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TLS Online TPP Program

#Question id: 15524

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

#Unit 4. Cell Communication and Cell Signaling
  1. Their receptors specifically recognize self-MHC molecules with intermediate affinity
  2. Their receptors specifically recognize self-MHC molecules
  3. These cells receive survival signals through their TCRs, and die by a process known as death by neglect.
  4. Their receptors do not specifically recognize self-MHC molecules
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TLS Online TPP Program

#Question id: 26950

#Unit 10. Ecological Principles

A population is growing logistically with a growth rate (r) of 0.16/month, in an environment with a carrying capacity of 200. What is the maximum growth rate (no. of individuals/ month) that this population can achieve? 
TLS Online TPP Program

#Question id: 10239

#Unit 10. Ecological Principles

Two species of barnacle, balanus balanoides and Chthamalus stellatus, occur in the intertidal regions of Scotland. As following

 Which of the following statements is correct?
TLS Online TPP Program

#Question id: 1234

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations would likely have a similar cancer-promoting effect as the RasD mutation?

a. mutation in Grb2 so that it cannot bind Sos

b. mutation in Sos so that it binds Ras independent of Grb2

c. mutation in GAP so that it cannot bind Ras

d. mutation in EGF receptor so that it binds GRB2 independent of EGF
TLS Online TPP Program

#Question id: 15673

#Unit 2. Cellular Organization

A urine sample with more than 100,000 organisms is considered indicative of infection. A urine sample containing 5,000 bacteria, with a generation time of 30 minutes, sits for 3 hours before finally being assayed. How many bacteria will then be present within the sample?
TLS Online TPP Program

#Question id: 15741

#Unit 5. Developmental Biology

The region of the Y chromosome have a male-specific DNA sequence that encodes a peptide of 223 amino acids. This gene is called: