Term 3 Reflection

In term 3, we covered the topic of light. It was rather hard at first, and we were given 10 worksheets at the start of the term, and were supposed to finish them by the end of this term. Basically, we learnt 3 different stuff about light: reflection, refraction, and lenses. They were all interesting and I actually quite like light as we are given pictures to show how light rays travel, which are much more helpful than just words for some visual thinkers like me. Also, I felt that it was actually quite fun to draw all the different lines, and it gives us a sense of accomplishment when we finish drawing them and look at the nice pieces of work. From this topic, we are able to prevent injuries. As now that we know that refraction may cause things to appear as though they are somewhere else, we are now conscious of that an are hence able to prevent injuries, for example when we dive in water. It also helps us, for example when we are netting fish, we will be able to move the net slightly away from the fish we see in the water so that we successfully catch it. This has been my favourite topic of all as we get to play with light in the labs. It was also so fascinating to see the normal white light split into a spectrum of colors thanks to a prism. All in all, this topic has certainly taught me a lot!

Term 2 Reflection

In term 2, we learned biology for our science lessons. We particularly did reproduction in humans, and I certainly did not expect it to be so difficult, especially for the menstrual cycle. There was certainly a lot for us to memorize in terms of the menstrual cycle, such as all the different hormones that take place. However, with the help of my friends and teachers, I eventually understood the topic. After being able to grasp the concept of this topic, I learned how disastrous pre-marital sex or having multiple sex partners is. Not only is it morally wrong, it may cause many bad things to happen such as unwanted pregnancy, or even cause us to have Sexually transmitted diseases such as AIDs. Hence, I feel that this topic was a good one to cover as it enlightens us on the human reproductive system in humans. After that, we had ecology. I feel that it was really easy to learn this topic, since we actually learned some of it, such as the food chain, in primary school. Thus, is was not so much of a new topic for us, but instead a recap and more in depth version of this topic. I felt that it was interesting as we are able to learn the characteristics of different habitats, and examples of biotic interactions. All in all, I feel that this term has certainly taught us valuable things!

Term 1 Reflection

In Science for term 1, we did chemistry. We did three topics: Acids alkali bases, equation writing, and chemical bonding. I preferred the acids alkali bases topic, as it was rather interesting and fun. We did a number of experiments that had to do with mixing an acid with a metal, and other stuff. I was particularly fascinated when we put hydrochloric acid and magnesium together. There was a rather cool reaction which produces hydrogen gas, with magnesium chloride. Then, we had to test for hydrogen, which was to place a glowing splint near the solution. If a 'pop' sound was heard, that means that hydrogen was present. When we did the test, we did not know that we would hear such a pop sound, and were startled when it happened. After that, we laughed happily. Although I did not quite like chemical equation as it was very difficult, I do not know why but still like chemical bonding. For me, I found it quite easy, as well as interesting, and I also felt that it was quite fun to draw our electrons. All in all, I liked chemistry in Term 1, and also did well for my test, and hence I feel really happy.

Reflection of light

Light:

v  Is the form of energy that enters our eyes

v  Enables us to see things

v  Can either be directly obtained from a luminous source or reflected off a non-luminous source into our eyes

v  A luminous source is an object that emits its own light such as the Sun

Reflection:

v  Incident ray

Ø  Ray of light that strikes the surface

v  Reflected ray

Ø  Ray of light that is reflected off a surface

v  Normal

Ø  Imaginary line that is perpendicular to the surface at the point of incidence

v  Angle of incidence

Ø  Angle between the incident ray and the normal

v  Angle of reflection

Ø  Angle between the reflected ray and the normal

Diffused reflection and specular reflection:

v  Diffused reflection

Ø  Reflected in all different directions

Ø  Produces a distorted image

v  Specular reflection

Ø  Reflected in the same direction

Ø  Produced a clear image

Image characteristics of mirror:

v  Image is formed in mirror as

Ø  Light rays reflect off you

Ø  Strikes the mirror

Ø  Goes back into your eyes

v  Image formed in  plane mirror

Ø  Has the same size as the object,

Ø  Is as far behind the mirror as the object is in front of the mirror,

Ø  Has the same orientation as the object (i.e. upright if the object is upright),

Ø  Is laterally inverted,

Ø  Is virtual.

v  Virtual image cannot be captured on a screen because no actual light rays meet at the image position.

v  Plane mirrors

Ø  Object position: anywhere

Ø  Image position: as far behind the mirror as the object is in front of it

Ø  Image type: virtual

Ø  Image orientation: same as object

Ø  Image size: same as object

v  Concave mirrors

Ø  Near mirror (inside F)

§  Image position: on the opposite side of the mirror as the object

§  Image type: virtual

§  Image orientation: same as object

§  Image size: larger than object (magnified)

Ø  Exactly at F

§  Image position: at infinity

§  Image type: -

§  Image orientation: -

§  Image size: -

Ø  Object distance less than     image distance (outside F)

§  Image position: on the same side of the mirror as the object

§  Image type: real

§  Image orientation: opposite of object

§  Image size: larger than object

Ø  Object distance is equal to image distance (outside F)

§  Image position: on the same side of the mirror as the object

§  Image type: real

§  Image orientation: opposite of object

§  Image size: same as object

Ø  Object distance greater than image distance (outside F)

§  Image position: on the same side of the mirror as the object

§  Image type: real

§  Image orientation: opposite of object

§  Image size: smaller than object

v  Convex mirrors

Ø  Object position: anywhere

Ø  Image position: on the opposite side of the mirror as the object

Ø  Image type: virtual

Ø  Image orientation: same as object

Ø  Image size: smaller than object

Ecology

Introduction:

v  What is ecology?

