During the race the concentration of sugar in the athletes blood decreases

I would think this is true.
This may be caused by cellular respiration, precisely, the glycolysis stage of anaerobic respiration (because an athletes in a race would need immediate energy). Glucose breaks down at this stage to produce lactic acid, so it would probably make sense that the concentration of sugar decreases.

This is only what I think, and may not all be truth, so I suggest that you wait for a more 'advanced' response :D

If you remove all the lions from the savanna it will lead to a increase of gazelle and a increase of cheetahs becasue of no competition

Schools are being forced to embrace computers. unlike their "digital immigrant" teachers, these students are "digital natives", born into a world where technology is an integral part of everyday life. almost every student has access to a multitude of computers, laptops and tablet devices. it would be crazy to assume an assignment would  notbe written on computer in this day and age.many schools now have a 1-to-1 computer policy, and many districts and states in the united states have mandated computers or ipads across the state for every student,  including los angeles, the second largest school district in the country.but the thing is, when they tried it in la, it wasn't the success they hoped for. that's because the tablets weren't used as much as they expected. rather, it appeared there was a gap between the digital native's love of technology and their use of it in the classroom.this conflicted relationship with computers is also underscored by much of the literature on education. it is also highlighted in professional development and conferences such as  edutech.