1.1.4 Using Units

Question 1

How to use appropriate units?

Answer 1

It essential that the correct scientific measurements are used when discussing biological experiments
Ensure that the correct symbols are used in conjunction with the unit of measurement
E.g. m3 for cubic metres
cm3 is the same as millilitre (ml)
dm3 is the same as litre (l)
Look at table on SME page

Question 2

How to use significant figures?

Answer 2

Significant figures must be used when dealing with quantitative data
Significant figures are the digits in a number that are reliable and absolutely necessary to indicate the quantity of that number
There are some important rules to remember for significant figures
All non-zero digits are significant
Zeros between non-zero digits are significant
4107 (4.s.f.)
29.009 (5.s.f)
Zeros that come before all non-zero digits are not significant
0.00079 (2.s.f.)
0.48 (2.s.f.)
Zeros after non-zero digits within a number without decimals are not significant
57,000 (2.s.f)
640 (2.s.f)
Zeros after non-zero digits within a number with decimals are significant
689.0023 (7.s.f)
When rounding to a certain number of significant figures:
Identify the significant figures within the number using the rules above
Count from the first significant figure to the specified number
Use the next number as the ‘rounder decider’
If the decider is 5 or greater, increase the previous value by 1