Consider the Keeling curve, which shows a steady increase in CO₂ levels over the past 50+ years. This steady rise has been attributed to both natural and human activity. Imagine if everyone in the world planted a fast-growing vine that was an annual (i. e., it grows large and fast, but dies after one year). Predict the effect this would hypothetically have on the level of CO₂ in the atmosphere over the next 20 years.
a. The level of CO₂ in the atmosphere will stay the same because the growing annuals will remove the extra CO₂ from human activity.
b. The level of CO₂ in the atmosphere will steadily decrease because of increased rates of photosynthesis.
c. The level of CO₂ in the atmosphere will steadily increase because decomposition of the annuals simply returns the CO₂ back into the atmosphere.

Bisphenol a (often called bpa) is a chemical found in products that people use every day, from water bottles to food containers to children's toys. unfortunately, bpa leaches out of its many products and makes its way into our bodies. what are the health effects of bpa exposure? ongoing research is finding that elevated exposure to bpa can affect a wide variety of developmental and physiological processes, but one of the first studies of bpa's health effects came about because of a simple mistake in the lab. at a laboratory at case western reserve university in 1998, geneticist patricia hunt was making a routine check of her female lab mice. as she extracted and examined developing eggs from the ovaries, she began to wonder what had gone wrong. she noticed that many of the eggs showed problems with their chromosomes, and some had irregular amounts of genetic material, which can lead to miscarriages and birth defects in mammals. she learned that a lab assistant had mistakenly washed the plastic mouse cages and water bottles with a harsh soap, releasing bpa from the plastic. knowing that bpa is an endocrine disruptor, a chemical that can enter organisms and mimic hormones, hunt set out to discover whether it had adversely affected her mice.