False. There is no magnetic bar inside the earth. The earth's magnetic field is created by movement of the earth, not a magnetic bar.
Compact bone is the outer layer that is packed together very tightly. This is mainly for support & balance. The spongy bone is strung together loosely and looks like *no surprise here* a sponge. This helps create blood cells & other bodily garbage.
Hello! Here Is The Answer:
• Weather/climatic conditions.
• Availability of sunsatinable food.
• Environment.
• The availability of resources.
I Really Hope This Helped You! ;)
<u>Answer</u>:- The three forms of nitrogen in an aquarium are
1. Nitrate NO3-
2Nitrite NO2-
3. Ammonia NH3
<u>Explanation</u>:
- The waste products produced by fishes is broken down into ammonia which is highly toxic for the fishes present in the aquarium.
- The nitrogen cycle takes place in the aquarium to convert this toxic <em>ammonia</em> into lesser toxic forms.
- This nitrogen cycle proceeds to convert ammonia into <em>nitrite</em> and then nitrite into <em>nitrate</em>. This means the cycle is ammonia——>nitrite——> nitrate.
- This conversion takes place with the help of several bacteria which establish a colony in the filter bed of the aquarium in the presence of ammonia .Then these bacteria help to finally convert ammonia to nitirite and then to nitrate.
- The bacteria that convert ammonia to nitrite are oxygen loving bacteria called as <em>Nitrosomonas</em>. The nitrite so formed is less toxic as compared to ammonia.
- The conversion of nitrite to nitrate takes place by the bacterial species called as <em>Nitrobacter</em> . The nitrate thus formed is harmless for the aquarium fishes at low levels.
Thus, in this nitrogen cycle we can see that<em> there are three different forms in which nitrogen is present- ammonia, nitrate and nitrite.</em>
I believe the best answer from the choices listed above is the third option. The Theory of spontaneous generation was A theory that wasdisproved by Redi and Pasteur. Hope this answers the question. Have a nice day. Feel free to ask more questions.