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 difference between light dependent and light independent reactions affect on plants is that during light dependent it needs light to react unlike light independent, it doesn't. Light dependent reactions happen by producing ATP and NADPH from all the energy that comes from the light.