Higher Biology Respiration Essays
The citric acid cycle occurs after glycolysis only if oxygen is present (it is an aerobic process). The pyruvate enters the matrix of the mitochondria and carbon dioxide is removed.
The removal of carbon forms an acetyl group. This acetyl group combines with coenzyme A to form acetyl coenzyme A.
Acetyl coenzyme A combines with a molecule called oxaloacetate to form citrate (this is where the citric acid cycle gets its name).
The cell regenerates oxaloacetate by breaking down citrate using an enzyme-controlled series of reactions.
Intermediate molecules are formed because the enzymes remove carbon (in the form of carbon dioxide) and hydrogen/electrons. The carbon dioxide is released as a by-product. The citric acid cycle also results in the creation of ATP.
Dehydrogenase enzymes remove hydrogen ions and electrons from intermediates, which are passed to coenzymes NAD or FAD (forming NADH or FADH2). The high-energy electrons are passed to the electron transport chain.
The Higher Biology Course provides a broad based integrated study of a selected range of biological topics which build on previous study. The course provides the opportunity for learners to acquire a deeper understanding of DNA and the genome and its applications, metabolism and how it
relates to organism survival as well as the human population and its interaction with the world around it.
DNA and the genome
This unit explores the molecular basis of evolution and biodiversity. Students will look at DNA, its organisation, replication and applications. Gene expression will be studied as well as protein expression and consequentially the unity of life. Differentiation, meristems, stem cells, ethical issues, genome changes, evolution and classification and the variety of roles played by organisms will also be considered.
Metabolism and survival
Central metabolic pathways and the challenges of maintaining metabolism for survival as well as the flexibility of the environmental and genetic control of metabolism in microorganisms is studied. The role played by enzymes, cellular respiration and ATP are key concepts. Adaptations for metabolism maintenance, survival and extreme conditions are also covered as is microbe manipulation
Sustainability and Interdependence
This unit looks at the complex interactions between many interdependent entities. Consideration is given to the human population, food production, photosynthesis, breeding of animals and plants, crop protection and animal welfare. Students will also learn about inter-relationships and dependence and social behaviour. Biodiversity studies attempt to catalogue and understand the human impact on patterns of biodiversity and extinction in our Biosphere.