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International Baccalaureate: Biology

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  • Marked by Teachers essays 11
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  1. Atomic structure for Biochemistry revision poster

    * There are 3 types: 1)Ionic bond: metal + non- metal (ex: NaCl, BeF2) and 2)Covalent bond: non-metal + non-metal (ex: O2, H2, N2) and 3)and 3)Polar Covalent bond: between 2 non-metals/metals, electrons are not shared equally.(ex: HCl) 1)London Forces ?Weakest, between atoms and molecules, Formed temporary by uneven number of electrons 2)Dipole-Dipole Forces ?between polar molecules ? positive end of one molecule attracts negative end of another molecule --Stronger than London forces 3)Hydrogen Bonds ?Strongest force ? between N, O or F of one molecule AND H of another.

    • Word count: 622
  2. Should CRISPR-Cas9 be used to revive extinct species?

    Although this method speeds the outcomes but is often misguided as it results in creating species that are not genetically diverse and incapable of adapting whenever there was any change in its environment. https://lh6.googleusercontent.com/FfAyVb31AH75JDOsznD5vlkCz27BO1jaFManXNRVpEHuwaWy4k--J-hX7mo9WaqTCggt8zvsubo6BZsIQec_Y_h9FmQKfjO6k4qa-aqeuxoj1uDJLpvzLK3RXrdP4TMh2pywZMZaklzup5j0Iw However, Scientists took other innovative approaches to fix the damage and revive extinct animals through gene-editing techniques. With the genetic engineering technology CRISPR-Cas9, researchers have discovered a way to reconstruct and edit DNA and restore the earth's natural restoration and function. CRISPR or (Clustered Regularly Interspaced Short Palindromic Repeats)

    • Word count: 1295
  3. Effect of Incandescent, Fluorescent and LED lights at 900 lumens on the concentration of vitamin C content in oranges and their effectiveness on metabolic efficiency

    Incandescent generate light by use of filaments and when power is applied, the filament glows generating heat and therefore light. Due to incandescent bulbs hot filament, they produce a continuous spectrum as all wavelengths of lights are present (Fielder 1). On the other hand, led produces lights through a cold process as it is stimulated by electron movement, hence creating photons, therefore, visible light and its wavelength is the only thing emitted by led bulbs (Lighting Division 1). Fluorescent lighting uses electricity to excite mercury gas and in the process emits ultraviolet light (Nave).

    • Word count: 6452
  4. Environmental Mangement - Upland Burning in Ireland and the Effects of the Heritage Bill 2016.

    The Heritage Bill 2016 will also Acts amend and extend the Wildlife Act 1976 and outline the powers issued to the authorized bodies under the Act. Provisions will also be made in the Bill to amend the Canals Act 1986 (Department of Arts, Heritage and the Gaeltacht, 2016). The Bill comes as a manifestation of the Irish Government?s poor record in listening to the cohorts of people who value our natural heritage. This is evident in the lack of scientific rationale to support these changes (birdwatchireland, 2017).

    • Word count: 3429
  5. River Thame Investigation How does the distribution of mayfly larvae depend upon the rate of flow of the river

    Variables: Independent ? speed of the stream Dependent ? number of mayfly larvae Controlled ? number of times data collected at each site, how the samples are collected ? kick sample and speed probe, transect across the stream at three places, data collected on the same day ? similar weather conditions. Method Materials: Speed probe from field centre, macro invertebrate net, Wellington boots, meter ruler, string, temperature probe The stream was sampled at the place it enters the field centre, where there is a meander and as it leaves the field centre ? just after a weir.

    • Word count: 1271
  6. Causes of Alzheimers Disease

    Plagues are clusters of protein fragments called beta-amyloid that are built up between the nerve cells. Tangles are made up of twisted strands of protein called tau. http://thebrain.mcgill.ca/flash/d/d_08/d_08_m/d_08_m_alz/d_08_m_alz_1a.jpg Beta-amyloid is a fragment of a protein found in the neuron?s cell membrane called amyloid precursor protein (APP). APP is a transmembrane protein, which means the APP molecule passes through the cell membrane of neuron. In order for beta-amyloid to be released from the APP molecule, two enzymes must be involved which are beta-secretase and gamma-secretase. http://thebrain.mcgill.ca/flash/d/d_08/d_08_m/d_08_m_alz/d_08_m_alz_1b.jpg First, beta-secretase cut the peptide chain of APP outside the cell membrane at a certain length.

    • Word count: 715
  7. What are the uses of enzymes to diagnose a disease?

    To diagnose whether a patient has a disease, the doctor will take some blood in order to look for abnormal amounts of specific enzymes in the blood and then measure the plasma levels of the enzyme. Below is an image illustrating this. (Figure 1 taken from ?Clinical Enzymology?) Higher levels intracellular enzymes indicate cell damage as enzymes are meant to be inside the cells. If you find them in the plasma that means the cell walls have been damaged. Although if someone has low levels, it could also simply be because of genetics or due to the fact that it is natural change with age.

    • Word count: 1120
  8. Comparing the Sexy Sons Hypothesis and the Pathogen Avoidance Models Effects on s****l Selection

    The pathogen avoidance model states that females select for males with secondary s*x traits in order to distinguish between the diseased and the healthy males in order to stay safe from pathogens. Both theories are widely used to explain many evolutionary trends, but are they mutually exclusive? It is possible that both theories are correct in certain scenarios. However, one must look into the mechanisms of both in order to find out. Overview of Sexy Sons Hypothesis The sexy son hypothesis which was popularized by Ronald Fisher is currently stated as a possible explanation for the great diversity of ornamental traits in animals.

    • Word count: 4422
  9. Designing an Osmotic Potential Experiment with Potatoes

    I will also be setting up an experiment to show the mass change of the vegetables in each of the solution, and trying to find the osmotic potential of the vegetable. Hypothesis. According to particle theory, water molecules are in constant motion. As they move, they hit the membrane and create a pressure against the membrane called the water potential. Solutions with a low water potential have a high solute (osmotic) potential. Therefore, solutions with a high water potential have a low solute (osmotic)

    • Word count: 1923
  10. Genetically Modified Organisms Essay

    With the world?s population expected to reach 9 billion by 2050 demand for critical resources such as proteins continue to exceed supplies. Scientists are close to developing and engineering a genetically modified salmon. Genetically Modified organisms (GM or genetically modified organisms) are organisms or plants with altered DNA, giving them greater resistance to pesticides and herbicides and improved nutritional content. GM foods were originally intended to reduce the diseases and pesticides on crops, leading to a larger output of crops for a cheaper price.

    • Word count: 2042
  11. Investigating the Effects of Salt on Seed Germination

    The dependent variable (the variable being measured): The dependent variable is going to be the percentage of seeds that germinate over one week in each petri dish/NaCl solution. We will count the total number of seeds in each petri dish and after one week; count the number of seeds that germinated so that we can calculate a percentage. The control variables (the variables kept the same): The other variables, which we need to keep constant, are: * The same number of seeds used for each petri dish (10 seeds).

    • Word count: 2728

IB Biology is the study of living organisms. The four basic concepts which run through the course are: evolution, equilibrium within systems, universality versus diversity, and structure and function. These concepts give the student a strong foundation upon which other detailed knowledge can be built. You will also be completing a significant amount of practical work and an experimental approach is strongly emphasised.

Assessment is both externally and internally organised. The external examinations are a mixture of multiple-choice, short answer and extended answer tests.The extended answer examinations require you express yourself in a concise and scientific manner and some great examples of these IB Biology essays can be found on Marked by Teachers. Science can bring enormous benefits to societies and you will be encouraged to become a responsible and ethically minded scientist.


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