In class, we have been studying the carbon cycle on earth and we learnt about global warming and why it is happening. The image below shows the carbon cycle that we created with a few classmates. After having learnt about the carbon cycle, we did an experiment in which we used a model of planet earth in order to see what happens when the level of carbon in the atmosphere increases. To do that, we used two big beakers with a little bit of water at the bottom; we put plastic film at the top of it to act as the atmosphere (so air cannot get in and out). Each beaker represented one planet earth. To represent the sun, we used a lamp that was shining equally above each beaker. Finally, we inserted carbon dioxide through a tube in one of the planet earths and not in the other in order to see what happens to the temperature (a thermometer was in the water since the start of the experiment). The photo below shows our experiment. After the experiment was finished, we found that the temperature of the water in the beaker with carbon dioxyde had risen by about 1degree C in 30 minutes. This means that we concluded that the rising level of carbon dioxide in our atmosphere leads to a rising temperature of the oceans which is causal for rising see levels (ice bergs melting). This explains global warming.
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We planted a cactus in a jar to see if it will survive for long. The jam jar has been completely closed and we are hoping that our plant can live in it's own little ecosystem.
We went out into nature to look at different types of organisms. The picture below is one of a ladybird that we found. They are heterotrophs as the feed on other living organisms. They are also detritivores as they digest internally. The next picture is one of a fungi. Mr.Lovat found a mushroom under a dead tree. Fungi is also a heterotroph as it feeds on other living organisms (wood in this case). It is a saprotroph because it obtains organic nutrients from dead organisms by external digestion. The last picture below shows a worm also found under a dead tree.
Worms are also heterotrophs as they eat things like bacteria and fungi in the soil. It is also a detritivore as it consumes nutrients using internal digestion. We investigated the rate of photosynthesis using different intensities of light.
Some groups decided to use different colour lights but my partner and I tested a strong light VS no light at all. To measure the rate of photosynthesis, we counted at the number of bubbles coming out of the water plant per minute. The bubbles coming out of the plant are oxygen bubbles which means that the more bubbles there are, the quicker photosynthesis is happening seeing as photosynthesis is WATER+CARBON DIOXIDE that uses LIGHT ENERGY to turn into OXYGEN+ENERGY. We found that the test tube left in an area with absolutely no light didn't emit any bubbles at all which means that photosynthesis does not work without light. We tested the effect different factors on the rate of respiration of maggots by measuring the amont of carbon dioxyde in the box the maggots were in.
We tested factors such as light, temperature and some students tested the effect of different musical styles on the rate of respiration of the maggots. This picture shows a model of a double stranded DNA that we created using sweets. It clearly shows the phosphate, the dioxyribose and the nitrogenous base. It also shows the bases and the hydrogen bonds (the sticks).
WaterWater is the only substance on our planet that occurs naturally is solid, gas and liquid form; the gaseous state of water is present continually in our atmosphere as water vapour. The liquid state is found everywhere in rivers, lakes, and oceans. The solid state of water, ice, is unique. Most liquids contract as they are cooled, because the molecules move slower and have less energy to resist attraction to each other. When they freeze into solids they form tightly-packed crystals that are much denser than the liquid was originally. Water doesn't act this way. When it freezes, it expands: the molecules line up to form a very 'open' crystalline structure that is less dense than liquid water. This is why ice floats. One of the reasons why life on earth can exist is because ice floats! If ice sank, than the oceans would over flow and all earth on our planet would be underwater.
Water covers about 70% of Earth's surface and it makes up 65-75% of our bodies (82% of our blood is water). Even though water seems boring - no colour, taste, or smell- all life as we know it is depend on water. The chemical composition of water is H2O - two hydrogen atoms and one oxygen atom are covalently bonded. Water molecules are polar, the hydrogen side of the molecule has a positive charge and the oxygen part of the molecule is negatively charged –these bonds are hydrogen bonds. This means that the positive end of the water molecule will connect with the negative end of other molecules. Water’s polarity allows it to dissolve other polar substances very easily, it’s a good solvent –there are more substances that can be dissolved in water than in any other liquid on earth-. Hydrophilic molecules dissolve in water because their polarity is stronger than the cohesive forced of the water, the water will hydrogen bong around theses polar substances. Glucose, amino acids, cholesterol, fats, oxygen and sodium chloride are transported in blood because they all dissolve in water and blood is made of 92 per cent water. A hydrophobic substance is a substance that doesn’t dissolve in water because it isn’t polar enough (non-polar) to come between the hydrogen bonds of water. Water has the highest cohesion of any non-metallic liquid, which means that water molecules stick to each other very well. Because of their polarity, water molecules are strongly attracted to one another, which gives water a high surface tension. The molecules at the surface of the water "stick together" to form a type of 'skin' on the water, strong enough to support very light objects. This high cohesion property allows some bugs and the “Jesus lizard” to walk on water. Surface tension causes water to clump in drops rather than spreading out in a thin layer. It also allows water to move through plant roots and stems and the smallest blood vessels in your body - as one molecule moves up the tree root or through the capillary, it 'pulls' the others with it. Water also has adhesive properties –adhesion is attraction between two different molecules- for example water and glass, water spreads out on glass instead of beading up. These two properties mean that water can defy gravity using capillary action. Water has a very high heat capacity which means that the oceans don’t change temperature very easily so they are like giant heat sinks that regulate the temperature and climate of our planet. The high heat capacity of water is also very useful to help cool down organisms by sweating. The daily mail published an article called “Wealthy background can raise the risk of cancer for teenagers” in June 2008.
The research starts by claiming that “children and teenagers from wealthier families may be more likely to develop cancer”. The study explained that, in contrast to cancers in adults, the number of new cases and deaths in youngsters is more likely to be lower in relatively deprived areas. Although this article has proof- to a certain extent- of the claims that it makes, the proof isn’t always reliable. For example, they provide their evidence using “recent studies” but do not explain who did the studies and how the study was done which mean we cannot evaluate the reliability and accuracy of the studies mentioned. 'Results show that in contrast to cancers in older people, incidence and mortality decreases with increasing deprivation in young people.’ Is a claim made after using the phrase “recent studies have been made”. This can be seen as unreliable as we do not know what studies the article is talking about and therefor the claims about cancer cannot be confirmed. Even though some of the claims here are unjustified, this article does give some reliable evidence for so of its claims. For example, the work of Professor Birch who is director of the Cancer Research at the UK Paediatric and Familial Cancer research group, at Manchester University is mentioned. The article explains that her findings follow a major earlier this year showing that children who attend day care or playgroups are significantly less likely to develop leukaemia than other youngsters. They explain that this is because the exposure to common infections from the first months and years of life helps switch on the immune system- a key player in the development of childhood leukaemia. However, the study here is not described so the claims are still not very reliable and the claim that “a wealthy background can raise the risk of cancer” is based on generalisations that all wealthy children do not attend day care and that all less wealthy families send their children to day care. http://www.dailymail.co.uk/health/article-1025375/Wealthy-background-raise-risk-cancer-teenagers.html |
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February 2017
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