Science : CHAPTER 5 - Acids & Alkalis (II)

Dear students of 7 Aqua & Aer,

** Do read through everything before you start to do anything. **

Please do a revision by reading up on the link Module 5 – Acids & alkalis again.

Once you have finished reading, I require every one of you to write a report by writing some short notes as a report on these few questions that I will list below. Please be advised that you are allowed to use the search engines on the internet to help you write your report. However, do read through the facts and only choose the relevant ones.

Guiding questions:

1) The characteristics of acids.

2) The characteristics of alkalis

3) Neutral substances

4) Everyday uses of acids and alkalis (make sure you state appropriate examples)

5) The common hazard symbols which are associated with acids and alkalis

You are to hand in the report at the end of the class.

For those of you who are able to finish up early, you might want to try out this activity of The Virtual Kitchen.Good luck and have fun – in Science! Please remember to hand in your report. I’ll see you tomorrow. ^_^

Chapter 5 : Acids & Alkalis - Indicators

Dear students,

Today we will be learning about INDICATORS. What are indicators actually? If you search from the dictionary, indicators means "to point out" or "to specify something". Those are very general definitons of what the word indicator is. However, in Science, when you mention an indicator, it gives a whole different meaning to it.

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Indicators

There is a device called a pH meter which you can dip into a liquid and which will measure its pH. However, it is easier to use an indicator.

An indicator is a chemical that changes colour. Indicators are liquids, but they can be soaked into a type of paper similar to blotting-paper to form strips of indicator paper.

Just dip the indicator paper into the unknown liquid and it will change colour to show the pH.

The simplest indicator is Litmus (from the Litmus plant). It goes red in acids, blue in alkalis.

pH = less than 7	pH = more than 7

Universal indicator is a better indicator than litmus because it can show a greater range of colours. The chart below shows the approximate colour that universal indicator goes when put into liquids of different pH values.

pH = 3 or less	pH = 4 or 5	pH = 6	pH = 7 (neutral)	pH = 8 or 9	pH = 10 or more

Universal indicator is available as a liquid or soaked into absorbing paper. It is often used to work out the pH of soil samples to see which plants can be grown in a certain patch of ground.

There are other indicators, for example, methyl orange (which changes colour from colourless to orange at pH of about 3). They all have different pH values where they change colour, and each has its own uses.

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If you want to find out more on indicators, click on this website What are some natural acid/base indicators?

Remember, if you have fun learning about Science, you will learn about Science!

Science: CHAPTER 5 - Acids & Alkalis (I)

Dear students of 7 Aer, Aqua & Terra,

Please google up "Acids and alkalis Year 7" and find out more on what exactly are they. Or you can go to Module 5 -Acids and alkalis.

Once you have done that, go to the link under "For My Students" for Alien Juice Bar. Try every component under that, only then proceed to The pH factor.

As you are playing those educational games, please be reminded that you are to read all the pop-ups that give you facts from time to time. From there you can gather on the whole on what acids and alkalis are like, what are their characteristics and identify certain examples.

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For revision, please try out Acids & Alkalis - Matching game and also read up on Acids & Alkalis - terms you need to know.

My wedding...

For those of you who knew about it and were also there for my big day, it was on the 10th November 2007. It was a church wedding, with all the frills and flowers as usually is seen in most church weddings. Some friends commented that it was so much like a fairytale wedding. ^_^ I myself wasn't sure because of the stress....which got me so preoccupied and single-minded focus on just surviving the day that I did not notice much.

However, there was one thing that I would like to share. =) My husband (at that time fiance.. =p) ....he gave me such a nice, romantic surprise till I dunno what to do but cry on the spot! It was so touching and really...such a BIG SURPRISE!! Honestly, I didn't expect that from him since he's quite a shy guy, which likes to attract the least attention from people. HAHA.... So it really hit me big time. And I was teased afterwards.... "How come you cried even before he started singing?" Haha..... How couldn't I?

That's why I love him so much!! He is always trying to give me little touching surprises everytime when I totally do not expect it coming. ^_^

Married?!?

It was a loooooooong time ago since I've updated my blog. Sorry bloggie dearie, I've been so bz bz bz with work and also the big "W"!! Hahaha...

Its my wedding!! My goodness....I can't believe I'm gonna be married in like what.....less than 2 weeks? =p Hehe. Most of the preparations are almost done - though most were done in a rush. Oh but who cares? Hehe.....I'll be married soon!

But the saddening thing is that I'll have to be resigned to be called 'aunty' from now on. Haha...Newayz, am vy vy looking forward to my big day! Ta-ta for now. Will update more as time pass...^_^

Reflection on the Weekend & Pain

Last weekend I was in church for our annual OA(Orang Asli) Youth Camp. On the whole, it was really good! Even with the rush of last minute preparations and running around, the organizing committee managed to make the entire camp a successful and enjoyable event!

On Sundaynight which was the Fun-Nite, the OA kids really did have fun. =) I personally felt that it was a good time for them to come out of their cliques and just have plain, unadultrated, mind-blowing F-U-N! ^_^ We had singing from some of the groups, rap and some were even brave enough to put up a sketch for the audience! And I tell you...it is not easy for these shy, quiet kids to even talk loud enough for you to hear their names. =) Praise God for His leading and blessings.

