Practice Questions

  1. Home
  2. Free Resources
  3. Practice Questions
  4. 56492
TLS Online TPP Program

#Question id: 5804

The gene that is mutated in cases of cystic fibrosis encodes an ion transporter protein normally expressed in the respiratory and digestive tracts along with other locations. Individuals homozygous for the most common mutation in this gene (ΔF508) died at very early ages prior to the advent of advanced medical intervention. Despite this, the mutation exists at relatively high frequency in populations of European descent. One potential explanation is that heterozygotes for such mutations may be relatively immune to the lethal effects of diseases such as typhoid fever. Which statement below is most accurate?

#Unit 8. Inheritance Biology

  1. The ΔF508 cystic fibrosis mutation is a beneficial mutation.

  2. The ΔF508 cystic fibrosis mutation is a lethal mutation.

  3. The ΔF508 cystic fibrosis mutation is a conditional mutation.

  4. The ΔF508 cystic fibrosis mutation is a neutral mutation

More Questions
TLS Online TPP Program

#Question id: 15526

#Unit 4. Cell Communication and Cell Signaling

If a thymocyte randomly generated a TCR with an affinity for MHC Class I, the TCR and CD8 would bind MHC Class I together, and generate a signal that specifically initiated a program that is 
a) silenced CD8 expression
b) silenced CD4 expression
c) induced expression of genes specific for helper T-cell lineage function
d) induced expression of genes specific for cytotoxic T-cell lineage function
TLS Online TPP Program

#Question id: 15525

#Unit 4. Cell Communication and Cell Signaling

In the instructive model, TCR/CD4 and TCR/CD8 coengagement generates unique signals, if a thymocyte randomly generated a TCR with an affinity for MHC Class I. which thymocyte would bind with MHC class I?
TLS Online TPP Program

#Question id: 15524

#Unit 4. Cell Communication and Cell Signaling

The bulk of DP thymocyte death (~95%) occurs among thymocytes that fail positive selection because 
TLS Online TPP Program

#Question id: 15523

#Unit 4. Cell Communication and Cell Signaling

The appearance of ϒδ thymocytes and αβ thymocytes during mouse fetal development. Fetal animals generate
a) more αβ T-cells than ϒδ T-cells
b) the proportion of ϒδ T-cells generated drops off dramatically after birth
c) the proportion of αβ T-cells generated drops off dramatically after birth
d) more ϒδ T-cells than αβ T cells
TLS Online TPP Program

#Question id: 15522

#Unit 4. Cell Communication and Cell Signaling

Double negative selection do not apply on which type of T-cells?
TLS Online TPP Program

#Question id: 15521

#Unit 4. Cell Communication and Cell Signaling

Rearrangement of the β, γ, and δ loci begins during the