Two general methods of reproduction
1. By Seeds (Bisexual)
- usually by flowering plants such as tomatoes, fruits such as apples, oranges etc
- Seeds will grow into new plant -->when conditions are right Eg Warmth, Air, Water
The process is called GERMINATION
Note : Sunlight is not needed for seeds to grow into new plants
The seedlings (grown from seed) will temporary obtain food from their SEED
LEAVES until they have leaves to make food.
- Cycle :
Seed --> seedling --> young plant --> adult plant --> back to seed again to complete the cycle
- For the seeds to grow into young plant succesfully and healthy, they are usually dispersed from the adult plant.
The different methods of dispersal are :
i) By water Eg coconut, nipah
ii) By wind Eg african tulip, lallang, shorea, angsana
iii) By animals Eg manago (juicy and freshy)
Eg Mimosa (with hooks)
iv) By explosive action Eg rubber, african tulip, cotton
- From the adult plant to seed -> Pollination and Fertilisation must happen.
* Pollination - transfer to pollen grains from the anthers to the stigma.
* Fertilisation - the fusion of pollen grains (male cells) with the ovule found in the ovary
(After fertilisation, the ovule will become the seeds and the ovary will become the fruit.
2. By Plant parts (Asexual)
- Plants can also reproduced from plant parts (it is a faster process)
* By Leaves : Bryophyllum, African Violet
* By Suckers : Banana, pineapple, heliconia, sealing wax palm
* By Underground stems : onion, ginger, water chestnut
* By underground root : turnip, tapioca, sweet potato
3. By Spores
- Eg Ferns, Fungi (mushrooms) - Note : Fungi not considered as plants.
Wednesday, May 13, 2009
Revision Notes for Electricity
Components of an Electricical System
1. Bulb
- parts of bulb :
i) glass casing (transparent- to allow light to pass through)
ii) metal casing (to allow electricity to pass through)
iii) Metal tip (allow electricity to pass through)
iv) Tungsten ( Poor conductor of electricity but is able to withstand high temperature so that the wire will not melt and electricity still can pass through)
- know how the wires are connected inside the metal casing. (that is, one end of the tungsten is connected to the metal casing and the other end to the metal tip)
2. Wires
- usually consist of wire (usually copper - good conductor of electricity) and outer covering (usually rubber - flexible for bending)
3. Cells/ Batteries
- to supply electricity for the system
- Arrangement of Batteries can affect the brightness of the bulb
i) Series arrangement
* bulb is brighter
* if one battery is removed, the bulb will not light up
ii) Parallel arrangement
* bulb has the same brightness
* If one battery is removed, the bulb will still light up.
4. Switches
- function/use : to control the flow of electricity in a circuit. (to open or close a circuit)
- Arrangement of switches
i) in series - the switch will control the main flow of electricity in the circuit
ii) in parallel - the switch will control the flow of electricity in that particular smaller loop.
Conductors of Electricity
Materials can be classified in the following way:
1. Insulators of electricity
- does not allow electricity to pass through at all
- Eg usually the non-metals such as wood, plastic, glass
2. Good conductors of electricity
- allows electricity to pass through easily
- Eg usually the metals such as copper, silver, aluminium
3. Poor conductor of electricity
- allows electricity to pass through but not so easily.
- Eg tungsten, nichrome
1. Bulb
- parts of bulb :
i) glass casing (transparent- to allow light to pass through)
ii) metal casing (to allow electricity to pass through)
iii) Metal tip (allow electricity to pass through)
iv) Tungsten ( Poor conductor of electricity but is able to withstand high temperature so that the wire will not melt and electricity still can pass through)
- know how the wires are connected inside the metal casing. (that is, one end of the tungsten is connected to the metal casing and the other end to the metal tip)
2. Wires
- usually consist of wire (usually copper - good conductor of electricity) and outer covering (usually rubber - flexible for bending)
3. Cells/ Batteries
- to supply electricity for the system
- Arrangement of Batteries can affect the brightness of the bulb
i) Series arrangement
* bulb is brighter
* if one battery is removed, the bulb will not light up
ii) Parallel arrangement
* bulb has the same brightness
* If one battery is removed, the bulb will still light up.
