Before The Test
In the last examination of the year, I planned to score a high A1, maybe 90 or high, just like what I did in term 3. To do that, I planned to revise all the chapters being taught, if I faced difficulties in a certain topic, I will ask my teacher and peers. I will also practice more so as to prepare for the questions being set in the test. I will revise more on Optics and Chemistry as I am weak at them and I may have forgot some important stuffs. For Ecology, I am quite confident but I was NOT be complacent and not revise for it. I will still revise for it, but not as much as the other topics.
During The Test
During the test, I will be much more careful than before but not spend so much time that will have no time to complete the paper. I will try my best to complete the MCQ in the shortest time possible, fast but careful. For the open ended question, I will underline and circle key phrases to help me understand the question better. For drawing, which is my weakest, will take a longer time. However, I will draw the diagrams much faster after I practice before the tests. I will be more careful and make my drawings look neat and accurate so as to not lose marks. After the paper, I will do and check the paper over and over again to minimize careless mistakes.
All I can do now is to study hard to ensure that I will get good results in my Science EOY paper. I hope that I will do well in both Math and Science and even all my other subjects so as to get into Science and Math Talent Program(SMTP), the course that I want to go. To do that I MUST get 2.0 and below and get a A1 in both Science and Math. Both Math and Science are my favorite subject and I am confident that as long as I study hard, I have no trouble in getting into SMTP and getting A1s in Math and Science. It is useless to count the chicken before it hatch so all I can do now is to study hard and use my own efforts to get into SMTP before it is too late as it is useless to cry over spilled milk after the results comes out.
Hi Readers, this is my Science E portfolio that I am required to do. Hope you love it!!! :)
Issues in teaching and Learning Science (Term 3)
In Term 3, we learned about Optics(Lens and Colors), Physics as we are unable to finish it in term 2 and also Biology(Ecology and Sexual Reproduction System). We managed to complete Ecology but we are unable to complete Sexual Reproduction System.
Lens
- There are 2 types and lens, concave and convex lens
- We learned how to draw the light rays entering from different angles and distance.
Colors
- There are a total seven bands of colours in a ray of white light
- The seven bands of colours are known as the visible spectrum
- Each color in the spectrum has a different wavelength
-The process of the seperation of white light to the seven bands of light is known as dispersion
Ecology
- Habitat is a place where organism live in
- Population is a group of organism of the same species living in a particular habitat
- Community is a place where all populations of organisms living and interacting with one another in a particular habitat
- Ecosystem is a community and its abiotic factors
Abiotic Factors
- Tempertaure
- Ph
- Oxygen Content
- Humidity
- Amount of water
- Wave Action
- Wind Speed
- Light Intensity
- Salinity
- Type of substratum
Biotic Factors
- Mutualism
- Commensalism
- Exploitative Relationship (Predation, Paratism, Herbivory)
- Competition
- Ammensalism
We also learned about:
- Feeding relationship
- Conservation
- Effects of selective addition/removal of species
- Carbon Cycle (refer to earlier blog post)
Sexual Reproduction
- is the biological process of forming a new individual through the fusion of two cells known a gametes
Puberty
- a process which every human beings go through at a certain age
- after this process, one will be able to reproduce
- one will mature
Puberty of Boys
- males might experience growth of hair on the face, underarm, chest, abdominal and pubic area, broadening of chest and shoulders, enlargement of penis, depening of voice, increase in height and muscle and getting pimples or acne
Puberty of Girls
- females might experience growth of underarn and pubic hair, broadening of hips, enlargement of breast and getting pimples
We also learn about:
- Menstrual Cycle
- Sexually Transmitted Diseases
MY REFLECTION FOR TERM 3
In this term, the topic being taught was fairly easy, especially for Ecology as I had gone to sabbatical for it. For lens, we just have to memorize the formulas and for Sexual Reproduction we just have to memorize. It seem that this term is a term for memorizing. The topics this term do not have much to think about as it was all formulas and definition or facts. I was not required to learn Sexual Reproduction System for the test as there was not enough time to teach before the test. I feel that Ecology is very educational as students learn to conserve their environment.
Lens
- There are 2 types and lens, concave and convex lens
- We learned how to draw the light rays entering from different angles and distance.
