Nitrogen and phosphorus are important limiting nutrients in some aquatic ecosystems and are determining factors in the amount of phytoplankton growth. when there is a large input of nitrogen and phosphorus the growth of phytoplankton and algae drastically increases, resulting in a large accumulation called an algal bloom and this in turn causes aphotic zones in aquatic ecosystems. in aphotic zones, photosynthetic organisms cannot survive. we would expect this to happen most often in what ecosystem(s)?
a) ocean
b) lake and pond
c) ocean and river
d) river and stream

Aresearcher has developed two stains for use with seed plants. one stains sporophyte tissue blue; the other stains gametophyte tissue red. if the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur? a) the pollen grains will be pure red.b) the pollen grains will be pure blue.c) the pollen grains will have red interiors and blue exteriors.d) the pollen grains will have blue interiors and red exteriors.

Match the types of competition to their descriptions

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 8 options: the cold balloon expands and rises. the warm balloon shrinks and sinks. the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the warm balloon expands and rises. the cold balloon shrinks and sinks.