The effect of temperature on the survival of yeast cells
Biology Planning Exercise - The effect of temperature on the survival of yeast cells Aim: To investigate the lowest temperature that kills all the yeast cells in a sample of yeast. Scientific Background Enzymes tend to work best at an optimum temperature (the temperature at which the reaction is most rapid) which varies depending on the enzyme and the conditions it requires. The general rule for enzymes is the higher the temperature the faster the reaction. However this is only up until a certain point where the enzyme begins to denature. An enzyme denatures when the temperature is above the optimum temperature for the enzyme and it begins to vibrate violently so all the bonds which make up the tertiary structure of an enzyme break therefore changing the shape of the enzyme making it unable to function. (The enzyme which catalyses this reaction is dehydrogenase) Enzyme performance depends on the active site, an area on the enzyme molecule in which the substrate fits into. This is what makes enzymes very specific as each enzyme only catalyses one reaction. Enzymes are tertiary globular proteins and their structure is held together by different types of bonds the strongest; the disulphide bridge which forms when two sulphur containing cysteine residues react together. Hydrogen bonds are also present in enzyme structure which bind the substrate to the active site and are
Ecology and Ecosystems.
Ecology Ecosystems undergo changes in their structure and function as time passes. Some of these changes are minor and only affect a small area, others are the cause of major changes in the species present and affect the ecosystem as a whole. Major changes can be caused by changes in climate, external factors such as fire, trampling or pollution and development due to the system itself. Succession is a result of these changes and is defined as a series of progressive changes in an area with one community replacing the other until a climax community is created. A climax community consists of plants and animals, the animals present are dictated by the plants available. There will normally be a dominant species of plant and animal or a number of co-dominant species, these species are normally the most numerous and have the greatest biomass. The climax community is normally seen as the ultimate development of the ecosystem. There are 2 types of succession; primary and secondary. Primary succession is the colonisation of an area which has not supported an ecosystem before, eg sand dunes, volcanoes and new ponds. Secondary succession is ecological succession in an area which has supported an ecosystem whose development to a steady state has been prevented by inhibitory factors such as grazing or fire. When the inhibitory factor is removed secondary succession takes the
descrive the biological importance of water
Making up between 70 and 95% of the mass of a cell, and covering over three quarters of the planets surface, water is one of the most important compounds on this planet. A single water molecule is made up of one oxygen atom covalently bonded to two hydrogen atoms. Covalent bonds are formed by sharing electrons between the outer shells of the oxygen and hydrogen atoms. However, what makes water so unique is the fact that it remains a liquid at room temperature. Many similar sized molecules (ammonia has a molecular mass equal to that of water-18) remain in their gaseous form at this temperature. The reasons for this unique thermal property are hydrogen bonds. The nucleus of an oxygen atom is larger and therefore contains many more protons that that of a hydrogen atom. Therefore, the electrons shared in the covalent bond between the oxygen and hydrogen atoms have a greater affinity for the oxygen atom than either hydrogen atom. This pulls the electrons closer to the oxygen atom and away from the hydrogen atoms resulting in the oxygen atom having a slightly negative charge and the hydrogen atoms developing slightly positive charges. These slight charges mean that when water molecules are close together, positively charged hydrogen atoms are attracted to the negatively charged oxygen atoms of a different water molecule. These attractions are known as hydrogen bonds and
Experiment examining the effect of mineral deficiencies on plant growth.
Core Practical Write Up Investigate the effect of plant mineral deficiencies Planning Dependant variable: we are going to be observing the changes in root length, plant body length, number of living leaves and colours of leaves. Independent variable: we will be varying the mineral deficiency in the agar jellies. There will be five ager jelly dishes. There will be one dish containing all nutrients; one dish lacking magnesium; one dish lacking nitrogen; one dish lacking calcium; and one without any of those nutrients. Controlled variables: We are going to be controlling the type of plant growing in the agar jelly. We are using Mexican hat plantlets for our experiment. The time between each measurement is going to be controlled, when one plant is observed all the other plants will also be observed so plants have equal amounts of time to grow. Hypothesis: From what I have learnt in class when a plant lacks nitrogen it should be unable to grow larger because amino acids production will be reduced. A plant lacking magnesium would be unable to produce chlorophyll therefore the leaves would become yellow coloured and not so green. The plant lacking calcium would have a stunted growth due to the role of calcium ions in the structure of the cell walls and membrane permeability. I expect the plant lacking all nutrients to have all three of these properties and possibly just die
Human Impact at Hastings Point Hastings Point is a small settlement on the coast just south of Tweed Heads and the NSW border.
