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25 mark essay question

would someone mind reading my essay please and seeing what mark i would get?
The importance of nitrogen containing compound in biological processes.
First nitrogen is an important molecule in the formation of nucleotides that form DNA. A DNA molecule consists of a deoxyribose sugar, phosphate group, and an inorganic nitrogenous base, which could be thymine, adenine, guanine, and cytosine. However, this is not just limited to DNA as nitrogenous bases are used to form MRNA, TRNA, siRNA, microRNA, and ribosomal RNA. Specifically, linked to the role of nitrogenous bases in DNA is that because the bases form specific complementary base pairings, this allows for DNA to be replicated. For example, adenine combines to thymine by two hydrogen bonds, and cytosine joins to guanine by three hydrogen bonds. It is this specific complementary base pairing of nitrogenous bases that allows DNA to be replicated over and over. The order of these bases’ codes to produce polypeptides or codes for specific genes. This is important to living organisms as without the nitrogenous bases having their complementarity to each other, then DNA could not be replicated, so chromosomes, would not contain the right number of genes, and when DNA goes to be divided during mitosis and meiosis, to produce somatic cells and haploid cells or gametes. They would not contain the correct number of genes within chromosomes to go onto produce specific proteins, such as haemoglobin. This means nitrogenous bases in DNA are crucial in ensuring that sections of DNA contain the right order of bases, and that cells contain the correct amount of DNA when undergoing cell division to be able to grow and repair living organisms.
Nitrogenous bases are also key to the process of respiration, specifically as nitrogen is found in two of the key coenzymes used during oxidative phosphorylation. Coenzyme NAD are used to oxidise triose phosphate to pyruvate, and then used to oxidise pyruvate to acetate. Then again, the coenzymes FAD+ and NAD+ are used to regenerate oxaloacetate. It is then at the mitochondrial matrix, the coenzymes FADH and NADH provide an electron and a proton to the electron transport chain to transport protons against their concentration gradient through a proton pump, to form an electrochemical gradient. It is this electrochemical gradient that drives ATP synthesis, which is an important molecule in every metabolic process in a living organism, such as active transport or regeneration of neurotransmitters at a synaptic cleft. Therefore, these nitrogen-based coenzyme are not only important in the oxidative phosphorylation part of aerobic respiration in synthesising ATP, but they are also paramount in ensuring that the other cycles continue, such as glycolysis, and the link reaction and the kerbs cycle. Without these coenzymes anaerobic and aerobic respiration would cease to occur, and ATP would no longer be synthesised.
Nitrogen containing compounds are also instrumental for digestion and absorption of biological molecules, such as glucose. Specifically, in producing enzymes. Enzymes are a type of protein formed by ribosomes during protein synthesis, enzymes have a specific tertiary structure, determined by a specific primary structure. The primary structure is determined by the order of nitrogenous bases found at a gene. When an enzyme coded for by a gene is transcribed to form a single stranded MRNA, the MRNA is translated by ribosomes to produce a polypeptide. The Golgi body then processes and modifies the polypeptide to produce an enzyme, which is then released by the cell via exocytosis inside a vesicle. Important digest enzymes include amylase and maltase. Amylase has a specific tertiary structure, and amylases active site is complementary to starch. So, amylase breaks down starch to maltose by a hydrolysis reaction. Then maltase hydrolyses maltose to alpha glucose. After starch is fully broken down by these enzymes, glucose can be absorbed by cotransport at the endothelial lining of the ileum using a cotransporter protein. Then glucose can be absorbed into the blood by a channel protein by facilitated diffusion. It is these transport proteins that are coded for by nitrogenous bases at DNA, as well as containing an amine group, which contains nitrogen. This is important as transporter proteins and enzymes are crucial in absorption of important biological molecules so that metabolic processes can occur, such as respiration.
Nitrogen containing molecules are also used in muscle contraction, especially, ATP. ATP contains a molecule of adenine which is a type of inorganic nitrogenous base. ATP is used during sarcomere contraction, first when the myosin head binds to the actin filament, this forms a myosin-actin cross bridge. ATP hydrolase enzymes, also formed from nitrogenous bases, are used to hydrolyse ATP to ADP and an inorganic phosphate. This then causes the myosin head to bend pulling the actin filament along. ATP then re-joins to the myosin head to cause the myosin-actin cross bridge to be broken, so the sarcomere relaxes. ATP is also then used to actively transport calcium ions back into the sarcoplasmic reticulum. This is so tropomyosin-troponin complex can recover the actin filament. This is important as nitrogen-containing ATP is an important molecule in providing energy for muscle contraction, which allows living organisms to move, respond to environmental stimuli. For example, muscle contraction is crucial to the reflex arc via the movement of an effector from a harmful stimulus, such as a hot stove.
