The infinitive is the base form of the verb, before the verb is conjugated. For example: to speak, to eat, to live are English verbs in the infinitive form; to + verb creates the infinitive of a verb in English. In Spanish the infinitives of verbs have three diferent endings: ar, er and ir.
Light dependent reactions produce ATP and NADPH from energy captured from light. Therefore without light it cannot proceed. Light independent reactions fix carbon dioxide into glucose using the ATP and NADPH produced in the light dependent reactions. So light independent reactions can occur without light as long as CO2, ATP and NADPH is present.
The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the effect on the dependent variable is observed and recorded. For example, a scientist wants to see if the brightness of light has any effect on a moth being attracted to the light. The brightness of the light is controlled by the scientist.