A level Biology Essay

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This is my first attempt at a biology essay for paper 3 we've had no guidance on how to do them yet but are about to begin but have been given this as homework for a base line.
I'm not a fan of the 1st and 4th paragraphs and I'm much more confident with the 2nd and 3rd.

Any suggestions/advice will be much appreciated.

Importance of Movement in Living Organisms

In the digestive system glucose is absorbed from the ileum across the epithelium into the blood. For this to happen co-transport and facilitated diffusion must occur. Three sodium ions are pumped into the blood and two potassium ions are pumped into the epithelium this requires ATP and causes a concentration gradient between the ileum and the epithelium. Sodium attaches to a co-transporter allowing a glucose molecule to also attach to the same co-transporter and diffuse into the epithelium via co-transport. Once in the epithelium glucose uses a specific carrier protein to move into the blood by facilitated diffusion. Without movement glucose wouldn’t be able to move into the blood and be used in respiration this would mean the living organism wouldn’t be able to produce energy.

Respiration is vital in the production of ATP and would not be possible without movement. Co-enzymes produced during the Krebs cycle must move to the inner mitochondrial membrane to the channel proteins to donate their electrons and protons. The protons can then move over the cristae through the channel proteins this creates a proton concentration gradient which they can move along by chemiosmosis. The electrons are also able to move along the carriers in a series of redox reactions to release energy. The energy released enables ATP to be formed, by oxidative phosphorylation, after protons pass through the ATP synthase. Without movement electrons wouldn’t be able to pass through the transport chain causing the rest of the processes to become ‘backed up’.

In plants the phloem transports vitamins and minerals from sources to sinks by translocation. Sucrose is actively transported into the companion cells and moves by diffusion into the sieve tube followed by water. Assimilates move from an area of high to low pressure. At the sink solutes are removed and water leaves via osmosis. Water moves by a process called transpiration this moves water against gravity and occurs in the xylem. The xylem is made up of dead cells which are long, thick walled and contain lignin. Lignin waterproofs and strengthens the xylem to prevent collapse of xylem. Transpiration relies on the cohesive properties of water, capillary action and root pressure. Without movement water within plants photosynthesis couldn’t occur meaning plants wouldn’t be able to grow.

During DNA replication RNA polymerase moves along and joins free RNA nucleotides to form pro mRNA which is then spliced before it leaves through the nuclear pores into the cytoplasm. In translocation tRNA attaches to a complementary anticodon transporting an amino acid with it. A tRNA carrying another amino acid bind with the next codon along the mRNA allowing a peptide bond to form between the two amino acids. The ribosome moves along the mRNA bringing together two tRNA molecules at any one time, each adding an amino acid to form a polypeptide chain which will combine with other polypeptides to form proteins. The movement of RNA polymerase along the DNA strand, pre mRNA across the nuclear pores and ribosome along the mRNA are essential in protein synthesis. Without movement living organisms wouldn’t be able to make proteins to carry out essential functions for the organism’s survival.
Last edited by diggerdog789; 6 months ago
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