Jun 26: The Quirks & Quarks listener question show
How much of a lake is fish pee? What's corn silk actually for? What happens if you break wind in a space suit?
To wrap up our season, here's another edition of our ever-popular Listener Question Show, where we find the experts to answer your questions.
Paula from Dartmouth asks: Every time I peel an ear of corn it gets a little messy. I wonder what purpose corn silk provides?
Manish Raizada, a professor of plant agriculture at the University of Guelph says corn silk facilitates corn sex. Corn silks capture pollen from the wind. Then sperm from the pollen use the silk as a channel to travel through to fertilize one of about 300 to 600 eggs awaiting on the immature cob. Every silk strand terminates in one egg, which results in one seed, or one kernel of corn. Raizada's latest study reveals that corn silk is home to 5,000 species of bacteria which help protect the corn from harmful pathogens.
10-year-old Felix from Montreal asks: What is space actually made of? Are there any gases or molecules that fill up the universe or is it really empty in between planets, stars and comets?
Laurie Rousseau-Nepton, an astrophysicist who is currently Resident Astronomer at the Canada-France-Hawaii Telescope, says that space is filled with atoms — primarily hydrogen, but also everything else on the periodic table as well. Gravity from stars and planets tugs on the atoms so gas is most dense near large objects. In our atmosphere, we have one million billion atoms per cubic centimetre, closer to the moon that number drops to five, and outside of the Milky Way there's one particle per cubic meter.
Bob from Vancouver asks: Is our sense of balance better in daylight than in low light? I do a yoga pose that involves balancing on one leg. It's challenging in semi-darkness but much easier in the daytime.
Gerome Manson, a professor of neuromechanics at Queen's University in Kingston, Ontario, says that it's not surprising that Bob feels unstable in semi-darkness, because vision is a key component of balance. It works with proprioception, or our sense of where our limbs are in space, and the vestibular system in our inner ear, to give us our sense of equilibrium relative to the environment. As light fades, and visual acuity declines, our brains are getting less precise information about where we are relative to our surroundings, and so balance is compromised.
Heather in Toronto asks: Deciduous trees lose their chlorophyll in the Fall. How does this happen and how do they get it back in the Spring?
Janice Cooke, a professor of biological sciences at the University of Alberta, says trees use their biochemical wizardry to recycle the investment they put into making chlorophyll. Plants use this pigment to capture the sun's energy through photosynthesis. Once days become shorter and nights colder, the plant breaks down its chlorophyll into simpler components, and pulls them into its bark, branches or roots. There those building blocks get transformed into starches, fats and proteins. In this way, the plant retains much of the carbon, nitrogen and magnesium it used to originally make chlorophyll, and can use it again the following spring when its leaves grow back again.
George from Kelowna asks: How do aquatic mammals like sea lions, whales, and dolphins obtain the fresh water needed for their survival?
Andrew Trites is the director of the Marine Mammal Research Unit at the University of British Columbia. He said that marine mammals have the same water requirements as humans do, but they get most of their water from their food. Their kidneys are also particularly efficient at filtering salt, like mini desalination plants, so they can actually get some fresh water from sea water. In addition, they don't sweat, and don't exhale as often as we do, so they are able to conserve the water within their bodies more effectively than we can..
Andrew from Calgary asks: Even astronauts get gassy sometimes. During space walks, what does the spacesuit do to protect the astronaut from their own flatulence?
Dr. Dave Williams is the Canadian astronaut who has spent the most time on spacewalks - 17 hours and 43 minutes, to be exact. He says that space suits are designed to tackle all bodily functions, including flatulence. There is a 100 percent oxygen environment within the suit that is constantly cycling and filtering to remove carbon dioxide and any odours that may pop out. He does say that weightlessness makes burping a challenge, as food floats around in your stomach, mixing with air, so you might not just be bringing up air when you let out a belch.
Ursula in Vancouver asks: How does water get up the tree? What pushes? What pulls? Some trees grow so high, it seems an impossible task.
Uwe Hacke, a professor of functional plant biology at the University of Alberta explains that the evaporation from leaves provides the force that pulls water up the trunk of the tree. As water molecules evaporate, or transpire, from the leaves into the dryer atmosphere, it creates negative pressure within the tree. This pulls water up through tubes, or vessels in the wood of the tree. The process relies on an ever-present column of water in the tree that originates in the soil, so it's not unlike sucking a drink up through a straw. As impressive as the mechanism is, there may be a limit. The tallest trees, such as redwoods, grow to just over one hundred metres in height.
Ron from Ottawa asks: Why do planets revolve in the same direction?
Emily Deibert, a PhD candidate in astronomy and astrophysics at the University of Toronto says there are two kinds of 'revolutions' for planets. All the planets in our solar system orbit around the sun in the same direction (counter clockwise if viewed from above Earth's north pole). The other is the rotation on their axis. All but two of the planets rotate on their axis in a counterclockwise motion. The reason the planets rotate in the same direction is due to residual rotation of the cloud of gas and dust that the solar system formed from. Venus rotates clockwise possibly due to the friction created by its thick atmosphere. Uranus rotates on its side possibly because it was knocked over by a large asteroid strike.
Luc in Edmonton asks: Many animals and birds are tagged for monitoring and study. Do they know they've been tagged and does it in any way affect their behaviour?
Bill Montevecchi, John Lewis Paton Distinguished University Professor of psychology, biology and ocean sciences at Memorial University, said from what he's seen it's pretty obvious birds are aware of the tags scientists attach to them. The concern, for biologists like him, is how well the animals tolerate the tags and how it might affect their natural behaviour. This is why Montevecchi, who studies seabirds, said scientists developed protocols and procedures to minimize potential effects on their behaviour, like keeping the weight of a device to less than three per cent of the animal's body weight. Scientists assess new devices by comparing a bird with a tag to a comparable bird without one, or to itself before it got the tag, to make sure the tags don't unduly influence animal behaviour, survival or reproduction.
John of Toronto asks: How much of a river is made up of fish pee? And is it good or bad for the water?
Sandra Klemet-N'guessan is a PhD candidate in biology at Trent university who studies the role that fish pee plays in aquatic ecosystems. She says that fish pee is a very important part of the nutrient cycle in any body of water, and by supplying nutrients like nitrogen, phosphorus, and carbon, it acts as fertilizer for the plants that live therein. And while it's hard to quantify how much fish pee is in any body of water, research has shown that fish pee can supply anywhere from five to eighty per cent of the nutrients needed by the plants in the water. So it's possible to have not enough nutrients, but also have too much, so it's all context dependent.
Greg from Orono, Maine asks: "Human Cells differentiate themselves to become different tissues in specific parts of the body. How do cells know where they are in the human body?"
Martin Hirst, a professor in the Department of Microbiology and Immunology at the University of British Columbia, said every cell in the human body contains the same genome, but changes to how those genes are read determine which cell tissue it becomes. This happens through a process called "epigenetics" which determines which genes in a cell are turned on or off and when. So Hirst said it's not so much the cells know where they are in the body, but due to the epigenetic changes that occur, the cells retain a type of memory about where it's been that's set it along the path to become one of more than 300 types of cells in our bodies.
Chris from Calgary asks: Will capturing energy out of the environment with solar and wind have negative consequences?
Nandita Basu, an associate professor of Civil and Environmental Engineering, and Earth and Environmental Science at the University of Waterloo says the short answer to that question is 'no', even though the wind is slowed by wind turbines, and solar panels prevent the sun from reaching the ground. Wind farms can change air circulation patterns and cause a slight rise in temperature around the wind farms, but she said this is not a huge problem.