A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and to lie in the grooves between larger, underlying cells (i. e., spiral cleavage). This embryo may potentially develop into a(n):.
A) turtle.
B) earthworm.
C) sea star.
D) fish.
E) sea urchin.

What re the two main phrases of the cell cycle.

Study this image. which statements best describe the rock shown? check all that apply. the grains of this rock are jagged. this rock has several coarse grains. the grains in this rock are very large. this rock has a non-banded pattern. the color of this rock is determined by its texture.

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area