What evidence supported the Davson-Danielli model for the cell membrane? A. Electron micrograph pictures showing a blue center surrounded by 2 layers. B. Diffusion models predicted fluid flowing into the cell at a rate consistent with their model. C. Presence of proteins that was unaccounted for. D. Electron micrograph pictures showing 2 separate layers.

The vaccine in a flu shot contains weakened flu viruses. how does a flu shot work with the immune system? a. it destroys lymphocytes. b. it destroys macrophages. c. it activates macrophages. d. it activates lymphocytes.

The cretaceous period spanned the time interval between and 65 million years ago. 250 million 144 million 75 million 200 million

Which of these is true of the cytoplasm of an unfertilized egg? a. it is an unevenly distributed mixture of mrna, proteins, organelles, and other substances. b. it does not contain substances that are important in directing development. c. these substances are supplied by the sperm. d. it does not contain substances that are important in directing development. e. development is directed solely by the surrounding cells. f. it is a homogeneous mixture of mrna, proteins, organelles, and other substances. g. it does not contain substances that are important in directing development. h. these substances are produced by the dna of the fertilized zygote.