Carlos is trying to determine how music affects the growth of bean plants. He hypothesizes that classical music will cause a plant to grow at a higher rate than no music or rap music. He grows nine bean plants in similar lighting, temperature, and soil conditions. Three are exposed to classical music 24 hours a day, three are exposed to rap music 24 hours a day, and three are grown in complete silence. Carlos measures the growth of the plants every day and finds that the plants all seem to have the same rate of growth. What can you infer is missing from Carlos's scientific investigation?

A specific hypothesis predicting a relationship between independent and dependent variables
Controlled variables to ensure only the independent variable is being changed
Experimental data collected regularly that can be recorded and analyzed
Research on what other scientists have observed and investigated on this topic

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.

Where in the cell are ribosomes made?

A(n) is a molecule influences the way that a molecule reacts.