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A-Level Biology has probably the most content of any of the A-Level sciences! Its tempting to memorise all the content in the textbook but in reality some textbooks will have extra information that is no...

they don't have a nucleus, the DNA is present in cytoplasm. prokaryotic cell has a cell membrane that controls movement of molecules in and out of the cell. prokaryotic cells also have cell walls that pro...

Blood flows through human bodies via a double circulatory system, the systematic system and the respiratory system, which are connected by the heart. Blood enters the right atrium of the heart from the ve...

Starch is a mix of 2 different polysaccharides:1) Amylose: a long chain of α-glucose monomers joined by 1,4-glycosidic bonds. The chain coils in a spiral shape, held together by hydrogen bonds. This shape...

A HIV molecule enters the blood stream and invades cells of the immune system (CD4 cells). To do this, proteins on the surface of the virus bind to receptors on the host cell. This then allows the envelop...