Colors
- There are a total seven bands of colours in a ray of white light
- The seven bands of colours are known as the visible spectrum
- Each color in the spectrum has a different wavelength
-The process of the seperation of white light to the seven bands of light is known as dispersion
Ecology
- Habitat is a place where organism live in
- Population is a group of organism of the same species living in a particular habitat
- Community is a place where all populations of organisms living and interacting with one another in a particular habitat
- Ecosystem is a community and its abiotic factors
Abiotic Factors
- Tempertaure
- Ph
- Oxygen Content
- Humidity
- Amount of water
- Wave Action
- Wind Speed
- Light Intensity
- Salinity
- Type of substratum
Biotic Factors
- Mutualism
- Commensalism
- Exploitative Relationship (Predation, Paratism, Herbivory)
- Competition
- Ammensalism
We also learned about:
- Feeding relationship
- Conservation
- Effects of selective addition/removal of species
- Carbon Cycle (refer to earlier blog post)
Sexual Reproduction
- is the biological process of forming a new individual through the fusion of two cells known a gametes
Puberty
- a process which every human beings go through at a certain age
- after this process, one will be able to reproduce
- one will mature
Puberty of Boys
- males might experience growth of hair on the face, underarm, chest, abdominal and pubic area, broadening of chest and shoulders, enlargement of penis, depening of voice, increase in height and muscle and getting pimples or acne
Puberty of Girls
- females might experience growth of underarn and pubic hair, broadening of hips, enlargement of breast and getting pimples
We also learn about:
- Menstrual Cycle
- Sexually Transmitted Diseases
MY REFLECTION FOR TERM 3
In this term, the topic being taught was fairly easy, especially for Ecology as I had gone to sabbatical for it. For lens, we just have to memorize the formulas and for Sexual Reproduction we just have to memorize. It seem that this term is a term for memorizing. The topics this term do not have much to think about as it was all formulas and definition or facts. I was not required to learn Sexual Reproduction System for the test as there was not enough time to teach before the test. I feel that Ecology is very educational as students learn to conserve their environment.
Issues in teaching and Learning Science (Term 2)
In Term 2, we learnt about Acids and Bases, Chemistry and Optics(Reflection and Reflection), Physics.
Acids and Bases
Acids
- An acid is a substance which produces hydrogen ions as the only positive ions when it is dissolved in water.
- The strength of an acid depends on its degree of dissociation/ionization in water to form hydrogen ions.
- A strong acid is one that ionizes/dissociates in water to produce hydrogen ions. There are no molecules left. The solution contains a high concentration of ions, which cause it to be a good conductor of electricity.
- A weak acid is one that ionizes/dissociates incompletely in water to produce few hydrogen ions. Most of the acids molecules remain as molecules. The solution contains a low concentration of ions, causing it to be a poor conductor of electricity.
- Acids have a sour taste
- contains hydrogen ions
- react with metal, carbonates and base
Reactions of Acids
1. Acid + Metal----> Salt + Hydrogen
2. Acid + Carbonate----> Salt + Carbon Dioxide + Water
3. Acid + Base----> Salt + Water
Bases and Alkalies
- Bases are the oxides or hydroxides of metals that reacts with an acid to form a salt and water only.
- An alkali is a metal hydroxides which is soluble in water and produces hydroxide ions in water
- All alkalies are bases but not all bases are alkalies
- The strength of an alkali depends on its degree of dissociation/ionization in water to form hydroxide ions. The properties of alkalies are due to the hydroxides ions.
- A strong alkali is one that ionizes/dissociates in water to produce hydroxide ions. There are no molecules left. The common strong alkalies are sodium hydroxide and potassium hydroxides.
- A weak alkali is one that ionizes/dissociates incompletely in water to produce few hydroxide ions. Most of the acids molecules remain as molecules.
- Alkalies have a soapy feel and a bitter taste
- Bases react with acids to for salt and water.
Reflection
- When light hits a mirror at a certain angle, that angle is known as the angle of incidence
- When light is reflected at a certain angle, it is known as the angle of reflection
Refraction
- Occurs when light travels through the medium
- Light is bend towards the normal, when it travels out of the medium, it will go back to its original angle
- The denser the medium, the more the light ray bend
MY REFLECTION FOR TERM 2
This topic was quite easy to understand. The only difficulty I faced was on Refraction. This topic requires lots of memorizing especially on the Acid and Bases parts. The worst was drawing as it required a lot of time and every ray must be accurate.
Acids and Bases
Acids
- An acid is a substance which produces hydrogen ions as the only positive ions when it is dissolved in water.
- The strength of an acid depends on its degree of dissociation/ionization in water to form hydrogen ions.
- A strong acid is one that ionizes/dissociates in water to produce hydrogen ions. There are no molecules left. The solution contains a high concentration of ions, which cause it to be a good conductor of electricity.
- A weak acid is one that ionizes/dissociates incompletely in water to produce few hydrogen ions. Most of the acids molecules remain as molecules. The solution contains a low concentration of ions, causing it to be a poor conductor of electricity.
- Acids have a sour taste
- contains hydrogen ions
- react with metal, carbonates and base
Reactions of Acids
1. Acid + Metal----> Salt + Hydrogen
2. Acid + Carbonate----> Salt + Carbon Dioxide + Water
3. Acid + Base----> Salt + Water
Bases and Alkalies
- Bases are the oxides or hydroxides of metals that reacts with an acid to form a salt and water only.
