The bell shaped curve indicates polygenic traits. A polygenic trait is controlled by multiple alleles. Hope this makes sense :)
The lac repressor prevents the lac genes in the DNA of E. coli from being expressed most of the time. The answer to your question is A. I hope this is the answer that you are looking for and it comes to your help.
The barnacles are only able to attach them selfs to surfaces in the water. Since the surface is limited, barnacles are attaching themselves to the other barnacles, crowding the rock. The muscles were not able to grow or attach themselves off the surface of the rock. Same thing with the mussels that are growing on the rock. So not only barnacles are crowding the rock, but Mussels as well are crowding the rock.
Answer:
c. Spindle fibers
Explanation:
In eukaryotic cells, the centrioles are small sets of microtubules composed of tubulin proteins. Moreover, in animal cells, a centrosome is an organelle localized near the nucleus which contains a pair of centrioles. These organelles (centrosomes) are referred to as microtubule-organizing centers. During Anaphase, centrioles move to opposite sides in the cell in order to organize the spindle fibers and separate the chromosomes during cell division.