Term 2
This term, I did 2 ACE projects for Science, a report on my science outing to the Botanic Gardens, as well as a Powerpoint Presentation on light and optics. However, due to my limited knowledge of programming, I am unable to show my Powerpoint Presentation. But, here is my report on my outing: (I have a lot of pictures of the plants I saw. However, I am unable to display them here)
My Science Outing to the Botanic
Gardens
A Brief History of the Botanic Gardens
The
Singapore Botanic Gardens was found in 1859 by the Agri-horiultural Society of
Singapore. However, it was eventually handed over to the government. In its
early years, the Gardens played an important role in fostering agricultural
development in Singapore and the region through collecting, growing,
experimenting and distributing potentially useful plants. One of its earliest
and more important successes was the introduction and experimentation of Para
Rubber in 1877. In 1920, the Gardens spearheaded orchid breeding and
hybridisation programme. It also played an important role in Singapore’s Garden
City programme through the continual introduction of plants of horticultural
and botanical interest.
The Eco-Garden
This name
of the area of the Botanic Gardens near Bukit Timah Road gets its name from 2
sources: “Economic” and “Ecological”. The former term reflects the many plants
of economic importance grown in the area. The latter, the strong attempt to
keep a natural feel to the landscape, particularly in the design and management
of the lake in the area.
The Trellis Garden
Located at the Bukit Timah Gate, the Trellis Garden showcases
the climber collection of the Botanic Gardens. Climbers are plants that require
support in order to grow upwards to harvest sunlight. There are many types of
climbers, such as twining vines which twin around its host, while others climb
using tendrils, thorns or hooks. Climbers can be showy, either with spectacular
flowers or with attractive foliage or both. Some even produce fragrant flowers
and edible fruits which attract wildlife such as butterflies and birds
One such
example of a climber is the New Guinea Trumpet Vine (above). It grows 3-5 large
evergreen leaflets. From its old stems arise very showy clusters of 20 or more
flowers each with a 10cm long dark pink tube. It is a non-aggressive vine and
can be found throughout New Guinea, New Britain and east into the Solomon
Islands.
The Bamboo
Collection
Bamboos are
giant grasses whose stems and light, strong and extremely flexible and can be
used to make many things. The young shoots are edible in some species. In the
wild, all the plants of a particular species may only flower at intervals of
decades after which all the adult plants die. Many ornamental bamboos are grown
in gardens.
Bougainvillea
Plant
The
Bougainvillea is one of the most common garden plants in the tropics. The
prickly shrub grows intensely colourful paper bracts that surround its flowers.
Garden Bougainvilleas (above) are mostly hybrids of several South American
Bougainvillea species. The generic name of the plants commemorates the French
explorer L.A. de Bougainville.
The Evolution Garden
Throughout
the garden, there are many “trees of stone” which can be found. These Trees of
Stone are “petrified” tree trunks, the persevered, fossilised remains of real
ancient trees (below).
Plants have
played a vital part in the natural world. The Evolution Garden provides an
impression of the fascinating history of plants. The layout of the garden
represents a time journey, starting from a period before life had evolved, and
then travel forward through time seeing the important ages of plants life of
Earth displayed.
3500
million years after the earth had formed, life was created in the form of
primitive bacteria. These bacteria were able to photosynthesise, making as
oxygen as a by-product by trapping light energy. These included colonial forms
that secreted calcium chloride slowly developing rock pedestals called
stomatolites (below).
About 450
million years ago, the first land plants appeared. They were algae and
liverworts which grew near rivers and were joined by small stick-like plants
without roots or leaves. After the initial colonisation, land plants diversified.
Ferns, seed ferns and primitive trees, climbers and epiphytes started
appearing. There were also huge swamps dominated by giant lycopod trees
(below). Coal formed during this age is one of our major energy sources now.
After the
swamps disappeared as the climate warmed up about 300 million years ago, giant
horsetails and clubmosses were greatly reduced in abundance but the ferns,
cycads and conifers all diversified (below). Reptiles evolved into the early
dinosaurs as they roamed the forests of tree ferns.
The Central Area of the Botanic Gardens
The Simpoh
Air Plant
On the side
of the walkway in the central area of the botanic gardens, the Simpoh Air
plants can be found in abundance. It is a native shrub that grows well in poor
soil, including marshy ground. The large leaves and yellow flowers make it easy
to recognise (although at that time, I could not spot any flowers). Its fruits
are leathery capsules that split open in a star-like fashion, revealing 5 pink
segments lined with the seeds.
Heliconia
Walk
Heliconias
are related to gingers and bananas. Except for a few species found in the south
pacific, they are restricted to tropical America where they are often
pollinated by humming birds. In Singapore, the native sunbirds take over this
job. These birds are often seen visiting the flowers of the plant (below).
The Orchid
Garden
The
national flower of Singapore: Vanda Miss Joaquim (below)
This orchid
is a hybrid between the Vanda teres and the Vanda hookerian. It is an extremely
hardy yet free flowering orchid. Described by the first director of the Botanic
Gardens in Singapore in 1893, it is the first orchid hybrid to be described
from Singapore. It was named after Agnes Joaquim whose garden the orchid grew
in.
