AQA A-Level Biology Paper 3 [21st June 2023] Exam Chat

@fruityoghurt

any chance I could please have that A* essay example? Would be a massive help

omg please I need them , I struggle with essays so much its terrific

Please post essay answers.

Thank you.

Please post your essays it would be so helpful

would love the essay!! so helpful thanks

Yes please could we get the essay answers to the essay titles

bless your heart. you legend

Here you go! Hope it helps https://drive.google.com/file/d/1PlMwWTFGh9YTt6prYGVMYlg7GQXkkhaz/view?usp=sharing

what would u say are some topics you can apply to basically almost any essay question? bcs sometimes i get stumped & cant think of any topics on the spot

Hey! Hope paper 2 went well for everyone My predictions have been correct so far for paper 1 and 2, so here are my paper 3 predictions:

- Cardiac cycle (may be linked to control of heart rate)
- Translocation and evidence for/against mass flow hypothesis (ringing experiments, tracers)
- Index of diversity (may be linked to transects/quadrats in topic 7)
(Protein synthesis may come up, but this may be linked to topic 8 content)
- Taxes/Kinesis (incl RP 10)
- Control of blood glucose concentration (incl RP 11)
- Stem cells
- Oestrogen - linked to transcription factors
- Photosynthesis/Respiration
- Inheritance unlikely to appear but may be some more juicy genetics qu's

Essay predictions (anything can come up, so here are 4 potential essay titles):

- The importance of proteins in the control of processes and responses in organisms
- The importance of hydrogen bonds
- The importance of water
- The importance of concentration gradients

(Microorganisms is unlikely to come up as a title, even though Miss Estruch predicted it -- most of the topics are overlapping and there's not enough content on microbiology, but it is a good idea to plan an essay for it!)

If there's enough people who want it, I may post my A* essay answers to the essay titles which got me the top band by my teacher. Good luck! ONE MORE PAPER AND THAT'S BIO DONE. YOU GOT THIS.

UPDATE: here's the essays https://drive.google.com/file/d/1PlMwWTFGh9YTt6prYGVMYlg7GQXkkhaz/view?usp=sharing

Here you go https://drive.google.com/file/d/1PlMwWTFGh9YTt6prYGVMYlg7GQXkkhaz/view?usp=sharing

anyone got a good example essay for importance of membranes?

A 24/25 essay i wrote which may be useful x
Write an essay on the importance of response to change in the internal and extenal environment of an organism. (25)

The eye is comprised of both cone cells, located at the fovea, and rod cells, located in the retinal periphery. These act as transducers, detecting light energy and from this creating nervous impulses. The rod cells contain a pigment called rhodopsin which is broken down by light. The cone cells facilitate the ability to see in colour, and have a high visual acuity, due to the fact that they are each connected to a single neurone, and thus a single impulse is sent through the optic nerve to the brain. The cone cells are however less sensitive, as the threshold for an action potential to be fired is generated solely from a single rod cell, meaning that coloured vision is only achieved in higher light intensity. Rod cells on the other hand are each connected to one another, and an action potential is fired as a result of retinal convergence and spatial summation, making the rod cells send impulses to the brain in lower light intensities. The ability to distinguish between two point is however difficult, as one impulse could have come from a number of connected rods, and is hard to exactly pinpoint the source. This explains why in the dark you can see only in black and white and with blurry vision.

