Given the background: As shown here, pressure decreases to less than 25% of ground-level atmospheric pressure when we get to an altitude of about six miles. Since this is a common cruising altitude for commercial airplanes, pressurized cabins are needed for the comfort and survival of the passengers. This is because the density of the air decreases along with the decreasing air pressure, so there is less oxygen in a breath of air. You've probably noticed this effect in high-mountain areas, as it often feels harder to breath. and the situation: John wanted to see how he would fare in high altitude compared to ground-level. So, he first measured his responses in ground-level. He labeled this part of the study as case A. Then he board on an airplane to reach high altitude, and measured his responses there. He labeled this part of the study as case B. Now, John knows how he needs to prepare for a high altitude hiking. Answer the following question: Which case would see lower atmospheric pressure, case A or case B?
Ans: case B

Given the background: During the 1670s, the Dutch tradesman Antony van Leeuwenhoek, shown in Figure below , used microscopes to observe many microbes and body cells. Leeuwenhoek developed an interest in microscopy and ground his own lenses to make simple microscopes. Leeuwenhoek was so good at making lenses that his simple microscopes were able to magnify much more clearly than the compound microscopes of his day. His microscope's increased ability to magnify over 200x is comparable to a modern compound light microscope. Compound microscopes , which are microscopes that use more than one lens, had been invented around 1595 by Zacharias Jansen, a Dutch spectacle-maker. Several people, including Robert Hooke, had built compound microscopes and were making important discoveries with them during Leeuwenhoek's time. and the situation: John is interested in the history of science. He went to a science museum to learn more about microscopes. First he saw a Leeuwenhoek microscope, which was labeled as item A, then he saw a compound microscope of Leeuwenhoek's time, which was labeled as item B. At the very end of his museum tour he saw a modern compound light microscope, which was labeled as item C. Answer the following question: Which one would have more lenses, item A or item B?
Ans: item B

Given the background: Another major cause of extinction is global warming , which is also known as global climate change. During the past century, the Earth's average temperature has risen by almost 1C (about 1.3F). You may not think that is significant, but to organisms that live in the wild and are constantly adapting to their environments, any climate change can be hazardous. Recall that burning fossil fuels releases gasses into the atmosphere that warm the Earth. Our increased use of fossil fuels, such as coal and oil, is changing the Earth's climate. Any long-term change in the climate can destroy the habitat of a species. Even a brief change in climate may be too stressful for an organism to survive. For example, if the seas increase in temperature, even briefly, it may be too warm for certain types of fish to reproduce. and the situation: Keith was reading a book on climate. He found an interesting table that showed the climatic conditions of the earth in two different times, time A and time B. Time A showed earth's climatic condition in the previous century. And, time B showed earth's climatic condition in the present century. Keith was amazed to see how the world has changed in just a century. Answer the following question: Which period would be more harmful for habitat of species, time A or time B?
Ans: time B

Given the background: Fish reproduce sexually. They lay eggs that can be fertilized either inside or outside of the body. In most fish, the eggs develop outside of the mother's body. In the majority of these species, fertilization also takes place outside the mother's body. The male and female fish release their gametes into the surrounding water, where fertilization occurs. Female fish release very high numbers of eggs to increase the chances of fertilization. and the situation: Dan and Fred were friends. they studied Biology at the same University. Fred studied bird reproduction this semester, while Dan studied fish reproduction. Answer the following question: Which friend studied more about male fish releasing their gametes into the surrounding water?
Ans: Dan