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A2 Biology Discussion and Help

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I've been interested in the molecular biology implications associated with aging so that'll be something I look at following in due course. In factn, I'm hoping to do something similar in my final year biochemistry projects.

Reply 81

Kallisto

Entertainment Forum Helper

Original post by HarryMWilliams

I've been interested in the molecular biology implications associated with aging (...)

Do you have dealing with one of the most unkown phenomenas yet? if yes, may I ask you some questions about aging? I'm interest in it too!

Reply 82

A-level_Student

Can any one tell me that where can I find Answers to question in Annfullick As-biology book Edexcel?

Reply 83

phaseshift

Original post by Kallisto

Ask away, if I can't help, I'll see if I can find something which can.

Reply 84

Kallisto

Entertainment Forum Helper

Original post by HarryMWilliams

Ask away, if I can't help, I'll see if I can find something which can.

As you will. I have read that apoptosis is a process which is also responsible for aging. As you know - I think so at least - apoptosis means that some cells 'commit suicide' to replace by new ones. It is the programmed cell death. This process is not endless, as it is determined how often cells can be replaced. This process is repeated a lifetime. So far so good.

But as far as I know it is still not confirmed that apoptosis is really responsible for aging. What do you think about that? can apoptosis be a reason for aging in your opinion and why?

(edited 10 years ago)

Reply 85

knope

Original post by HarryMWilliams

I've been looking a little at the potential role of DNA methylation in that; looks fascinating. Let me know when you get close to immortality, kind sir. :wink:

Reply 86

phaseshift

Original post by Kallisto

It's difficult. Apoptosis, as you say, is responsible for cellular death, but thats only when stimulated by external agents, or the cell has reached the limit at which it can divide to replace itself. In all honesty, apoptosis, if responsible, will only be a very small part of the general picture.

Original post by knope

That's what I'm in it for! Want to live forever me, at least longer than 80-100 years anyway!

Reply 87

DavidYorkshireFTW

Original post by HarryMWilliams

You need to be looking at immunosenescence then, if you prevent that, which is the involution of the thymus gland which produces T-cells, which weakens the immune system, I am sure mortality rates in humans would be higher!

Reply 88

Kallisto

Entertainment Forum Helper

Original post by HarryMWilliams

(...) That's what I'm in it for! Want to live forever me, at least longer than 80-100 years anyway!

Why you are interest in to live forever or to extent the mortality rate of humans? what is your goal?

Reply 89

DavidYorkshireFTW

Original post by Kallisto

Why you are interest in to live forever or to extent the mortality rate of humans? what is your goal?

He might just dislike wrinkles :dontknow:

Reply 90

Kallisto

Entertainment Forum Helper

Original post by DavidYorkshireFTW

What about the apoptosis in terms of mortality rate? it is inter alia responsible for replacing rogue cells. As written above the cellular death is limited. If apoptosis doesn't work anymore, so cancer/tumor cells are extended in the whole organism. I guess if humans are able to influence the limited function of apoptosis by extending the limitation of apoptosis, humans are capable of increasing the mortality rate of humans as well. What do you mean?

Reply 91

DavidYorkshireFTW

Original post by Kallisto

I wasn't aware apoptosis had a limit, but it does make sense!
Look it up, which bit don't you understand?

Reply 92

thecurlymedic48

Can some please explain transmission of action potentials and local currents in mylinated and non mylinated neurons i dont get it

Reply 93

Sherry Yin

Hi, currently I am doing the issue report for As biology unit3, the topic I chose is sleeping sickness and I've already done lots of research on it. But just now I found that nobody did this topic from the examiner's reports so I am a little panic...Anyone can give me some suggestions about this topic? Whether I should continue? Although I haven't met any 'fatal' problem while doing the research for this topic...thanks a lot

Reply 94

king101

I am stuck on a few understandings from the Nelson Thorne’s Text Book and would really appreciate some guidance.
In the MW document I will write what ‘text (from the text book) I am having trouble in understanding and then my understanding of it so you guy’s can correct me exactly where I am going wrong please.
Just to provide ease of understanding of what I am trying to put across: TB= Text Book (what they say) and MU= My Understanding

To anyone that can answer all my queries in enough sense that would allow me to understand my confusion I will send £5.00 via paypal. The reason for the cash is since my understanding of these bits sucks and I’m really panicking.