- An alkali is a metal hydroxides which is soluble in water and produces hydroxide ions in water
- All alkalies are bases but not all bases are alkalies
- The strength of an alkali depends on its degree of dissociation/ionization in water to form hydroxide ions. The properties of alkalies are due to the hydroxides ions.
- A strong alkali is one that ionizes/dissociates in water to produce hydroxide ions. There are no molecules left. The common strong alkalies are sodium hydroxide and potassium hydroxides.
- A weak alkali is one that ionizes/dissociates incompletely in water to produce few hydroxide ions. Most of the acids molecules remain as molecules.
- Alkalies have a soapy feel and a bitter taste
- Bases react with acids to for salt and water.
Reflection
- When light hits a mirror at a certain angle, that angle is known as the angle of incidence
- When light is reflected at a certain angle, it is known as the angle of reflection
Refraction
- Occurs when light travels through the medium
- Light is bend towards the normal, when it travels out of the medium, it will go back to its original angle
- The denser the medium, the more the light ray bend
MY REFLECTION FOR TERM 2
This topic was quite easy to understand. The only difficulty I faced was on Refraction. This topic requires lots of memorizing especially on the Acid and Bases parts. The worst was drawing as it required a lot of time and every ray must be accurate.
Issues in teaching and Learning Science (Term 1)
In Term 1, we mainly covered on chemistry. We learnt about the periodic table, atomic structure, the two types of bonding and equation writing.
Periodic Table
In term 1, I learned how to read the periodic Table. In fact, it was easy, the hard part is to memorize the whole table.
- The elements in the periodic table are arranged in ascending of their atomic numbers.
- The elements are arranged in groups and periods. Groups are vertical while periods are horizontal. Elements in the same group have similar properties. When you move across elements in the samePeriod, you will see that the properties of these element will slowly change from metallic to non-metallic.
- Each element have its own atomic and mass numbers, in a periodic table.
Atomic Structure
After learning to read the periodic table, we were taught about Atomic Structure. We learned the following:
- Mass number is number of proton + the number of neutrons
- When we are drawing an atomic structure, we have to write the number of proton and the number of electron in the middle of the structure. We have to draw circles to represent the shells of an atom, the number of circles depends on how many shells the atom have. Dots will represent electrons.
- The first shell only consist of 2 electrons, second shell can have only 8 electrons , third shell can have only 8 electrons.
- When drawing if the atom is a cation, we bracket the structure and draw a plus sign at the top right hand corner outside of the bracket. For anion, it is the same except using the plus sign, we use the minus sign.
The 2 bondings
Next, we learned about the 2 types of bondinsg the occur in atoms. The following explains the 2 bondings, Ionic Bonding and Covalent Bonding.
Ionic Bonding
- Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal.
- In ionic bonding, the atoms of one element will lose one or more electrons and becomes a cation and the atoms of the other element will gain the electrons from the other element and become an anion.
Covalent Bonding
- Covelent bond is a bond formed by sharing of a pair of electron between atoms of non-metals.
Equation Writing
Next, we learn how to write an equation. We learn how to write a
- Word Equation
- Chemical Equation
- To make a balanced equation, we have to make sure that the positive and negative charges of the element add up and equals to the charge of the result.
MY REFLECTIONS FOR TERM 1
In this topic, I had faced numerous difficulties and obstacles as I did not understand some parts. In this topic, the greatest problem I faced is to write a word and chemical equation. Later, I realized that to write a word equation, we must read and memorize the numerous formulas, and maybe sometimes guess. For Chemical Equation, I finally understood how it works, with the help of my Science Teacher, Miss Lim and friend, Bram. They were kind and patience in teaching me. Thanks to them I finally understood. The rest was okay, however for periodic table, it was hell to memorize it.
Source of Pic: http://www.ptable.com/
Periodic Table
In term 1, I learned how to read the periodic Table. In fact, it was easy, the hard part is to memorize the whole table.
- The elements in the periodic table are arranged in ascending of their atomic numbers.
- The elements are arranged in groups and periods. Groups are vertical while periods are horizontal. Elements in the same group have similar properties. When you move across elements in the samePeriod, you will see that the properties of these element will slowly change from metallic to non-metallic.
- Each element have its own atomic and mass numbers, in a periodic table.
Atomic Structure
After learning to read the periodic table, we were taught about Atomic Structure. We learned the following:
- Mass number is number of proton + the number of neutrons
- When we are drawing an atomic structure, we have to write the number of proton and the number of electron in the middle of the structure. We have to draw circles to represent the shells of an atom, the number of circles depends on how many shells the atom have. Dots will represent electrons.
