The level of total cholesterol and HDL cholesterol relative to LDL cholesterol in the blood can be useful in determining the health of the arteries and the risk of developing heart disease. The optimal level of blood lipids includes a lower total cholesterol and LDL cholesterol to reduce the amount of lipids that infiltrate the arterial wall, which ultimately results in plaque buildup.
1. Consuming excess saturated fat, trans fat, and dietary cholesterol can result in increased levels of LDL cholesterol. Read the statements below and select the correct statements regarding the role of cholesterol in health and disease.
Select all that apply.
a. Cholesterol is a component of bile.
b. Cholesterol is a precursor for the formation of vitamin A.
c. Cholesterol is a key component of cell membranes.
d. Cholesterol must be obtained from the diet.

Secondary succession would most likely be taking place in a(n)

White-tailed deer are considered to be an overpopulated species in the central united states. which of these events probably contributed the most to white-tailed deer exceeding their carrying capacity?

Experiments in environmental toxicology can sometimes be manipulative experiments in which the researcher actively chooses and manipulates the independent variable. in hunt's study, for example, dosages of bpa were manipulated and the effects were measured. in manipulative studies, the researcher controls all the other variables in the experiment, so any health effects observed in the test subjects can be attributed to differences in the independent variable. in other cases, researchers use natural experiments in which the dependent variable (typically a measure of organism health) is measured under differing contexts that are not manipulated. say, for example, that an accidental chemical spill contaminates five ponds. to determine the possible effects of the toxic chemical on frogs, a researcher could compare the hatching rate of frog eggs laid in those five ponds to the hatching rate of eggs laid in five uncontaminated ponds nearby. this would be an example of a natural experiment because concentrations of the toxic chemical in the ponds were not controlled by the experimenter, but rather resulted from the chemical spill. drag type of experiment on the left to the example of experiment on the right. blood concentrations of bpa in college students are compared to their recent manipulative consumption of canned food items 2. the feeding behavior of fish in streams that receive acidic runoff from strip mines is compared to the feeding behavior of fish in unaffected streams. the deformity rate in baby birds from nests in pesticide-sprayed fields is compared to the deformity rate in birds from nests in unsprayed fields 4 tumor development is compared in mice exposed to five dosages of a known carcinogen in the laboratory foraging activity levels are compared in tadpoles exposed to four concentrations of toxic metals in the laboratory. growth of corn plants is compared in field plots sprayed with three different dosage: s of weed killer 7 bpa concentrations in the urine of people with diabetes are compared to bpa concentrations in the urine of people without diabetes - natural; manipulative