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TLS Online TPP Program

#Question id: 1986

The following events occur when a mammalian immune system first encounters a pathogen. Which shows the correct sequence in which they occur?

I.   Pathogen is destroyed.

II.  Lymphocytes secrete antibodies.

III. Antigenic determinants from pathogen bind to antigen receptors on lymphocytes.

 IV.  Lymphocytes specific to antigenic determinants from pathogen become numerous.

V.   Only memory cells remain.

#Unit 4. Cell Communication and Cell Signaling

  1. I → III → II → IV → V

  2. III → IV → II → I → V

  3. II → I → IV → III → V

  4. IV → II → III → I → V

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TLS Online TPP Program

#Question id: 218

#Unit 1. Molecules and their Interaction Relevant to Biology

We use the term tetrahydrofolate to designate a family of related compounds. What is the main difference between members of this family?
TLS Online TPP Program

#Question id: 4942

#Unit 11. Evolution and Behavior

Which of the following has not yet been synthesized in laboratory experiments studying the origin of life?
TLS Online TPP Program

#Question id: 3382

#Unit 11. Evolution and Behavior

Researchers in the Netherlands studied the effects of parental care giving in European kestrels over 5 years. The researchers transferred chicks among nests to produce reduced broods (three or four chicks), normal broods (five or six), and enlarged broods (seven or eight). They then measured the percentage of male and female parent birds that survived the following winter. (Both males and females provide care for chicks.) Which of the following is a conclusion that can be drawn from this graph?
TLS Online TPP Program

#Question id: 13065

#Unit 13. Methods in Biology

Precision will be reduced, but yield will be increased
Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.
Agglutination of antigens by utilising specific antibodies can only occur, if
TLS Online TPP Program

#Question id: 11087

#Unit 7. System Physiology – Animal

Which of the following oxygen-hemoglobin dissociation curves corresponds to normal blood (red line) and blood containing carbon monoxide (green line)?