Answer:
The correct answer is - option A.
Explanation:
Protists are single-celled eukaryotic organisms and usually move by cilia, flagella. Generally, they lack cell walls however, some forms may have a cell wall. They have organelles including a nucleus and may have chloroplasts, so some will be green and others won't be. They also contain the mitochondria for energy purposes.
Thus, laura should place the organism she found in the Protista biological kingdom according to their characteristics.
Answer:
C. The basic effect of the cholera toxin is signal amplification.
Explanation:
Cholera toxin can cause its symptoms by amplifying the signals responsible for intestinal electrolyte transport through the following process:
The toxin binds to a membrane ganglioside (a phospholipid with carbohydrate residues) in the secretory cells in the small intestine. After that, a toxin subunit penetrates the cell, causing permanent activation of a G protein.
G protein activates adenylate cyclase, which catalyzes the formation of cAMP (A type of secondary messenger, important in signal transduction in cells), responsible for activating protein kinases.
Proteins undergo phosphorylation, this process amplifies chloride ions (Cl⁻) secretion.
The flow of negatively charged chloride ions out of the cell causes positively charged sodium ions to follow them in the flow.
Then water follows the electrolytes to the lumen of the small intestine by osmosis, resulting in severe diarrhea.