How do water bears obtain their oxygen (substance + process)?
Through water via gas exchange.
Why do water bears enter their dormant (shrivelled state)?
There is not enough water - therefore they become ‘dry’ and ‘shrivelled’ to keep as much water as possible.
What type of communities live in the hot springs?
Extremophile communities (e.g. sulphur bacteria, algae, protoza) WHICH ARE ALL ONE CELLED ORGANISMS.
What level of resolving power does the human eye have?
It has a limited resolving power - which is why we rely on microscopes to see smaller details.
What 2 things are needed to be done to increase magnification?
- Place most promising region in central area under lens.
- Change the objective lens to a higher magnification (usually, for school microscopes, the choices are x40, x100, or x400).
What 4 things are needed to be done to look after your microscope?
(F, S, T, S)
Focus, Slide, Touch (none!), Support
Focus: specimen + lens move AWAY not CLOSER when you want to focus.
Slide: Both bottom and upper layer of slide must be clean and dry before on stage.
Touch: DO NOT touch the lenses w/ anything.
Support: Support microscope by putting one hand under.
How do you focus the microscope?
Put most promising region of slide directly under the lens. Use the lowest powered objective lens first. Focus w/ larger, coarse knob first (forming rough image) before using the fine focusing knob (for clearer image).
How to make a temporary slide?
- Place one cell thick layer onto slide.
- Add a drop of water/stain (helps to see specimen).
- Place cover slip over top - try to avoid bubbles.
- Remove excess liquid - place slide into folded paper - then gently press down.
What is a temporary slide and how does it differ from a permanent one?
Temporary slide is one you make yourself - it doesn’t last forever (unlike a permanent one).
Permanent slides are also much harder to make - require thinner layer of cells.
Name all problems with focusing, their cause, and if they can be counteracted.
- Nothing visible
- ensure specimen is visible - use low powered objective lens first and position most promising area of flide under centre of lens. - Circle w/ black rim visible:
- A bubble has formed (often found in temporary slides). Improve application of cover slip to reduce # of bubbles. - Blurred image, even if focused:
- Lens/ slide is dirty. Clean it. - Dark image:
- Not enough light is coming through - Adjust diaphragm to increase amount of light entering. - Bleached image:
- Too much light - adjust diaphragm to reduce amount of light.
Prepping different types of cells for microscope:
- Moss leaves
- Lower epidermis of leaf
- Banana
- Human cheek
- Liver cells
- WBC
Moss leaves:
- choose variety with very thin leaves.
- remove one leaf and place on slide.
- Mount w/ water or methylene blue stain.
Leaf lower epidermis:
- peel off lower epidermis.
- Mount in water/ methylene blue.
Banana:
- Scrape SOFT TISSUE and mount in IODINE solution.
Human cheek cells.
- Use cotton bud to scrape cells off of cheek.
- Smear on slide and stain with methylene blue.
Liver cells.
- Scrape layer of cells off a fresh (NOT frozen) liver. Smear on slide and add methylene blue.
WBC:
- Smear thin layer of blood and add Leichman’s stain (which only shows the WBCs within blood).
What does an artefact refer to?
Something that was introduced in the preparation of the slide - it was not originally there e.g. bubbles.
Name 2 ways you can record the observations from the microscope.
- Take photo using phone
- Draw typical cell.
What are the main points to remember when drawing a cell?
Do not overshade - only lightly.
Draw cell membrane - even though not visible can guess.
Draw everything to scale - and include magnification
If labelling items - use ruler and write name/description of item outside of drawing.
Why are photos so helpful?
They show real data - drawings however are based on a scientist’s interpretation of what he sees.
What is the function of objective lenses?
Objective lenses - allow you to see different levels of magnification
What is an eyepiece graticule?
An eyepiece graticule is a callibrated scale in the eyepiece. Different objective lens = different scale. Lower objective power = bigger magnification.
What are the typical magnifications for different objective lenses in a microscope?
40x (low), 100x (medium), 400x (high).
What is a photo of a microscope called?
A micrograph (aka a photomicrograph).
What is an electron micrograph?
A photo taken with an electron micrograph.
What is resolution defined as?
The ability to distinguish between 2 points.
What is the equation for magnification?
Magnification = Image size / actual size. (also remember as AIM)
THE UNITS MUST BE THE SAME FOR I AND A!!!
What is a scale bar
A line labelled with the actual size - e.g. a=may be put next to a cell to show 10 micrometres.
Longer wavelength = lower resolution - which type of microscope does this apply to?
Light microscopes - they have longer wavelengths and thus a lower resolution
Mnemonic - remember, they all start with L.
