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Alveoli have features that speed up the rate of diffusion so that gases can be exchanged quicly. They have a thin exchange surface - the alevolar epithelium is only one cell thick, which means there's a s...

Haemoglobin is an oxygen carrying molecule found in red blood cells. Haemoglobin is made up of four polpeptide chains (2 alpha, 2 beta), and consists of four haem groups (iron associated with heam) contai...

a i) a gene is a section of DNA that codes for a protein and has a specific location on a chromosome while an ellel is just a different form of a gene

ii) a recessive allele is one that is expresse...

Unlike unmyelinated axons, myelinated axons are surrounded by an insulatory myelin sheath produced by Schwann cells. Because of this insulatory sheath, action potentials cannot occur along the entire leng...

Viruses are generally smaller than bacteria and are not living, whereas bacteria are considered as living species as a prokaryote. Viruses have no cytoplasm, cell membranes or cell wall and instead have a...