A multicellular organism develops from a zygote that undergoes both cell division and differentiation as it grows into an adult what explains the fact that cells are able to differentiate into adult cells with different structures and functions even though they all have the same DNA? A. External and internal cues trigger different genes to turn on and off in different cells
B. The cell nucleus controls the expression of genes based on a pre-determined sequence
C. Chromosomes are keyed to be expressed only in some cells but not in others
D. Cells randomly express different genes during development

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

the "power" of a lens is its resolution power, or its ability to distinguish between to closely located points. with the low power lens, it is likely you will see the rough form of the hay and maybe some movement of dots around the hay. however, when observed with the high power lens, the detailed features of the hay become visible and the microbes being grown are more clearly visible.

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when it is at an intermediate population density