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Topic: Turgor Pressure Why does a touch me not plant close? Hey!! Don't touch that plant. You will get scared. See, you did not listen to me. Don't worry!! Nothing to be scared about. Let me tell you more about this plant. This plant is called the Mimosa Pudica plant. Another name for it is "Touch Me Not" Plant. When anyone touches this plant, it closes its leaves with the help of pulvini. Pulvini are present at the base of each leaflet. They consist of cells filled with water. This water applies pressure against the walls of the cells. This pressure is called the turgor pressure. It helps the leaflets to stand upright. Now, when we touch a leaflet of the touch me not plant, specific parts of the plant release certain chemicals. These chemicals cause the cells in the pulvini to lose water. When water is lost, there is no more turgor pressure. As a result, the cells collapse, resulting in the closing of leaflets.

5:25 video introduction to Vision 2020

Updated meiosis video. Join the Amoeba Sisters as they explore the meiosis stages with vocabulary including chromosomes, centromeres, centrioles, spindle fibers, and crossing over. This video also compares meiosis with mitosis.

Plants need sunlight to live, but they also need to block the sun's more harmful rays. Plants can't put on sunscreen or find shade, so how do they avoid getting a gnarly sunburn?

Discover what happens when random events meet allele frequencies: genetic drift! This Amoeba Sisters video also discusses the bottleneck and founder effect as well as contrasts genetic drift with natural selection.

1:30 A short film about DNA microarrays, and how they are used to show dynamic gene expression levels.

Review of many examples of epigenetics and mechanisms. Discussion incorporates evolution.

Rat-smell-fear epigenetic summary in cartoons

engaging 2:30 whiteboard video

Within every cell in our body, two copies of a tumor suppressor gene called BRCA1 are tasked with regulating the speed at which cells divide. Michael Windelspecht explains how these genes can sometimes mutate, making those cells less specialized and more likely to develop into cancer.

Have you ever heard that you become more powerful in life-or-death situations? There are a lot of anecdotes about super strength, but is it a real thing?

Explore speciation with The Amoeba Sisters. This video discusses sympatric and allopatric speciation and covers several types of isolation types including behavioral, temporal, and habitat isolations.

5:12 video animation describes the basics of enzyme structure and function. This includes enzyme substrates and active sites, enzyme denaturation, and competitive and non-competitive inhibition.

This movie explains the biology of enzymes. My hope is that it will catalyze lots of learning.

On July 26, 1943, Los Angeles was blanketed by a thick gas that stung people's eyes and blocked out the Sun. Panicked residents believed their city had been attacked using chemical warfare. But the cloud wasn't an act of war. It was smog. So what is this thick gray haze actually made of? And why does it affect some cities and not others? Kim Preshoff details the science behind smog.

Topic: Diffusion Why can we smell hot food from a distance?

Behold the microscopic jungle in and around you: tiny organisms living on your cheeks, under your sofa and in the soil in your backyard. We have an adversarial relationship with these microbes -- we sanitize, exterminate and disinfect them -- but according to microbiologist Anne Madden, they're sources of new technologies and medicines waiting to be discovered. These microscopic alchemists aren't gross, Madden says -- they're the future.

When plastic trash degrades in the ocean, it doesn't just go away: It becomes countless tiny particles, and little creatures called larvaceans sweep it up--and into the food chain.

A new report shows bee populations are on the rise, but the hives are still facing major threats.