- The first shell only consist of 2 electrons, second shell can have only 8 electrons , third shell can have only 8 electrons.
- When drawing if the atom is a cation, we bracket the structure and draw a plus sign at the top right hand corner outside of the bracket. For anion, it is the same except using the plus sign, we use the minus sign.
The 2 bondings
Next, we learned about the 2 types of bondinsg the occur in atoms. The following explains the 2 bondings, Ionic Bonding and Covalent Bonding.
Ionic Bonding
- Ionic bonds are formed between a cation, which is usually a metal, and an anion, which is usually a nonmetal.
- In ionic bonding, the atoms of one element will lose one or more electrons and becomes a cation and the atoms of the other element will gain the electrons from the other element and become an anion.
Covalent Bonding
- Covelent bond is a bond formed by sharing of a pair of electron between atoms of non-metals.
Equation Writing
Next, we learn how to write an equation. We learn how to write a
- Word Equation
- Chemical Equation
- To make a balanced equation, we have to make sure that the positive and negative charges of the element add up and equals to the charge of the result.
MY REFLECTIONS FOR TERM 1
In this topic, I had faced numerous difficulties and obstacles as I did not understand some parts. In this topic, the greatest problem I faced is to write a word and chemical equation. Later, I realized that to write a word equation, we must read and memorize the numerous formulas, and maybe sometimes guess. For Chemical Equation, I finally understood how it works, with the help of my Science Teacher, Miss Lim and friend, Bram. They were kind and patience in teaching me. Thanks to them I finally understood. The rest was okay, however for periodic table, it was hell to memorize it.
Source of Pic: http://www.ptable.com/
Carbon Cycle
The Carbon Cycle exists in the ecosystem and plays a very important role in it. Carbon is found in every ecosystem, because every living things, whether it is humans, tigers or even plants, are composed of carbon compounds. The atmosphere is the main source of carbon for all ecosystem. The Carbon Cycle also ensures that there is a continuous supply of carbon dioxide for plants to carry out photosynthesis, which in turn produce oxygen and food, which is necessary for living things to survive. With food produce, it enables energy to flow through the ecosystem.
So, how does the process work? The following is the process taken:
Photosynthesis
- Carbon is absorbed in the form of CO2, carbon dioxide and is converted to glucose which may then be used for respiration and for building of protoplasm in plants.
- The plants are then consumed by primary consumers, which carbon and energy is then transferred in to them. With successive feeding, carbon compounds move up to higher tropic levels in the ecosystem.
Respiration
- When plants and animals respire, carbon dioxide is released into the atmosphere.
Decomposition
- As organisms die, they decay and decomposed, which releases carbon dioxide back into the environment.
Destruction of vegetation
- As bush fires occurs, plants are being burnt down by large forests which releases large quantities of carbon dioxide into the environment.
Sedimentation and Mineralization
- In the form of fossils where carbon is stored into organism which did not undergo decomposition when they died.
- Found in shells of organisms in the sea where they are in the form of bicarbonate. When the organisms die, their shells sink to the bottom of the sea and become compacted. Over a long period of time, they become limestone(calcium carbonate) which stores carbon.
The above can be seen in the diagram below:
Picture from: http://www.google.com.sg/imgres?imgurl=http://www.visionlearning.com/library/modules/mid95/Image/VLObject-2637-031218011217.jpg&imgrefurl=http://www.visionlearning.com/library/module_viewer.php%3Fmid%3D95&h=318&w=400&sz=60&tbnid=ejrAO1i2jAdvsM:&tbnh=90&tbnw=113&prev=/search%3Fq%3Dcarbon%2Bcycle%26tbm%3Disch%26tbo%3Du&zoom=1&q=carbon+cycle&docid=9E72nxc7lHaAnM&sa=X&ei=26ZpTv2dGY_irAfJ8smoBQ&ved=0CDkQ9QEwAg&dur=159
So, how does the process work? The following is the process taken:
Photosynthesis
- Carbon is absorbed in the form of CO2, carbon dioxide and is converted to glucose which may then be used for respiration and for building of protoplasm in plants.
- The plants are then consumed by primary consumers, which carbon and energy is then transferred in to them. With successive feeding, carbon compounds move up to higher tropic levels in the ecosystem.
Respiration
- When plants and animals respire, carbon dioxide is released into the atmosphere.
Decomposition
- As organisms die, they decay and decomposed, which releases carbon dioxide back into the environment.
Destruction of vegetation
- As bush fires occurs, plants are being burnt down by large forests which releases large quantities of carbon dioxide into the environment.
Sedimentation and Mineralization
- In the form of fossils where carbon is stored into organism which did not undergo decomposition when they died.
