eyeball. 1  Photoreceptors are the cells in the retina that respond to light. Their distinguishing feature is the presence of large amounts of tightly packed membrane that contains the photopigment rhodopsin or a related molecule.
In chemical analysis,  matrix refers to the components of a sample other than the analyte of interest. The matrix can have a considerable effect on the way the analysis is conducted and the quality of the results obtained; such effects are called matrix effects. For example, the ionic strength of the solution can have an effect on the activity coefficients of the analytes.
Definitions A sample is the group of people who take part in the investigation. The people who take part are referred to as âparticipantsâ. Sampling is the process of selecting participants from the population. The target population is the total group of individuals from which the sample might be drawn. Generalisability refers to the extent to which we can apply the findings of our research to the target population we are interested in.