Practical Techniques Flashcards
How to see xylem?
Put leaf stalk/petiole in dye/stain and then cut transversely
How to see fish and insects better?
Removal of operculum
Cut open exoskeleton
OBSERVE fish by placing a rod into buccal cavity to see lamellae
Stain tracheoles with methylene blue (insects)
Biological drawing
Title
Label lines not crossing over
Continuous lines
No shading
Plane paper - at least 50% of space
Line transect advantages
Enables spearman’s rank to be used to measure correlation - unbiased as only those plants touching the line are sampled
Easily repeatable
Stratified sampling advantage
More representative of sub-regions
Line transect disadvantage
Only plants touching the line should be sampled which may lead to gaps in the data
Strategy for choosing a plant nearest sampling point may lead to bias
Stratified sampling disadvantage
Time consuming
Requires accurate estimation of sub-region
Target species may be absent in randomly selected area
Limitations of line transect
Needs a gradient
Transect usually runs in one direction but needs many directions to cover a field
Some species are more easily counted - others are covered by grass
Wrong identification
With sampling experiments always…
Identification keys
Experiment should be carried out at different times - different seasons - different days
Method of ensuring individuals are not counted again
Example of sampling technique
SD
Small SD = little variation in repeats and high repeatability
Error bars overlap
Difference in the data may be uncertain
Ada vantage of using liver for enzyme
More enzyme per gram and easier to blend for high SA
Advantages of using celery for enzyme
Cheaper - slower activity = more results
Disadvantage if using liver for enzyme
Religious objections from animal source/messy to prepare
Disadvantages of using celery
May be out of season or different parts of the plant have different activity levels
More accurate experiment instruments
Graduated/tear pipette
Volumetric pipette
1/2 cm^3 syringe
Transpiration bubble
Stem cut under water
Apparatus under water
Joints sealed
No air to block xylem for continuous stream
What should you use for rate of transpiration of potometer
Use syringe to move bubble - not too far
Air bubble should not enter xylem
To ensure validity/transpiration accurately
Purpose of calibrating a colorimeter
All values ar measured to the same standard - comparable ; reduces systematic error
Precision
Closeness of agreement between measured values obtained by repeated measurements
5 kingdom vs 3 domain system
Kingdom - eukaryotic group is divided but mainly based on physical characteristics
Domain - three divisions, prokaryotic divided into archae and bacteria ; based on molecular/physiological/embryological/behavioural characteristics
Evolution definition
Change in characteristics of an organism over time
