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GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
Triple Award Science, commonly referred to as Triple Science, results in three separate GCSEs in Biology, Chemistry and Physics and provide the broadest coverage of the main three science subjects. The qualifications are offered by the five main awarding bodies in England; AQA , Edexcel , OCR , CIE and Eduqas .
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
The phototropins trigger many responses such as phototropism, chloroplast movement and leaf expansion as well as stomatal opening. [5] Not much was known about how these photoreceptors worked prior to around 1998. The mechanism by which phototropins work was elucidated through experiments with broad bean (Vicia faba).
For GCSE Science the old single-award ‘science’ and ‘additional science’ options are no longer available, being replaced with a double award ‘combined science’ option (graded on the scale 9–9 to 1–1 and equivalent to 2 GCSEs). Alternatively pupils can take separate qualifications in chemistry, biology and physics.
Leaves of most plants include a flat structure called the blade or lamina supported by a network of veins, a petiole and a leaf base; [1] but not all leaves are flat, some are cylindrical. [citation needed] Leaves may be simple, with a single leaf blade, or compound, with several leaflets.
Anatomy of a eudicot leaf The plant cuticle is a layer of lipid polymers impregnated with waxes that is present on the outer surfaces of the primary organs of all vascular land plants. It is also present in the sporophyte generation of hornworts , and in both sporophyte and gametophyte generations of mosses . [ 2 ]
The nodes are the points of attachment for leaves and can hold one or more leaves. There are sometimes axillary buds between the stem and leaf which can grow into branches (with leaves, conifer cones, or flowers). [2] Adventitious roots (e.g. brace roots) may also be produced from the nodes. Vines may produce tendrils from nodes.