4. Switches
- function/use : to control the flow of electricity in a circuit. (to open or close a circuit)
- Arrangement of switches
i) in series - the switch will control the main flow of electricity in the circuit
ii) in parallel - the switch will control the flow of electricity in that particular smaller loop.
Conductors of Electricity
Materials can be classified in the following way:
1. Insulators of electricity
- does not allow electricity to pass through at all
- Eg usually the non-metals such as wood, plastic, glass
2. Good conductors of electricity
- allows electricity to pass through easily
- Eg usually the metals such as copper, silver, aluminium
3. Poor conductor of electricity
- allows electricity to pass through but not so easily.
- Eg tungsten, nichrome
Tuesday, May 12, 2009
Revision for SA1 (Set 1) - Booklet A
Qn 1 ( 2) Number of seeds
Qn 2 (4) Spiny Anteater lays eggs
(ref : http://www.americazoo.com/goto/index/mammals/1.htm)
Qn 3 (1)
Concept : conductors of heat
- from the graph, at mid-time (draw a line upward from midtime - x-axis crossing the two line graphs), the temperature of water at A is higher than the temperature of water at B.
Hence we can say that the heat is not lost so quickly in beaker A. The material of Beaker A must be a poorer conductor of heat -> in the option, styroforam is the one that is the poorest in conducting heat.
Qn 4 (4)
Qn 5 (3)
Concept : Gravitational potential energy - The higher the object is from the ground, the higher gravitational potential energy it has.
- From the options, look for the one which is highest from the ground.
Qn 6 (3)
Qn 7 (2)
At A- elastic potential energy
At B - kinetic energy(moving) and gravitational potential energy (above the ground)
At C - similar to B
Qn 8 (4)
Battery - chemical potential energy
Pendulum held at an angle - hanging in the air above the ground (potential energy)
A wound-up toy car - potential energy
A car moving down a ramp - Kinetic energy (moving) and gravitational potential energy (still above the ground)
Qn 9 (1)
Qn 10 (2)
Concept : Effects of force
1) changes the direction of a moving object
2) changes the speed of a moving object (faster or slower)
3) makes a moving object stop
4) makes a stationary object move
5) change the shape of an object
In this case, Meimei smashed with a lot of force, the above works except (3) and (5).
Qn 11 (2)
Qn 12 (3)
Qn 13 (3)
Qn 14 (2)
Qn 15 (4)
Qn 16 (1)
Concept - pond community : classification of plants - totally submerged, partially submerged and on the surface.
Group A - partially submerged
Group B - microorganism
Group C - totally submerged
Group D - floating on the surface.
-> Arrowhead - partially submerged plant
Qn 17 (2)
Concept : Food Chain and effects of introduction of prey or predator.
When a predator is introduced, the prey will reduce in population.
When a prey is introduced, the predator will increase in population.
In this question, when Z was introduced in Wk 2 :
- Population Y increase - possible reasons :
i) more food for Y - Z is a prey of Y Option 4 - wrong
or ii) Z has eaten up X which could be eating Y - X is a predator of Y Option 1 - wrong
- Population X decrease - possible reasons :
i) Z has eaten up X - Z is a predator of X Option 2- correct
Qn 18 ( 4) we have done this qn before
Qn 19 (3)
Concept : food chain and food web - Fish can eat the mosquito when it is at the larva stage (still in the water).
When the mosquitoes are at the larvae stage, they will be low in population as they are eaten by the fish. Hence the population should not be increasing as they are eaten at that stage. ( option 1, 2 and 3 shows that it is increasing over time)
Qn 20 (2)
Concept : factors that affect the survival of animals
- when the pond is completely covered by water hyacinth, there will be less chance for the oxygen in the air to dissolved into the pond water.
- there are no submerged plants to provide dissolved oxygen and food for the tadpoles.
- Sunlight has no effect for the tadpole in terms of food making. althought sunlight helps to heat up the water, but the carbon dioxide given out by tadpole can help to trap the heat in the water to keep the tadpole warm.
Qn 21 (3)
Negative effects (effects that are no good)
Qn 22 (4)
Factors affecting survival:
In this case, the variable that is changed is the temperature of the surrounding. Hence the aim of the experiment is to see how temperature affects the response of the fruitflies.
Qn 23 (2)
The amount of gases given out by the decomposer is carbon dioxide.
Qn 24 (3)
The first food consumer in every food chain can be a carnivore too.
