AQA A2 BIOL5 22nd June 2012

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How can you forget diabetes, with insulin, glucagon and adrenaline :eek:

Probably get ATP in there somewhere too.

Enzymes too - they control / increase the rate of reaction.

Then hormonal / nervous control of heart and blood vessels too.

Muscle contraction. (ATP could be brought in here)

i got the hormones and the nervous system in Homeostasis, ooh ATP :tongue:

Reply 141

F1's Finest

Doing some revision and notes on Muscle Contraction. I love this unit compared to Unit 4

Reply 142

al_habib

Original post by Anamika19

Muscle stimulation:
an action potential causes calcium ion channels to open which leads to influx of calcium ions in th presynaptic neurone which cause the vesicles to bind to the membrane of the presynaptic neurone and acetyl choline diffuses via the synaptic cleft into the post synaptic neurone where it binds to the receptor sites on the sodium ion channels.

Musle contraction:
an action potential travels via the T-tubules into the sarcoplasm (cytoplasm) and into the sarcoplasmic reticulum (endoplasmic reticulum). an action potential in the sacroplasmic reticulum causes an influx of calcium ions. the calcium ions diffuse out of the sarcoplasmic reticulum and into the sarcoplasm.
The influx of calcium ions causes the tropomyosin to move from the binding sites on the actin filament so that the myosin can attatch. An ADP molecule attaches to the myosin head and the myosin head then attaches to the actin filament. When the myosin attaches to actin filament, it changed the angle of its head and pulls the actin filament along and also releases an ADP molecule. An ATP molecule causes the dettatchment of the myosin head from the actin filament. the calcium ions then activate the enzyme ATPase which hydrolyses the ATP --> ADP + Pi and the angle of the myosin heads return to normal.
The myosin head then reattaches further along the actin filament again and the cycle repeats.

Musle relaxation:
when the impulse ceases, the calcium ions are actively transported back into the sarcoplasmic reticulum (using the energy from the hydrolysis of ATP). the reabsorption of the calcium ions cause the tropomyosin to block the binding sites on the actin filament again so the myosin head can no longer bind to the actin and the muscle stimulation ceases.

:smile:

This is brilliant notes :yy:

Reply 143

Onee-chan

Original post by al_habib

really narrow essay but thats a good connection with the functions of cell membrane, lets see if we can get more points on this "Feedback system and control in biology" i got a few:-

-Limiting Factors
-Ecology
-Natural Selection
-Homeostasis
-Oestrous Cycle
-Mitosis & Meiosis

Original post by thegodofgod

How can you forget diabetes, with insulin, glucagon and adrenaline :eek:

Those covers the important ones! Though some superficial ones like protein synthesis = control phenotype and immunity = control pathogens may be added. :tongue:

Another title:

"The ways in which different species of organisms differ from each other"

It's such a vague and massive topic and I need to write an essay plan for it as well :c.

Plan:

-DNA (genetic differences)
which leads to:
-different proteins (enzymes, antigens/ antibodies, haemoglobin, hormones = talk about protein synthesis)
-different carbohydrates (like glycogen and starch)
-cell structure (= prokaryotic and eukaryotic which further splits into plant and animals)
which then leads to:
-gas exchange systems (maybe add a bit of extra info about avian lungs and reptilian ventilation)
-circulatory mechanisms (heart pump vs. cohesion tension)
-nervous control in animals and hormonal control in plants
-courtship behaviour
which ultimately leads to:
-species diversity (can't remember what's covered in this chapter apart from human activities :colondollar:

)

Please feel free to add to the list! :biggrin:

Oh and is anyone brave enough/ ready to upload a fully written essay?

(edited 12 years ago)

Reply 144

SyedaA7

been given an essay on 'the role of glucose in organisms'

so far, i've got the obvious (formation of maltose, fructose, starch and their uses; respiration and the effects of ATP on the body as a result) but my mind has gone totally blank! there's clearly more, but i can't think of any. can anyone help? thanks.

Reply 145

Insanity514

Can't stop myself writing too much for the essay...must cut down writing!

Reply 146

Besakt

Original post by Insanity514

Can't stop myself writing too much for the essay...must cut down writing!

Quality > Quantity.

Reply 147

Bonjour

Hey can you help me with this question from a past paper?

Menopausal women have few follicles left in their ovaries. Explain why these women have large amounts of FSH in their urine.

Thanks in advance...:]

Reply 148

ilovemath

Original post by Bonjour

little or no oestrogen;
produced by follicle;
oestrogen inhibits FSH;

Reply 149

Insanity514

Original post by Besakt

Quality > Quantity.

The golden rule, will keep that in mind next time :tongue:

Reply 150

EffKayy

Original post by al_habib

you better start now

why?
There's a lot of time left tbh.. and we havent even covered the whole spec yet

kthanksbye

(edited 12 years ago)

Reply 151

Roxas

I had to do an essay on "the ways in which inorganic ions are used by organisms" if people need more titles :smile:

I did stuff like:
Cholera/ORT
Active transport in roots
Respiration/photosynthesis
Nitrogen cycle
Muscle contraction/synapse/sodium potassium pumps..

