One obstacle I faced was to understand how to draw a ray diagram for a converging lens. I was completely confused by the drawings at first, but slowly found my way out through trial and error, again. From this I figured out that science is not all about memorizing, but more of making sense of what you have learned and applying it correctly. It was amazing to be able to draw any ray diagram just by knowing a few simple rules. Moving on to ecology, I think that ecology was a very easy topic, as we already know most of the things taught at this level, which made it very boring. However I cannot help but realize that I was underestimating this topic, as ecology is a very broad topic, and can cover many things.
One of the most interesting works that I done this term in the curriculum was where we had to do our own research on two questions, whether the moons surface is bumpy or smooth, and how mirages are formed by using our knowledge of reflection and refraction only. I roughly knew how mirages was created, by the temperature differentials in the air called the temperature gradient, which caused the light reflecting from the sun on the object into your eyes refract differently, distorting the image and making it look nearer than it is. However I did not know how to answer the first question. I knew that the moon was not smooth as planetary objects can never form perfectly spherical and smooth, and coupled with the fact that billions of asteroids impacted the moon that has no atmosphere, life and water, meaning no erosion, meant that it could never be smooth. I went on to research on this question and found out that one of the most famous astronomers, Galileo, had hypothesized that the moon was rough from his knowledge of specular and diffused reflections. He did an experiment by placing a mirror beside a wall, and observed that the rough wall was considerably brighter from a distance than the mirror, and he thus hypothesized that the moon, being visible from such great distance, must be rough and not smooth, and that if it were to be smooth, it would be invisible from the earth. It was wonderful to think that we can apply our knowledge to discover new stuff by mere observing and applying your knowledge.
This term’s term test would be counted as a satisfying one. I did not lose any marks because of carelessness, which was one of the reasons why I was pleased by the results. However I did lose a mark because I did not understand the question, and I actually put the correct answer at first, but changed it at the end of the test, and got it wrong. I think that this test was finally a well done one, but I have to admit that it was considerably easier than the previous one done in term two.
SUMMARY
LENSES / COLORS OF LIGHT
There are five situations when light reflected from an object passes through a converging lens.
First Scenario: Object distance < Focal Length (F)
Image is upright, Virtual and magnified.
Image is behind object, on the same side of the lens as the object
Usage: Magnifying Glass
Second Scenario: Object Distance = Focal Length (F)
Image is upright, virtual and magnified.
Image is at infinity (No Image), on the same side of the lens as the object
Usage: Spotlight
Third Scenario: 2 Focal length (2F) > Object Distance > Focal Length (F)
Image is inverted, real and magnified
Image is at the opposite side of the lens as the object
Usage: Projector, Photographic Enlarger
Forth Scenario: 2 Focal Length (2F) = Object Distance
Image is inverted, real and same size as object
Image is at the opposite side of the lens as the object
Usage: Photocopier making same sized copy
Fifth Scenario: Object Distance < 2 Focal Length (2F)
Image is inverted, real and diminished
Image is at the opposite side of the lens as the object
Usage: Camera, Eye
There are 7 colors of light, red, orange, yellow, blue, indigo and violet. White light is actually a mixture of these 7 colors of light, and if light is shone through a prism, it would disperse, forming the 7 colors of light. The band of light produced is called the visible spectrum. The light would disperse as every color of light has its own wavelength, and thus travel at different speeds, resulting in different degrees of refractions when in contact with a prism, causing dispersion. Red light has the longest wavelength, thus travelling the fastest, and violet has the shortest wavelength, thus traveling the slowest. Light can be recombined with a similar prism placed upside down in relation to the first prism that dispersed the light. There are 3 primary colors of light, red, blue and green. Red and blue can mix together to form magenta, blue and green can mix together to form cyan and red and green can mix together to form yellow. Colored objects can only reflect the color of light that they are. For example, red objects can only reflect red light, and if green light is shone on it, it would not reflect any light, resulting in a black object. When light is shone through a color filter, the filter only lets colors that it can transmit pass through, in other words, when yellow light is shone through a magenta filter, red light would be transmitted as both yellow and magenta is made up of red light.
