Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 2859
TLS Online TPP Program

#Question id: 2884

When the temperature of a solution of DNA is raised to near the boiling point of water, the optical density, (called absorbance) at 260 nm markedly increases, a phenomenon known as hyperchromicity. Which of the following statement is INCORRECT from the given set of statements?

#Unit 2. Cellular Organization

  1. The explanation for this increase is that duplex DNA absorbs more ultraviolet light by ~40% than do individual DNA chains.

  2. This hyperchromicity is due to base stacking, which increases the capacity of the bases in duplex DNA to absorb ultraviolet light.

  3. The sharpness of the increase in absorbance at the melting temperature tells us that the denaturation and renaturation of complementary DNA strands is a highly cooperative, zippering-like process.

  4. At high ionic strength, the negative charges are shielded by cations, thereby destabilizing the helix. Conversely, at low ionic strength, the unshielded negative charges render the helix more stable.

More Questions
TLS Online TPP Program

#Question id: 12503

#Unit 8. Inheritance Biology

In this pedigree II 1 is affected with an autosomal recessive disorder. The disease status for II 2 is unknown. A and B represent alleles at a locus which is tightly linked to the disease locus with recombination fraction of 0. Using the linked markers, II2 can be told that:
TLS Online TPP Program

#Question id: 12504

#Unit 8. Inheritance Biology

In this pedigree II 3 and III 1 are affected with an X-linked recessive disorder which is tightly linked to a marker locus with alleles A and B, with a recombination fraction of 0 between the disease and marker loci. Analysis of the linked marker results indicates that the disease must be segregating with:
TLS Online TPP Program

#Question id: 12505

#Unit 8. Inheritance Biology

The marker genotype for I 2 must have been:
TLS Online TPP Program

#Question id: 12506

#Unit 8. Inheritance Biology

Using the linked markers III 3 can be told that:
TLS Online TPP Program

#Question id: 12507

#Unit 8. Inheritance Biology

In this pedigree I 1 and II 2 have Becker muscular dystrophy which shows X-linked recessive inheritance. III 2 has oculocutaneous albinism which shows autosomal recessive inheritance with an incidence in the general population of 1 in 10 000. The disease status for both Becker muscular dystrophy and oculocutaneous albinism is unknown for IV 1 and IV 2.
What is the probability that III 3 is a carrier of Becker muscular dystrophy?
TLS Online TPP Program

#Question id: 12508

#Unit 8. Inheritance Biology

In this pedigree I 1 and II 2 have Becker muscular dystrophy which shows X-linked recessive inheritance. III 2 has oculocutaneous albinism which shows autosomal recessive inheritance with an incidence in the general population of 1 in 10 000. The disease status for both Becker muscular dystrophy and oculocutaneous albinism is unknown for IV 1 and IV 2.
What is the probability that III 3 is a carrier of oculocutaneous albinism?