Mark my biology essay (aqa paper 3 a level)
Its just a draft but i would like feedback
In the arteriole end , water in the blood plasma contributes to a high hydrostatic pressure which forces tissue fluid (water with dissolved other substances). Large plasma proteins remain in blood This decreases water potential in the venue end of the capillary bed, causing water to be reabsorbed via osmosis down a water potential gradient.
Water is an important medium here for respiratory substrates like oxygen and glucose which are vital for glycolysis and oxidative phosphorylation in respiration. if water wasn’t reabsorbed by osmosis in the venue end, tissue fluid would accumulate surrounding cells leading to oedema.
In the light dependent reaction, chlorophyll undergoes photoionisation where an electron is excited and lost for chemiosmosis to occur. Water is crucial in the LDR, as it is split into its protons electrons and oxygen, replacing the electrons lost by the chlorophyll molecule.
This replacement of electrons by water is crucial as it allows continual photoionisation. Without this, electron supply would be exhausted and thus less would be transferred down the ETC, decreasing the electrochemical gradient used to pump protons into the thylakoid. So less protons able to diffuse down ATP synthase and phosphprlate ADP and Pi. And also less protons able to reduce NADP. Therefore, water is imperative to ensure enough electron for chemiosmosis, so that there is continual production of tje products of lDR (NADPH and ATP) required in the light independent reaction
A decrease in blood water potential below average is detected by osmoreceptors in the hypothalamus. These cells shrink when blood water potential is too low, stimulating the secretion of antidiuretic hormone from the posterior pituitary gland. ADH binds to specific tertiary structure receptors on the collecting duct and signal convoluted tube. This stimulates vesicles to fuse with the membrane, inserting aquaporins which increase the collecting ducts permeability for water. Therefore, more water diffuses into the blood from the nephron down a water potential gradient. This results in higher solute concentrated urine, and more water concentrated in the blood plasma. If low water potential of blood wasn’t detected, Cells would thus shrink, losing water via osmosis as it moves down a water potential gradient out of cells into a hypotonic solution.
water is cohesive, which means it is held by hydrogen bonds and its polarity means that molecules of water tend to stick together in a continuous column. This is crucial for the mass transport of nutrients in plants via the xylem. When water diffuses into roots via osmosis, it causes a high hydrostatic pressure which causes a forced upwards pressure which draws water up the xylem in a continuous column. The water also contains dissolved nutrients in the form of nitrates and phosphates. The movement of water as a cohesive column up the xylem is thus crucial in allowing nutrients from the soil to be uptaken to cells all over the plant via the central stem. For example nitrate ions from the soil are incproporated into plants biomass, by synthesising the nitrogenous base in ATP, DNA and RNA. This movement of water thus allows the semiconservative replication of DNA in cells as well as the synthesis of proteins from mRNA in ribosomes.
In the arteriole end , water in the blood plasma contributes to a high hydrostatic pressure which forces tissue fluid (water with dissolved other substances). Large plasma proteins remain in blood This decreases water potential in the venue end of the capillary bed, causing water to be reabsorbed via osmosis down a water potential gradient.
Water is an important medium here for respiratory substrates like oxygen and glucose which are vital for glycolysis and oxidative phosphorylation in respiration. if water wasn’t reabsorbed by osmosis in the venue end, tissue fluid would accumulate surrounding cells leading to oedema.
In the light dependent reaction, chlorophyll undergoes photoionisation where an electron is excited and lost for chemiosmosis to occur. Water is crucial in the LDR, as it is split into its protons electrons and oxygen, replacing the electrons lost by the chlorophyll molecule.
This replacement of electrons by water is crucial as it allows continual photoionisation. Without this, electron supply would be exhausted and thus less would be transferred down the ETC, decreasing the electrochemical gradient used to pump protons into the thylakoid. So less protons able to diffuse down ATP synthase and phosphprlate ADP and Pi. And also less protons able to reduce NADP. Therefore, water is imperative to ensure enough electron for chemiosmosis, so that there is continual production of tje products of lDR (NADPH and ATP) required in the light independent reaction
A decrease in blood water potential below average is detected by osmoreceptors in the hypothalamus. These cells shrink when blood water potential is too low, stimulating the secretion of antidiuretic hormone from the posterior pituitary gland. ADH binds to specific tertiary structure receptors on the collecting duct and signal convoluted tube. This stimulates vesicles to fuse with the membrane, inserting aquaporins which increase the collecting ducts permeability for water. Therefore, more water diffuses into the blood from the nephron down a water potential gradient. This results in higher solute concentrated urine, and more water concentrated in the blood plasma. If low water potential of blood wasn’t detected, Cells would thus shrink, losing water via osmosis as it moves down a water potential gradient out of cells into a hypotonic solution.
water is cohesive, which means it is held by hydrogen bonds and its polarity means that molecules of water tend to stick together in a continuous column. This is crucial for the mass transport of nutrients in plants via the xylem. When water diffuses into roots via osmosis, it causes a high hydrostatic pressure which causes a forced upwards pressure which draws water up the xylem in a continuous column. The water also contains dissolved nutrients in the form of nitrates and phosphates. The movement of water as a cohesive column up the xylem is thus crucial in allowing nutrients from the soil to be uptaken to cells all over the plant via the central stem. For example nitrate ions from the soil are incproporated into plants biomass, by synthesising the nitrogenous base in ATP, DNA and RNA. This movement of water thus allows the semiconservative replication of DNA in cells as well as the synthesis of proteins from mRNA in ribosomes.
Reply 1
I just read the first paragraph but I think u need to go into more detail about the importance of water causing hydrostatic pressure. maybe talk about a specific ion or mineral which is part of the tissue fluid, it's function and then link back to what would happen if water didn't create high hydrostatic pressure at the arteriole end.
