Weak acids such as carbonic or sulfuric acid react with rocks in the ground, such as limestone. Groundwater reacts with limestone and the dissolving of limestone takes place which forms karst features, such as caverns.
I think the answer is photosystem
A control group is sort of the normal group. The group you aren't changing or messing with. It is to show what the species/experiment acts like on its own in response to something without you having to change it at all.
With an experimental group, you are changing something about the subject before putting it in the conditions it will need to respond to.
I don't entirely understand, but I know the control group is constant, unchanging. It sort of helps with distinguishing things. I have examples of experiments if that will help you understand what a control group is to answer the question. I also have a The Death Cure example if you have seen or read the book. I hope you do not fail this assignment, but even if I did not answer with an answer you were looking for, it could have helped you answer the question on your own.
I saw somewhere a similar question, though I was given the answer choices. If this is the answer you are looking for: variable(s).
Control groups don't use variables because you aren't changing them.
In the ear, the sound waves enter through the auditory canal and hit the eardrum (tympanic membrane). The eardrum amplifies the sound and the waves move on to the middle ear, where three bones called the ossicles (malleus, incus, and stapes) amplify the sound further and vibrate. Then, the sound waves go to the cochlea where tiny hairs and other receptors turn the sound waves into a nerve impulse. This impulse is sent to the brain via the auditory nerve and interpreted by the brain.