Carnivorous
Plants in the Cool House
A selection
of plants native to South East Asia is
grown in the cool house. The plants in it are arranged to simulate the
vegetation of a tropical mountain forest. On the far side of the cool house
there is a display of carnivorous plants.
The pitcher
plant: It attracts insects with its colour and nectar-secreting glands. Once
inside of the pitcher, the insects are trapped. They cannot climb out as the walls
of the pitcher are slippery with wax, and the rim of the pitcher is lined with
an overhanging row of “teeth”. Finally, the insect drowns in the fluid in the
pitcher. Special glands secrete acids and digestive enzymes to digest the dead
insect. The nutrients are then absorbed
through the wall of the pitcher.
My Reflection
I felt that
this trip to the botanic gardens was very interesting as I learnt a lot about
the history of plants as well as plants native to our country. Also, I learnt
much about the history and important role of Singapore’s very own Botanic
Garden.
Throughout
the garden, there were many plagues which have descriptions of the plants shown.
These were very helpful as they let visitors know more about a certain plant of
flower. Through this, I have greatly widened my knowledge about botany, which
at first may seem like a boring topic, turned out to be a very exciting and
interesting field of science.
The role of
the botanic gardens has played an important part of Singapore’s development as
a “garden city”, as well as in the field of botany. Research on different
plants are done right there in the botanic garden, contributing greatly to many
areas such as spearheading the garden city project in the development of
Singapore and even saving the environment.
In
conclusion, I felt that the trip was a very fruitful one indeed and hope that I
can find the time to visit the gardens once more to admire the great works of
mother nature.
Year 2011
For our ACE projects, we can do whatever we want, as long as Mr Low approves of it.
Term 2
In term 2, I did an ACE project on black holes. In order to get the information I needed, I searched the web for useful facts that I thought I could add to my report. Also, I consulted some of my seniors in the astronomy club to clarify any doubts I had about black holes. After I got the information I needed through research, i summarised them and made them a lot simpler to understand. Also, I added pictures I obtained from the web and an astronomy software that I have. The end product was a 5 page report. I decided to do a project on black holes, as I am very interested in them. Black holes are the only place in the universe where the laws of physics do not apply. This is also part of my interest, astronomy. Click here to find out more.
Here is the entire report.
Black Holes
Formation of Black Holes
The main formation of black holes is the gravitational collapse of extremely heavy objects such as stars, but there are other ways in which black holes are formed.
Towards the end of a star’s life, depending on the mass of the star, the star will swell up and become a red giant before shrinking to become a white dwarf. These stars will be in this state until they completely cool down to become a black dwarf (no such thing exists yet as the time taken for a white dwarf to cool down is longer than the age of the universe now). These stars have a mass of 1.38 solar masses, which is the Chandrasekhar Limit, or lower (below 1.38 times the mass of our sun).
For the stars that have a mass higher than the Chandrasekhar Limit, the maximum mass a white dwarf can have, they undergo gravitational collapse which makes the pressure and temperature in the core rise. The outer layer of the star collapses inward before crashing downwards towards its core at extremely high speeds. Due to the formation of neutrons in the core of the star, the core sends out a shockwave which hits the in-falling outer layer. In this collusion, the outer layers of the star are blasted off in a violent explosion known as a Type II Supernova.
Despite this, the core of the star remains intact, but the core is ultra-compressed, a huge amount of mass squeezed into a small space. This core is called a neutron star, a super dense star with a diameter of just 15km.
But there is a limit to which the neutron star can withstand. If the mass of the neutron star exceeds the mass of 2.98 solar masses, the Tolman-Oppenheimer-Volkoff Limit, the neutron star is unable to hold its own weight. The gravity of the neutron star crushes the entire star downwards, causing the whole star to collapse. With nothing to resist this, the whole star is compressed to a single point: a singularity.
What are Black Holes?
Suppose the universe is a piece of fabric. A cloth in which everything else rests on. Since it’s there across all the space of the universe, and always present throughout all the time which the universe existed, it will be called the space-time fabric.
If an object (such as the sun) is present on this space time fabric, the mass of the object will cause the space-time fabric to be depressed, as in the picture on the left.
But in a black hole, the space-time fabric is depressed so much, that the two sides of the fabric touches each other. Once the incoming object passes this point, it drops into this singularity, forever lost to the universe. Even light is unable to escape this point (that’s why black holes are black), so if the object is travelling faster than the speed of light, it wouldn’t be able to escape the gravitational pull of the black hole. This point is called the event horizon.
Classification of Black Holes
The no-hair theorem states that Black holes are mainly classified into 4 categories according to their spin and electric charge. It is called the no-hair theorem as the founder of this theory was a monk who said, “I have no hair and hence my theory would have no hair too. The 4 categories of black holes are: Kerr, Schwarzchild, Kerr-Newman and Reissner-Nordstrom. Kerr black holes have spin, but no charge. The spin came from the rotation when the black hole was still a star. Schwarzchild black holes have no spin and no charge. They have no spin likely because they had an extremely slow rotation when they were stars. It’s likely that faster rotating stars become Kerr, while slower rotating ones become Schwarzchild. However, stars spin faster as they become smaller, such as when supergiants become neutron stars. So when stars become a singularity, or a black hole, it’s highly likely that they will spin fast, therefore Kerr black holes are the most common type. Kerr-Newman black holes have spin and charge. Reissner-Nordstrom black holes have spin but no charge.
