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ENZYMES – FULL EXPLANATION Enzymes are biological catalysts that increase the rate of chemical reaction in the body. They are all produced inside cells. Some are intracellular and they catalyse reactions within the cells. Others are extracellular and are secreted out of the cells where they work e.g. digestive enzymes   Properties of Enzymes Enzymes are protein in nature Enzymes are specific to the type of reaction they catalyse This is referred to as substrate specificity Enzymes work in very small amounts They remain unchanged after the reaction They catalyse reversible reactions They work very fast (high turnover numbers) e.g. the enzyme catalase works on 600 thousand molecules of hydrogen peroxide in one second   Naming of enzymes Enzymes are named by adding the suffix -ase to: Name of substrate that they work on e.g. Carbohydrates – carbohydrases e.g. sucrase Starch (amylose) – amylase Protein – proteinase (protease) Lipids -lipases… Read More »ENZYMES – FULL EXPLANATION



SEED GERMINATION CONDITIONS, CONDITIONS NECESSARY FOR GERMINATION What are the conditions necessary for seed germination? Seeds can easily be destroyed by unfavourable conditions such as excessive heat, cold or animals. Seeds need certain conditions to germinate and grow. Some of these conditions are external, for example water, oxygen and suitable temperature while others are internal such as enzymes, hormones and viability of the seeds themselves.   Water A non-germinating seed contains very little water. Without water a seed cannot germinate. Water activates the enzymes and provides the medium for enzymes to act and break down the stored food into soluble form. Water hydrolyses and dissolves the food materials and is also the medium of transport of dissolved food substances through the various cells to the growing region of the radical and plumule. Besides, water softens the seed coat which can subsequently burst and facilitate the emergence of the radicle.  … Read More »SEED GERMINATION CONDITIONS

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