien kinases or growth factors (not in the answer choices). Since one of the factors that leads to cancer is present in answer choice A, I think that is the one. However, this is just my reasoning, I am not 100% sure!
<span>C. population growth begins to slow down</span>
The question is incomplete. Th ecomplete question is as following:
All of the following protect the skin and mucous membranes from infection EXCEPT
A) multiple layers of cells.
B) tears.
C) saliva.
D) HCl.
E) the "ciliary escalator."
Answer: D) HCl.
Explanation:
- The epidermis, the outer layer of the skin provides waterproofing and serves as a barrier to infection and other laers also sustain any type of injury.
- Tears wash out foreign bodies which enter the eye. In addition, tears contain a substance called lysozyme which has an antibacterial function and works to prevent microbial invasion and infection.
- Saliva protects against infection, especially via the innate immune system. This mechanism is an important first-line protection against bacterial and viral infection
- The mucociliar escalator is within the conducting airways and is composed of mucus and cilia that transfer the mucus up and out of the lungs where it can be removed by coughing or swallowing,
Whereas HCL helps in the digestion process.
Hence, the correct option is D.
Depressants often cause slow movements and loss of sense of balance. These chemical substances reduce the speed and ability of neurotransmitters to communicate. Included in this category of substances are opioids, alcohol and marijuana related products. Pharmacological-related substances are sleeping pills and pain relievers, to help aid sleep and relax muscles.