Original post by edna565
would someone mind reading my essay please and seeing what mark i would get?
The importance of nitrogen containing compound in biological processes.
First nitrogen is an important molecule in the formation of nucleotides that form DNA. A DNA molecule consists of a deoxyribose sugar, phosphate group, and an inorganic nitrogenous base, which could be thymine, adenine, guanine, and cytosine. However, this is not just limited to DNA as nitrogenous bases are used to form MRNA, TRNA, siRNA, microRNA, and ribosomal RNA. Specifically, linked to the role of nitrogenous bases in DNA is that because the bases form specific complementary base pairings, this allows for DNA to be replicated. For example, adenine combines to thymine by two hydrogen bonds, and cytosine joins to guanine by three hydrogen bonds. It is this specific complementary base pairing of nitrogenous bases that allows DNA to be replicated over and over. The order of these bases’ codes to produce polypeptides or codes for specific genes. This is important to living organisms as without the nitrogenous bases having their complementarity to each other, then DNA could not be replicated, so chromosomes, would not contain the right number of genes, and when DNA goes to be divided during mitosis and meiosis, to produce somatic cells and haploid cells or gametes. They would not contain the correct number of genes within chromosomes to go onto produce specific proteins, such as haemoglobin. This means nitrogenous bases in DNA are crucial in ensuring that sections of DNA contain the right order of bases, and that cells contain the correct amount of DNA when undergoing cell division to be able to grow and repair living organisms.
Nitrogenous bases are also key to the process of respiration, specifically as nitrogen is found in two of the key coenzymes used during oxidative phosphorylation. Coenzyme NAD are used to oxidise triose phosphate to pyruvate, and then used to oxidise pyruvate to acetate. Then again, the coenzymes FAD+ and NAD+ are used to regenerate oxaloacetate. It is then at the mitochondrial matrix, the coenzymes FADH and NADH provide an electron and a proton to the electron transport chain to transport protons against their concentration gradient through a proton pump, to form an electrochemical gradient. It is this electrochemical gradient that drives ATP synthesis, which is an important molecule in every metabolic process in a living organism, such as active transport or regeneration of neurotransmitters at a synaptic cleft. Therefore, these nitrogen-based coenzyme are not only important in the oxidative phosphorylation part of aerobic respiration in synthesising ATP, but they are also paramount in ensuring that the other cycles continue, such as glycolysis, and the link reaction and the kerbs cycle. Without these coenzymes anaerobic and aerobic respiration would cease to occur, and ATP would no longer be synthesised.
Nitrogen containing compounds are also instrumental for digestion and absorption of biological molecules, such as glucose. Specifically, in producing enzymes. Enzymes are a type of protein formed by ribosomes during protein synthesis, enzymes have a specific tertiary structure, determined by a specific primary structure. The primary structure is determined by the order of nitrogenous bases found at a gene. When an enzyme coded for by a gene is transcribed to form a single stranded MRNA, the MRNA is translated by ribosomes to produce a polypeptide. The Golgi body then processes and modifies the polypeptide to produce an enzyme, which is then released by the cell via exocytosis inside a vesicle. Important digest enzymes include amylase and maltase. Amylase has a specific tertiary structure, and amylases active site is complementary to starch. So, amylase breaks down starch to maltose by a hydrolysis reaction. Then maltase hydrolyses maltose to alpha glucose. After starch is fully broken down by these enzymes, glucose can be absorbed by cotransport at the endothelial lining of the ileum using a cotransporter protein. Then glucose can be absorbed into the blood by a channel protein by facilitated diffusion. It is these transport proteins that are coded for by nitrogenous bases at DNA, as well as containing an amine group, which contains nitrogen. This is important as transporter proteins and enzymes are crucial in absorption of important biological molecules so that metabolic processes can occur, such as respiration.
Nitrogen containing molecules are also used in muscle contraction, especially, ATP. ATP contains a molecule of adenine which is a type of inorganic nitrogenous base. ATP is used during sarcomere contraction, first when the myosin head binds to the actin filament, this forms a myosin-actin cross bridge. ATP hydrolase enzymes, also formed from nitrogenous bases, are used to hydrolyse ATP to ADP and an inorganic phosphate. This then causes the myosin head to bend pulling the actin filament along. ATP then re-joins to the myosin head to cause the myosin-actin cross bridge to be broken, so the sarcomere relaxes. ATP is also then used to actively transport calcium ions back into the sarcoplasmic reticulum. This is so tropomyosin-troponin complex can recover the actin filament. This is important as nitrogen-containing ATP is an important molecule in providing energy for muscle contraction, which allows living organisms to move, respond to environmental stimuli. For example, muscle contraction is crucial to the reflex arc via the movement of an effector from a harmful stimulus, such as a hot stove.

