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" White tigers today are only seen in zoos, but they belong in nature, say researchers reporting new evidence about what makes those tigers white. Their spectacular white coats are produced by a single change in a known pigment gene, according to the study, appearing on May 23 in Current Biology, a Cell Press publication."

In this interrupted case study developed for use in a flipped classroom, students read about a picnic that takes place in autumn during the peak of fall color and along the way learn about light absorption by photosynthetic pigments, why leaves turn color in the fall, atmospheric CO2 concentrations and their effect on photosynthesis, and the C3, C4, and CAM photosynthetic pathways. The case is designed to provide introductory biology students with a basic understanding of photosynthetic pathways and how environmental factors affect plants using these pathways. The activity could also be used in an advanced high school biology course covering photosynthesis. The case includes several short videos that students watch as homework before coming to class so that they are prepared to work together in class in small groups to answer the case questions.

Normally, male squirrel monkeys can't distinguish between red and green hues-they're what is called color-blind in humans. The South American Saimiri genus lacks a gene that allows color-sensitive cells in the eye, called cones, to differentiate red and green from gray. To these animals, other colors, such as blue, brown and orange, appear faded. But Sam was one of two males in the experimental group of a groundbreaking 2009 ophthalmological study conducted at the Washington National Primate Research Center in Seattle. Husband-and-wife vision researchers Jay and Maureen Neitz injected a viral vector behind the retinas, the part of the eye that responds to color, of Sam and his simian lab partner, Dalton. The virus contained the genetic code in human eyes for red pigment, giving the monkeys an extra class of cone photoreceptor.

3:32 video Narrated by anthropologist Nina Jablonski, this engaging animation shows how human skin cells produce the pigment melanin, which gives skin its color.

When the scientists analyzed the water under a microscope, they quickly deduced what was causing the red liquid. In a newly-published study in Spanish Royal Society of Natural History Journal, they reveal that the culprit is Haematococcus pluvialis, a freshwater green microalgae that's capable of synthesizing a red carotene pigment called astaxanthin.

o why are these lakes pink anyway? It's been a mystery for some years, but the puzzle's finally been cracked. Scientists found that pink bodies of water like Lake Hillier contain both Halobacteria and a type of algae known as Dunaliella salina, which thrive in salty environments like the pink lakes. The carotenoid red pigments secreted by Halobacteria and d. salina are responsible for the pink lakes' otherworldly colors. These same algae also flourish in the Dead Sea.

When ultraviolet sunlight hits our skin, it affects each of us differently. Depending on skin color, it'll take only minutes of exposure to turn one person beetroot-pink, while another requires hours to experience the slightest change. What's to account for that difference, and how did our skin come to take on so many different hues to begin with? Angela Koine Flynn describes the science of skin color.

Learn how the light dependent and light independent cycles work together to create glucose for plants. We'll also explain why this is so important for humans! Get ready to start cooking with photosynthesis.