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ETD 26: Draw + Explain All A.Explain what cyto, sis, exo, endo, phago, and pino mean. B. What does the graph show is happening to bags A, B, +C C. Do Fish Drink
November 20, 2013 at 10:15am


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Jon Neil (Instructor)
November 20, 2013 at 12:02pm

Gretchen Wulfing learned the following:

 Caroline taught me that freshwater and salt water fish function differently. The water concentration in the freshwater fish is equal to the water surrounding it.  Therefore water moves in and out of the fish. Because of this, the fish needs to recycle the water out of it because if there’s too much fresh water going into the fish without an exit, the cells would absorb too much water, expand, and explode.  To prevent that, the freshwater fish pees in order to release some of the water.


When we are looking at a salt water fish the environment is different.  Instead of a low concentration of solutes there is a high concentration of solutes in the environment around the fish.  In environments like this, water moves toward the high concentrate solute solution because there is less water there.  Water wants to move from high concentrations of water to low concentrations of water.  The fish naturally wants to push water out of it which dehydrates it.  Therefore this kind of fish drinks the salt water so that its cells don’t shrivel up from dehydration, which would kill the fish.  But when the fish is drinking the salt water, it is consuming salt. The salt in the fish would make the cells want to push water out of them (high to low) which would dehydrate the cells. To prevent this from happening, the fish filters out the salt and poops it out as a solid, so there isn’t a high concentration of solutes in the fish.


The freshwater fish doesn’t drink water because it already gets the water it needs but the salt water fish drinks water to get the water it needs. The freshwater fish pees out the water so it’s cells don’t explode, killing the fish. The salt water fish poops out the solutes (from drinking the salt water) so the cells don’t dehydrate themselves, shrivel up, and die.



Caroline learned:


I learned the difference between a hypertonic environment and a hypotonic environment. At first I thought the “hypo” and “hyper” were related the concentration of water inside the cells, but I learned the it was related the concentration of solutes in the surrounding environment. This showed me that in a hypotonic environment water is entering the cell faster than the water is leaving the cell, which causes a build-up of water leading to the cell exploding. In a hypertonic environment, there is less water in the environment because there is more solute in the environment. This causes the cell to push water out (because it wants to move from a higher concentration to a lower concentration) which dehydrates the cell causing it to shrivel up and die. So “hypo” means less solutes in the environment and more water for the cells, and “hyper” means more solutes in the environment and less water for the cells.

Jon Neil (Instructor)
November 20, 2013 at 12:05pm

A great example of how teaching others forces you to expand your learning.  I'm glad to see students looking up the roots of words like Tonic = Tension so that they can utilize this strategy with other terms this year.  Biology is unlocked by knowing the roots of words, and then coming up with your own connections(analogies) to help you remember them.

Tyler Brenneman
November 24, 2013 at 6:36pm


Tyler taught what each prefix or suffix stood for. Cyto represents Cell (as in cytoplasm), Sis represents process (such as photosynthesis), Exo represents out (such as exoskeleton), Endo represents Inside , Phago represents engulfs and Pino represents Drink. 

I learned that fish who live in fresh water are hypertonic, meaning there is less water concentration within the fish than in the water the fish lives.  These fish urinate.  Fish that live in salt water are considered hypotonic, meaning there is more water concentration within the fish than within the water the fish lives.  These fish "poop".


Tyler: After teaching my mom this lesson, I was curious if salt water fish actually do pee, a very small amount. I re-learned that salt water fish have body fluids that are weaker than the surrounding water and it uses energy to stop it's body fluids from flowing out into the water. What was new to me is that to do this it must drink copious amounts of water and produce only a little but very concentrated urine in a process called osmotic regulation.

Sophie Wulfing
November 25, 2013 at 9:51pm

Sorry it took me so long to transfer this to the page. I had a small technology issue.



Cyto - cell

Exo - out

Endo - In

Sis - process

Phago - engulfs

Pino - drink


Can combine these prefixes / suffixes i.e. phagocytosis - process that amoebas use to eat.  Amoebas surround their food and engulf it.


Another concept is do fish drink?  Depends on salt or fresh.  Fresh water - Hypotonic is low concentration, makes the fish hypertonic, meaning the fish 'breath the water (tony's words) and don't have to drink water.  To keep from cells exploding due to too much water, fish pee constantly.  Process of peeing is called active transport ,because pee is going from low to high and requires energy.  Salt water fish - in a hypertonic environment - high concentration.  Makes the fish hypotonic.  Water goes from high to low concentration is always pushing out of the fish, therefore the fish has to drink all day long.Cells taking in the water have special cell transport proteins which separates the salt from the water inside the fish, causing it to poop all the time with active transport.





There was a lot of confusion based on which was hypo tonic, and which was hypertonic. Because hyper means more, we thought it meant more water. I was later able to prove that it was the opposite. I googled the root word tonic and found that it actually meant tension. This could imply that it if it's hyper, it has more tension, and therefore needs to intake water to be balanced. Even if this is not the real meaning behind the word, I think it's a good way to remember it for myslef.