Qn 25 (4)
Qn 26 (2)
Qn 27 (3)
Caterpillar does not eat rotting log but it eats leaves.
Qn 28 (3) Simple machines (not tested in sa1)
Qn 29 (4) Simple machines (not tested in sa1)
Qn 30 (3) Simple machines (not tested in sa1)
Qn 2 (4) Spiny Anteater lays eggs
(ref : http://www.americazoo.com/goto/index/mammals/1.htm)
Qn 3 (1)
Concept : conductors of heat
- from the graph, at mid-time (draw a line upward from midtime - x-axis crossing the two line graphs), the temperature of water at A is higher than the temperature of water at B.
Hence we can say that the heat is not lost so quickly in beaker A. The material of Beaker A must be a poorer conductor of heat -> in the option, styroforam is the one that is the poorest in conducting heat.
Qn 4 (4)
Qn 5 (3)
Concept : Gravitational potential energy - The higher the object is from the ground, the higher gravitational potential energy it has.
- From the options, look for the one which is highest from the ground.
Qn 6 (3)
Qn 7 (2)
At A- elastic potential energy
At B - kinetic energy(moving) and gravitational potential energy (above the ground)
At C - similar to B
Qn 8 (4)
Battery - chemical potential energy
Pendulum held at an angle - hanging in the air above the ground (potential energy)
A wound-up toy car - potential energy
A car moving down a ramp - Kinetic energy (moving) and gravitational potential energy (still above the ground)
Qn 9 (1)
Qn 10 (2)
Concept : Effects of force
1) changes the direction of a moving object
2) changes the speed of a moving object (faster or slower)
3) makes a moving object stop
4) makes a stationary object move
5) change the shape of an object
In this case, Meimei smashed with a lot of force, the above works except (3) and (5).
Qn 11 (2)
Qn 12 (3)
Qn 13 (3)
Qn 14 (2)
Qn 15 (4)
Qn 16 (1)
Concept - pond community : classification of plants - totally submerged, partially submerged and on the surface.
Group A - partially submerged
Group B - microorganism
Group C - totally submerged
Group D - floating on the surface.
-> Arrowhead - partially submerged plant
Qn 17 (2)
Concept : Food Chain and effects of introduction of prey or predator.
When a predator is introduced, the prey will reduce in population.
When a prey is introduced, the predator will increase in population.
In this question, when Z was introduced in Wk 2 :
- Population Y increase - possible reasons :
i) more food for Y - Z is a prey of Y Option 4 - wrong
or ii) Z has eaten up X which could be eating Y - X is a predator of Y Option 1 - wrong
- Population X decrease - possible reasons :
i) Z has eaten up X - Z is a predator of X Option 2- correct
Qn 18 ( 4) we have done this qn before
Qn 19 (3)
Concept : food chain and food web - Fish can eat the mosquito when it is at the larva stage (still in the water).
When the mosquitoes are at the larvae stage, they will be low in population as they are eaten by the fish. Hence the population should not be increasing as they are eaten at that stage. ( option 1, 2 and 3 shows that it is increasing over time)
Qn 20 (2)
Concept : factors that affect the survival of animals
- when the pond is completely covered by water hyacinth, there will be less chance for the oxygen in the air to dissolved into the pond water.
- there are no submerged plants to provide dissolved oxygen and food for the tadpoles.
- Sunlight has no effect for the tadpole in terms of food making. althought sunlight helps to heat up the water, but the carbon dioxide given out by tadpole can help to trap the heat in the water to keep the tadpole warm.
Qn 21 (3)
Negative effects (effects that are no good)
Qn 22 (4)
Factors affecting survival:
In this case, the variable that is changed is the temperature of the surrounding. Hence the aim of the experiment is to see how temperature affects the response of the fruitflies.
Qn 23 (2)
The amount of gases given out by the decomposer is carbon dioxide.
Qn 24 (3)
The first food consumer in every food chain can be a carnivore too.
Qn 25 (4)
Qn 26 (2)
Qn 27 (3)
Caterpillar does not eat rotting log but it eats leaves.
Qn 28 (3) Simple machines (not tested in sa1)
Qn 29 (4) Simple machines (not tested in sa1)
Qn 30 (3) Simple machines (not tested in sa1)
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