- Found in shells of organisms in the sea where they are in the form of bicarbonate. When the organisms die, their shells sink to the bottom of the sea and become compacted. Over a long period of time, they become limestone(calcium carbonate) which stores carbon.
The above can be seen in the diagram below:
Picture from: http://www.google.com.sg/imgres?imgurl=http://www.visionlearning.com/library/modules/mid95/Image/VLObject-2637-031218011217.jpg&imgrefurl=http://www.visionlearning.com/library/module_viewer.php%3Fmid%3D95&h=318&w=400&sz=60&tbnid=ejrAO1i2jAdvsM:&tbnh=90&tbnw=113&prev=/search%3Fq%3Dcarbon%2Bcycle%26tbm%3Disch%26tbo%3Du&zoom=1&q=carbon+cycle&docid=9E72nxc7lHaAnM&sa=X&ei=26ZpTv2dGY_irAfJ8smoBQ&ved=0CDkQ9QEwAg&dur=159
Personal Work Sample (ACE)
Hi Readers, the following is an Ace which I had done for term 3. Hope you like it. In the rubrics I have no idea what "personal work" really meant so I assume it is Ace, something that I had done. Hope you like it :D
Adaptation of Sharks
What are sharks?
Sharks are a type of fish with a full cartilaginous skeleton and a highly skeleton and streamlined body. Did you know the earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs. Scientist has only found 440 species of sharks. Ranging from small-sized dwarf shark to the enormous whale shark, which can grow up to approximately 12 metres (39 ft 4 in) and which feeds only on plankton, squid and small fishes by filter feeding. Sharks are found in all seas and are common down to depths of 2,000 metres (6,562 ft). Most sharks lived in the ocean but some sharks like the bull shark can live in fresh water too. All sharks breathe through 5 to 7 gill slits and they do not have scales but a toothed-like skin which enable them to shark faster.
Firstly, what is adaptation?
- The evolutionary process whereby a population becomes better suited to its habitat. This process takes place over many generations, and is one of the basic phenomena of biology.
- A feature which is especially important for an organism's survival and reproduction.
- Produced in a variable population by the better suited forms reproducing more successfully, that is, by natural selection.
Sharks’ adaptation to the world around them/ Biotic Factors
- Sharks have a large oily liver and light cartilaginous skeleton, unlike fish that have a swim bladder to regulate buoyancy. These adaptations allow the shark to control their buoyancy in water. With an oil filled liver instead of a swim bladder, sharks are able to make fast changes in depth without having to wait for gas pressure to be equalize, which is a necessary adaptation for pursuing preys in the depth of the surface to 100m. Did you know that even though sharks’ cartilage is about half as dense as bone and the liver constitutes up to 30% of their body, sharks still have to keep on swimming or they would sink. To prevent sinking, the sharks employ dynamic lift to maintain depth. Some sharks such as Sand Tiger sharks store air in their stomachs, using it as a form of swim bladder. However, certain shark species, such as the nurse shark, are capable of pumping water across their gills, allowing them to rest on the ocean bottom.
- Most sharks have streamlined body, which are torpedo shape; this will enable the shark to swim faster so as to pursue prey. Also, the shark have a tailfin with a longer lobe, which is necessary as it provides a downward driving force to balance forward lift caused by the pectoral fins and flat ventral surface of the snout.
- All sharks have dermal denticles, which feel like sandpaper. This will channel the surrounding water to produce laminar flow, which lowers friction, making the shark hydrodynamic. With the shark having lesser water resistance, the shark is able to swim much faster, allowing it to hunt for its prey easier.
- Another adaptation of many predatory shark species have a nictitating lower eyelid, such as the Tiger Shark, which slides across the eyeball allowing the shark to protect its most vulnerable organ at the time of the attack. However, some sharks like the great white shark, do not have the nictitating eyelid. Instead of using the eyelid, they roll their eyes backwards, preventing injuries in their eyes from the threshing of prey.
- A sharks’ most important sense is smell. It is so powerful that sharks are able to niff a tea spoon of blood in an Olympic size pool, sharks can smell up to 100m or more. Once the shark identifies the scent, it will start swimming. The sharks’ natural swimming motion of moving its head back and forth provides further assistance in determining where the scent is coming from. With each movement, the snout picks up more water for the shark to analyze, and the shark is able to tell whether it’s coming from the right or left nares. This helps them determine which way to swim. The shark’s nose may work so well because it does not have to do anything else. Shark use their nose just for smelling and the sharks’ sense of smell is not connected to its mouth so sharks often do not know how something is going to taste until they have taken a bite. With this keen form of smell, sharks are able to locate weak, injured and old preys, making it easier for the shark to hunt for its prey.
