getting errors, can't fix them

populateIdWithHTML: function(id, next) {
        var element = document.getElementById(id);
        element.innerHTML = text;

    }

function Questions(, 'How many total presidents have served in the U.S.?', 'What is the Answer to the Ultimate Question of Life, the Universe, and Everything?') {

 this.questions= [];

}

// array of questions
var questions = [
    new Questions("Who was the first President of the United States", ["George Washington", "Thomas Jefferson"], "George Washington"),
    new Questions("What is the answer to the ultimate Question of Life, the Universe, and Everything?", ["Food?", "42"], "42")
    // why did he write the options of the answers and then the answer? isn't that going against keeping your code DRY?
    // why did he type an array and then what looks like a array within an array for the two arrays above?

];


//this intiates the quiz
var quiz = new Quiz(questions);

//this displays the quiz
QuizUI.displayNext();

// constructor function for questions and input from user?
function Questions(text, choices, answer) {

    this.text = text; // why is this here?
    this.choices = choices;
    this.answer = answer;

}

// checks to see if it has the correct answer or the incorrect answer
Questions.prototype.isCorrectAnswer = function(choice) {

    return this.answer === choice;
};

var QuizUI = {

    // I am compleletly lost at this syntax, NEVER seen it before in my life, 
    //is this an array with a function as the key of each value?
    displayNext: function(){
        if (quiz.hasEnded()) {
            this.displayScore();
        } else {
            // this updates all parts of the UI
            this.displayQuestion();
            this.displayChoices();
            this.displayProgress();
        }

    },
    displayQuestion: function(){
        this.populateIdWithHTML("question", quiz.getCurrentQuestion().text);

    },
    displayChoices: function(){
        var choices = quiz.getCurrentQuestion().choices;

        for(var i = 0; i < choices.length; i++){
            this.populateIdWithHTML("choice" + i, choices[i]);
            this.guessHandler("guess" + i, choices[i]);
        }

    },

    displayScore: function(){
        var gameOverHTML = "<h1>Game Over</h1>";
        gameOverHTML += "<h2> Your score is: " + quiz.score + "</h2>";
        this.populateIdWithHTML("quiz", gameOverHTML);
    },

    populateIdWithHTML: function(id, next) {
        var element = document.getElementById(id);
        element.innerHTML = text;

    },

    guessHandler: function(id, guess){
        var button = document.getElementById(id);
        button.onclick = function(){
            quiz.guess(guess);
            QuizUI.displayNext();
        }
    },

    displayProgress: function(){
        var getCurrentQuestion = quiz.currentQuestionIndex + 1;
        this.populateIdWithHTML("progress", "Question" + currentQuestionNumber + " of " + quiz.questions.length);
    }


};

//this keeps track of the totals for correct answers

function Quiz(question){
    this.score =0;
    this.questions = questions;
    this.currentQuestionsIndex = 0;

}


// evalues the answer
Quiz.prototype.guess = function (answer){
    if(this.getCurrentQuestion().isCorrectAnswer(answer)){
        this.score++; // if correct increments the score
    }
    this.currentQuestionsIndex++; /// moves forward by one in the array of questions

};

//this gets current question, but why create a prototype for getting it?
// if this is optional, then why did he create it again?

Quiz.prototype.getCurrentQuestion = function(){
    return this.questions[this.currentQuestionsIndex];

};


//ends the quiz when it reaches the limit of question
Quiz.prototype.hasEnded = function(){

    return this.currentQuestionsIndex >= this.questions.length;
};

quiz_ui.js:38 Uncaught ReferenceError: text is not defined
    at Object.populateIdWithHTML (quiz_ui.js:38)
    at Object.displayQuestion (quiz_ui.js:17)
    at Object.displayNext (quiz_ui.js:10)
    at app.js:15