Ø  How life processes have adapted to its environment

Ø  How organisms are distributed in various environments

Ø  How materials and energy is moved through systems of interacting organisms and their environment

Ø  How an ecosystem changes over time

Ø  How biodiversity is influenced by the environment

v  Scales and level of complexity

Ø  Individual

Ø  Population

Ø  Community

§  Is an assemblage of two or more populations occupying the same area

Ø  Ecosystem

Ø  Biome

Ø  Biosphere

v  Examples of biomes

Ø  Desert

Ø  Savanna

Ø  Boreal forest

Ø  Intertidal zone

Ø  Tropical rainforest

Ø  Coral reef

v  Factors influencing ecology

Ø  Abiotic factors

§  Temperature

§  Rainfall

§  Light intensity

§  Salinity

§  Humidity

§  Wind speed

§  Wave action

§  pH

Ø  Biotic factors

§  Abundance of prey

§  Presence of predators

§  Competition

Ecological Interactions:

v  Mutualism

Ø  Both organisms A and B benefit from the interaction between them

§  Clownfish and sea anemone

§  Ants and aphids

§  Egyptian plover and crocodile

§  Cleaner shrimps and eel

v  Commensalism

Ø  Only organism A benefit from the interaction between them, while organism B receives no advantage or disadvantage

§  Epiphytes and rain tree

§  Cattle egret and cattle

§  Remora and shark

§  Barnacles and scallop

v  Exploitative relationships

Ø  Only organism A benefit from the interaction between them,  while B is harmed in some way or may even die from the relationship

§  Predation: Cheetah and gazelle

§  Herbivory: Zebra and grass

§  Parasitism: Tree ear fungus and tree

v  Competition

Ø  Both suffer some form of disadvantage

§  Great blue heron,  great egret and snowy egret hunting fish

§  Reindeers competing for their mate

§  Trees competing for light

Energy and Productivity

v  Food Chain

Ø  Producers: Plants

§  Obtain energy directly from the sun

Ø  Primary consumers: Herbivores

§  Obtain energy indirectly from the sun

Ø  Secondary consumers

§  Obtain energy indirectly from the sun

v  Dietary

Ø  Herbivores

§  Have a strict diet consisting of plant material only

Ø  Carnivores

§  Have a strict diet consisting of the flesh of other animals

Ø  Omnivores

§  Have a diet of both plant material and flesh of other animals

v  Decomposers

Ø  All organisms will die eventually

Ø  Bodies will undergo decomposition

Ø  Will be broken down into simpler substances

Ø  Accelerated by decomposers

Ø  Are organisms that feed on dead plants and animals, breaking them down into simpler substances

v  Non-cyclic flow of energy

Ø  Energy is always lost along a food chain

Ø  Cannot be recycled

Ø  Gets lost through the form of heat and other life processes

Nutrient cycles:

v  Carbon cycle

Ø  Carbon dioxide in water precipitate to form limestone

§  Plants take up carbon dioxide and convert it to carbohydrates

·         Carbohydrates could be:

¨       Sent back to the atmosphere through respiration

¨       Be present in the plant when it dies

Ø  Respired by decomposers

Ø  Buried and turn into fossil fuels

§  Burn fossil fuels and release carbon dioxide in the air

¨       Eaten by an animal 

Ø  Sent back to the atmosphere through respiration

§  Taken up by plant through photosynthesis

§  Dissolved in the oceans

¨       Be present in the animal when it dies

Ø  Respired by decomposers

Ø  Buried and turn into fossil fuels

§  Burn fossil fuels and release carbon dioxide in the air

v  Nitrogen cycle

Ø  Nitrogen gas in air

§  Lightning can turn it to nitrate

§  Nitrogen fixing bacteria fix it to nitrate or ammonia

·         Plants take up nitrate and convert it to amino acids

¨       Eaten by animals

Ø  When die, ammonia released back into soil

§  Nitrite bacteria change ammonia to nitrite

·         Nitrate bacteria change nitrite into nitrate

Conservation:

v  Why must we conserve?

Ø  Prevent extinction

Ø  Maintain stability in ecosystem

Ø  Maintain large gene pool and preserve useful genes

Ø  Sources of raw materials

Ø  Scientific value

Ø  Recreational purposes