International Baccalaureate: Biology
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554 International Baccalaureate Biology essays
- Marked by Teachers essays 11
- Peer Reviewed essays 1
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.
- Essay length: 4552 words
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.
- Essay length: 748 words
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.
- Essay length: 2612 words
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.
- Essay length: 1944 words
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
- Essay length: 1232 words
The Effect of Temperature on Enzymatic Activity. Aim To investigate enzyme activity of yeast on glucose at different temperatures3 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.
- Essay length: 862 words
* 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.
- Essay length: 1206 words
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
- Essay length: 1166 words
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)
- Essay length: 1975 words
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.
- Essay length: 751 words
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.
- Essay length: 1397 words
Enzyme Coursework. Investigation to find the effect of substrate concentration on the rate of an enzyme controlled reaction5 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.
- Essay length: 1640 words
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
- Essay length: 7423 words
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.
- Essay length: 924 words
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)
- Essay length: 2205 words
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
- Essay length: 2831 words
Most of polar molecules can't cross the lipid membrane freely, as they are too big to cross the membrane, like sugars and proteins. Whereas, water molecules are polar, but they can pass through the membrane freely, since they are small enough. This case of diffusion involves the movement of water molecules crossing the membrane called osmosis. (Factors Affecting the Rate of Osmosis, 2010) "Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration."
- Essay length: 3165 words
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: 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.
- Essay length: 709 words
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)
- Essay length: 1146 words
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.
- Essay length: 1368 words
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,.
- Essay length: 853 words
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)
- Essay length: 1048 words
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.
- Essay length: 2100 words
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.
- Essay length: 1628 words
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.
- Essay length: 2165 words