- Sharks have probably the most efficient teeth in the animal world as they are able to remove tissues/flesh up to 10kg or more from their prey from just a single bite. The teeth are arrange in rows, which moves up when those that are in used are damaged or lost in the struggle with the prey. This process will last a life-span, meaning to say that the sharks will continuously have teeth. It was said by some researchers that sharks can lose up to 5000 teeth per life time. Their teeth also get replaced by bigger teeth as they get bigger. The bite-force of a shark can be enormous, with a large force of 18 tons per square inch. Different teeth have different functions. The Mako’s and Sand Tiger’s have fang-like teeth for seizing and holding their fast moving prey, in which the prey is swallowed whole. In another case, the Great White Shark have large triangular teeth for cutting large cunk of flesh from its prey.
Abiotic Factors
- Salinity. Sharks tend to live in salty water, however there are still sharks that are able to live in fresh water, such as the bull shark.
- Temperature. For every shark, there is a different amount of temperature for the shark to survive. Great white sharks live in water where the temperature is between 12°C and 25°C (54°F to 78°F), while nurse sharks tend to stay in warm waters.
Habitat
The approximate 500 different shark species can be found in all of the oceans and the vast majority of the seas throughout the world. Because water covers an enormous percentage of the earth’s surface, this implies a significant number of animals inhabiting its depths. There are a small number of shark species that are able to live in freshwater rivers and lakes as well. Most sharks live between the water’s surface and 2000 metres down. It is rare to find sharks living at 3000 metres or more below sea level, but it has been witnessed, such as the goblin shark. Sharks tend to prefer the shallower continental shelf areas. This is because these are the areas at which rivers deposit nutrients into the oceans. These nutrients feed the marine lives in this water from a cellular level, which, in turn, feed larger and larger species. The chain continues until it reaches predators such as sharks and even human beings, who feed off fish, crustaceans and molluscs.
Adaptation of Sharks
What are sharks?
Sharks are a type of fish with a full cartilaginous skeleton and a highly skeleton and streamlined body. Did you know the earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs. Scientist has only found 440 species of sharks. Ranging from small-sized dwarf shark to the enormous whale shark, which can grow up to approximately 12 metres (39 ft 4 in) and which feeds only on plankton, squid and small fishes by filter feeding. Sharks are found in all seas and are common down to depths of 2,000 metres (6,562 ft). Most sharks lived in the ocean but some sharks like the bull shark can live in fresh water too. All sharks breathe through 5 to 7 gill slits and they do not have scales but a toothed-like skin which enable them to shark faster.
Firstly, what is adaptation?
- The evolutionary process whereby a population becomes better suited to its habitat. This process takes place over many generations, and is one of the basic phenomena of biology.
- A feature which is especially important for an organism's survival and reproduction.
- Produced in a variable population by the better suited forms reproducing more successfully, that is, by natural selection.
Sharks’ adaptation to the world around them/ Biotic Factors
- Sharks have a large oily liver and light cartilaginous skeleton, unlike fish that have a swim bladder to regulate buoyancy. These adaptations allow the shark to control their buoyancy in water. With an oil filled liver instead of a swim bladder, sharks are able to make fast changes in depth without having to wait for gas pressure to be equalize, which is a necessary adaptation for pursuing preys in the depth of the surface to 100m. Did you know that even though sharks’ cartilage is about half as dense as bone and the liver constitutes up to 30% of their body, sharks still have to keep on swimming or they would sink. To prevent sinking, the sharks employ dynamic lift to maintain depth. Some sharks such as Sand Tiger sharks store air in their stomachs, using it as a form of swim bladder. However, certain shark species, such as the nurse shark, are capable of pumping water across their gills, allowing them to rest on the ocean bottom.
- Most sharks have streamlined body, which are torpedo shape; this will enable the shark to swim faster so as to pursue prey. Also, the shark have a tailfin with a longer lobe, which is necessary as it provides a downward driving force to balance forward lift caused by the pectoral fins and flat ventral surface of the snout.
- All sharks have dermal denticles, which feel like sandpaper. This will channel the surrounding water to produce laminar flow, which lowers friction, making the shark hydrodynamic. With the shark having lesser water resistance, the shark is able to swim much faster, allowing it to hunt for its prey easier.
- Another adaptation of many predatory shark species have a nictitating lower eyelid, such as the Tiger Shark, which slides across the eyeball allowing the shark to protect its most vulnerable organ at the time of the attack. However, some sharks like the great white shark, do not have the nictitating eyelid. Instead of using the eyelid, they roll their eyes backwards, preventing injuries in their eyes from the threshing of prey.
