(Question)
Q: What builds up in an artery and reduces blood flow? Choices: - pressure - calcium deposits - surface tension - plaque A:
(Answer)
plaque

(Question)
Q: Which single most factor is responsible for the extinction of hundreds of species of birds? Choices: - diet - animal actions - habitat - human actions A:
(Answer)
human actions

(Question)
Q: What type of proteins bind to foreign substances and attempt destruction? Choices: - membranes - ribosomes - antigens - antibodies A:
(Answer)
antibodies