# Tutor profile: Allyson K.

## Questions

### Subject: Chemistry

Consider the reaction NO2 + CO ----> NO + CO2 with the rate equation rate = k[NO2]^2. Determine the unit of the rate constant.

The rate constant is the k term in the rate equation (rate = k[A][B}). To determine the unit of k, the overall order of the reaction needs to be known. To find overall order of a reaction, one just sums the exponents on the reactant terms in the equation. For the reaction in the question there is only one exponent, 2. Therefore the overall order of the reaction is 2nd order. The unit of k for a second order reaction is L mol^-1 s^-1. The student needs to memorize the orders and units from a chart.

### Subject: Biology

Describe the different steps of mitosis.

1. Prophase: The chromosomes condense and become visible, spindle fibers emerge from the centrosomes, the nuclear envelope breaks down, and centrosomes move toward opposite poles. 2. Prometaphase: The chromosomes continue to condense, kinetechores appear at the centromeres, mitotic spindle microtubules attach to kintechores. 3. Metaphase: The chromosomes are lined up at the metaphase plate, each sister chromatid is attached to a spindle fiber that begin at opposite poles. 4. Anaphase: The centromeres split in two, the sister chromatids are pulled towards opposite poles of the cells, and some fibers begin to elongate the cell. 5. Telophase: The chromosomes arrive at the opposite poles of the cell and begin to decondense, the nuclear envelope material surrounds each new set of chromosomes, the mitotic spindle breaks down, and spindle fibers continue to elongate cell.

### Subject: Algebra

Solve for x. x^2+5x+6

Set the polynomial equal to 0. Using the concept of roots and expansion, two numbers that add to 5 and multiply to 6. The equation becomes (x+2)(x+3)=0. Then set each of the terms in the () equal to 0 to get x+2=0 and x+3=0. To solve x+2=0, subtract 2 from each side and get x= -2. The same technique is used to solve x+3=0, which gives x= -3. Therefore x = -2, -3.