Spin
|
No spin
| |
No charge
|
Kerr
|
Schwarzchild
|
Charge
|
Kerr-Newman
|
Reissner-Nordstrom
|
Detection of Black Holes
Hawking Radiation
Hawking Radiation describes the loss of material from a black hole. It is a very recent breakthrough coined and explained by Professor Stephen Hawking. He showed that black holes would emit a small amount of thermal radiation due to the formation of particle and anti-particle pairs at the black hole’s event horizon. These particle and anti-particle pairs usually cancel out each other as one is positively charged while one is negatively charged, but when the pair is at an event horizon of a black hole, the negative mass particles will fall into the black hole while the positive mass particle will manage to escape. The positive mass particles that escape are observed as radiation, therefore it seems that black holes emit this thermal radiation. As for the negative mass particles, they fall into the black holes and slowly decrease the black hole’s mass over time as they have negative mass. According to Einstein’s theory of relativity, E=MC², when an object loses mass, it loses energy. Therefore, when the black hole loses mass due to the negative mass particles that fall in, it loses energy too. As the black hole loses mass, it gets smaller and smaller, and at the same time, it gets hotter and hotter. It keeps increasing in temperature until it gets to a point where it’s so hot, it eventually explodes, losing the remainder of its mass in a very short time.
Resources
Hwa Chong JC Astro Club
http://www.youtube.com/watch?v=S6srN4idq1E--------------------------------------------------------------------------------------------------------------------------
Term 3
In term 3, I did an ACE project on stem cells. During science lesson, we were starting a new topic on cells. As Mr Low was talking about the cells in the human body, he mentioned about stem cells and said that it was a possible topic for an ACE project. I was immediately interested in this as stem cells are like "blank cells", so they can change into many specialised cell types. After learning this, I decided to do an ACE project on these as I wanted to learn more about them. The final result of all my research on them was a 3 page report on stem cells.
Here is the entire report.
Stem Cells
What are Stem Cells?
Stem cells are a class of undifferentiated cells (blank cells) that do not have any function yet, but are able to differentiate or change into many specialised cell types. Here is a picture of an embryonic stem cell (the stem cell which comes from an embryo 3 to 5 days old):
The source of Stem Cells
Commonly, stem cells come from 2 main sources:
1. Embryos formed during the blastocyst phase (4 to 5 days after the ovum has been fertilised) of embryological development (embryonic stem cells). See the picture above.
2. Adult tissue (adult stem cells). These stem cells are found in many parts of the human body, including the brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, gut, liver, ovarian epithelium, and testis.
Adult Stem Cells
In many tissues, current evidence suggests that some types of stem cells compose the outermost layer of small blood vessels. Stem cells may remain at a stage in which they are non-dividing for long periods of time, until they are activated by a normal need for more cells to maintain tissues, or by disease or tissue injury.
Normally, there is a very small number of stem cells in each tissue, and once removed from the body, their capacity to divide is limited, making generation of large quantities of stem cells difficult. Therefore, scientists are trying to find better ways to grow large quantities of adult stem cells in cell culture and in order to change them into a specific cell types so they can be used to treat injuries or diseases.
Embryonic Stem Cells
Embryonic stem cells are obtained from a four to five day old human embryo. These embryos are usually extras that have been created in In Vitro Fertilization (IVF) clinics where several eggs are fertilized in a test tube, but only one is implanted into a woman.
Cord Blood & Cord Blood Banking
Cord Blood
Cord blood is the blood that remains in a new born baby’s umbilical cord after birth. Cord blood, similar to bone marrow, is an invaluable source of a type of stem cell that can be used in a variety of medical treatments. A process known as cord blood banking allows families of new born babies to save this valuable resource for potential future medical use. If it is not saved, it is discarded at the hospital.
The Difference between Cord Blood Stem Cells and Other Stem Cells
Cord blood stem cells are biologically younger than other stem cells from other sources such as bone marrow. Therefore, cord blood stem cells have several advantages compared to other stem cell sources:
1. There is less risk of complications when used in transplants.
2. They are immediately available, and early treatment can minimize disease progression.
3. Freezing them protects them from environmental damage, age, and common viruses that will impact the stem cells in our bodies over time.
4. Collection of cord blood is simple, safe, and painless.
Cord blood stem cells are not the same as embryonic stem cells.
Sources:
Term 4
Although term 4 has just started, I have received the results of my ICAS science competition which I took part in last term. My total score was 39/45, which is also a Distinction ( I missed high distinction by 1 mark). Overall, my score was in the top 2 percent of Secondary 1 participants who took part in this. I have been taking part in the ICAS assessments since I was in primary school.