Biology AQA Understanding Revision.docx18.9KB

Reply 95

Munrot07

Original post by king101

1) With hormones two things can happen, either a stimulus is detected and a signal is sent to the brain e.g. hypothalamus, and the brain will cause hormones to be secreted which will then go to the effector cells. Or, in the B cells example, the B cells are the receptor, they detect the change and will then secrete insulin directly into the blood (the pancreas is the gland, the islets of langerhans are the endocrine area). Insulin will then go through the body, in the blood and act on muscle and liver cells, the effectors which will create a change. In the second example, no action potential is needed.

2) You seem to understand that one pretty well

3) Hormones are proteins. On cell membranes there are receptors (often glycoproteins). Hormones have a specific shape which is complimentary to that of certain receptors. Only target cells have these receptors, so Insulin receptors will be found on the liver (the target organ), as well as muscles. When inuslin binds to the liver cells it will cause a series of reactions in the liver to occur. Since hormones travel in the blood they will come in to contact with most parts of the body but will only bind to cells with these receptors, so for example, brain cells will not be affected as they do not have these membrane bound receptors

4) The pancreas is an organ which produces hormones such as Insulin. Inuslin is not made in every cell. The pancreas is a glandular organ. It is an organ and a gland. In plants, hormones can be produced and secreted in most places in the plant, not just one organ.

5) You have a muscle in your arm. If there was one point (say point A) where it gets stimulated, the wave of contraction would start from point A and have to go all the way to point Z, that takes time. If there are junctions at every point, A-Z, then the contraction can occur at each point, at once. This is fast and ensures the contraction happens at the same time across the whole arm. (Btw it is acetylCHOLINE, not chlorine :P ).

The amount of time for neurotransmitter to reach all receptor sites is faster, and again, all at the same time, than if you had a wave of contraction moving from site A to site Z.

6) An ectotherm's metabolic rate changes as temperature does. Due to factors such as rate of reaction being faster at a higher temperature (more kinetic energy, more collisions) and enzymes working better at an optimum temperature. You have pretty much got it, Low temperature means they do not have a high metabolic rate (due to stuff like enzymes such as the ones in respiration) so don't have as much energy. As temperature increases, so does their internal temperature and their metabolic rate so they can move faster but yes, they wouldn't want to exercise to generate heat because they have already got sufficient heat.

7) Hormones are produced in glands. The B cells in the islets of langerhans are in the pancreas which is a gland.

I hope this all makes sense and I answered your questions. Please reply if I didn't explain anything well enough or you have any other questions.

Reply 96

Tlgayle

Hey im currently studying A2 biology Aqa and im really struggling with the synoptic essays, does anyone have any advice as to how to prepare for them?

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Reply 97

king101

Original post by Munrot07

1) x

Thank you so much. You don't understand how I am so lucky to have someone literally help me to that extent thank you. Really grateful. There was just just a few concepts I'm a little confused about which I have attached to the word document.

Also if you could email me your paypal thing I can send you £5.00's for such great help! :smile:

(edited 10 years ago)

Biology AQA Few little things.docx550.5KB

Reply 98

Munrot07

Original post by king101

I don't use paypal but even if I did I wouldn't expect money for it :P seriously, keep your money :P

Reply 99

Munrot07

Original post by king101

Now for your questions :smile:

1) With temperature control, some of it is a nervous response but some hormones will be used to (for example, hormones used to control metabolic rate). It was more an example saying something can be stimulated by a nervous impulse and then hormones are released. The no action potential is needed is referring to the example of B-cells. It had nothing to do with the hypothalamus example.

2) Pretty much as cells in organs are cells in the body

3) Honestly, you seem to understand it very well. Everytime you said "one thing I don't get" you actually explained it very well and got it right :P I can't really fault what you wrote :smile: