A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method.
-The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration):

Which of the following would be his most logical assumption?
A) The substance has moved quickly from region 5 to region 1.
B) Some other material in the embryo is causing accumulation in region 1 due to differential binding.
C) The cytosol is in constant movement, dispersing the polypeptide.
D) The substance is produced in region 1 and diffuses toward region 5.
E) The substance must have entered the embryo from the environment near region 1.

Question

A researcher has arrived at a method to prevent gene expression from Drosophila embryonic genes. The following questions assume that he is using this method.
-The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration):

Which of the following would be his most logical assumption?
A) The substance has moved quickly from region 5 to region 1. 
B) Some other material in the embryo is causing accumulation in region 1 due to differential binding. 
C) The cytosol is in constant movement, dispersing the polypeptide. 
D) The substance is produced in region 1 and diffuses toward region 5. 
E) The substance must have entered the embryo from the environment near region 1.

Quizplus · Accepted Answer

The concentration gradient suggests that the substance is being produced in region 1 and diffusing toward region 5. This is a common pattern in many developmental processes, as different regions of an embryo produce and secrete different signaling molecules that guide the differentiation and patterning of adjacent tissues.

A Researcher Has Arrived at a Method to Prevent Gene