Reply 2
Here are my thoughts when reading this:
I would give this 15-17 marks, it falls midway between multistructural and relational, higher band on multistructural lower band on relational.
Easy quick fixes you’ll be on your way to 21 at least
•
Whats the main question you are answering?
•
The first paragraph is a bit too short expand on it, good AO2 but quite short
•
Amazing AO2 you have expanded here! AO1 is on the short end, use of keywords is great make sure you don’t abbreviate in the exam (e.g LDR, ETC)
•
In para 3 contrast to para 1 and 2 there’s too much AO1 in comparison to AO2 expand on your AO2
•
You could definitely throw in some more alevel terminology here, sounds slightly GCSE level, you seem to loose structure here almost like you are trying to throw in your last couple points. Clarity is very important. AO2 isn’t as strong as paras 1 and 2.
•
No significant biology errors overall,
Easy quick fixes you’ll be on your way to 21 at least
(edited 3 weeks ago)
Reply 3
10
Original post by EZIKIEL04
Here are my thoughts when reading this:
I would give this 15-17 marks, it falls midway between multistructural and relational, higher band on multistructural lower band on relational.
Easy quick fixes you’ll be on your way to 21 at least
•
Whats the main question you are answering?
•
The first paragraph is a bit too short expand on it, good AO2 but quite short
•
Amazing AO2 you have expanded here! AO1 is on the short end, use of keywords is great make sure you don’t abbreviate in the exam (e.g LDR, ETC)
•
In para 3 contrast to para 1 and 2 there’s too much AO1 in comparison to AO2 expand on your AO2
•
You could definitely throw in some more alevel terminology here, sounds slightly GCSE level, you seem to loose structure here almost like you are trying to throw in your last couple points. Clarity is very important. AO2 isn’t as strong as paras 1 and 2.
•
No significant biology errors overall,
Easy quick fixes you’ll be on your way to 21 at least
Importance of proteins in control of processes and responses in organisms
Proteins are polymers formed by a sequence of amino acids joined by peptide bonds, where folding occurs due to hydrogen bonds between the NH and C=O groups in the polypeptide chain. The 3D folding involves more hydrogen bonds, disulfide bridges, and ionic bonds, creating the specific structure of enzymes. Enzymes have active sites where substrates bind with complementary shapes to form an enzyme-substrate complex. An example is ATPase, which is essential for the hydrolysis of ATP into ADP and inorganic phosphate during muscle contraction. When the myosin head with ADP attaches to the binding site on actin, it forms a crossbridge, causing a power stroke that pulls the actin filament along the myosin using energy from ATP hydrolysis. ATP hydrolysis also re-energises the myosin head, allowing it to detach and repeat the cycle. Without ATPase, the myosin head would be unable to change shape and pull actin, so muscles would not contract or produce movement. This would prevent mammals from escaping predators, reducing their chances of survival and reproduction. Therefore, proteins are crucial for forming enzymes that control processes like muscle contraction, enabling organisms to respond effectively to their environment.
Quaternary structure of proteins involve more than one polypeptide chain joined together by interactions such as hydrogen bonds between polypeptides. An example of this are antibodies, which are secreted by B lymphocytes during humoral immune response, where B cells differentiate into plasma cells and memory cells. Antibodies bind specifically to antigens, forming an antigen antibody complexes. Each antibody can bind complementary to two pathogens at the same time causing agglutination. This allows phagocytes to easily engulf pathogens and hydrolyse them. Antibodies can be produced from vaccines to provide immunity, if there is a change in protein structure due to gene mutation,then primary structure of antibody alters affecting the foldings of tertiary and quaternary structures.This results in antibodies no longer complementary antigens and can not bind, so organisms are no longer immune to infection.
Another crucial protein that controls a process is transcription factors (TF) found in cytoplasm and regulate transcription of specific target genes in eukaryotes. This happens by TF binding to a specific DNA base sequence on the promoter region of the gene when entering the nucleus, TF can stimulate transcription by helping RNA polymerase to bind and produce mRNA that then undergoes splicing to remove introns. Environmental factors can lead to epigenetic changes that can either stimulate or inhibit TF binding to the promoter region. Increased methylation of DNA allows chromatin to condense making nucleosomes pack more tightly together and prevents TF and RNA polymerase from binding to promoter regions inhibiting transcription. Similarly this occurs with decreased acetylation of histones, increasing positive charge and binding more tightly to DNA. This leads to uncontrolled transcription and cell division that can form tumours that can either be malignant or benign. Thus, the protein TF is important to regulating gene expression and ensuring mitosis is controlled to prevent the mass of abnormal cells from forming.
Reply 4
I am so sorry if I am too late for this, were you in year 13 per chance? If so are your alevels done?
Quick Reply
Related discussions
- A-level exam boards
- A Level Bio Predictions
- Aqa vs ocr for a level sciences
- Can you do law with all stem a levels
- URGENT- Spanish A level
- A level bio
- Exam board difficulty levels
- GCSE Grade 9 student
- AQA Chemistry A-level
- 🎀GYG-Academic victim to Academic weapon A-level 2024-2026🎀
- chemistry vs psychology
- My A- levels choices-should I have an essay based subject???
- Workload
- AQA Biology A2 A* Revision notes
- How to get out of B grade for A-Level sciences
- help with chossing bio or chem for a level
- Psychology A level
- Can I get grade 8s and 9s?
- Appeals and Remarks 2024
- Do certain A level bio exam board have a 25 markers etc?
Latest
Trending
Last reply 2 months ago
Why does meiosis 1 produce two haploid cells where mitosis produced two diploids?
