Threshold characteristics display only two possible phenotypes—the trait is either present or absent.

TLS Online TPP Program

#Id: 9921

#Unit 4. Cell Communication and Cell Signaling

Cell-Mediated Immunity against Virus

Both CD8+ TC cells and CD4+ TH1 cells are required components of the cell-mediated antiviral defense.

Activated TH1 cells produce IL-2, IFN-ϒ, and tumor necrosis factor-α.

TLS Online TPP Program

#Id: 7343

#Unit 11. Evolution and Behavior

TLS Online TPP Program

#Id: 3236

#Unit 3. Fundamental Processes

transitions, which are pyrimidine-to-pyrimidine and purine-to-purine substitutions, such as T to C and A to G;

TLS Online TPP Program

#Id: 2182

#Unit 11. Evolution and Behavior

Change in environmental condition is not necessary for natural selection.

TLS Online TPP Program

#Id: 7329

#Unit 11. Evolution and Behavior

Genetic Disorder

An autosomal recessive condition affects 1 newborn in 10,000 in a random mating population without any  disruptive acting force. What is the approximate expected frequency of carriers in this population?

1 in 1000 newborns

1 in 500 newborns

1 in 100 newborns

1 in 50 newborns