Human Impact at Hastings Point Hastings Point is a small settlement on the coast just south of Tweed Heads and the NSW border. The effects have been largely felt at Hastings Point; human impact has been the cause of a great deal of damage to the abiotic and biotic factors of the surrounding environments such as the mangroves, rocky shore, and sand dunes. Hastings Point in the last 5 years to 10 years has been subject to a great deal of negative development, corrupt council members which has resulted in sewage flooding, dredging , sewage into the creek, mangrove degradation, destruction of rocky shore environments and longshore drift. The mangroves are being destroyed for development; the rocky shores are suffering from people taking too many sea urchins and oysters which destroy the wildlife. The sand dunes have been degraded by humans walking all over the dunes which wear them down and have caused them to be so far back from the water. (3), (1) and (4) One of the main concerns of human impact in Hastings Point is the residential and the commercial development that was approved by the corrupt council members and the development areas never underwent environmental checks which has led to a great deal of damage. When unchecked development happens and sewage pipes get cracked, eutrophication can happen and decaying algae can build up and cause the water which the sewage has
The Ways in Which Organisms Use ATP
The Ways in Which Organisms Use ATP ATP, the standard abbreviation of Adenosine-5'-triphosphate is a multifunctional nucleotide used in cells as a coenzyme, and can be best summarised as the standard energy currency universal to all organisms, and as such is utilised in metabolic (and other) processes throughout the cells of organisms, and is highly adapted to its function therein due to its high instability in aqueous solutions (eg tissue fluid) due to its easily hydrolysable phosphoannhydride bonds which when broken release a proportionally huge amount of energy. ATP is required during the contraction of skeletal muscle. ADP is released by the myosin head, this allows it to change shape thereby pulling the actin filament across itself. In order to detach the myosin molecule (for it to bind to a myosin binding site further along the actin) ATP binds to the myosin head, where it is hydrolysed to release ADP (which remains on the head) and inorganic phosphate. The energy released allows the myosin head to resume its normal position prior to the release of its ADP molecule, ready to bind further along the actin filament. Furthermore, ATP is utilised elsewhere within the same process, as it is used by carrier proteins on the membrane of the sarcoplasmic reticulum as a source of energy for the active transport of Ca2+ ions into the sarcoplasmic reticulum. It is when these
Succession is the progression of plant and animal species in an area from smaller simpler organisms to larger more complex organisms, eventually leading to a climax community.
Succession Introduction Succession is the progression of plant and animal species in an area from smaller simpler organisms to larger more complex organisms, eventually leading to a climax community. The climax community is reached when the species found in the area remain constant over time with few or no species being wiped out or starting to grow- there is an equal balance between births and deaths and gross primary productivity is the same as total respiration. The climax community exists as long as biotic and abiotic factors allow. Things which could devastate a climax community include forest fires and drastic changes in climate, or biotic factors like Dutch elm disease, a fungus transmitted by European and American bark beetles which killed millions of elm trees in the 1980's. The climax community arises in stages called seral stages. There are two types of succession, primary and secondary. Primary succession A primary succession is one that takes place in an area or piece of land which was not previously populated by other organisms. Examples of places where primary successions can take place include newly bared rocks, sand dunes, river deltas where fertile silt is deposited, hardened lava from a volcanic eruption or in a freshwater lake. A xerosere is the name given to a succession which begins on dry rock and the plants which grow there are called
AS Edexcel Biology - Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas).
The effect of caffeine on heart rate. Aim: To investigate the effect of caffeine on the heart rate of Daphnia (water fleas). Background Information: Plants produce caffeine as an insecticide. Cocoa in South America, coffee in Africa and tea in Asia has all been used as 'pick-me-up' drinks containing caffeine. These days caffeine is used in a wide variety of soft drinks such as cola to enhance flavours. In addition to this, stimulant drinks such as Red Bull and Boost also carry high levels of caffeine as well as some weight-losing drugs and medicines such as Aspirin. IN humans, caffeine acts as a stimulant drug, causing increased amounts of stimulatory neurotransmitters to be released. At high levels of consumption caffeine has been linked to restlessness, insomnia and anxiety, causing raised stress and blood pressure. This can lead to heart and circulation problems. Hypothesis: I think that the Daphnia's heart rate will rapidly increase when the caffeine solution is added. This is because increases the amount of neurotransmitters released in the body so everything in the body will be working at a faster rate because of these. Planning: -Risk Assessment: 1. I need to be aware of weils disease so I will not come in to direct contact with the pond water and regularly wash my hands thoroughly throughout the experiment. 2. I will need to constantly keep my glassware on
How caffeine affects daphnia heartrate
Aim: How caffeine affects the heart rate of Daphnia (water fleas) During this experiment we were examining the effects of different concentrations of caffeine on a type of water fleas called daphnia; the heart-rate is the dependant variable and the concentration of the caffeine is the independent variable. We tried to keep all of the other variables constant by controlling them. Such as the room temperature; the volume of caffeine; the type of water fleas ect. Our hypothesis is that as the caffeine increases so will the heat rate of the daphnia. This is because caffeine is a stimulant that increases the amount of neurotransmitters being released and therefore the production of the heart. Equipment: * A culture of Daphnia in a beaker of water * A microscope- with two cavity slides * Two dropping pipettes- one with a large mouth and one with a small opening * Cooled Distilled water * Cotton wool * Paper towels * A stop clock Method: . We picked out a couple of daphnia from the culture in the beaker with the pipette that has a big mouth. 2. Then, we got rid of the excess water, by squeezing the pipette to get rid of the extra water onto a paper towel. 3. Then, one of the daphnia was placed onto the small bit of wool which was on the cavity slide. 4. After that, we placed a small amount of cooled distilled water onto the second cavity slide before putting that
An Experiment to Show the Rate of Respiration In a Locust.
An Experiment to Show the Rate of Respiration In a Locust Aim The rate of respiration in an organism can be determined either by measuring the volume of oxygen taken in, or the volume of carbon dioxide produced. The aim of this experiment was to determine the rate of respiration of a locust using an instrument called a respirometer. Method * The respirometer consisted of 2 equal chambers- an experimental one containing the respiring organism, and a control one, containing an equal volume of non-respiring material (in this case a marble). * The 2 chambers were connected by a U-shaped manometer tube that had a diameter of 1mm, containing a coloured fluid (manometer fluid)- this differential respirometer ensured that any fluctuations in temperature or pressure affected both sides of the manometer equally and so they cancel each other out. * An equal volume of some soda lime (a carbon dioxide absorbing material) was added to each chamber. * I then left the apparatus in a water bath filled with water of approximately 32 degrees for about 5 minutes to allow it to reach the desired temperature. * I left screw clips A and B open at these times to allow air to escape as it expands. * I closed both screw clips after 5 minutes, allowing the experiment to start. * The carbon dioxide given off by the respiration of the locust was absorbed by the soda lime, hence a reduction in
