Biology; Chemistry; Physics: Post your doubts here!

Dream.Eater

Dream.Eater

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funky brat said:
How does star formation occur?
Click to expand...
Its really simple....
Stars are formed by huge clouds of gas mainly heavy hydrogen(deuterium) and dust particles.They form a Nebula.The particles in the nebula are pulled together due to gravity and it forms a number of blobs.The blobs at the centre grows bigger than the rest and GPE is turned in thermal energy so the temp of the blob will increase and when it reaches abt 15,000,000°C fusion reactions will start. Now,the sun is combining H2 to give He and is giving out a large amount of heat and light energy.
 
funky brat

funky brat

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Awesome12 said:
In Bio ATP, they ask,
'How the flower is pollinated?'
So when will we know when to write insect/wind or self/cross pollination?
funky brat: Bio master :D, looking for some assistance from you
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Whenever they ask this question, they have either made the diagram or given some other information. Wind pollinated flowers/seeds usually have some extensions such as the sycamore flower which has wing-like extensions, or dandelion which has fine hair or the flowers have huge petals (that may attract insect), the stigma is hairy, pollen grains are either small in size (in wind pollinated flowers so they may float in the air for longer distances) If the pollen grains are large, rounded and hairy, the plant is insect pollinated ( the grains can cling onto the insect body hence hairy). Also the wind pollinated flowers have long dangling filaments and the reproductive parts are exposed whereas in insect pollinated flowers, the stigma is hidden between the petals. Also if there is any hint of plant producing nectar, then it's obvio an insect pollinated flower.
And about the self and cross pollination part, the info can be given in the question. Mostly legumes like peas and beans are self pollinating. Though most flowers cannot self pollinate because their reproductive parts do not mature at the same time and they might be self-sterile.
 
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funky brat

funky brat

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Dream.Eater said:
Its really simple....
Stars are formed by huge clouds of gas mainly heavy hydrogen(deuterium) and dust particles.They form a Nebula.The particles in the nebula are pulled together due to gravity and it forms a number of blobs.The blobs at the centre grows bigger than the rest and GPE is turned in thermal energy so the temp of the blob will increase and when it reaches abt 15,000,000°C fusion reactions will start. Now,the sun is combining H2 to give He and is giving out a large amount of heat and light energy.
Click to expand...
Thanks a bunch. :)
 
funky brat

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Awesome12 said:
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_w06_qp_6.pdf
Look at question 2 c ii)
It asks on ways to improve reliability of experiment. What could be the possible points if the question was
'Ways on improving ACCURACY of the experiment'
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What points do you include for reliablility?
If asked for accuracy you may state that the water should be heated every time it is put into the measuring cylinder and initial temperature noted. You may cover the pots with a shiny wrap to prevent heat loss by radiation.
 
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If we are asked to determine the focal length in Physics ATP, are we supposed to place the unit like 0.14m etc?
 
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