Answer: (A) The conclusion is valid because the independent and dependent variables in experiment were controlled.
Explanation: There are some basics requirements in order for an experiment to be valid: hypothesis, monitoring, independent and dependent variables and constants.
The rods are photoreceptor cells that respond to the longest wavelengths of light, ranging from approximately 500-700 nm. Rods are responsible for vision at low light levels (scotopic vision).
The cones, on the otehr hand are the other <span>photoreceptors in the human retina that </span>are active at higher light levels (photopic vision).
Antibiotics are usually what can help. Depends what kind of infection you get and how severe it is.
Earth's long-term warming trend can be seen in this visualization of NASA's global temperature record, which shows how the planet's temperatures are changing over time, compared to a baseline average from 1951 to 1980. The record is shown as a running five-year average.
A population that has been isolated, especially a smaller one, could have a high level of homozygosity and therefore not a lot of genetic variation. Gene flow between such populations can increase the level of heterozygosity, and therefore up genetic variation.