English is over! Hurray! It was a slightly easier paper compared to last year for Paper 1. That is based on my own opinion of course. Hope that it was easy for you or manageable. The format was a formal email and the picture had lots of ideas to talk about. Anyway, English is officially over and you have 3 more to go.
Here's the notes for Science Part 4.
Primary 5
Reproduction in Plants
- Seeds -> Seedling --> Adult plant --> Flowers --> Fruits --> Seeds (Reproduction in FLOWERING PLANTS)
- For non-flowering plants, they can reproduce by spores like the mushroom and ferns.
- Spores are found on the underside of the leafs and the mushroom cap.
- Seeds --> Seedling (Germination) Germination requires air, warmth and water. In specific, it requires oxygen for respiration because it does not have leaves to photosynthesize yet. It does not need light (Please remember!)
- During the growth of the seed, the seedling gets the nutrients from the seed leaf so the size of the seed leaf will gradually decrease together with the seed coat as nutrients is used up to make way for the eventual growth of the plant and the adult leaves.
- Roots will grow first, downwards and then the shoot grows upwards to reach towards the light.
- Plants grow towards the direction of the light.
- Pollination is the process in which pollen grains is transferred from the anther to the stigma. For plants with their antler and stigma hanging out of the petals, it is usually pollinated by wind.
- During pollination and fertilisation, the most important part that cannot be missing is the STIGMA.
- Ovary becomes the fruit and the ovules become the seeds.
- Anther can be compared to the testes of the human part as both are male parts that produce the pollen grains and sperms respectively.
- Stigma and vagina are similar as they received the pollen grains and sperm respectively for fertilisation.
- If overcrowded, seeds will compete for water, nutrients and sunlight. Air is all around so they would not compete for air. If plants grow taller, it is usually in search of light as they are competing for it.
Water Cycle
- Water cycle involves water which is a matter. It has mass and occupies space. Water can take the form of solid, liquid and gas.
- Solid -> Ice
- Liquid -> Water, Clouds, Water droplets, Steam (can be seen)
- Gas -> Water vapour
- Water can go through melting, freezing, evaporation, boiling and condensation.
- Melting (Solid to liquid) Ice to water. For ice to melt, it is usually at 0 degrees celcius. Ice remains at 0 degrees celcius until all of it has melted completely. Even if it is melting halfway, it is still at 0 degrees celcius. For melting, the ice gains heat. To slow down melting, we can apply sawdust or wrap newspapers or poor conductors of heat around the ice. Poor conductors of heat do not gain heat quickly for the ice and can conduct the heat away.
- Freezing (Liquid to Solid) Water to Ice. For water to freeze, it is usually at 0 degrees celcius. Water remains at 0 degrees celcius until all of it has froze completely. Even if it is freezing halfway, it is still at 0 degrees celcius. For freezing, the water loses heat.
- Boiling (Liquid to gas) For water to boil, it takes place at 100 degrees celcius. Water with impurities in it will boil at a higher temperature.
- Evaporation (Liquid to gas) For evaporation to take place, it takes place at any temperature. However, the higher the temperature, the faster the rate of evaporation. The more the wind, the lower the humidity (amount of water vapour in the air) and the more the EXPOSED surface area of the object, the HIGHER the rate of evaporation.
- Condensation (Gas to liquid) For condensation to take place, the warm water vapour from the surrounding air condenses on the cool surface into water droplets. WCCW
- Water cycle involves water from the rivers and the grounds to evaporate into water vapour into the air which will then form clouds (liquid form, tiny water droplets) through condensation. Then, these clouds will form and fall as rain (liquid) through the process known as precipitation.
- How to show that water has mass? Take two identical dry clothes and put them onto a Beam balance, one on each side. They will be at the same height initially. then, soak one cloth with water. You will observe that the cloth with water will dropped lower, showing that it is heavier than the other dry cloth. This shows that water has mass.
- How to show that there is air in water? Heat up a beaker of water wit ha bunsen burner. You will observe air bubbles being produced in the water.
- How to show that there is water in plants? Cover a potted plant with a plastic bag. You will observe water droplets formed on the inner surface through condensation. Plants will transpire through the leaves and water from the soil will also evaporate and condense on the inner cool surface.
Cells
- Cells are the basic unit of life.
- Cells can be from animals or plants.
- Animal cells include nucleus, cell membrane and cytoplasm.
- Nuclues controls the activities in the cells and passes down genetic information to the next generation. It also helps in the repair of damaged cells.
