Which statement about retrospective and prospective toxicity studies is correct? (a) Retrospective studies are not conducted on humans. (b) Prospective studies are only conducted on wild animals. (c) Retrospective studies monitor health effects from future chemical exposures. (d) Prospective studies monitor health effects from future chemical exposures. (e) Prospective studies monitor health effects from past chemical exposures.

A farmer with 2000 meters of fencing wants to enclose a rectangular plot that borders on a straight highway. If the farmer does not fence the side along the highway, what is the largest area that can be enclosed?

Describe how the avian influenza virus is transmitted to humans.

Relate this answer to the avian influenza virus and how it could cause a human pandemic.

The table shows Emma's midyear exam results. The exam results for each subject are normally distributed with the mean $\mu$ and standard deviation $\sigma$ shown in the table.

$$\begin{matrix} \text{Subject} & \text{Emma's score} & {\mu} & {\sigma}\\ \text{English} & \text{48} & \text{40} & \text{4.4}\\ \text{Mandarin} & \text{81} & \text{60} & \text{9}\\ \text{Geography} & \text{84} & \text{55} & \text{18}\\ \text{Biology} & \text{68} & \text{50} & \text{20}\\ \text{Maths} & \text{84} & \text{50} & \text{15}\\ \end{matrix}$$

Arrange Emma's subjects from 'best' to 'worst' in terms of the z-scores.

Choose the best answer. Which statement about dose-response studies is NOT true? (a) Dose-response studies test chemicals across a range of concentrations. (b) Dose-response studies only test for lethal effects. (c) Dose-response studies can last for days or months. (d) LD50 values are divided by 10 to determine safe concentrations for wildlife.

The primary advantage of experimental research over correlational research is that experiments:

a. can determine cause-effect relationships.

b. are easier to conduct than correlational studies.

c. involve more natural behavior than correlational studies.

d. use descriptive statistics rather than inferential statistics.

Choose the best answer. What is NOT true about the two approaches to regulating chemicals? (a) The innocent-until-proven-guilty principle assumes chemicals are safe unless harm can be demonstrated. (b) The precautionary principle is used in the United States. (c) The innocent-until-proven-guilty principle allows rapid approval of chemicals by regulatory agencies but increases the risk that harmful chemicals will be approved. (d) The precautionary principle can cause delays in the use of beneficial chemicals but reduces the risk of harmful chemicals being approved.

Choose the best answer. Which toxins cause birth defects? (a) neurotoxins (b) carcinogens cause (c) teratogens (d) endocrine disruptors

Which statement is true regarding the relationship between health risks and income? (a) A major risk in high-income countries is a lack of food. (b) A major risk in high-income countries is poor sanitation. (c) A major risk in low-income countries is obesity. (d) A major risk in low-income countries is a lack of food. (e) The major risks in high-and low-income countries are similar.

Which statement about toxins is correct? (a) Neurotoxins impair the nervous system. (b) Carcinogens cause birth defects. (c) Teratogens cause cancer. (d) Allergens mimic naturally occurring hormones. (e) Endocrine disruptors cause allergic reactions.

Choose the best answer. Most people die from (a) infectious diseases. (b) respiratory and digestive diseases. (c) cancers. (d) cardiovascular diseases.

Choose the best answer. Which statement about emerging infectious diseases is NOT true? (a) HIV is a virus that most likely came from chimps. (b) Ebola hemorrhagic fever causes a high rate of death. (c) Mad cow disease is spread when cows are fed grain in large feedlots. (d) Bird flu is a virus that jumps from birds to people.

Define in your own words the following terms:

a. Cohort

b. Cohort effect

c. Population-based cohort

d. Exposure-based cohort

e. Comparison groups in cohort studies

f. Prospective cohort study

g. Retrospective cohort study

h. Ambispective cohort study