EC
14 this year
2P1'12
I love science!
A Night To Forget - IDS (21st-24th August)
(Saturday, September 1, 2012) (7:42 AM)
Instead of having sabbaticals during week 9, we were going to have IDS. At first when I realised we were going to have IDS, I got quite upset as I missed a chance of having fun in a new sabbatical course. However, on the first day of IDS which was Tuesday (Monday was a School Holiday), I found out that we were actually going to do forensic science which helped with our critical thinking and questioning. This was quite a challenge as we were all new to this topic and were a bit confused at the start, however after doing many experiments, tests and useful information from our instructor, we managed to solve the crime in the end!Here are just some of our experiments :
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| Plaster mixing |
Chromatography
Reproduction
(Tuesday, August 21, 2012) (4:11 AM)
ReproductionReproduction is required for the production of new individuals for the continuity of species.
Reproduction can be classified as asexual or sexual reproduction.
Asexual reproduction results in the production of genetically identical offspring from one parent, without the fusion of gametes.
Sexual reproduction involves the fusion of two gametes to form a zygote, resulting in the production of genetically dissimilar offspring.
Asexual reproduction
- Beneficial in a stable environment
- Less energy
- Less time
- Useful in a changing environment
- Requires more energy
- Requires more time
Unicellular organisms, e.g. bacteria, reproduce by binary fission, a form of asexual reproduction.New daughter cells have the same characteristics as parent cells.
In multi-cellular organisms, gametes are produced. The fusion between two gametes results in a combination of genetic material in offspring. New cells formed from sexual reproduction do not have the same characteristics as their parents.
Heredity
Male Gamete/Sperm
- 23 chromosomes
- Large nucleus carries haploid set of chromosomes
- Contains an acrosome. Sac containing enzymes that break down egg membrane
- Middle piece contains numerous mitochondria to provide energy for the sperm to swim
- Has a tail/flagellum which enables movement of the sperm
- It is motile
- Found in testes
- Largest cell in body
- Cannot move by itself
- Found in the ovaries
The Male Reproduction System
Testis
- Two ovoid testes. The testes produces sperms.
- Each testes also produces male sex hormones such as testosterone.
- The hormones are responsible for development and maintenance of the secondary sexual characteristics.
- Each testis receives blood from blood vessels in a spermatid cord.
- Leading from the end of each testis is a narrow, much coiled tube called the epididymis.The epididymis stores inactive sperms from the testis.
- The testes lies between the thighs, in a pair of pouch like sacs called the scrotums or scrotal sacs.
- They are outside main body cavity and thus are at a lower temperature than the body.
- Essential for the sperms development
- Sperms can only develop at a temperature lower than that of the body.
- Each vas deferens, loops over a ureter then open into the urethra.
- After sperms are released from a testis, they travel through the sperm duct.
- The seminal vesicle is a g;and that opens into each sperm duct. It stores sperms temporarily before being released into the urethra.
- Prostate gland, the seminar vesicles and the Cowper's gland secrete a slippery fluid which mixes with sperms.
- This fluid contains nutrients and enzymes which nourish the sperms and activates them.
- The mixture of fluid and sperms are called semen.
- Urethra is a tube which both semen and urine pass out from.
- Semen and urine do not pass through the urethra at the same time. This is because of a circular band of muscle called the sphincter muscle.
- Sphincter muscle can be controlled to prevent urine from coming out from the bladder during release of the semen or ejaculation.
- The tissue in the penis has numerous spaces that can be filled with blood.
- When this happens, the penis becomes erect and hard.
- This allows it to enter the vagina of a woman during sexual intercourse to deposit semen containing sperms.
- The penis is called a erectile organ. It contains erectile tissue.
Ovary
- Two ovoid ovaries produces eggs and female sex hormones such as oestrogen and progesterone.
- When eggs become mature, they are released.
- Each ovary released mature eggs into an oviduct or fallopian tube.
- Funnel-like opening lying close to the ovary, making it easier for the egg to enter the oviduct.
- The egg is usually fertilized in the oviduct.
Uterus
- The womb or the uterus is where the fetus or unborn baby develops.
- The uterus is shaped like an upside-down pear.
- It has elastic muscular walls. The smooth muscle tissue in the walls of the uterus contract to push the fetus out during birth.
- The soft, smooth inner lining of the uterus is called the uterine lining or endometrium.
- It plays a part in embryo implantation. Every month, the endometrium is broken down and it flows out of the body together with some blood.
- It is later build up again.
- Leading from the cervix to the outside is the birth canal or vagina. The opening of the vagina is the vulva.
