Determine the relationship between light intensity and the rate of photosynthesis in spinach leaves.

Abstract: This study was undertaken to determine the relationship between of light intensity and rate of photosynthesis in spinach leaves. Rate of photosynthesis was determined at pH 7, 0.2% NaHCO3, room temperature, and under white light using light intensities of 2200, 4250, 5300, 14400, 20600 lux. The amount of oxygen production was determined after five minutes at each light intensity. Spinach leaf segments were infiltrated with 0.2% NaHCO3 and made to sink in solutions of 0.2% NaHCO3 so that rate of oxygen , production could be estimated from the rate at which the leaf segments floated. The rate of oxygen production increased relatively rapidly at lower light intensities but leveled off at intensities greater than 5300 lux, suggesting that light intensity is a limiting factor of photosynthesis below 5300 lux. At light intensities greater then 5300, however, light intensity is no longer limiting. Instead other factors such as amount of water, NaHCO3, chlorophyll, and other reagents of photosynthesis become limiting. Introduction: Photosynthesis is a process that underlies all life on Earth. It is essential in creating the sugars that sustain life. By converting light energy into chemical energy in the form of carbohydrates, it not only sustains the life of photosynthetic organisms themselves (called autotrophs), but also provides food for the heterotrophs

  • Word count: 1311
  • Level: University Degree
  • Subject: Biological Sciences
Access this essay

Cerealor Sugar Case Studies.

Title: Cerealor Sugar Case Studies - Rice Date: 21.11.01 Botany Rice is a semiaquatic, annual grass of the family Graminae, genus Oryza. It has a panicle inflorescence with one floret per spikelet (Marshall & Wadsworth., 1993). Furthermore, it has a perfect flower (both male and female), which consists of two interlocking hulls, six anthers and a single ovary. Most importantly, rice is naturally self-pollinating (Marshall & Wadsworth., 1993). Rice growers in some countries such as USA use pure line cultivars whereas most of them in China use hybridisation. Taxonomy Cultivated rice is referring to either Oryza sativa L. or Oryza glaberrima Steud (Marshall & Wadsworth., 1993). However, O. sativa is the predominant species and O. glaberrima is grown only in Africa on a limited scale (Marshall & Wadsworth., 1993). Oryza sativa is a tremendously variable species whish has worldwide distribution. Kato et al. (1928) classified these varieties into indica, the tropical race and japonica types, the temperate race. However, Morinaga (1954) proposed another group called javanicas. Several authors have ranked javanicas at the same taxonomic level as indicas and japonicas. (Singh et al, 2000) Domestication The date and geographical location of the first cultivated rice (Oryza sativa L.) is unclear. Nonetheless, domestication of

  • Word count: 1604
  • Level: University Degree
  • Subject: Biological Sciences
Access this essay

The combination of constant warmth and abundant moisture of the tropical regions demonstrates a successful environment for many plants and animals.

Sex and the tropics The tropical forests have their origins almost 200 million years ago, during the early days of dinosaurs. The continents were huddled together in a giant super-continent called Pangea. Gradually the Pangea started breaking off giving rise to separate continents. Through the process of division and development of the territories the ecosystem also took its course of progression. Thus the forest monkeys that evolved in the old and new worlds, while coming from the same ancient stock and living similar lives are now anatomically quite distinct. Similarly, lemurs survived only on Madagascar, partly because the island had no large predators. We also examine the evidence that Cactoblastis, cactus moth, has been rather successful in Australia, yet caused so many problems in North America. To capitalise the response we must note that Australia has no native cactus species, and so far the moth has not attacked any other type of plant. In areas where there are other native species of Opuntia, the exotic moth is destructive and unfavourable. Classes of organisms introduced to regions beyond their original ranges are known to achieve much greater population densities in comparison with their origins. The pending explanation explores the fact of no predators occupying the newly attained territory. Although the motion carries then the introduction of predators and

  • Word count: 1417
  • Level: University Degree
  • Subject: Biological Sciences
Access this essay