90 mammal species become extinct in the period 1901-2000 than became extinct in the period 1801-1900.
Extinction is a situation in which something no longer exists. Their can be many reasons associated like species have been hunted to the point of extinction, scarcity of food or natural disasters.
Their are two main types of extinction firstly Mass extinction that has occurred only five times in history. The other is Background extinctions which occurs over longer period of time and are considered important in natural extinction rate.
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Explanation:
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An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bioproductivity at each trophic level in a given ecosystem.
A pyramid of energy represents how much energy, initially from the sun, is retained or stored in the form of new biomass at each trophic level in an ecosystem. Typically, about 10% of the energy is transferred from one trophic level to the next, thus preventing a large number of trophic levels. Energy pyramids are necessarily upright in healthy ecosystems, that is, there must always be more energy available at a given level of the pyramid to support the energy and biomass requirement of the next trophic level.
A pyramid of energy shows how much energy is retained in the form of new biomass at each trophic level, while a pyramid of biomass shows how much biomass (the amount of living or organic matter present in an organism) is present in the organisms. There is also a pyramid of numbers representing the number of individual organisms at each trophic level. Pyramids of energy are normally upright, but other pyramids can be inverted or take other shapes.
Ecological pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain.
 
        
             
        
        
        
I believe the answer to this question is the filtrate is reabsorbed.
This is brought into the system because it still contains the useful products for other biological processes.   Thank you for your question. Please don't hesitate to ask in Brainly your queries. 
        
             
        
        
        
Answer:
A. Burning fossil fuels
C. establishing state parks
E. using renewable energy sources
Explanation:
 
        
             
        
        
        
Answer:
F: The oxygen atom has a greater attraction for the electrons in the surrounding covalent bonds than the
hydrogen atoms.
Explanation:
Between hydrogen and oxygen atoms exist a covalent bond. Oxygen is more electronegative than hydrogen atom hence its ability to get attracted to itself more electrons than hydrogen.