- Semen is deposited in the vagina during mating.
Puberty
Boys
- Between 12 to 14 years old
- Reproductive organs grow in size and start to produce sperms
- Physical changes
- Body grows rapidly; height increases rapidly
- Body becomes more muscular
- Hair grows on face and body (esp. under armpits and around reproductive orgams)
- Voice breaks
- Between 10 to 12 years old
- Mensuration begins
- Physical changes
- Height increases rapidly
- Breast grow larger
- Hips become rounder and wider
- Hair grows under armpits and around reproductive organs
STDs
- Gonorrhea
- Pain when passing urine
- Damage reproduction system
- Cause blindness in babies
- Sores on mouth and reproductive organs
- Deformity in joints, abnormal development of teeth, blindness as well as serious heart and brain problems.
- Baby might have blindness, deafness or even death.
- HIV- infected people may develop signs and symptoms such as tiredness, weight loss, fevers and severe diarrhea only after a few months or years.
- Full blown aids occur within eight to ten years of HIV infection
- People suffer from pneumonia, cancer of the blood vessels and damage to the brain
Contents learnt in 2012
(Monday, August 20, 2012) (6:56 AM)
Term 1 Contents
-Atomic structure and Periodic Table
->Basically for this chapter we needed to learn the electronic structure of the atom which meant how many protons, neutrons and electrons it had.
->All atoms have the same number of protons as electrons making it a stable atom
->When there are less or more electrons, it becomes unstable thus covalent and chemical bonding occurs to make them from cations and anions to become stable.
->Required to memorise the numbers for the first 20 elements
-Acids and Bases
->Definition of and acid and a base. Acid: Substance which produces hydrogen ions when dissolved in water. Base: Oxides or hydroxides of metals which react with acid to produce salt and water only.
->Take note: All alkalis are bases, whoever not all bases are alkalis
->Strong acids: Hydrochloric acid (HCl)/Nitric Acid (HNO3)/ Sulfuric Acid (H2SO4) - ionises/dissociates completely in water to produce hydrogen ions
->Weak acids: Ethanoic acid: Vinegar - ionises/dissociates partially in water to produce hydrogen ions
->Strong Alkalis: ionises/dissociates completely in water to produce hydroxide ions (OH-)
->Weak Acids: ionises/dissociates partially in water to produce hydroxide ions (OH-)
->Indicators of acids and bases -Litmus paper -> Acids turn it blue to red. Alkalis turn it red to blue.
- Methyl Orange -> Colour change at ph4. Strong acids = orange>red
Alkalis = orange>yellow
- Phenolpthalein -> Colour change at ph9. Strong acids = colourless>pink
- Universal Indicator -> Neutral = green. Strong acid = red. Strong alkali = violet
-Writing chemical equations
Common Cations:
Common Anions:
| Name | Formula | Other name(s) | |
| Aluminum | Al+3 | ||
| Ammonium | NH4+ | ||
| Barium | Ba+2 | ||
| Calcium | Ca+2 | ||
| Chromium(II) | Cr+2 | Chromous | |
| Chromium(III) | Cr+3 | Chromic | |
| Copper(I) | Cu+ | Cuprous | |
| Copper(II) | Cu+2 | Cupric | |
| Iron(II) | Fe+2 | Ferrous | |
| Iron(III) | Fe+3 | Ferric | |
| Hydrogen | H+ | ||
| Hydronium | H3O+ | ||
| Lead(II) | Pb+2 | ||
| Lithium | Li+ | ||
| Magnesium | Mg+2 | ||
| Manganese(II) | Mn+2 | Manganous | |
| Manganese(III) | Mn+3 | Manganic | |
| Mercury(I) | Hg2+2 | Mercurous | |
| Mercury(II) | Hg+2 | Mercuric | |
| Nitronium | NO2+ | ||
| Potassium | K+ | ||
| Silver | Ag+ | ||
| Sodium | Na+ | ||
| Strontium | Sr+2 | ||
| Tin(II) | Sn+2 | Stannous | |
| Tin(IV) | Sn+4 | Stannic | |
| Zinc | Zn+2 |
Common Anions:
| Simple ions: | |||
| Hydride | H- | Oxide | O2- |
| Fluoride | F- | Sulfide | S2- |
| Chloride | Cl- | Nitride | N3- |
| Bromide | Br- | ||
| Iodide | I- | ||
| Oxoanions: | |||
| Arsenate | AsO43- | Phosphate | PO43- |
| Arsenite | AsO33- | Hydrogen phosphate | HPO42- |
| Dihydrogen phosphate | H2PO4- | ||
| Sulfate | SO42- | Nitrate | NO3- |
| Hydrogen sulfate | HSO4- | Nitrite | NO2- |
| Thiosulfate | S2O32- | ||
| Sulfite | SO32- | ||
| Perchlorate | ClO4- | Iodate | IO3- |
| Chlorate | ClO3- | Bromate | BrO3- |
| Chlorite | ClO2- | ||
| Hypochlorite | OCl- | Hypobromite | OBr- |
| Carbonate | CO32- | Chromate | CrO42- |
| Hydrogen carbonate or Bicarbonate | HCO3- | Dichromate | Cr2O72- |
| Anions from Organic Acids: | |||
| Acetate | CH3COO- | formate | HCOO- |
| Others: | |||
| Cyanide | CN- | Amide | NH2- |
| Cyanate | OCN- | Peroxide | O22- |
| Thiocyanate | SCN- | Oxalate | C2O42- |
