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.
Examples: A scientist is testing the effect of light and dark on the behavior of moths by turning a light on and off. The independent variable is the amount of light and the moth's reaction is the dependent variable. A change in the independent variable (amount of light) directly causes a change in the dependent variable (moth behavior).