A Level Biology Revision Notes

Comprehensive A Level Biology revision notes providing information and assistance for all UK examination boards (AQA, OCR, Edexcel) as well as international curriculum (CIE).

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Plant Reproduction System

   Plants can reproduce two ways, via insects or the wind. Insect-pollinated flowers usually have bright colours and a scent to attract the insects while wind-pollinated plants are usually absent of both bright colours and scent. The flower is comprised of many different parts, each with a different function, it’s the organ of reproduction …

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Phloem – Plant Tissue

Made up from 4 different parts: Phloem fibres Phloem parenchyma Sieve tubes Companion cells The sieve tubes and companion cells are both involved with the mass flow hypothesis. Sieve Tubes Cell membrane broken down Fluid cytoplasm No vacuole No nucleus With the end of the sieve wall broken down it allows inter cellular movement. Translocation …

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The Five Kingdoms Classification System

All living things can be grouped into five categories. This is called the five kingdom proposal and was introduced by Robert Whittaker in 1968 as a way to categorise all organisms. Living organisms are divided into five kingdoms: Prokaryotae Protoctista Fungi Plantae Animalia Prokaryotae Unicellular and Microscopic. Non-membrane bound (no nuclear membrane, no ER, no …

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The Digestive System

Digestion is the breaking down of chemicals in the body to a form that can be absorbed and used. Digestion begins, in mammals, with the saliva in the mouth. The Mouth This is the buccal cavity in a human and is where mechanical digestion and mastication (chewing) takes place. Saliva in the mouth consists of …

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Respiration is a set of metabolic reactions and processes that take place with in the cells of organisms. It stores biochemical energy within adenosine triphosphate (ATP) molecules. There are two types of respiration, aerobic and anaerobic. Respiration is also the process of making ATP rather that breaking it down. ATP (Adenosine triphosphate) ATP is the …

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Biological Compounds

Carbohydrates are made up of monosaccharides – which are with relatively small molecules used as building blocks. As well as monosaccarides other monomers like amino acids and nucleotides are also used as building-blocks for the larger polymer structures. Polymers are the larger structures, built from monomers, and include carbohydrates, proteins and nucleic acids. The diagram …

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