- A sharks’ most important sense is smell. It is so powerful that sharks are able to niff a tea spoon of blood in an Olympic size pool, sharks can smell up to 100m or more. Once the shark identifies the scent, it will start swimming. The sharks’ natural swimming motion of moving its head back and forth provides further assistance in determining where the scent is coming from. With each movement, the snout picks up more water for the shark to analyze, and the shark is able to tell whether it’s coming from the right or left nares. This helps them determine which way to swim. The shark’s nose may work so well because it does not have to do anything else. Shark use their nose just for smelling and the sharks’ sense of smell is not connected to its mouth so sharks often do not know how something is going to taste until they have taken a bite. With this keen form of smell, sharks are able to locate weak, injured and old preys, making it easier for the shark to hunt for its prey.
- Sharks have probably the most efficient teeth in the animal world as they are able to remove tissues/flesh up to 10kg or more from their prey from just a single bite. The teeth are arrange in rows, which moves up when those that are in used are damaged or lost in the struggle with the prey. This process will last a life-span, meaning to say that the sharks will continuously have teeth. It was said by some researchers that sharks can lose up to 5000 teeth per life time. Their teeth also get replaced by bigger teeth as they get bigger. The bite-force of a shark can be enormous, with a large force of 18 tons per square inch. Different teeth have different functions. The Mako’s and Sand Tiger’s have fang-like teeth for seizing and holding their fast moving prey, in which the prey is swallowed whole. In another case, the Great White Shark have large triangular teeth for cutting large cunk of flesh from its prey.
Abiotic Factors
- Salinity. Sharks tend to live in salty water, however there are still sharks that are able to live in fresh water, such as the bull shark.
- Temperature. For every shark, there is a different amount of temperature for the shark to survive. Great white sharks live in water where the temperature is between 12°C and 25°C (54°F to 78°F), while nurse sharks tend to stay in warm waters.
Habitat
The approximate 500 different shark species can be found in all of the oceans and the vast majority of the seas throughout the world. Because water covers an enormous percentage of the earth’s surface, this implies a significant number of animals inhabiting its depths. There are a small number of shark species that are able to live in freshwater rivers and lakes as well. Most sharks live between the water’s surface and 2000 metres down. It is rare to find sharks living at 3000 metres or more below sea level, but it has been witnessed, such as the goblin shark. Sharks tend to prefer the shallower continental shelf areas. This is because these are the areas at which rivers deposit nutrients into the oceans. These nutrients feed the marine lives in this water from a cellular level, which, in turn, feed larger and larger species. The chain continues until it reaches predators such as sharks and even human beings, who feed off fish, crustaceans and molluscs.
Reflections of laboratory sessions
Sadly, this year, we did not have any Science excursion or Field Trip due to the fact that we did not have any time. However, we have practical lessons every week for Chemistry and Physics.
For Chemistry, we started off with acid and bases and learn the basics but important reactions between Acids, Bases, Metals and Carbons. It was really wonderful to look at the reactions being carried out during these lessons. It was not really interesting as it used to be as we are doing Acid and Bases over the whole term, however the good things is that we are able to do the experiment on our own and be amaze by the results that we have found. This was something that could never be achieved no matter how vividly and excitingly the textbook describes the experiment. It was both enjoyable and fruitful for the Practical lessons.
In Physics, we just did some experiments on light, which was really boring. Maybe that was what made me dislike Physics. Anyway it was boring as it has no reaction, just only how light move and nothing more.
In these practical lessons, we were thought not too look at one angle but many other and not to be narrow-minded. It tells us that Science is limitless and something new can happen anytime and it is up to us, humans to find out how it happened. It also tells us that getting an A1 is not that important, but the important thing is to have fun and continuously learn and find out.
For Chemistry, we started off with acid and bases and learn the basics but important reactions between Acids, Bases, Metals and Carbons. It was really wonderful to look at the reactions being carried out during these lessons. It was not really interesting as it used to be as we are doing Acid and Bases over the whole term, however the good things is that we are able to do the experiment on our own and be amaze by the results that we have found. This was something that could never be achieved no matter how vividly and excitingly the textbook describes the experiment. It was both enjoyable and fruitful for the Practical lessons.
In Physics, we just did some experiments on light, which was really boring. Maybe that was what made me dislike Physics. Anyway it was boring as it has no reaction, just only how light move and nothing more.
In these practical lessons, we were thought not too look at one angle but many other and not to be narrow-minded. It tells us that Science is limitless and something new can happen anytime and it is up to us, humans to find out how it happened. It also tells us that getting an A1 is not that important, but the important thing is to have fun and continuously learn and find out.
Science Test Reflection (Term 3)
In this test, we are tested on Ecology, part of biology and Optics, part of Physics. That's all simple. It was quite simple for me, however Optics really worry me as I am not very good in physics, which can be seen in how I fared in Term 2.
I decided to focus more on optics as I understand my Ecology well. I tried to memorize the numerous properties of different optic lenses. Then, the difficult part was the application of it on real life objects. Also, I used those old worksheet to practice on how to draw the lens as I did not want to take too much time drawing the light rays, which had caused my downfall in the Term 2 test.