ECOLOGY
A habitat is a place where organisms live, a population is a group of organism of the same species in a habitat, and a community is the populations of different species of organisms interacting with each other in a habitat. An ecosystem is a community in with relationships with abiotic factors.
There are 9 abiotic factors:
Temperature and ph: Temperature and ph levels affect the functionality of enzymes and their hydrophobic, hydrophilic and ionic interactions.
Oxygen Content: Oxygen is required for respiration and low oxygen means slow metabolism.
Humidity: Humidity affects the rate of transpiration and is essential for some organisms like epiphytes to survive.
Amount of Water: Affect location of flora and fauna.
Wave Action: Prevents marine organisms from settling and feeding, depleting food sources.
Wind Speed: High wind speed can dissipate humidity and might break certain species of plants.
Light Intensity: Affects the rate of photosynthesis
Salinity: Affects the osmotic balance in marine organisms
Type of Substratum: Affects the survivability of animals and plants
There are five Biotic Factors
Mutualism: Both organisms benefit together
Example: Lichen
Commensalism: One organism benefits from the other organism, but the other organism does not benefit nor get harmed.
Example: Remora Fish and Shark
Exploitative relationships: Predation, patriotism and herbivory. One organism benefits from the other, but at the same time harming it.
Example: Snake eating rabbit
Competition: Two or more organisms competing for one source of essentials
Example: Snake and eagle competing to feed on rabbits
Ammensalism: Substances produced by one organism’s natural processes like metabolism harms other organisms.
In the food web, there is the producer, or autothrophs, which are able to synthesize organic molecules from a source of energy and other inorganic molecules, providing energy for the whole food chain. Heterothrophs on the other hand are organisms that obtain energy from the organic molecules of other organisms. Heterothrophs are not necessarily herbivores and carnivores, as carnivorous plants like the venues flytrap is an example of Heterothrophs that are able to photosynthesize. Consumers, primary consumers and secondary consumers, are heterotrophic organisms that obtain energy and carbon by feeding only. Primary consumers are herbivores that feed directly from the primary producers. Secondary consumers are organisms that feed on primary consumers. Organisms can be both primary and secondary consumers, in the case of herbivores. Decomposers are organisms that break down dead organic matters into smaller pieces to be recycled again.
The carbon cycle is the cycle whereby carbon is cycled naturally in an ecosystem by a few processes:
Photosynthesis:
Carbon dioxide CO2 is being converted to glucose C6 H12 O6, through photosynthesis.
Carbon is then passed to other organisms through feeding, taking in the glucose into their bodies.
Respiration:
Plants and animals alike respire converting glucose into energy, at the same time releasing the carbon trapped inside in the form of carbon dioxide.
Excretion and egestion:
Microorganisms in the digestive systems of herbivores and omnivores ferment carbon rich plant cells, releasing carbon into the atmosphere in the form of methane, CH4.
Undigested food that is excreted contains all the leftover carbon from digestion and respiration to be decomposed.
Decomposition:
Decomposers produce methane when decomposing dead and fecal matter, releasing most of the trapped carbon in the form of methane.
Destruction of Vegetation:
Bush fires burn carbon trapping plants, releasing their carbon contents in the form of carbon dioxide.
Sedimentation and Mineralization:
When organisms die and are buried immediately, they would not decompose and instead be compressed over layers and layers of sediments. Overtime they become fossil fuels.
Carbon dioxide is being dissolved in the seas, forming carbonate and bicarbonate ions that go into the formation of hard shells of marine organisms, and when they die, the shells fall to the seabed and over time be compressed into limestone, storing the carbonate and bicarbonate ions.
Dissolution
In events like acid rain, limestone can be dissolved, releasing the carbonate and bicarbonate ions back into water bodies like rivers, lakes and seas.
Combustion
Stored fossil fuels are being burned by humans, releasing their carbon content back into the atmosphere in the form of carbon dioxide, methane and carbon monoxide, etc.
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