Hi, I'm taking my A Levels this year, so please take this advice with a grain of salt (I'm not a teacher :smile:)

Firstly you've integrated multiple topics, all relevant to the essay title and from a range of areas of the course, which is really good. I like how you repeated the key focus of the essay throughout to make sure you stayed on track and made the topics related. I think improvements can be made eg possibly more of an introduction and conclusion to improve reading. It starts and ends quite abruptly. It doesn't have to be convoluted, just a simple opening and closing sentence explaining that nitrogen atoms are used to make up many compounds used in biology.

There were some mistakes made, the first of which was noticeable- "A DNA molecule consists of a deoxyribose sugar, phosphate group, and an inorganic nitrogenous base, which could be thymine, adenine, guanine, and cytosine." You mean a single DNA nulceotide. (It would be up to the examiner whether they see any errors as significant). Little things like saying "combines" bases by hydrogen bonds isn't quite right. You would say "bonds them together". I don't know how much time you spent writing, but I would definitely plan more to make the writing more coherent. It seems like you're jumping between many different areas of the course very quickly without always keeping to the essay title, and it seems a bit jumbled. Take time to write each paragraph's focus, and keep to that focus. You only need 4 to 5 relevant topics, which you did, but during these you started talking about different things eg Focus more on how enzymes work in general once you have introduced them and how they work in organisms. Don't try and show breadth of knowledge in favour of depth like jumping between DNA codes and proteins and cells in quick succession. These can be paragraphs in their own right. I get that you've tried to integrate lots of different areas at once, but try not to let that distract you from your main points. This is where it's good to have a clear plan.

Following on from this, I think including so many areas leads to a less developed argument in some places. Your final paragraph was very good and your paragraph on respiration was also excellent, lots of A Level detail, but leaving out the induced fit model of the enzyme doesn't show the examier much knowledge of enzyme action in principle. You explained it well generally with your use of the starch example and stated hydrolysis, but what is it? Show me you know it's adding water, talk about glycosidic bonds hydrolysed, where is maltase located? etc

Finally, notice how it says biological processes in the essay title. You did focus well on these processes, but the title doesn't specify animals, plants or microorganisms of any kind. You only spoke about the processes, not about their importance to organisms. There was no mention of plants, fungi, bacteria or viruses. Viruses aren't living, but we learn about them. You could use reverse transcriptase in HIV as an example of an enzyme working, or talk about extracellular digestion from fungi excreting enzymes onto external material. This will gain you more marks as it is a more holistic approach to biology, rather than just focusing on the processes themselves. It's tempting to just write about animals too, write about plant DNA coding for amino acids for ATP synthase in photosynthesis.

I would give you a 16/17 out of 25 because you had some well developed areas eg respiration, muscles, and some which were glossed over with room for more detail. There were also a few small errors having scanned through it. I hope this wasn't too harsh, I just wanted to help you improve. If there is another reply from someone who actually knows what they're talking about please ignore this. I'm just giving advice I've been told by my teacher to improve my own essays, especially the points about covering many different organisms, giving them their own paragraph. :smile:
Reply 2
thank you for the feedback, much appreciated. :smile:

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