Biology Concepts and Experimental Techniques

In a scientific experiment, what is the variable that is changed by the experimenter?

• Independent variable

• Dependent variable

• Control variable

• Extraneous variable

What is a method to reduce parallax error when reading a measurement from a ruler or measuring cylinder?

• Taking multiple readings and calculating a mean

• Ensuring your eye is in line with the measurement

• Using a digital measuring device

• Repeating the experiment on different days

When preparing an onion skin sample for microscopy, what is the purpose of adding a drop of iodine?

• To prevent the sample from drying out

• To increase the magnification of the cells

• To stain the cells for better visibility

• To preserve the cells from decay

When starting to view a specimen under a microscope, which objective lens should be used first?

• The highest magnification objective lens

• The lowest magnification objective lens

• Any objective lens can be used first

• The objective lens with the largest field of view

In an osmosis experiment with potato cylinders, what does the point where the line of best fit meets the x-axis on a graph of percentage change in mass vs. sugar concentration represent?

• The maximum water absorption by the potato cells

• The concentration of sugar in the potato cells

• The point where the potato cells burst

• The minimum water loss from the potato cells

In an enzyme experiment involving starch, what color change indicates the continued presence of starch when iodine is added?

• Orange to black/dark purple

• Blue to green

• Yellow to orange

• Clear to cloudy

Which reagent is used to test for the presence of protein in a food sample, and what color change indicates a positive result?

• Iodine solution, turning orange to black

• Benedict's solution, turning blue to brick red

• Biuret's reagent, turning blue to purple

• Cold ethanol, turning clear to cloudy

What is the expected result when testing for lipids (fats) using cold ethanol followed by mixing with water?

• The solution turns black

• The solution turns green

• The solution turns purple

• The solution turns cloudy

What is the independent variable when investigating the relationship between light intensity and the rate of photosynthesis?

• The volume of oxygen produced.

• The number of bubbles released.

• The distance between the plant and the light source.

• The amount of sodium hydrogen carbonate added.

How does light intensity change if the distance from the light source is doubled?

• It doubles.

• It halves.

• It becomes one-quarter.

• It remains the same.