- Cell membrane allows the movement of objects in and out of the cell. (Allows nutrients and air to enter and waste to leave)
- Cytoplasm allows for movement in the cell.
- Plant cells include nucleus, cell membrance (Allows nutrients and air to enter and waste to leave), cytoplasm, CELL WALL and CHLOROPLAST.
- Cell wall gives the cell its shape and protects the cell.
- Chloroplast contains chlorophyll to trap sunlight to photosynthesize for the plant.
- Photosynthesis requires sunlight, carbon dioxide and water and in turn, produces oxygen and sugar (starch) which is stored in the roots of plants.
- In some cells of plants, you might will find the chloroplast like the root hair and stems because these parts do not photosynthesize. However, all parts of the plants contains the cell wall.
Air
- Originally, air is made up of many gases with nitrogen being the most (78%), Oxygen (21%) and carbon dioxide and other gases (less than 1%)
- Water vapour is also part of air.
- Plants take in carbon dioxide and give out oxygen during photosynthesis which is important for mankind. However, they only photosynthesize in the presence of light and mostly during the day.
- Plants also respire all the time and take in oxygen and give our carbon dioxide, although lesser in the day compared to the night. They do this through their stomata, tiny openings found on both the upper and under side of the lead. However, there is more stomata on the UNDER side.
- So, if you were to coat the underside of the leaf, the leaf will not be able to transpire and respire as much.
- Fish take in oxygen and release carbon dioxide through their gills.
- Humans take in oxygen and give our carbon dioxide through our respiratory system consisting of the nose, windpipe and lungs.
- When we burn items, oxygen is need for burning and carbon dioxide is produced.
- Limewater turns chalky in the presence of limewater.
- How do we know that humans and animals breathe out carbon dioxide? Place a jar of limewater in an enclosed area. Breathe out and observe that the lime water turns chalky.
- a candle in an enclosed tank will not burn after a while as the oxygen is used up and not replenished.
- When we have a HOLE in the straw, we cannot drink the water in a cup as the hole in the straw allows air to escape and there is not air pressure to PUSH the water up the straw.
- Water plants will produce air bubbles when they respire or photosynthesize as air escapes from the plant through air bubbles.
Plant Transport System
- Plant transport systems consist of Food carrying tubes (Phloem tube) and Water carrying tubes (xylem tubes)
- Remember the concept of PX (P on the outside and X on the inside)
- The outer ring of the stem is the food carrying tube.
- The inner ring of the stem is the water carrying tube.
- If you cut the outer ring of the stem, food cannot be carried downwards from the leaves to the roots. Thus, the stem above the cut area will swell as food is stuck there!
- Food is transported downwards from the leaves to all parts of the plant.
- Water and minerals are transported upwards from the roots to all parts of the plant.
- A plant will turn red if it is placed in a container of red dye as the roots absorb the colouring and transport the coloured water up the stem to all parts of the plant.
Electricity
- Electric circuit can be open or closed. If it is open, there is a gap and electricity cannot flow through. If it is closed, there are no gaps and electricity can flow through.
- Closed circuits can be series or parallel
- Electric circuit consists of batteries, wires, light bulbs, switches. Brightness is affected by arrangement of bulbs, number of bulbs and number of batteries.
- There are no GOOD CONDUCTORS OR POOR CONDUCTORS OF electricity!
- An item is either A CONDUCTOR or NON-CONDUCTOR (Insulator)
- In a parallel circuit, the bulbs will receive the same amount of voltage and be as bright as the total number of voltage of the batteries. For example. there is 1 battery of 10 Volts and there are 3 bulbs connected in parallel. Each bulb will be as bright as each other with 10 Volts of brightness each.
- In a series circuit, the bulbs will split the amount of voltage from the battery. For example, if there are 3 bulbs and 1 battery of 9 Volts, then each bulb receives 3V of brightness each.
- Thus, bulbs in parallel tend to be brighter than series.
- Also, in series, when one bulb fuses, the other will not be able to work as there will be a gap.
- In parallel, when one bulb fuses, the others can still light up.
That's the end of the the P5 topics. Your next post will be your last post on the revision notes for P6 science. There will be extra lessons on Saturday from 8 - 10.30am in school. Wait for me at the canteen. I require everyone to stay back on Monday too for extra lessons. I will give you the timings tomorrow.
All the best for Maths tomorrow. Bring your calculators and Maths instruments with your rulers. :)
Thank you,
Sincerely,
Mr Nelson Ong
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