If it's not on the spec, no point learning it because the wording won't be on the mark scheme - the spec just considers white blood cells as a whole. Although if you just happen to remember it naturally (like I do with biology), no harm in including the detail in an answer (but making sure you include the info in the spec first) :biggrin:

Reply 86

Excuse Me!

19

I have some questions on growing bacteria which have confused me.

1) When using inoculating loops to transfer bacteria what must be done to avoid contamination?
Is this just sterilisation? Also what is an inoculating loop?

2) Why must petri dished be taped shut?
Is this to stop unwanted microorganisms entering the petri dish?

3) Why is the maximum temperature that cultures can be incubated in schools 25*C?
For this is it just health and safety?

Reply 87

noodle01

2

Original post by GS98

How do you get them anyways?

You can get the aqa science papers (if that's what you mean) on their website: http://www.aqa.org.uk/subjects/science/gcse/biology-4401/past-papers-and-mark-schemes :colondollar:

Reply 88

kelly_kelly

6

Original post by Excuse Me!

I have some questions on growing bacteria which have confused me.

1) When using inoculating loops to transfer bacteria what must be done to avoid contamination?
Is this just sterilisation? Also what is an inoculating loop?

2) Why must petri dished be taped shut?
Is this to stop unwanted microorganisms entering the petri dish?

3) Why is the maximum temperature that cultures can be incubated in schools 25*C?
For this is it just health and safety?

You've practically answered your own questions there! :tongue:

Inoculating loops are used to transfer the microorganism into the culture medium, and they're made of a wooden handle and the loop is nichrome wire - sterilised by heating in a Bunsen flame.

Health & safety - it prevents the growth of pathogens that grow at 37°c / human body temp, so it's less harmful to humans.

Posted from TSR Mobile

(edited 9 years ago)

Reply 89

revisiongeek1234

Guys , how are you all revising right now, since the exam is on Friday.I'm actually really stressed out :s-smilie:

Reply 90

MrVirtuoso

1

Anyone up for asking each other revision questions?

Reply 91

GS98

8

Original post by noodle01

You can get the aqa science papers (if that's what you mean) on their website: http://www.aqa.org.uk/subjects/science/gcse/biology-4401/past-papers-and-mark-schemes :colondollar:

Dude I know that haha, I dont think exams such as jan 14 will be released yet as exams are released 9 moths after the exam has took place, so I was wondering how you got your hands on that paper?

Reply 92

Rtdsv

14

Original post by Excuse Me!

I have some questions on growing bacteria which have confused me.

1) When using inoculating loops to transfer bacteria what must be done to avoid contamination?
Is this just sterilisation? Also what is an inoculating loop?

2) Why must petri dished be taped shut?
Is this to stop unwanted microorganisms entering the petri dish?

3) Why is the maximum temperature that cultures can be incubated in schools 25*C?
For this is it just health and safety?

You are pretty much correct.

An inoculating loop is used to transfer bacteria into a petri dish

Second one is correct but you need to write contamination

Yes but it's because new bacteria can be created at high temperatures and it's only used in industry. So yes for safety. Sometimes they want extra detail, there's no harm in adding it.

Reply 93

Rtdsv

14

Original post by MrVirtuoso

Anyone up for asking each other revision questions?

Why not? I'm still trying to revise, might use this thread for procrastination breaks

Reply 94

MrVirtuoso

1

Original post by Rtdsv

Why not? I'm still trying to revise, might use this thread for procrastination breaks

OK...outline the differences between tissue culture and taking cuttings.

Reply 95

aerohotchoc

3

Original post by MrVirtuoso

Anyone up for asking each other revision questions?

Okay....

1) Describe the process of embryo transplantation (don't really know how to word this)
2) What health problems do people suffer due to lack of food?
3) Why do we need to control our body temperature?
4) Name three things that new drugs are tested for

Reply 96

Rtdsv

14

Original post by MrVirtuoso

OK...outline the differences between tissue culture and taking cuttings.

Not fair, I'm not on reproduction yet. Only on Biomas/Decay :P

Reply 97

Rtdsv

14

Original post by aerohotchoc

Okay....

1) Describe the process of embryo transplantation (don't really know how to word this)
2) What health problems do people suffer due to lack of food?
3) Why do we need to control our body temperature?
4) Name three things that new drugs are tested for

2) They will suffer from malnutrition. This can lead to deficiencies such as type 2 diabetes or ricketts disease as they don't have the right nutrients to live healthily.

3) In order to maintain the optimum temperature enzymes work best at for important processes in your body. If it's too high or low your body can
shut down and that's dangerous.

4)Toxicity, Efficiency and Dosage.

Reply 98

calculatorxox

1) Yeah an inoculating loop is just a wire loop. To avoid contamination, it can be passed through a flame

2) The petri dish must be taped shut to stop unwanted microorganisms from the AIR entering

3) Harmful microorganisms are unlikely to grow at this temperature

Reply 99

MrVirtuoso

1

Original post by aerohotchoc

Okay....

1) Describe the process of embryo transplantation (don't really know how to word this)
2) What health problems do people suffer due to lack of food?
3) Why do we need to control our body temperature?
4) Name three things that new drugs are tested for

1. Do you mean IVF (in vitro fertilisation)?

2. They can suffer anaemia from a lack of iron (since haemoglobin are made of iron, and less haemoglobin means less oxygen carried, therefore less respiration and less energy). I'm not sure about other specific problems, but do we need to know specific problems?

3. To ensure our body is at the optimum temperature. If the temperature is too high or too low, the metabolic rate (the rate of chemical reactions in the body) will be too slow, which can cause problems to do with digestion and energy.

4. Toxicity (harmful side-effects), efficacy (whether it works) and dosage. The tests are first on cells and tissues before moving on to clinical trials (which are often double-blind trials, whereby both the doctors and patients don't know whether or not what they are giving/taking is a placebo). The clinical trials are initially low dosage, although if it is clear there are no side effects, the dosage will be increased.

GCSE AQA Biology Unit 1 Friday 6th June 2014

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