2. Life finds a way.
Questions and Answers from the live classes:
Sarah Weis Denton- Could spores do both asexual and sexual reproduction?
Spores are similar to seeds in that they contain genetic information but can lie dormant for a long time, waiting until conditions are good for growth. Plants, fungi, and bacteria all produce spores as part of their reproductive processes.
Spores being released from a puffball fungus. Image credit: Kalyanvarma https://commons.wikimedia.org/w/index.php?curid=18500829
When plants (mosses and ferns) produce spores, it's part of their sexual reproduction process.
Fungi can produce spores as either a means of cloning themselves (asexual) or a way of producing individuals that are different from the parents (sexual reproduction).
Certain types of bacteria also produce spores, and this is usually asexual reproduction. One of the most notable of these is anthrax. Spores of the anthrax bacterium can remain dormant for a long time, but if they enter an animal's body and then begin growing, they cause a severe illness.
Flying Dragon- Could spores possibly wait forever to sprout?
This is an excellent question! DNA is a fragile molecule that will eventually break down. But just how long could DNA inside a spore or seed last? We don't know for sure, but we have evidence of seeds laying dormant for thousands of years and then germinating. And in the year 2000, scientists found spores of a bacterium in a salt crystal that germinated and grew. They estimated this spore to have been 250 million years old! There's an article about that discovery in the journal, Nature.
Silver DragonAR- How do scientists determine a new species' name?
This is done using a system created by Carl Linnaeus, called binomial nomenclature (meaning two names). For example, the domestic dog has the scientific name Canis familiaris. The first part (Canis) is the name of the genus, and the second (familiaris) is the species name or species modifier.
To properly name a new species, first, a scientist must determine which species this new one is related to! If it isn't closely related to any other species, then they must create a name for a new genus as well as a new species name.
The way in which they chose the name can vary. Sometimes a scientist will use a Latin or Greek word that describes a characteristic of the species, other times it may describe where a species was discovered, and sometimes they can even include names of favorite characters, celebrities, or fellow scientists. The person who first describes the new organism gets to name it. In 2011, a group of mycologists discovered a new species of fungus that looked like a sponge:
Image credit Tom Bruns https://commons.wikimedia.org/w/index.php?curid=15529277 (A picture of a fungus that looks like lungs)
Apparently, it reminded them of a favorite cartoon character. Its official scientific name is Spongiforma squarepantsii.
Read more about the process scientists use to name new species at:
Gabriel - Can a starfish arm grow 2 starfish?
No. In fact, the only way a starfish can grow one body back from a severed arm is if that arm has some of the central disc area from the original starfish. If it doesn't include that, the arm will not regrow a body at all. The entire process for the original starfish to grow a new limb, and for the severed limb to grow a new body takes quite a while to accomplish, often a year or more.
Isra Syed: How did the first banana come about?
Bananas started off wild, many believe in Southeast Asia. There are hundreds of varieties of wild bananas in the tropics, and many of them look very different from what we see in the store! The pink velvet banana is full of seeds and has a fuzzy pink peel:
Photo credit: David Monniaux, https://commons.wikimedia.org/w/index.php?curid=295538 (pink bananas growing)
In populations of wild bananas, some of the bananas have 2 copies of each chromosome (2n). Others have 4 copies (4n).
At some point, a 2n variety cross-pollinated a 4n variety or visa versa, and a triploid (3n) banana was produced. This banana couldn't make seeds because it had an odd number of chromosomes. It might have led to the eventual extinction of that banana, but a certain mammal (us) really appreciated the seedless trait!
Here is a link to a website dedicated to the tasty fruit..including a short video on the history of the banana (about halfway down the page!)
Shadowmation- @Science Mom do twins also have the same genetic code?
The short answer: no.
There are several different types of twins, but the 2 most common are dizygotic (fraternal) and monozygotic (identical).
Fraternal twins are two completely different people, just like non-twin siblings. They each began as two separate fertilized eggs that happen to be carried within the same womb, and do not share the same genes.
Identical twins on the other hand are twins that began with one fertilized egg that split into two. It has long been said that identical twins carry the same DNA, hence why they look exactly the same. And it's true that identical twins started out with the same DNA, but recent studies have shown that even identical twins don't actually have identical DNA. As they get older, more and more changes to their code take place, mostly in regard to how or if the genes are expressed.
In this picture of chromosome pairs from 3 year old vs 50 year old identical twins, the color yellow represents identical DNA while the colors red and green represent DNA that has differences in how it's being expressed.
You can see a lot of red and green in older chromosomes!
(chromosomes side by side with a few differences highlighted)
As it turns out, even identical twins aren't exactly identical.
Photo from an excellent article at https://learn.genetics.utah.edu/content/epigenetics/twins/
Khadija Millwala: Why does the red panda look more like a fox than a panda?
Interestingly enough, red pandas are not a fox, or a panda. They are in a family all to themselves called Ailuridae.
Their scientific name is Ailurus (meaning cat) and fulgens (meaning fire-colored). It is believed the word panda comes from the Nepali word ponya, which means "bamboo eater". Since the red panda eats bamboo, the name is fitting, but that's where the similarities end between red pandas and panda bears.
People often associate red pandas with foxes due to their size and fur color, but they actually most closely resemble a raccoon.
Here's a great link to learn more about this fascinating creature:
From several students: will we find out if the animal was a dog or coyote?
The genetic results revealed that the animal was 100% coyote! About a week before the results came in, the animal surprised everyone by escaping into the wild. The employees at the wildlife center said that it never displayed aggressive behavior and its health was improving with food and treatment for mange. They were completely shocked to return to the wildlife center one morning and discover that it had chewed through its crate and escaped out a window! Which, I suppose, adds further evidence to the DNA test of it being 100% coyote.
Perry Family - We commonly refer to organisms by their genus and species name. Is it correct to say that mules and ligers have no species name because, given the current definition of species, they are not actually a species?
That is correct. If you look up the scientific name for a hybrid animal, you'll just get the cross of its parents. (Equus asinus × Equus caballus for a mule, and Panthera leo × Panthera tigris for a liger).
Although the biological species concept for a species defines a species as a group of individuals that can interbreed and produce offspring, another and perhaps better way to think of a species is as a "gene pool" where you have a regular flow of genetic information between individuals in a population.
With that idea of species in mind, even though we have a few ligers in the world in various zoos, it doesn't make sense to give these hybrids their own species classification because there is no gene pool for ligers -- there's no genetic information being shared within a population.