For ecology, I forced myself to read the numerous notes. I also did some practice paper to test myself. It was quite easy, however I knew that I cannot underestimate what will pop out in the test. Even after finishing the paper, I forced myself to memorize all the definitions as we are not allowed to refer to notes in a test.
During the test, I headed into the paper without much difficulty, maybe due to my rigorous attempt to study. After 25 minutes, I finished the paper. I used the remaining time to check my paper so as to prevent me from making careless mistakes like what had happened during the last 2 terms.
After the paper, after much discussions with my friends, I realized that I did not make any mistakes in the questions being discussed. However, I was still afraid as my optic is not strong. I prayed for the best, hoping that I would score an A1.
After 2 weeks of nervous waiting, the papers are being given out one by one. I was surprised when I received my papers, I had scored 36/50. What a surprised! I had never scored this well since Primary 6. My efforts paid off. However, after going through the paper, I realized I had made some careless mistakes but not as much as the last term. I could have gotten 39/40--- higher than the highest in class. Although I was not the highest, I was still please with myself for obtaining such a mark. However, I will NOT be complacent and will work my very best for the EOYs.
I decided to focus more on optics as I understand my Ecology well. I tried to memorize the numerous properties of different optic lenses. Then, the difficult part was the application of it on real life objects. Also, I used those old worksheet to practice on how to draw the lens as I did not want to take too much time drawing the light rays, which had caused my downfall in the Term 2 test.
For ecology, I forced myself to read the numerous notes. I also did some practice paper to test myself. It was quite easy, however I knew that I cannot underestimate what will pop out in the test. Even after finishing the paper, I forced myself to memorize all the definitions as we are not allowed to refer to notes in a test.
During the test, I headed into the paper without much difficulty, maybe due to my rigorous attempt to study. After 25 minutes, I finished the paper. I used the remaining time to check my paper so as to prevent me from making careless mistakes like what had happened during the last 2 terms.
After the paper, after much discussions with my friends, I realized that I did not make any mistakes in the questions being discussed. However, I was still afraid as my optic is not strong. I prayed for the best, hoping that I would score an A1.
After 2 weeks of nervous waiting, the papers are being given out one by one. I was surprised when I received my papers, I had scored 36/50. What a surprised! I had never scored this well since Primary 6. My efforts paid off. However, after going through the paper, I realized I had made some careless mistakes but not as much as the last term. I could have gotten 39/40--- higher than the highest in class. Although I was not the highest, I was still please with myself for obtaining such a mark. However, I will NOT be complacent and will work my very best for the EOYs.
Science Test Reflection (Term 2 + Retest)
For the actual test... I do not really want to talk about it as I did very badly. However as it is a requirement in this Science E portfolio, I have not choice but to talk about it. In this test I scored 20.5/40. Very Very bad for my standard I would say. In this test I was tested on Light Physics(my worst of the 3 sciences). Honestly, I do not have any interest in Physics as I thought that it is really boring. When I have doubt I would not ask the teacher as I was too lazy to ask. In this test, I took too much time drawing the ray diagrams and doing the MCQs that I did not complete the paper, resulting in the lost of marks. In this test, many of my classmates had gotten A1, thus I was the bottom of the bottom in my class.
Luckily, Miss Lim was kind enough to give us a retest for those who did not receive a B3. In the retest, I did quite well for someone who did not like physic. I had gotten an A1. All that I had studied paid off, but the test is capped at B3. I should really have study for the first test and gotten a A1. Oh and in this test I had gotten 32/40, an A1.
Luckily, Miss Lim was kind enough to give us a retest for those who did not receive a B3. In the retest, I did quite well for someone who did not like physic. I had gotten an A1. All that I had studied paid off, but the test is capped at B3. I should really have study for the first test and gotten a A1. Oh and in this test I had gotten 32/40, an A1.
Science Test Reflection (Term 1)
In this science test, I scored 30 out of 40. Although it is a A1, I am very disappointed in myself as I was below average in my class and was a boarder line A1. In this test, I was tested on Acid and Bases, which is a topic in chemistry. After this test, I felt that I am very weak in Chemistry as I do not understand much about it. In this test, I was a little careless as I did not read the question properly, resulting in the lost of 2 marks. More importantly, during the day before the test, I did not have much time, studying for the test as I had CCA which ended at 6.00pm. With the lack of studying, it was obvious that I would not do well for my test.
From that day onward, I will study harder and try my best not to make careless mistakes anymore. I will also study a few days before the test in case there is CCA before the test.
From that day onward, I will study harder and try my best not to make careless mistakes anymore. I will also study a few days before the test in case there is CCA before the test.
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