I am really struggling with unit 5 I think, it's tricky! Still got homeostasis and oestrogen that we haven't even started yet :redface:

Also effkay do you understand restriction endonucleases now? I can write up my notes on them if you still need :smile:

Reply 152

EffKayy

Original post by Roxas

Also effkay do you understand restriction endonucleases now? I can write up my notes on them if you still need :smile:

Erm, I still don't understand the mapping thing..? \:

Can you please write up your notes..? That would be amazing! Thanks

Reply 153

kingam

Original post by Anamika19

calcium ions in th presynaptic neurone which cause the vesicles to bind to the membrane of the presynaptic neurone

im sure that its the post synaptic neurone where the calcium ions come from :biggrin:

Reply 154

Rizzy J

DNA; Transfer and and manipulation essay

transfer-horizontal and vertical gene transmission(antibiotic resistance)
- mitosis, meiosis, sexual and asexual reproduction
- DNA replication

manipulation- in vivo- isolation, insertion, transformation
- in vitro- seperation of dna strand, addition of primers, synthesis of DNA

anything else??

Reply 155

thegodofgod

Original post by Rizzy J

You could probably talk about enzymes, e.g. DNA polymerase, helicase, ligase, and endonucleases, in relation to the manipulation of DNA.

You could also mention mutations - that's manipulating the DNA as you're changing the base sequence, so that's substitution, addition and deletion.

DNA hybridisation too.

Okay, time for another question :biggrin:

Point mutations and their consequences.

So far, I've got:

•

Sickle cell

•

Proteins (functioning, non-functioning)

•

Cell cycle (G₁, checking if DNA is okay for replication)

•

Genetic code (Degenerate, so chance of a non-functional protein being formed is small)

•

An example about a rabbit (?) in the Nelson Thornes text book about it losing its melanin, so camouflage / survival / natural selection stuff

•

Could bring in horizontal / vertical gene transmission in bacteria

Not sure if I could bring in any Ecology from Unit 4, and I don't think there's much you can bring in from Unit 5 on point mutations specifically. :s-smilie:

Any ideas? :redface:

Reply 156

Roxas

Original post by thegodofgod

Point mutations and their consequences.

So far, I've got:

•

Sickle cell

•

Proteins (functioning, non-functioning)

•

Cell cycle (G₁, checking if DNA is okay for replication)

•

Genetic code (Degenerate, so chance of a non-functional protein being formed is small)

•

An example about a rabbit (?) in the Nelson Thornes text book about it losing its melanin, so camouflage / survival / natural selection stuff

•

Could bring in horizontal / vertical gene transmission in bacteria

Not sure if I could bring in any Ecology from Unit 4, and I don't think there's much you can bring in from Unit 5 on point mutations specifically. :s-smilie:

Any ideas? :redface:

Is it awkward that I don't even know what a point mutation is? :eek:

Reply 157

Rizzy J

Original post by thegodofgod

Point mutations and their consequences.

So far, I've got:

•

Sickle cell

•

Proteins (functioning, non-functioning)

•

Cell cycle (G₁, checking if DNA is okay for replication)

•

Genetic code (Degenerate, so chance of a non-functional protein being formed is small)

•

An example about a rabbit (?) in the Nelson Thornes text book about it losing its melanin, so camouflage / survival / natural selection stuff

•

Could bring in horizontal / vertical gene transmission in bacteria

Not sure if I could bring in any Ecology from Unit 4, and I don't think there's much you can bring in from Unit 5 on point mutations specifically. :s-smilie:

Any ideas? :redface:

Nothing from unit 4 as it's not relevant and would loose marks
Everything u have said is good, also refer to cancer when talking about cell cycle
Structure of DNA, PCR, Gene therapy, meiosis, mitosis, asexual/sexual reproduction, genetic variation, genetic diversity, genetic engineering, in vivo in vitro are other staff that can be included.

Reply 158

Anamika19

Original post by kingam

What??

Nope, the calcium ion channels are on the presynaptic neurone and the action potential causes the calcium ion channels to open so there is an influx of calcium ions in the presynaptic neourone. This influx of calcium ions cause the vesicles (containing the acetylcholine) to fuse with the membrane of the presynaptic neurone. The acetylcholine then diffuses across the synaptic cleft and binds to the sodium receptor sites on the postsynaptic neurone.
:smile:

As a reference you can check Page 189 on Nelson Thornes AQA book and the first bullet point says 'causing the calcium ion channels to open and calcium ions enter the synaptic knob'. The synaptic knob is only a feature of the presynaptic neurone, hence the calcium ions are present in the presynaptic neurone and not the postsynaptic neurone.
Also you can check the diagram on page 179 of the same Nelson Thornes AQA book and they show the calcium ion channels on the presynaptic neurone
:smile:

(edited 11 years ago)

Reply 159

F1's Finest

Revision is going well on my part. Just finished writing down some exam questions from the DNA topics that I think could pop up in the exam. I'm referring to chapter 14 and 16 in the book :tongue: