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International Baccalaureate: Biology

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  • Marked by Teachers essays 11
  • Peer Reviewed essays 1
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  1. Marked by a teacher

    Neurology and Behaviour. Focus question: Is there an increase in the perception and rating of disgust in females rather than males?

    5 star(s)

    These signals are then combined by the different receptors in order to create what individuals perceive as smell. Olfactory receptor neurons in the nose are different to other neurons due to their short lifespan however regenerate on a regular basis. (Moran, 2007) Vision however is the ability of the eye to focus and detect light using the photoreceptors located on the retina of each eye. The photoreceptors sense and encode the patterns created by light found in the individuals surroundings. These photoreceptors are sensory neurons and the axons of particular retinal ganglion cells start from the back of the eyeball in the individual's optic nerves and then following the central nervous system to reach the brain where the information is then processed.

    • Word count: 4552
  2. Marked by a teacher

    Experiment to investigate the effect of different antibiotics on the bacteria Bacillus subtilis:

    4 star(s)

    Gram-positive organisms normally do not have the outer membrane, whereas Gram-negative organisms do. Gram-positive bacteria include many well -known genera like Streptococcus and Bacillus. Most pathogenic bacteria in humans are Gram-positive organisms and these are used to manufacture antibiotics. Bacillus subtilis, also known as the hay bacillus or grass bacillus is a Gram- positive bacterium, which is mostly found in soil. Bacillus subtilis is not a human pathogen and it can contaminate food but rarely causes food poisoning. Bacillus subtilis spores can survive the extreme heat during cooking and Bacillus subtilis is responsible for causing a sticky, stringy consistency in spoiled bread dough.

    • Word count: 748
  3. Marked by a teacher

    Osmosis Internal Assessment (Biology)

    4 star(s)

    to the area of lower water concentration (potato cell). However, as the duration given for osmosis to occur increases, the volume of fluid in the cell will increase as water continually enters the cell, increasing its turgidity (when pressure inside the cell increases as the volume of its contents increases). Eventually, the cell wall will be stretched to the maximum, achieving full turgor, which will then force water back out of the cell due to the high pressure within the cell.

    • Word count: 2612
  4. Marked by a teacher

    Biology: Lab report Germination

    4 star(s)

    seeds are placed in a hot environment, then their germination will be positively affected compared to cress seeds grown in a normal light environment because seeds Variables The independent variables in this experiment were the light and the temperature. We put some of the cress seeds under a bright light and others in a dark cupboard. As for the temperature, we put some cress seeds in a stove and others in a fridge. The dependent variable in this experiment is the germination.

    • Word count: 1944
  5. Marked by a teacher

    The effect of temperature on amylase activity

    4 star(s)

    After adding in iodine, when amylase breaking down starch, less and less starch will be present and the color of this solution will become lighter and lighter. Equipments 0.1% Amylase 0.5 ml 1% Starch 5ml 10 Test tubes and rack Iodine solution Syringes Marker pen Electronic water bath set at 20, 30, 40, 50, 60 and 70ºC with thermometers Dropper Thermometer Beakers Spot-plates Stopwatch Controlled variables Same temperature of amylase and starch solution This can ensure that amylase can react with starch solution in the same temperature, a more accurate result can be received Same amount of amylase and starch

    • Word count: 1232
  6. Marked by a teacher

    The Effect of Temperature on Enzymatic Activity. Aim To investigate enzyme activity of yeast on glucose at different temperatures

    3 star(s)

    5 cm3 syringes x5 10 cm3 of 10% yeast solution 15cm3 of 2% glucose solution 1 thermometer 2 hotplates Stopwatch Ice cubes x 6 400mL water Observations chart & pen Method 1. 1. Place 6 ice cubes and 80 mL of water into Beaker A 2. 2. Measure and record the temperature (should be around 10°C) 3. 3. Fill 3cm3 of glucose solution into the syringe and then in the same syringe insert 2 cm3 of the yeast solution 4.

    • Word count: 862
  7. Marked by a teacher

    Effect of substrate concentration on catalase activity (Biology IA)

    3 star(s)

    * 4% Hydrogen Peroxide Solution (5cm3) * 3% Hydrogen Peroxide Solution (5cm3) * 2% Hydrogen Peroxide Solution (5cm3) * 1% Hydrogen Peroxide Solution (5cm3) * 0.5% Hydrogen Peroxide Solution (5cm3) * Coloured Liquid * Distilled Water * 3x 20cm3 Syringes * 1x U-Shaped Tube (manometer) * 1x Stopwatch * 1x Retort Stand with clamps * 1x Rubber Bung * 1x Tube * 1x Forceps * 1x Scalpel * 1x Ruler * 1x White tile * 4x Plastic Containers * 1x Safety Goggles * 1 pair of gloves Procedure 1. The chicken liver was cut into pieces each measuring approximately 1cm by 1cm by 1cm.

    • Word count: 1206
  8. Marked by a teacher

    The Roles of ATP

    3 star(s)

    As far as it is known every living thing uses ATP as its primary source of energy, from bacteria to plants. At any instant in time a cell in the human body can contain about one billion ATP molecules, but this amount is used up quite quickly and is normally recycled straight away in the mitochondria where chemiosmotic phosphorylation occurs. One way that ATP is used is for muscle contractions, when you are running, walking, even me typing this essay, your body is using ATP to move muscles for movement, but not only movement, but it isn't only used for

    • Word count: 1166
  9. Marked by a teacher


    3 star(s)

    The cups used for the solutes must be completely dry before adding the solutes in. The same potato must be used to obtain all potato chips, in order to keep the water potential of the potato. The experiment must occur at room temperature. The same balance must be used, to achieve accuracy in measuring the mass. Equipment List: - Stop Watch - Electronic Scale - 1 whole potato - Cork Borer - 1 Piece of paper towel (cut into 5 pieces)

    • Word count: 1975
  10. Marked by a teacher

    Investigating the relationship between cell size and rate of diffusion

    Variables: In this investigation, the variable I am manipulating, the independent variable are the dimensions of surface area to volume ratio of the agar cube. The variable I am observing/recording, the dependent variable, is the rate of diffusion (NaOH turns the agar cube pink as it disperses into it). The controlled variables will be keeping the concentrations of the Sodium Hydroxide constant, to use agar jelly from the same batch (so the type of agar jelly is exactly the same), and to keep the time even for all cubes so the NaOH has the same amount of time to disperse into the cube.

    • Word count: 751
  11. Marked by a teacher

    The effect of Pectinase Concentraton on the production of apple juice

    By using a range of concentrations (1-5%) there should be a notable change in the results to show its effect in the production of apple juice as its concentration increases. Dependent - The volume of apple juice (ml) The volume of apple juice is the effect the concentrations have on and will vary depending on the concentration used and only due to the concentration. Control - To keep the experiment fair and ensure that the results are accurate, the following factors need to be kept the same: * pH - Different enzymes work better in different pH conditions as they have their optimum pH which allows them to react at different rates.

    • Word count: 1397
  12. Peer reviewed

    Enzyme Coursework. Investigation to find the effect of substrate concentration on the rate of an enzyme controlled reaction

    5 star(s)

    The rate of an enzyme controlled reaction are mainly affected by: temperature, substrate concentration, enzyme concentration and pH. By increasing the substrate concentration, there is a higher chance of a substrate colliding with an enzyme and subsequently reacting (as there is simply more substrate moving around in the solution). Increasing the substrate concentration further will cause the rate of reaction to plateau when all of the enzymes' active sites are constantly in use - at which point the enzyme concentration can be considered a limiting factor.

    • Word count: 1640
  13. Should Animals have the same rights as Humans? Both animals and humans exhibit behaviours in reaction to their environment. Some of this behaviour is learned and some instinctive.

    Instinctive behaviour is automatic and involuntary, it is not controlled by forethought and not based on prior experience. For example, sea turtles which have just hatched on a beach will automatically move toward the ocean though they have never experienced being in that environment. A further example of instinctive behaviour can be seen in woodlice. Woodlice cannot control or regulate their water level which means they can dehydrate quickly. Instinctively woodlice move to dark damp areas. We conducted an experiment to demonstrate this behaviour. We placed the woodlice in a box divided into four segments as follows: Dry / Light Dry / Dark Damp / Light Damp / Dark After leaving the woodlice for a short amount of

    • Word count: 7423
  14. Biology - HIV Prevention and Transmission

    Normally a hunter's body could have fought off the SIV, but in a few cases it adapted to its new human host and evolved into HIV. The Contaminated Needle Theory is an extension to this hunter theory. In Africa the enormous amount of needles needed to give inoculations and other medication would have been very costly. It is likely that one syringe would have been used to give multiple people injections without sterilizing the needle. This resulted in spreading HIV rapidly.

    • Word count: 924
  15. Biodiversity Investigation The aim of this investigation is to determine plant biodiversity of both land next to the pond and land away from the pond to discover what the different in plant biodiversity will be. The degree of biodiversity achieved using t

    species within the area Aspect 2 Controlling Variables The Controlled Variables: -Control of Quadrats -The quadrats' length is 100 centimetres by 100 centimetres and is used for sampling all the directed areas to sample -Quadrats are also set consistently in the same position to ensure uniformity; determined by the middle 50 cm point facing the shoreline direction -Quantitative counting within the quadrat of different species and the quantity of the given species -Control of Sampling/Measuring Area -Determined circumference of the lake; assigned every metre (location)

    • Word count: 2205
  16. The Effect of Temperature on the Rate of Activity of the Enzyme Catalase in Hydrogen Peroxide Experiment.

    Rate of Enzyme Catalase, Mean Relative Rate of Enzyme Catalase and Standard Deviation for Mean Relative Rate of Enzyme Catalase for Filter Paper Disk coated with Catalase Enzyme exposed to 3% hydrogen peroxide Solution in Culture Tubes Target Catalase Enzyme Temperature (°C) Trial Number Relative Rate of Enzyme activity of catalase (/s) Mean Relative Rate of Enzyme activity of catalase (/s) Standard Deviation for Mean Relative Rate of Enzyme activity of catalase (/s) 0 1 0.25 0.28 0.044 2 0.34 3 0.29 4 0.28 5 0.23 20 1 0.29 0.29 0.033 2 0.28 3 0.32 4 0.24 5 0.32 40

    • Word count: 2831
  17. Research Question: Does the influence of human beings, have an impact on the environmental gradient of species diversity found within Pruhonsky Haj?

    This variable is a factor of observation as explained in the Research Question. Steps 2-6. Dependent: Diversity (certainty) -This variable is dependent on the human impact. A change in level of human impact will affect this variable, and since we are differentiating between the ranges of various diversity according to the human impact, it will ultimately affect the data. Steps 2-8. Controlled[2]: Location (Pruhonsky Haj), Measuring Device (Quad-rat) -This variable must stay the same throughout the experiment. A change in the location would introduce alternate factors that could affect the dependent variable, like various different conditions such as weather and population factors, that might not have been present in the current location.

    • Word count: 709
  18. Do people that play instruments have longer hands than people that do not play instruments?

    We also decided to limit it to 11th graders since hand sizes generally increase with age so this would allow us to gather more accurate results. The null hypothesis is "There is no significant difference between hand lengths for instrument players and people that don't play instruments." Variables Independent: Whether they play an instrument or not Dependent: Hand length Controlled: Gender (Male), Measurement Method (Ruler), Grade (11th graders), left hand only Materials 1 Ruler for measuring 1 Notebook for recording data 1 Pencil for recording data Method (Procedure)

    • Word count: 1146
  19. Long QT Syndrome. Long QT syndrome is a rare heart rhythm disorder. It causes a very rapid heartbeat.

    With every heartbeat, and electrical signal is spread from the top of the heart to the bottom. When the signal travels is causes the heart to contract and pump blood around the body. When there is a problem with the heart's electrical system it cases an arrhythmia, like in long QT syndrome. Implantable cardioverter defibrillators use electrical shocks to treat the potentially fatal arrhythmias that occur in the ventricles of the heart. People with long QT syndrome often faint because ventricular arrhythmias mean that the heart cannot pump blood well. The electric shocks treat the arrhythmias and prevent death.

    • Word count: 1368
  20. When does childhood obesity become abuse? Obesity is plaguing Americas children with a multitude of health problems

    in children, due to the prevalence of obesity," said Jessica Bartfield, MD, internal medicine and medical weight-loss specialist at Gottlieb Memorial Hospital, part of the Loyola University Health System. When and where are we going to draw the line between poor choices and out right abuse. "So many children are obese and the majority is to do with the cost of fresh foods, versus their shelf life- as well as lower income mothers loving their children with the only thing they can afford to give, food", says Ron Jones, a corporate wellness expert based in Atlanta and Los Angeles,.

    • Word count: 853
  21. Investigation into the Enzyme Activity of Catalyze in the Decomposition of Hydrogen Peroxide while exposed to different substrate concentrations

    In each trial a 1 cm³ (+/- 0.05 cm³) potato was used, and the different amounts of hydrogen peroxide used were 0.50, 0.75, 1.00, 1.25, and 1.5 ml (+/- 0.5 ml). To further catalyze the experiment and to make the oxygen released clearly visible in the form of bubbles both 10 grams (+/- 0.05 grams) of potassium iodide and 0.5 ml (+/- 0.5 ml) of detergent were added to the potato before the addition of the hydrogen peroxide. Quantative Data TABLE OF RESULTS Amount of Hydrogen Peroxide (ml +/- 0.05 ml)

    • Word count: 1048
  22. Modelling Surface Area to Volume Ratio in Cells with Agar Cubes

    Single celled organisms can survive as they have a large enough surface area to allow all the oxygen and nutrients they need to diffuse through. Larger multi celled organisms need specialist organs to respire such as lungs or gills. (http://www.neiljohan.com/projects/biology/sa-vol.htm) A cell is a metabolic compartment where a multitude of chemical reactions occur. The number of reactions increase as the volume of metabolic volume within a cell increases. (The larger the volume the larger the number of reactions) All raw materials necessary for metabolism can enter the cell only through its cell membrane.

    • Word count: 2100
  23. Lab of genetics.You will determine your phenotype and try to determine your genotype for the traits listed below.

    People who have a dominant gene, B, may have different shades of brown, hazel, or green eyes. Check your eye color. 2. Record your phenotype and genotype in the table. (Remember that you may not be able to determine your exact genotype; in that case, record B_ in the table). * A Widow's peak is a hairline that forms a downward point in the middle of the forehead. This is caused by a dominant gene, W. A smooth hairline is caused by the recessive genotype ww.

    • Word count: 1628
  24. Bilharzia. Schistosomiasis, commonly known as snail fever, bilharzia and bilharziasis, is a disease caused by parasitic worms.

    and Schistosoma haematobium (causes urinary schistosomiasis). People get infected when they come into contact with contaminated ponds, streams and rivers inhabited by snails carrying the parasite. It is also common in local waterways polluted with human waste. Normal daily activities for domestic, personal and professional can lead to infection, such as swimming, bathing, fishing, irrigation, rice cultivation etc. Human schistosomiasis is confined to freshwater, and therefore cannot be acquired from saltwater. All ages are at risk for infection, whether travelling or living at endemic areas and freshwater exposure.

    • Word count: 2165
  25. Yves Engler explains in his article, Obesity: Much of the Responsibility Lies with Corporations, that corporations are little to absolutely no help with resolving the obesity epidemic that is running ramped in todays society.

    He shows that year after year the number of obese people including adults and children are on a steady incline, and that the advertisements of unhealthy foods grow stronger each year to simply reel society in to buy and eat their products. Not only food corporations are the problem, the governments along with corporations that have no relevance to food have done little throughout the decades to try and stop unhealthy habits, but in retrospect only have been encouraging unhealthy activity in adults and young people today by not setting limits and restrictions to what is being served throughout the schools, and in everyday life.

    • Word count: 1420

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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