8. When a patient receives a vaccine against pneumonia, the patient's immune system produces memory cells. How do memory cells prevent
illness? *
O A) They weaken the pneumonia pathogens
O B) They kill the pneumonia pathogens from the vaccine
C) They produce antibodies quickly the next time pneumonia pathogens invade
OD) They differentiate into B cells that attack the pathogens

The location of the water table is subject to change. select the best answer from the choices provided ot of

Looking at this image, what relationship can be drawn from it? the lower the degree of latitude, the lower the degree of temperature there is no relationship between latitude and temperature the higher the degree of latitude, the higher the degree of temperature the lower the degree of latitude, the higher the degree of temperature

Rease is an enzyme used by plants to break down urea (a nitrogen-containing compound) into carbon dioxide and ammonia. urease urea > > > carbon dioxide and ammonia ammonia is broken down by plants into a nitrogen source plants need to grow. thus, plants could not use urea as a nitrogen source unless it was first converted to ammonia. in soybean plants there are two different kinds of urease, one produced in the seeds and the other produced in the leaves of the plant. three types of soybean plants were used in a set of experiments: normal soybeans and two mutant strains, one lacking the urease in the seeds only (strain 1) and one lacking urease in the leaves only (strain 2). experiment 1 separate areas in a field were planted with normal, strain 1, and strain 2 soybeans. all types of soybeans appeared to grow, flower, and produce seeds equally well. there were no externally detectable differences among the strains. experiment 2 small pieces of plant leaves of equal weight were obtained from each type of soybean plant and separately placed on media in culture dishes. tissue growing in this way will become an unorganized clump of cells referred to as callus. to provide a controlled nitrogen source, half the tissue samples of each type were placed on media containing urea, and the other half of the samples were placed on media containing ammonia. after 30 days, the weight gain for each of the callus samples was determined. results are shown in the table below.