biology

McIntosh and Fildes' anaerobic jar

McIntosh and Fildes' anaerobic jar is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand McIntosh and Fildes' anaerobic jar rather than just read about it. In short: McIntosh and Fildes' anaerobic jar is an instrument used in the production of an anaerobic environment. This method of anaerobiosis as others is used to culture bacteria and other germs (e.g., Trichomonas vaginalis) which die or fail to grow in presence of oxygen (strict anaerobes).

Key takeaways

McIntosh and Fildes' anaerobic jar belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect McIntosh and Fildes' anaerobic jar to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of McIntosh and Fildes' anaerobic jar from memory before moving on to harder problems.

Reference excerpt

McIntosh and Fildes' anaerobic jar is an instrument used in the production of an anaerobic environment. This method of anaerobiosis as others is used to culture bacteria and other germs (e.g., Trichomonas vaginalis) which die or fail to grow in presence of oxygen (strict anaerobes). It was originally introduced by James McIntosh, Paul Fildes and William Bulloch in 1916. McIntosh and Fildes, after whom the device has been named, published an improved version in 1921.

Construction The jar, about 20 by 12.5 inches (510 mm × 320 mm) is made of metal. Its parts are as follows:

The body made up of metal (airtight) The lid, also metal can be placed in an airtight fashion A screw going through a curved metal strip to secure and hold the lid in place A thermometer to measuring the internal temperature A pressure gauge to measuring the internal pressure (or a side tube is attached to a manometer) Another side tube for evacuation and introduction of gases (to a gas cylinder or a vacuum pump) A wire cage hanging from the lid to hold a catalyst that makes hydrogen react to oxygen without the need of any ignition source

Method of use First: The culture: The culture media are placed inside the jar, stacked up one on the other, and Indicator system: Pseudomonas aeruginosa, inoculated on to a nutrient agar plate is kept inside the jar along with the other plates. This bacteria need oxygen to grow (aerobic). A growth free culture plate at the end of the process indicates a successful anaerobiosis. However, P. aeruginosa possesses a denitrification pathway. If nitrate is present in the media, P. aeruginosa may still grow under anaerobic conditions. Second: 6⁄7ths of the air inside is pumped out and replaced with either unmixed Hydrogen or as a 10%CO2+90%H2 mixture. The catalyst (palladium) acts and the oxygen is used up in forming water with the hydrogen. The manometer registers this as a fall in the internal pressure of the jar. Third: Hydrogen is pumped in to fill up the jar so that the pressure inside equals atmospheric pressure. The jar is now incubated at desired temperature settings.

References

Illustrations

Worked examples

Example 1 — a first encounter with McIntosh and Fildes' anaerobic jar

Start with the simplest possible case. Write down what McIntosh and Fildes' anaerobic jar claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to McIntosh and Fildes' anaerobic jar before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about McIntosh and Fildes' anaerobic jar ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of McIntosh and Fildes' anaerobic jar

In research: McIntosh and Fildes' anaerobic jar appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses McIntosh and Fildes' anaerobic jar in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: McIntosh and Fildes' anaerobic jar is common in secondary-school and first-year university syllabi. It links to neighbouring topics Microbiology equipment, Microbiology terms, so understanding it makes those chapters shorter.
In everyday life: Look for McIntosh and Fildes' anaerobic jar outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study McIntosh and Fildes' anaerobic jar in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what McIntosh and Fildes' anaerobic jar means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain McIntosh and Fildes' anaerobic jar out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is McIntosh and Fildes' anaerobic jar in simple terms?

Why does McIntosh and Fildes' anaerobic jar matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study McIntosh and Fildes' anaerobic jar?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on McIntosh and Fildes' anaerobic jar.