On Fun-Nite we had BBQ for dinner. That was the beginning, the alpha, the genesis of my misery. When I woke up the next day (Monday), I vomited. And I found that it was the dinner from the night before. Throughout the rest of the day, I had bad tummy cramps and I cannot remember how many times I ran to the toilet. By the time I reached home, I only had enough strength to bathe and collapse onto my nice, comfy, soft and super inviting bed. Now when I look back, I didn't even enjoy the outing to the Eye on Malaysia we had on Monday afternoon.



I totally slept Monday away, and into Tuesday. And even though I felt much more alive on Tuesday, a little effort like walking from my room out into the living hall was just too much for me. I kept on making short but sweet..... yeah rite, who am I kidding? =p Well, short and not sweet at all trips to my poor, abused WC. (Dear WC, I promise, cross my heart and hope to die that I will, at all cost wash and scrub you till you're all clean and sparkly this Saturday!) If I ever write a short story on the autobiography of a WC, I think I sorta know which angle it should be approached from.

But as my title states "reflection"....the final word is, I have forgotten how it is to experience the pain and suffering of being sick and confined to bed. And now I would want to praise our ever loving, merciful and forgiving Father in heaven, for giving me the strength to recover, for my loving family members who worried and cared for me, for my darling fiance who also worried as much if not more than my family and for dear friends who still remembered me when I felt as though I was dead and 6feet down under, sleeping in the damp, soft and moist earth. Thank you, Father for everything and especially the life that I have everyday which I tend to take for granted. Amen! ^_^

Meiosis (For my dear students ^_^ )

Why do we look like our parents?

Each parent donates genes to their offspring via sexual reproduction. The genes combine to give different but similar looking offspring.

Homologous chromosomes

a) Humans have 46 chromosomes consisting of 23 homologous pairs. Each parent donates one chromosome to each of the 23 homologous pairs. That means, half of an individual’s chromosomes comes from the female parent while the other half comes from the male parent.

b) Homologous chromosomes are the same length and carry the same genes in the same location. Those genes could be different versions. E.g., imagine the homologous chromosomes carry the eye color gene but one produces blue eyes while the other produces brown.

c) The exception is the sex chromosomes. For these, females have a homologous pair (XX) while males do not (Xy).

d) The other chromosomes are called autosomes (non-sex chromosomes).

Two types of cells in general

a) Somatic – diploid (2n) body cells. Contain a complete set of chromosomes.

b) Reproductive cells – haploid (n) sex cells. These cells are called gametes and contain only half the number of chromosomes. If one somatic cell (2n) is fertilized by another (2n), the resulting zygote would contain twice the number of chromosomes (4n). I.e., the chromosome number would double each generation (4n, 8n, 16n etc.). For this reason, the chromosome number must be reduced during the production of gametes. This way, one haploid (n) gamete is fertilized by another (n) and the resulting zygote is diploid (2n).

c) The zygote carries a complete set of chromosomes. Half from the the female parent and half from the male.

d) Every cell in the resulting organism is diploid and arises by mitotic division of the original zygote.


The main stages of meiosis are the same as those in mitosis

a) Meiosis happens in two stages: Meiosis I and Meiosis II. The two cell divisions result in 4 haploid daughter cells.

b) During Meiosis I (the reduction division) homologous chromosomes are separated.

c) In Meiosis II, sister chromatids are separated.

d) After the chromosomes are replicated, sister chromatids remain attached at the centromere. Also, homologous pairs (each consisting of two sister chromatids) remain close together. The four sister chromatids are called a tetrad and the process is called synapsis.

e) During synapsis, the arms of chromosomes in a homologous pair become intertwined. Pieces of the homologous chromosomes break off and switch places. This phenomenon is called crossing over. This increases genetic diversity which results from sexual reproduction.

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MEIOSIS I

Interphase - duplication of DNA

Prophase I - similar to mitosis except for synapsis
1. Synapsis - pairing of homologous chromosomes
2. Chromatin shortens & thickens to become chromosomes
3. Nuclear envelope disappears
4. Nucleolus disappears

Metaphase I
1. Homologous chromosomes line up in pairs across the equator
2. Spindle fibers attach to the centromeres of the chromosomes

Anaphase I - separation of homologous chromosomes

Telophase I
1. Chromosomes arrive at spindle poles
2. Nuclear envelope reforms in some cells
3. Each cell has one each homologous chromosome, cytokinesis occurs to split cells

No Interphase

Prophase II
1. Chromosomes shorten and thicken
2. Nuclear envelope disappears
3. No duplication occurs

Metaphase II
1. Chromosomes line up along the equator
2. Spindle fibers attach to the centromeres

Anaphase II
1. Centromeres divide
2. Sister chromatids separate, become chromosomes

Telophase II
1. Nuclear envelope forms around each set of chromosomes
2. Nucleolus appears in each nucleus
3. Chromosomes lengthen and become indistinct

---> Cytokinesis occurs forming 4 cells

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For further illustration/information, please check out these links:

1) http://www-users.york.ac.uk/~mal503/common/thesis/jpegimages/meiosis.jpg

2) http://www.sfu.ca/~fankbone/biol/meiosis.jpg

3) http://tutor.lscf.ucsb.edu/mcdb/tutorial/meiosis/

Also do check out the link under "For My Students" for Animations on Meiosis, Click and Clone, Meiosis = double cell division and Meiosis tutorial.