| Hydroxide | OH- | Permanganate | MnO4- |
-Reproduction in plants
->Functions and structure of the parts of the flower
Term 3 test and Reflections
() (5:20 AM)
Hi again, welcome to my Science eportfolio! This term was pretty awesome as we had self study!! Miss Nada literally gave us all the worksheets and assignments and asked us to do it every week and if we had any questions, we would just have to ask her. This took studying to a whole new level as it was more fun and enjoyable which was way better than boring lectures by other teachers. So this term I had to be really independent and disciplined. And anyways, here is another piece of good news! Although I am not really good in physics especially reflection and refraction, however I still managed to get top 3 in the class with 39.5/45 ^^. I am really satisfied with my results and I cannot give myself all the glory! I must thank my teacher, my parents and GOD! Thank you for guiding me and helping me all these years :) Since I have been actively participating in class and scoring well, I hope Miss Nada would let me get an exemption for the End-Of-Year examinations. Although I have a high chance, I will still continue working hard and do my school proud! The challenge for this term was mainly convex and concave mirrors. I was not really sure of the concepts and the image produced especially when there were so many situations the object could be placed at.http://physics.bu.edu/~duffy/PY106/Reflection.html
Term 2 Test and Reflections
() (5:09 AM)
So term 2 has already passed and I finally have a one month holiday! Phew thank god I have time to relax after all the hard work i put in! This term for Science we learnt plant reproduction and chemical equations. I felt the portion on chemical equations slightly tougher as it required much more studying as we had to memorize the atomic number and the number of molecules and atoms. Thus, I found plant reproduction easier as it also required basic knowledge which made it easier to understand and apply. This term we did some practicals, however the practical that left a great impression on me was the practical where we had to go around the entire Hwa Chong campus and find flowers that are pollinated by wind and insect. The tough part here was mainly identifying the flowers as there were no sign boards anywhere! As for term 2's test, I did even better than term 1 with a score of 41.5/45! I think I am getting better at Science each day!Term 1 tests and reflections
() (2:46 AM)
Hey guys, so term 1 has already ended and I found it rather easy as we were doing chemistry and I am best at chemistry. I was glad as we were still able to do practicals in the lab as they are not only fun gives one a lot of experience. Chemical bonding was more of a continuation from last year where we had already started chemical bonding. I was quite satisfied for my results as I got the top in my class with a score of 40/45! There was also a new component in the Science test called QMCT where we would have to answer questions using critical analysis and thinking. I found this part quite easy as most of them were based on one's opinions and not really needing to study for it thus I got 5/5 for that section. In term 1 we were alse required to do a project here it was.
This was the website I used while revising for term 1's test!
http://www.visionlearning.com/library/module_viewer.php?mid=55
Introduction to 2012 - Science
() (1:20 AM)
Hey guys so its already a year and I am Secondary 2!! This post will not be too long as its just an introduction to the new school year. I am so happy :) So for the holidays, I went to Japan with my family and friends. Although I am still in the holiday mood ._. but I am really determined to do well this year as it is streaming year and I have to make my dream come true! The next best thing just happened! Miss Nada is my Science teacher again! I swear she is one of the best teachers iv'e ever had! Miss Nada not only teaches us well, but her style of teaching also interest me. She believes in independent studying such that she would teach however its up to us to revise. She requires homework to be handed up, however for those who do not wish to hand it up, she will not scold but she will just take note. After checking out the topics for this year, I felt quite afraid as I am not very good with biology and physics while my main subject is chemistry. However, I am determined to do well for this year which means i would have to work hard!