Given the background: Because of human activities, there is more carbon dioxide in the atmosphere today than in the past hundreds of thousands of years. Burning fossil fuels and has released great quantities of carbon dioxide into the atmosphere. Cutting forests and clearing land has also increased carbon dioxide into the atmosphere because these activities reduce the number of autotrophic organisms that use up carbon dioxide in photosynthesis. In addition, clearing often involves burning, which releases carbon dioxide that was previously stored in autotrophs. and the situation: John has been hearing about climate change for last couple of years. He wants to understand the science behind climate change. For that, he picked up two eras in earth's history, era A and era B. Era A was hundred thousand years ago, and era B is in the present day. He now wants to compare these to eras to understand the change in climate better. Answer the following question: Which era would have more carbon dioxide in the atmosphere, era A or era B?
Ans: era B

Given the background: When you go to the dentist to get a tooth pulled, you really don't want to feel any pain. The dentist injects an anesthetic into your gum and it eventually becomes numb. One theory as to why anesthetics work deals with the movement of ions across the cell membrane. The anesthetic gets into the membrane structure and causes shifts in how ions move across the membrane. If ion movement is disrupted, nerve impulses will not be transmitted and you will not sense pain at least not until the anesthetic wears off. and the situation: Jake and his brother Jordan both have to go to the dentist to get a tooth pulled. Jake is allergic to the anesthetic unfortunately, so he has to have the procedure done without it. Jordan isn't allergic, so he is able to get his tooth pulled after an anesthetic is injected. Answer the following question: Who will experience less pain during the tooth extraction?
Ans: Jordan

Given the background: Because of human activities, there is more carbon dioxide in the atmosphere today than in the past hundreds of thousands of years. Burning fossil fuels and has released great quantities of carbon dioxide into the atmosphere. Cutting forests and clearing land has also increased carbon dioxide into the atmosphere because these activities reduce the number of autotrophic organisms that use up carbon dioxide in photosynthesis. In addition, clearing often involves burning, which releases carbon dioxide that was previously stored in autotrophs. and the situation: Two researchers looked at the human influence on atmospheric carbon dioxide levels. Tim studied a human settlement from 10000 years ago, while Bob studied a present day county. Today's economy in the county revolved around extensive agriculture. Answer the following question: Which researcher found more evidence of land clearing?
Ans: Bob

Given the background: Acromyrmex heyeri is a species of leaf-cutter ant, a New World ant of the subfamily Myrmicinae of the genus Acromyrmex. Acromyrmex heyeri workers construct the colonies nest by thatching together cut grass. At temperatures ranging from 2030 C, workers created more openings in the nest thatch as the internal nest temperature goes up as a method of temperature regulation for the colony. The workers will close openings in the nest thatch as the air humidity surrounding the nest decreases to reduce water loss for the colony. and the situation: Ants are one of the most interesting creatures on earth. David wants to study ants for his biology project. He is specifically interested in ant species Acromyrmex heyeri. This semester he studied this ant in Americas. First day when he studied the ants the temperature was 10 degree Centigrade. In the second day of his study the temperature rose to 25 degree Centigrade. In the third day of his study the air humidity was high. But in the fourth day of his study air humidity dropped. David wants to continue his study of this same ant species in Asia next semester. Answer the following question: On the fourth day would david see the openings in the nest hatch open or closed?
Ans: closed