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Physics, Chemistry and Biology: Post your doubts here!

always-smile :)

always-smile :)

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sma786 said:
i din knew a word "monochromatic" existed before solving w11 past paper :p
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hhhhhhhhhh..... u should read the syllabus well while studying from the text book to knw the required info. and be sure u didn't miss any piece of info required :)
 
Y

Yousif Mukkhtar

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Can some one explain this part of the syllabus for me:
Explain why there is an increased efficiency in supplying green plants as human food and that there is a relative inefficiency, in terms of energy loss, in feeding crop plants to animals

In my notes the explanation is as follows"
If plants are fed to animals, and the animals are then eaten, it is less efficient than directly eating the plants, because the animal hasn’t used up some of the plants energy, allowing plants to feed more people.
 
always-smile :)

always-smile :)

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Yousif Mukkhtar said:
Can some one explain this part of the syllabus for me:
Explain why there is an increased efficiency in supplying green plants as human food and that there is a relative inefficiency, in terms of energy loss, in feeding crop plants to animals

In my notes the explanation is as follows"
If plants are fed to animals, and the animals are then eaten, it is less efficient than directly eating the plants, because the animal hasn’t used up some of the plants energy, allowing plants to feed more people.
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that explanation is correct
it means that when human eats plant directly less energy is lost than being eaten by another animal like cows and then cows eaten by human
this makes a great loss in energy so it is inefficient
hope i helped :)
 
afshinsalim

afshinsalim

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Yousif Mukkhtar said:
Can some one explain this part of the syllabus for me:
Explain why there is an increased efficiency in supplying green plants as human food and that there is a relative inefficiency, in terms of energy loss, in feeding crop plants to animals

In my notes the explanation is as follows"
If plants are fed to animals, and the animals are then eaten, it is less efficient than directly eating the plants, because the animal hasn’t used up some of the plants energy, allowing plants to feed more people.
Click to expand...
In terms of conservation of energy, short food chains are more efficient than long ones in providing energy to the top consumer. Below are 2 food chains and energy values for each level in them. Both food chains have a human being as the top consumer.
maize -> cow -> human
units of energy 100 10 1
maize -> human
units of energy 100 10
Ten times more energy is available to the human in the second food chain than in the first. In the second food chain, the human is a herbivore (vegetarian). But eating parts of a cow provides humans with other nutrients, as well as those we gain energy from - it would be very difficult to persuade everyone to become vegetarian for the sake of energy efficiency.
Some farmers try to maximise meat production by reducing movement of their animals (keeping them in pens or cages with a food supply) and keeping them warm im winter. This means less stored energy is wasted by the animals.
Hope I helped:)
 
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Lichaba West

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Astellaz said:
Pls help me solve this question:cry:
I know its rather hard but just tell me what you think is right please...
A uniform metre rule of weight 0.9N is suspended horizontally by 2 vertical loops of thread A and B placed at 20cm and 30cm from its ends respectively. Find the distances from the centre of the rule at which a 2N weight must be suspended:
i) to make loop A become slack
ii) to make loop B become slack
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i got i) 9cm and ii) 13.5cm. do you have the answers somewhere and if it is right i can tell you how i worked it out
 
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