Nuclear Power [ACE]

This is the ACE assignment that I had done in Term 2 on a poster on Nuclear power.

http://www.mediafire.com/?rvzvjw17651ig3e

Term 3 IDS PowerPoint Presentation

For Term 3 Sabbaticals, we worked on crime scene investigation and through the duration of the course, we learned various techniques that forensic scientists applied during investigations to attain their results. At the end of the course, we penned down the things that we learned as a group in the PowerPoint below.

Reflections on Biology

In Term 3, we learnt a little on lenses, which was part of physics and also, on ecology. For me, I feel that this term's topics were type of familiar as we were briefly introduced to the ecosystems in primary school. However, we are supposed to define various terms like abiotic and biotic factors and also, the carbon cycle. These aspects of the topic was the harder parts. Not like physics, biology requires quite a bit of memorising too, but not as much as chemistry, when it comes down to memorising of the various definitions of terms.

In the open-book assignment, despite it being open-book, I did not manage to score well due to the lack of understanding of the chapter. As there were other commitments beside the academic workload, I required much time management to balance the time well for everything. However, after this assignment, I realised the need to catch up as quickly as possible with the rest to achieve better results. For the actual test, I managed to score 76 which was good in my opinion as it was an A1. However, I feel that it was possible for me to do much better with additional effort put in. Overall, for all the terms, I managed to score an A which is quite remarkable and I am contented with the results after the hard work that I put in.

As we head to the last term and nearing the End-Of-Year Examinations, I need to work double hard to ensure that I carry on with this chain of good results and to attain similar results in the coming examinations. I still remembered that I got 1 mark off an A for last year's EOYs and I am determined to better the result that slightly pulled me down. ^^

Reflections on Physics

In Term 2, we mostly did physics and on subjects like reflection, refraction and light. I feel that this term's topics were slightly easier to grasp than the previous topics in Term 1 as it requires less memorizing and more of understanding. Despite not understanding everything since the start of Term 2, I managed to slowly catch up with the rest of the class. Additionally, I required some help from other classmates who are better in this aspect. Also,   the afternoon lesson that was conducted as it was nearing the test date helped quite a bit too in refreshing all the things  that were taught before.

In my opinion, one of the harder part of these topics was the drawing of the diagram. It requires us to fully understand things that were taught in class to ensure that we are able to correctly sketch out the required diagram. Additionally, we need to read questions fully and to have accurate drawings to get the full marks given for the questions.

For this test, I managed to get 70 marks. Although it may not seem ideal as it was merely a borderline A, I feel that I tried my best and also, I managed to get 6 marks above the average score which I think was quite an achievement as I did not manage to do so the previous time. So, all in all, I feel that I have sustained the momentum from Term 1 and hopefully, continue with these results in the following term and lastly, in the End-Of-Year Examinations. ^^

Reflections on Chemistry

As, it was the start of the year, I feel that it took me a longer time to adapt to the new topics and especially after a long break where I had forgotten much of the basics. So after a holiday that was close to 2 months, much revision was required to ensure that I have gotten my basics right and move on to harder topics in Secondary 2.

For our class, we started off with the topic Chemistry, which I realised after the first few lessons, required much memorising and to have a strong grasp of the various techniques, for example balancing equations. I started off the topic thinking that it was hard, thus not being able to grasp the things that were taught in class. As Science is one of my weaker subjects and requires me to put in quite a lot of effort to ensure that I understand, I went home and looked through quite a number of times and managed to gradually understand the topic.

The result of Term 1's test was still okay, although it was 2 marks off the average which was 77, I still managed to attain an A1 which was quite a good score for me already. Considering that Science is one of my weaker subject, I felt that I had already put in quite a lot of effort to get this type of results. With this grade, it pushed me harder to improve and focus more for Term 2. 

Ecology

Definitions: 
Habitat - where an organism lives
Population -  group of organisms of the same species living in a particular habitat
Community - All populations of organisms living and interacting with one another in a particular habitat


Abiotic factors:

Factor	Examples of how factor influences life
Temperature	Affects the proper functioning of enzymes. Extreme temperatures and pH disrupts the hydrophobic, hydrophilic and ionic interactions in enzymes, causing them to lose their shape and functionality.
pH
Oxygen content	Oxygen is required for aerobic respiration. Lack of oxygen slows down metabolism.
Humidity	High humidity slows down the rate of transpiration in plants but is also critical to the survival of epiphytes and organisms living in arid places.
Amount of water	Affects number and locations of flora and fauna. Dependent on rain pattern
Wave action	Prevents marine organisms from settling down and feeding.
Wind speed	High wind speed may break the stems of certain plant species and may dissipate humidity.
Light intensity	Low light intensity retards plant growth, but high light intensity may bleach chlorophyll and impairs the ability of plants to photosynthesize.
Salinity	Affects osmotic balance in many aquatic animals and coastal plant species.
Type of substratum	Clayey, sandy or rocky substratum influences ability of plants and sessile organisms to anchor themselves.

Biotic factors:

Interaction	Organism A	Organism B	Example
Mutualism	+	+	Lichen
Commensalism	+	0	Remora fish and Shark
Exploitative Relationships (Predation, Parasitism, Herbivory)	+	-	Snake and Rabbit
Competition	-	-	Snake and Eagle have similar feeding habits
Ammensalism	-	0

Food Chain


Definition:


A food chain is a diagram, of some sort, that describes how energy is passed from one living thing to the other in a community.



