AT AQA Biology apparatus and techniques Questions

Specification route: AT
Question bank: 22 questions
Course stage: AS / Year 12

Sample questions

QUESTION 1 · AT d · LEVEL 3

When viewing a cell under an optical microscope, how do you calibrate an eyepiece graticule?

By using a stage micrometer, which is a special slide with a microscopic scale of known length, to calculate the length of one graticule division at that specific magnification.
By measuring the diameter of the field of view with a clear plastic ruler.
By multiplying the eyepiece lens magnification by the objective lens magnification.
By dividing the real size of a standard cell by the size of the image produced.

Show clue

The graticule is just a meaningless set of lines. You need to look at a microscopic 'ruler' to give those lines physical value.

Show answer and explanation

Answer: By using a stage micrometer, which is a special slide with a microscopic scale of known length, to calculate the length of one graticule division at that specific magnification.

Apparatus and Techniques (AT d). The eyepiece graticule has arbitrary units. It is calibrated by lining it up against a stage micrometer (a slide with an exact known scale, e.g., $0.1\ mm$ divisions) to find the value of one graticule unit.

QUESTION 2 · AT a · LEVEL 3

A student measures $15\ cm^3$ of a solution using a measuring cylinder with increments of $1\ cm^3$. What is the absolute uncertainty of a single reading from this measuring cylinder?

$\pm 0.5\ cm^3$
$\pm 1.0\ cm^3$
$\pm 0.1\ cm^3$
$\pm 15\ cm^3$

Show clue

The uncertainty is typically half of the smallest scale division.

Show answer and explanation

Answer: $\pm 0.5\ cm^3$

PS 3.3 / AT a. For analogue instruments like measuring cylinders or rulers, the absolute uncertainty of a single reading is generally assumed to be half of the smallest division. Since the smallest division is $1\ cm^3$, the uncertainty is $\pm 0.5\ cm^3$.

QUESTION 3 · AT c · LEVEL 2

A student is creating a dilution series. They take $1\ cm^3$ of a $100\%$ stock solution and add it to $9\ cm^3$ of water in Tube 1. They then take $1\ cm^3$ from Tube 1 and add it to $9\ cm^3$ of water in Tube 2. What is the concentration in Tube 2?

$1\%$
$10\%$
$0.1\%$
$20\%$

Show clue

This is a serial dilution. Each step dilutes the previous tube by a factor of 10.

Show answer and explanation

Answer: $1\%$

AT c. Tube 1 is a 1-in-10 dilution, so its concentration is $100 / 10 = 10\%$. Tube 2 is a 1-in-10 dilution of Tube 1, so its concentration is $10 / 10 = 1\%$.

QUESTION 4 · AT e · LEVEL 1

Which of the following is a strict convention when producing a scientific biological drawing from a microscope observation?

Lines must be clear, continuous, and unshaded.
Shading should be used to indicate areas of high density or darker pigmentation.
The drawing must be exactly the same size as the real biological specimen.
Label lines must always cross each other to save space on the page.

Show clue

Biological drawings are meant to clearly record anatomical structures, not to be artistic sketches.

Show answer and explanation

Answer: Lines must be clear, continuous, and unshaded.

AT e. Scientific drawings must use sharp, continuous lines (no sketching). There must be no shading or stippling. Label lines should be drawn with a ruler and must never cross.

QUESTION 5 · AT h · LEVEL 1

When using living organisms (like woodlice or maggots) in experimental procedures, what ethical consideration must be strictly adhered to?

The organisms must be handled carefully to avoid stress or harm, and must be returned safely to their natural habitat immediately after the experiment.
The organisms must be sterilized in an autoclave before use to protect the students.
The organisms must be permanently kept in the laboratory to prevent contamination of the wild gene pool.
There are no ethical considerations for invertebrates; they can be disposed of in standard waste.

Show clue

Biological ethics applies to the treatment of all living subjects.

Show answer and explanation

Answer: The organisms must be handled carefully to avoid stress or harm, and must be returned safely to their natural habitat immediately after the experiment.

AT h: safely and ethically use organisms. Ethical practice dictates minimizing distress to live subjects and returning them unharmed to their natural environment once data collection is complete.

QUESTION 6 · AT d · LEVEL 4

A student calibrates their eyepiece graticule at $x400$ magnification. They find that $40$ eyepiece divisions equal $10$ divisions on the stage micrometer. If one stage division is $0.1\ mm$ ($100\ \mu m$), what is the length of one eyepiece division?

$25\ \mu m$
$2.5\ \mu m$
$40\ \mu m$
$4\ \mu m$

Show clue

$10$ stage divisions = $10 \times 100\ \mu m = 1000\ \mu m$. Divide this total length by the $40$ eyepiece divisions.

Show answer and explanation

Answer: $25\ \mu m$

AT d: Use of a light microscope and a stage micrometer. $10$ stage divisions = $1000\ \mu m$. If $40$ eyepiece divisions (epu) cover this distance, then $1$ epu = $1000 / 40 = 25\ \mu m$.

QUESTION 7 · AT c · LEVEL 3

To create a serial dilution decreasing by a factor of 10 each time, a student starts with $10\ cm^3$ of a $1.0\ mol\ dm^{-3}$ solution. To make the next concentration ($0.1\ mol\ dm^{-3}$) with a total volume of $10\ cm^3$, what must they do?

Transfer $1\ cm^3$ of the $1.0\ mol\ dm^{-3}$ solution into a new tube and add $9\ cm^3$ of distilled water.
Transfer $10\ cm^3$ of the $1.0\ mol\ dm^{-3}$ solution and add $90\ cm^3$ of distilled water.
Transfer $0.1\ cm^3$ of the $1.0\ mol\ dm^{-3}$ solution and add $9.9\ cm^3$ of distilled water.
Add $10\ cm^3$ of distilled water directly to the original tube.

Show clue

You want a 1-in-10 dilution. This means 1 part original solution to 9 parts water.

Show answer and explanation

Answer: Transfer $1\ cm^3$ of the $1.0\ mol\ dm^{-3}$ solution into a new tube and add $9\ cm^3$ of distilled water.

AT c: Use of serial dilutions. To dilute by a factor of $10$ and end up with $10\ cm^3$, take $1$ part stock ($1\ cm^3$) and add $9$ parts diluent ($9\ cm^3$).

QUESTION 8 · AT g · LEVEL 2

A student uses an eyepiece graticule to measure the diameter of a cell. The cell spans $15$ eyepiece units. If the calibration shows that $1$ eyepiece unit equals $4\ \mu m$, what is the real diameter of the cell?

$60\ \mu m$
$3.75\ \mu m$
$0.26\ \mu m$
$600\ \mu m$

Show clue

Simply multiply the number of units by the value of one unit.

Show answer and explanation

Answer: $60\ \mu m$

AT g. Number of eyepiece units $\times$ length of one unit = real size. $15 \times 4\ \mu m = 60\ \mu m$.

Practise this topic

22 questions are available. No sign-in required.

Start 20-question quiz Use all available questions