Which of the following best describes an example of a specific immune response to pathogens?
a: cytotoxic t cells are activated and destroy cells that pathogens have invaded.
b: fever increases body temperature and speeds up the body's reaction to pathogens.
c: phagocytes identify cells invaded by pathogens and mark them for destruction.
d: mucus traps pathogens and destroys them before they can enter the body.

The trp operon in e.coli regulates genes that code for enzymes required for synthesis of the repressible operon. when tryptophan is not available amino acid tryptophan. the trp operon is a in the environment, the trp repressor protein activeinactiveregulated. therefore, rna polymerase can bind to the genes to begin transcription.

Zoe decided to measure the hand length of each of her classmates. first she marked a line across each student's wrist and lined up a ruler from this mark to the top of the middle finger to measure the length. then she recorded the measurements in the table below. marla did this the same way for each classmate, and then zoe used this ruler to measure each straight line and record the data below. this data is invalid. what is the most likely reason why it is invalid? the ruler is marked in centimeters, but zoe recorded data in inches. the range of lengths is too wide, so zoe must have misread the ruler. marla’s complicated measuring procedure was overly confusing. marla could have been inconsistent while drawing outlines of fingers.

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it