Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

[EX Q]: Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme.', "Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to destruction of DHFR-TS enzyme function in an alveolate thereby causing an auxotrophy for thymidine. A second aspect is to knock in an expression cassette encoding for a foreign gene with subsequent expression of the target protein.
[EX A]: Does the bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provide a tool for molecular and biotechnology applications?

[EX Q]: To describe the prevalence of prolonged fatigue, chronic fatigue syndrome (CFS)-like illness, and associated symptom patterns in adolescents attending primary care.', 'The design was cross-sectional. A questionnaire designed by the authors assessing fatigue and associated symptoms was administered to 901 adolescents (aged 11-18 years) attending 12 primary care clinics in the Chicago area. Prevalence rates for prolonged fatigue and CFS-like illness were calculated. Univariate comparisons involving sociodemographic data and fatigue severity were made between adolescents with and without prolonged fatigue, and sociodemographic and symptom predictors of prolonged fatigue were identified using logistic regression analysis.', 'Prolonged fatigue (> or = 1 month) occurred at a rate of 8.0% and CFS-like illness occurred at a rate of 4.4%. Adolescents with prolonged fatigue were significantly older and also reported greater fatigue severity than those without fatigue. Findings from logistic regression indicated that, in addition to increasing age, headaches, muscle pains, fever, and fatigue made worse by exercise were significantly associated with prolonged fatigue.
[EX A]: Does sociodemographic and symptom correlate of fatigue in an adolescent primary care sample?

[EX Q]: Whether higher penile human papillomavirus (HPV) viral load is associated with a lower rate of HPV clearance remains unknown.', 'We examined the association between penile HPV16 and HPV18 viral load and subsequent HPV clearance in uncircumcised Kenyan men.', 'Participants were human immunodeficiency virus (HIV)-seronegative, sexually active, 18- to 24-year-old men randomized to the control arm of a male circumcision trial in Kisumu, Kenya. Men provided exfoliated penile cells from two anatomical sites (glans/coronal sulcus and shaft) every 6 months for 2 years. GP5+/6+ polymerase chain reaction was used to identify 44 HPV-DNA types. Human papillomavirus viral load testing was conducted using a LightCyler real-time polymerase chain reaction assay; viral load was classified as high (>250 copies/scrape) or low (≤250 copies/scrape), for nonquantifiable values. The Kaplan-Meier method and Cox regression modeling were used to examine the association between HPV viral load and HPV clearance.', 'A total of 1097 men, with 291 HPV16 and 131 HPV18 cumulative infections over 24 months were analyzed. Human papillomavirus clearance at 6 months after first HPV detection was lower for high versus low viral load HPV16 infections in the glans (adjusted hazard ratio [aHR], 0.65; 95% confidence interval [CI], 0.46-0.92)] and shaft (aHR, 0.44; 95% CI, 0.16-0.90), and HPV18 infections in the glans (aHR, 0.05; 95% CI, 0.01-0.17).
[EX A]:
Do higher HPV16 and HPV18 Penile Viral Loads Are Associated With Decreased Human Papillomavirus Clearance in Uncircumcised Kenyan Men?