A student set up an experiment to show that carbon dioxide is consumed by Elodea plants during photosynthesis. She filled two test tubes with distilled water and placed a piece of Elodea in each of the tubes. She added a drop of phenol red, which turns red in a basic solution and yellow in an acidic solution. She blew in each tube to add carbon dioxide, which caused the distilled water to become more acidic so the phenol red turned yellow. She wrapped Tube A in aluminum foil and left Tube B exposed to the light. After 15 minutes, what should she expect to observe? rev: 05_30_2020_QC_CS-214531

Multiple Choice

Both tubes will have turned red.

Tube A will be yellow and Tube B will be red.

Both tubes will remain yellow.

Tube A will be red and Tube B will be yellow.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!