The importance of regulation of blood-glucose concentration is vital to maintain many homeostatic processes. Having too high a glucose level within the blood would lead to having a very low water potential, which would cause water to enter through the capillary endothelium, increasing the blood pressure and impacting the osmotic balance of the body. Having too low a blood glucose concentration can lead to there not being sufficient respiratory substrates for respiration, causing symptoms such as fatigue and weight loss due to gluconeogenesis of lipid stores and even muscular tissues. When the alpha cells of the eyelets of langerhans detect a low blood glucose concentration, or hypoglycaemia, glucagon is secreted from the pancreas, initiating the break down of glycogen into glucose, the process of glycogenolysis. When hyperglycaemia occurs, the beta cells of the eyelets of langerhans secrete insulin, initiating glycogenesis, converting glucose to glycogen. Diabetes occurs when the control of blood glucose is not sufficiently regulated, due to the faulty or non-existent secretion of insulin. In patients with diabetes, (most commonly type 2), diabetic retinopathy often occurs, where the capillaries within the retina are damaged, due to the extremely high blood glucose levels, preventing the blood supply to the eyes components, and casuing a decline in vision. This can also occur in the capillaries in the extremeties, causing insufficient blood supply and leading to amputations in extreme cases.

External response to change is incredibly important for organisms, and can be displayed through the use of selection pressures and natural selection. Stabilising selection has occurred over time with babies birth weights, as the smallest babies often died due to having underdeveloped lungs and other vital organs, and the extremely large babies often died due to being at far higher risks of complications during birth such as shoulder dystocia, which causes the baby to get stuck within the birth canal, starving their brain of oxygen, and often causing the development of cerebral palsy or death. Due to this, the mass of babies has evolved over time to become a less extreme weight, with those surviving most commonly being of mean birth weight, and therefore when they themselves become parents and pass on their genotypes to their offspring, they too are more likely to survive and be of a more average mass. In the ecological world, directional selection has played a vital role in facilitating the survival of organisms facing selection pressures such as trees increasing in height. Giraffes are a great example of this, with their elongated necks being beneficial to reach the high trees which provide the nutrition that they need, and cannot be reached by other herbivores on the floor. This means that because of the selection pressure of a lack of food, the giraffes with longer necks were more likely to survive and pass on their alleles to their offspring, in turn increasing the allele frequency of such long necks, and causing those without to become less frequent, as they would become malnourished and not reproduce. This is directional selection.

Finally the immune response is a way in which the human body responds to change in both internal and the invasion of external environmental factors. The non-specific immune response initiates the response through the process of phagocytosis. After a phagocyte has recognised the pathogens foreign antigen, it engulfs the phagocyte through endocytosis, and secretes lysozymes into the vesicle formed to hydrolyse the pathogen. The phagocyte then ejects everything other than the invading cells antigens through exocytosis, and presents these antigens on its cell surface membrane, becoming an antigen presenting cell. When a t-helper cell comes into contact with this antigen presenting phagocyte, it initiates the next stage of the cellular immune response. Cytokines are release by cytotoxic t-cells which cause cell death by apoptosis. Other helper T cells stimulate B-cells, which divide by mitosis into memory b-cells, which stay in the blood providing longer-term immunity for the secondary exposure, and plasma cells, which secrete the monoclonal antibody complementary to the antigen presented on the phagocyte. This enables the body to fight against and destroy invading pathogens to prevent the development of severe disease. This is so important, as the impacts of having a faulty immune response can be observed within the immunodefficiant population. This can be a result of having AIDS, preparing for a transplant or undergoing cancer treatment for cancers such as leukaemia where a bone marrow transplant requires the patient to be placed on immunosuppressive drugs beforehand. The most common cause of death from AIDS, where the helper-t cell count is depleated as a result of the helper-t cells being used to manufacture more viral molecules, is bacterial and paracitic infection such as toxoplasmosis or tuberculosis. This is due to an insufficient immune response, meaning that something like the common cold or urinary tract infection can develop into such catastrophic and fatal illnesses.

when we get our results back, how do we know what we got on the essay?

Here it is, hope it helps! https://drive.google.com/file/d/1PlMwWTFGh9YTt6prYGVMYlg7GQXkkhaz/view?usp=sharing

what would u say are some topics you can apply to basically almost any essay question? bcs sometimes i get stumped & cant think of any topics on the spot

does anyone know if i can use the first few lines on the essay to do a quick plan and do a box around it saying plan. Or am i not allowed to write anything there that i dont want to be marked. Not sure ive worded that write lol