TLS Online TPP Program

#Question id: 3830


Why is DNA damage in skin cells from exposure to excessive UV light not completely reversed by photoreactivation?

#Unit 3. Fundamental Processes
  1. DNA photolyase in humans is activated only under conditions of heat shock.

  2. Humans lack a photoreactivation repair mechanism.

  3. The presence of histones greatly slows photoreactivation, thus humans depend primarily on other forms of DNA repair.

  4. Photoreactivation is specific for the removal of thymine dimers. Thymine dimers do not form in human DNA.

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TLS Online TPP Program

#Question id: 4516

#Unit 3. Fundamental Processes

High mobility group (HMG) proteins

A. are a common type of architectural regulator

B. facilitating the looping of the DNA

C. the binding is relatively very specific

D. are abundant in chromatin and bind to DNA with limited specificity.

TLS Online TPP Program

#Question id: 24585

#Unit 3. Fundamental Processes

The eukaryotic MutS/L system is particularly important for repairing errors caused by

TLS Online TPP Program

#Question id: 8892

#Unit 9. Diversity of Life Forms

Which of the following correctly characterizes the phylum Rotifera?

TLS Online TPP Program

#Question id: 3583

#Unit 8. Inheritance Biology

In sesame plants, the one-pod condition (P) is dominant to the three-pod condition (p), and normal leaf (L) is dominant to wrinkled leaf (l). Pod type and leaf type are inherited independently. Determine the genotypes for the two parents for all possible cross producing the following offspring:

(a) 300 one-pod, normal leaf and 100 one-pod, wrinkled leaf

(b) 323 three-pod, normal leaf and 106 three-pod, wrinkled leaf

(c) 150 one-pod, normal leaf, 147 one-pod, wrinkled leaf, 51 three-pod, normal leaf, and 48 three-pod, wrinkled leaf

(d) 223 one-pod, normal leaf, 72 one-pod, wrinkled leaf, 76 three-pod, normal leaf, and 27 three-pod, wrinkled leaf

TLS Online TPP Program

#Question id: 17995

#Unit 8. Inheritance Biology

Consider a heritable autosomal disease with an incidence in the population of 1 per thousand. On average, individuals with the disease have 80% as many children as the population average. In answering the various parts of this question, assume that mating is random. What mutation rate would be required to maintain the observed incidence of the disease in the population if the disease is recessive?