In order to establish a cause-and-effect relationship between regular exercise and improved cognitive functioning in older adults, a researcher would need to do which of the following?
Survey persons over the age of 55 to determine their activity level and exercise routines, then administer assessments of verbal and spatial cognitive abilities.
Administer cognitive assessments to people living in a retirement community that provides opportunities for an active lifestyle and to people living in a retirement community that does not provide such opportunities.
Randomly assign a group of adults over the age of 55 to either an exercise or an alternative sedentary activity, and administer a cognitive assessment at the beginning of the study and again after three months.
Conduct a case study of a 60-year-old individual who lifts weights competitively.
Administer cognitive assessments to members of a biking club and to a book discussion group for senior citizens.
The Correct Answer is C
A. Survey persons over the age of 55: This is a correlational survey design; it can identify associations between exercise and cognition but cannot establish causation because of possible confounds and lack of experimental control.
B. Compare residents of active vs non-active retirement communities: This is a quasi-experimental / naturalistic comparison; it’s stronger than a simple survey but still vulnerable to selection effects and other confounds (not true random assignment).
C. Randomly assign adults to exercise or sedentary activity and test pre/post: This is a true experimental design (random assignment + control) with pre/post measures, which is the method required to infer cause-and-effect.
D. Case study of a 60-year-old competitive weightlifter: A single case study provides rich detail but has no generalizability and cannot demonstrate causation.
E. Compare a biking club to a book discussion group: This is an observational/comparative design subject to self-selection bias (active people join biking clubs), so it shows association but not causation.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
A. Stepsiblings: Stepsiblings share no biological parentage by definition; genetic similarity depends on any prior biological relation but typically they are not genetically related.
B. Adopted siblings: Adopted siblings usually are not genetically related to each other (unless coincidentally biologically related), so genetic similarity is low/zero.
C. Paternal cousins: Paternal cousins (first cousins) typically share about 12.5% of genes on average.
D. Dizygotic twins: Dizygotic (fraternal) twins share, on average, about 50% of their segregating genes-same as ordinary siblings.
E. Monozygotic twins: monozygotic (identical) twins originate from one zygote and share virtually 100% of their genes, making them the most genetically similar relatives listed.
Correct Answer is D
Explanation
A. A maternal age greater than 35:Advanced maternal age is a risk factor for chromosomal abnormalities (e.g., nondisjunction) but is not itself an external teratogenic agent.
B. A genetic mutation during meiosis:A meiotic error is a genetic cause of birth defects (endogenous), not a teratogen (which is an external environmental agent).
C. Neonatal exposure to the flu:Exposure after birth (neonatal) is not a prenatal teratogen affecting embryonic/fetal development.
D. The mother having chicken pox during pregnancy:maternal infection with varicella during pregnancy can act as a teratogen (congenital varicella syndrome) and cause fetal anomalies - infections are classic teratogens.
E. The mother having an amniocentesis:Amniocentesis is an invasive diagnostic procedure that carries some risk (e.g., miscarriage) but is not classified as a teratogenic agent in the same sense as drugs/infections/radiation.
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