TLS Online TPP Program

#Question id: 760


Which force can stabilize a DNA double-helix?

#Unit 1. Molecules and their Interaction Relevant to Biology
  1. Hydrophobic bases are found in the interior of the helix where each base pair is stabilized by the same number of hydrogen bonds.

  2. Hydrophilic sugar-phosphate groups are found on the exterior of the helix where they can interact with water.

  3. Non-covalent N-glycosidic bonds can form between nitrogenous bases in opposite strands in the helix.

  4. Covalent base-stacking interactions can occur between adjacent bases within the same strand in the helix.

More Questions
TLS Online TPP Program

#Question id: 12086

#Unit 10. Ecological Principles

The herbaceous plant Achillea lanulosa is widespread in the Northern Hemisphere. Phenotypic variation in the species has been extensively studied along an altitudinal gradient from sea level to over 3,000 meters. In California there is conspicuous variation in  height; alpine plants are only several centimeters tall  while  those in  the San Joaquin Valley may reach a height of 1.8 meters. Adaptation to different local environments also results in variation in physiological processes such as photosynthetic rate, resistance to cold, and the timing of dormancy.


The genetic polymorphism found in Achillea lanulosa is most likely maintained primarily by

TLS Online TPP Program

#Question id: 2936

#Unit 2. Cellular Organization

The stable attachment of sister kinetochores to microtubules emanating from opposite spindle poles is called:

TLS Online TPP Program

#Question id: 1092

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements is true of steroid receptors?

TLS Online TPP Program

#Question id: 5450

#Unit 8. Inheritance Biology

Which of these definitions of heritability is most correct?

TLS Online TPP Program

#Question id: 882

#Unit 1. Molecules and their Interaction Relevant to Biology

Choose correct statements about thermophilic proteins

I. The proteins found in thermophilic species are much more stable than their mesophilic counterparts.

II. All thermostable proteins have such a high incidence of salt bridges

III. the most important of which are an increased size of the protein’s hydrophobic core, an increased size of the interface between its domains and/or subunits, and a more tightly packed core as evidenced by a reduced surface-to-volume ratio.

IV. Several of these thermostable enzymes have a superabundance of salt bridges on their surfaces.