Term 2

Scope of Term 2:

1. Acids and Bases
2. Sexual Reproduction

In this chapter, I would be sharing with you my time during school term and my revision after the school term during the holidays.

Acids and Bases

In acids and bases, we learnt about the properties of acid and alkaline, as well as their effects on indicators such as the universal indicator and the red and blue litmus paper. We went through several practicals on the reaction of acids and bases with other substances. We were also required to remember some key equations such as "acid + carbonate > salt + carbon dioxide + water" and "acid + metal = salt + hydrogen". At first, this task seemed tedious for I could not quite get it. 

However, through the practicals, I started to get a slightly better understanding of the topic and could familiarize with the formulas. The practicals did give me a "boost" in memory work. We were also required to remember the colours of indicators under different pH, as well as learn how to test for products of the equations. Lots of memory and understanding required!

Definition of Acid

An acid is a substance which produces hydrogen ions as the only positive ions when it is dissolved in water.

The strength of Acids depends on its degree of dissociation / ionization in water to form hydrogen ions.

A pure acid does not have the corrosive properties alone. These properties occur only when there is ionization to produce hydrogen ions, or in other words, when acid is dissolved in water.

Definition of  Bases and Alkali

Bases are the oxides or hydroxides of metal that reacts with an acid to form salt and water only.

Where else, An alkali is a metal hydroxide which is soluble in water and produces hydroxide oxides (OH-) in water.

Therefore, all alkali are bases but not all bases are alkali.

Types of Oxides include Acidic oxides, Basic Oxides, Neutral Oxides and Amphoteric Oxides. Acidic oxides are non-metallic, while Basic Oxides are metallic. Both require the presence of water to show Acidic and Alkaline properties.

The strength of Alkali depends on its degree of dissociation/ionization in water to form hydroxide ions.

Writing Chemical Equations

After learning the equations to how acids and bases react to different substances, it is time for Balancing of Equations! This part of the topic of acids and bases was the most interesting. At first it would seem confusing, but after several rounds of practice, and understanding the formula of ionic compounds, the task would be easy. This also required the understanding of Term 1's topic of cation and anions. 

Sexual Reproduction in Plants

In sexual reproduction in plants, we are required to memorize facts, make logical inferences as well as make observations. We learnt pollination and fertilization, the processes withing them, and the plant parts supporting the processes. Therefore, in my opinion, memorizing the facts had the largest component for this topic. However, there were activities to enrich our learning. For the practicals, we explored the school campus for different types of flowers and classified them according to their method of pollination. We also learnt to draw the flower parts in one of the practicals.

Pollination (Methods)

Pollination is the transfer of pollen grains from the anther to the stigma

In Self-pollination; pollen grains are transferred to the stigma of the same flower or a different flower on the same plant, while,

In Cross-pollination, pollen grains are transferred to the stigma of a different flower on a different plant of the same species.

There are advantages and disadvantages to both Self-Pollination and Cross-Pollination.

Advantages of Self-pollination                             Advantages of Cross-pollination

- Only one plant is required                            - Offsprings inherit beneficial traits from one another

- Does not depend heavily on pollinators          - More varieties of offsprings are produced making 

- Less pollen grains and energy is lost                 it more adaptive to environmental changes

- Higher probability of pollination                     - Seeds produced are more viable over a longer

                                                                              period of time

Disadvantages of Self-pollination                          Disadvantages of Cross-pollination

- Offsprings are less adaptive to new                  - 2 parents are required

environmental challenges.                                   - Dependent on pollinators

- Continued self-pollination results in weaker,     - Lower probability of successful pollination

smaller offsprings that are less resistant to         - More energy and pollen grains are wasted.

diseases.

Fertilisation and Pollination

Reflections

I did very badly in this term's test as I was not able to fully understand the topic of Acids and Bases. At the same time, I did not memorize all the names and functions of the flower parts in the plant. After reflecting upon this, I found out that I have been over-confident this Term. A drop from A1 to D7 was very depressing, and I regretted not paying close attention to the notes and worksheets provided by the teacher, and left some worksheets undone. Therefore, during the holidays, I made use of my time wisely to thoroughly revise through my notes and worksheets. To further my understanding I bought assessment books for practice. I suddenly felt that the topic on Acids and Bases, which I previously thought was too complicated to comprehend, was much more exciting and interesting than I expected.

I also completed all the practices on Acids and Bases and read through the notes for Biology and managed to memorize all of the facts for sexual reproduction in Plants. I was overwhelmed having found out that I could have done much better if I had been more serious and managed my time more properly.

Nevertheless, this term has taught me an important lesson, and has driven me into looking closer at the mistakes I made previously. My holiday time was used to catch up with the others and I was pleasantly surprised with how I went through the fulfilling holidays.

Additional Websites

Strength of Acids and Bases:
http://chempaths.chemeddl.org/services/chempaths/?q=book/General%20Chemistry%20Textbook/Reactions%20in%20Aqueous%20Solutions/1437/conjugate-acid-base-pairs

Some Experiments(Acids and Bases) made by Online Users:
http://www.funsci.com/fun3_en/acids/acids.htm

Reproductive Processes:
http://ananthacompapp.yolasite.com/reproduction-processes.php