IGCSE Biology Paper-1: Specimen Questions with Answers 172 - 172 of 208

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Question 172



The diagram from X to Z shows the stages in the germination of a seed. The figures show the total mass at each stage.

Germination of a Seed

Which process causes the increase in mass between stage 1 and stage 2?


Choice (4)




Absorption of water








Resumption of embryo growth, called germination, is dependent upon a number of factors, but three are especially important: adequate water to re-hydrate the tissues, the presence of oxygen to support aerobic respiration, and a ‘’ physiological ‘’ temperature. Although many seeds will germinate over a wide range of temperatures, the optimum range for most seeds is 25◦C to 45◦C. The lower limit is highly variable, depending on the species. The upper limit reflects the temperature which denatures proteins. Water: it is extremely necessary for the germination of seeds. Some seeds are extremely dry and need to take a considerable amount of water, relative to the dry weight of the seed. But most seeds need enough water to moisten and not soak as it leaks away from a germination inhibitor in the seed. Water plays an important role in seed germination. It helps by providing necessary hydration for the vital activities of protoplasm, provides dissolved oxygen for the growing embryo, softens the seed coats, and increases the seed permeability. It also helps in the rupturing of seed and converts the insoluble food into soluble form for its translocation to the embryo.

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