Food Web


Definition:


A food web comprises interlinked food chains involving organisms from the same ecosystem.


The need to conserve environment

We conserve to:

• prevent extinction of plant and animal species
• maintain a stable and balanced ecosystem, prevents disruption of natural cycles such as water and carbon cycles; also prevents global warming
• maintain large gene pool, preserve favourable genes; helps to improve agricultural produce or crops with better resistance to diseases 
• conserve marine life as a food source
• scientific value – study of evolution
• nature appreciation – recreational purposes such as hiking, fishing, skiing
• maintain biodiversity – economical, medical and industrial uses

Carbon Cycle

• photosynthesis
• respiration
• excretion and egestion
• decomposition
• destruction of vegetation
• sedimentation and mineralization
• dissolution (chemical weathering)
• combustion

Colours

COLOURS

The colour white is composed by 7 different colour components, also known as the 7 colours of the rainbow. Thus when white light is shone onto a prism, a spectrum of seven colour components will be dispersed as shown below.

This situation can be reversed by placing another prism with the vertices and bases in opposite directions as shown below.

Primary colours are red, green and blue.

 Secondary colours include: 

-Yellow (red + green),

-Magenta (red + blue), 

-Cyan (green + blue).

A leaf appears green to an observer. When white light strikes a leaf, only green light is reflected to the observer. The rest of the colours is absorbed by the leaf. Therefore, the leaf appears green to the observer. From this example, we can see that the colour of an object depends on the colour of light being reflected to the observer. 

Lenses

Classified into:

Converging and Diverging lens.



The diagrams above show the parts and the movement of the rays as they pass through the converging lens.

Definition of the parts:

1.Optical center C: The midway between the lens surfaces on its principal axis. Rays passing through the optical center will not be refracted.


2.Principal axis: The horizontal line passing through symmetrically through the optical centre of the lens. 


3.Focal point F (principal focus): The point at which all rays parallel to the principal axis converge to after refraction by the lens. 


4.Focal length f: The distance between optical centre C and focal point F.


5.Focal plane: The plane which passes through F and P (perpendicular to principal axis)









This table shows the movement of the rays as compared to its focal length.


*Diagrams taken from textbook.

Light, Reflection and Refraction

Light:

-A form of energy
-Can be obtained from a luminous source or reflected off non-luminous objects
-travels in a straight line

Reflection

The Laws of Reflection:

1. The incident ray, reflected ray and the normal lie on the same plane
2.The angle of incidence is equal to the angle of reflection.

Characteristics of plane mirror image:

-same size as object
-laterally inverted
-virtual - cannot be captured on a screen
-upright
-distance between image and mirror is the same as the distance between object and mirror


Refraction

Definition:

When light rays strike an optical medium, the light that is transmitted through the medium bends due to the difference of optical density between air and the block of plastic/glass. This light-bending effect is called refraction.


From this diagram, we can see that as the light ray passes through glass, which is an optically denser medium, from air, thus it will bend more and when it travels from glass to air, it will bend more inwards.


TOTAL INTERNAL REFLECTION

The critical angle is defined as the angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90 degrees.

incident angles greater than the critical angle there will be total internal reflection.

When does total internal reflection occur?

Total internal reflection takes place only when a ray of light travels from an optically denser to a less dense medium, and the angle of incidence in the optically denser medium is greater than the critical angle.

Acids, Bases & Salts

Acid, Bases & Salts
Strength of acid.

The strength of an acid depends on its degree of dissociation / ionisation in water to form hydrogen ions.

Properties of ACID:

1. 1. sour taste.
2. 2. change the colour of indicators (e.g. turn blue litmus paper red).
3. 3. contain hydrogen ions and conduct electricity.
4. 4. react with metals, carbonates and bases.

STRONG ACIDS

Hydrochloric acid -> Hydrogen chloride -> HClNitric acid -> Hydrogen nitrate -> HNO3Sulfuric acid -> Hydrogen sulfate -> H2SO4

WEAK ACIDS

Ethanoic acid -> Vinegar
Citric acid -> Lemon
Tartaric acid -> Grape



Reaction with METAL:


Acid + metal → salt + hydrogen


(a) Effervescence observed. Colourless, odourless gas evolved which extinguished a lighted wooden splint with a ‘pop’ sound.
(b) Grey solid reduced in size (when in excess). Grey solid dissolves to form a colourless solution
(c) Heat liberated.

Potassium	Most Reactive
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold	Least reactive

*Metals less reactive than HYDROGEN isn't able to react with acid.



Reaction with CARBONATE:

Acid + carbonate → salt + carbon dioxide + water

(a) Effervescence occurs. Colourless, odourless gas evolved which reacts with calcium hydroxide to form a white precipitate.
(b) White solid dissolves to form a colourless solution.




Reaction with BASES:

Acid + base → salt + water



PH LEVELS

Observation(s)	Indicators
Litmus paper	1.	An acid turns blue litmus paper red.
Methyl Orange	2.	Used to identify strong acids. Colour change at pH 4 Strong acid turns methyl orange red. Alkali turn methyl orange yellow.
Phenolphthalein	3.	Used to identify strong alkalis. Colour change at pH 9 Strong alkali turns phenolphthalein pink. Phenolphthalein remains colourless in acid.
Universal Indicator	4.	In neutral solutions, universal indicator remains green. Strong acid: red Strong alkali: violet