A team of scientists uses radioactive carbon to label glucose molecules. The radioactivity does not affect the chemical or biological properties of the glucose molecules. In an experiment, the team places red blood cells in an isotonic solution. Then they add radioactive glucose to the solution. They observe that levels of radioactivity increase in the interior of the cell, indicating that the cell has taken up the radioactive glucose from the solution. Which observation best supports the conclusion that the glucose entered the red blood cells by means of passive transport? A. Glucose can pass through specific proteins in the cell membrane. B. Glucose can pass through the lipid bilayer of cell membrane. C. The cell expended energy in the form of ATP during the experiment. D. The cell did not expend energy in the form of ATP during the experiment.

Option A => Glucose can pass through specific proteins in the cell membrane.

Explanation:

Ok, we are are given the following information or data from the question above that is;

(1). "red blood cells in an isotonic solution."

(2). "Then they add radioactive glucose to the solution."

(3). "They observe that levels of radioactivity increase in the interior of the cell, indicating that the cell has taken up the radioactive glucose from the solution."

Key observation: glucose is able to pass through the cell membranes because of transporters which are known as transmembrane proteins. Glucose in particular is transported through a uniporterin the red blood cells

good one: produce hormones that plants grow.

bad one: the problem with organic matter is that while plant nutrients are needed for crop growth, they can also stimulate excessive growth of the wrong plants – mainly, algae.