Cory Cox
November 26, 2013 at 8:19pm

Cyto: Cells

Sis: Process

Exo: Out

Endo: In

Phago: Engulf

Pino: Drink

These terms are like puzzle pieces. Each word is a piece, two or more come together to form a term used in biology. For example; Endo-cyto-sis= endocytosis, which is the process of getting cells out.

The graph shows the concentration of the bags in the 0.5M sucrose. 'A' is going right along the x axis, which means it is isotonic and is at equilibrium. Bag 'B' is hypertonic, the outside is hypotonic and fills the bag with water. Because water goes where the solutes are!

Some fish do drink. The fish that live in salt water do, yet the ones that live in fresh water do not. Salt water fish are hypotonic, the water is hypertonic, so the fish is constantly releasing water out of it's system all day long. A fish that lives in fresh water is hypertonic, the fresh water is hypotonic, so throughout the day, water is always rushing into the fish. Leads to the fish having to constantly pee all day long.

Parent: My brain just grow two sizes. I find it fascinating that these simple words come together to make "biology talk" It is almost like an entirely different language that will need to be studied a little longer. I discovered what hypertonic and what hypotonic is, and that doctors use selectively permeable membranes, which resembles the bags. I have always wondered if fish drink, and now i know thanks to AP Biology. Keep the ETD's coming.

My Response: I feel that throughout the year so far, I have struggled grasping all the big concepts and most importantly the words. Taking a word apart helps me a lot. So next time I am stuck on a quiz or test, I can refer to what I am learning right now, take each word, break it apart, and discover the code!  

Neil Cochran(parent of Johnny)
December 01, 2013 at 10:53pm

Cyto- means a cell

Cytoplasm is the gell inside the cell where reactions occur.

Sis- Is a process

Photosynthesis is process plant use convert energy

Exo- Outside the cell

Exocytosis is a process where something is going out of the cell

Endo- Inside the cell

Endocytosis is something going into the cell

Phago- Engulls

Phagocytosis is something engullfing a cell

Pino- Drinks

Pinocytosis is something drinking (consuming) the cell

Do fish drink? Saltwater fish do drink while freshwater do not drink. The saltwater fish is hypotonic while the water is hypertonic. The hypertonic has higher salt to water ratio so the saltwater fish drink it. They excrete a solute so they stay isotonic.

Freshwater fish do not drink because they are hypertonic compared to the water which is hypotonic. The freshwater fish would explode if they drank the water because they could not get rid of the water.

I explained to my dad what the different parts of what make up some cellular words are and a little bit of why they are called that. During the fish drinking discussion I explained that salt water fish need to drink to survive, and excrete excess solute, while fresh water fish have no need to drink because if they did then they would have too much water on the inside of them and would explode if they did because their bodies could not support it.

Jon Neil (Instructor)
December 02, 2013 at 4:08pm

Quality work from both the parents and students.  I 'm glad to see some new posters and some return visitors to the Bio Blog.  Parents please feel free to challenge your students with clarifying questions during their teaching sessions with you as this will push them to elaborate and build their own ideas and analogies on top of what they have learned in class.  I'll keep the ETDs coming.  I am glad to see that Cory and others are starting to break the code of biology by breaking apart the terms to discover the combined meaning of their prefixes and suffixes, which is a strategy that you can use in all of your classes in High school and beyond in college.

Kevin Turek
December 31, 2013 at 9:40am

Parent: I learned that cyto means cell. Sis means process. Exo means out. Endo means inside. Phago means engulfs. Pino means drink. My son showed me the pictures of each of these for cyto he drew a cell. For sis he drew a step by step list. Exo he drew an open door. For endo he drew a closed door. Phago he drew pacman. For pino he drew a cell with a straw. Then for the graph he showed me the three lines. He said B was hypertonic(lots of solute) and was above .5 molar. He said A was isotonic (equal solute and water), and about .5 molar. And that C was hypotonic(lots of water) that it was below .5 molar. Then he explained that fish do not really if they live in fresh water. But instead go through active transport through there gills. How ever salt water fish drink all day.

Student: I explained to my mom what each of the different roots meant and gave her pictures to describe each one. Then I showed her the graph of the hypertonic, isotonic, and hypotonic solution. I told her that from looking at this we can find their approximate molarities. She learned this easily as I already showed her this in the other ETD. Then I explained how salt water fish drink while fresh water fish do not but instead undergo active transport through their gills. She already knew this though because she had studied marine biology a little bit in college.

Madison Boggan
November 22, 2014 at 3:50pm

Parent: Cyto-cell. Sis-process. Exo-out. Endo-in. Phago-engulf. Pino-drink.

An upward line means water still coming in (hypotonic solution). Horizontal line means no change or same (isotonic). Downward line means losing water (hypertonic solution). 

I had no idea that some fish drink and some don't! It all depends on salt and water concentration. This reminds me of the other ETD about slugs. 

Student: I made connections for my mom to understand the prefixes and suffixes. Cyto is like cell, they both start with c and cytoplasm is within the cell. Sis is a process, being a sister is a process. Exo, like exit is out. Endo, is the opposite of exo so in. Phago-engulf can be remembered because the opposite is pino-drink, like the wine. 

It was rewarding to see my mom connect the slug ETD to this one regarding fish drinking because they are both about water following salt and wanting to be at a lower concentration. 

Lauren Masters
January 02, 2016 at 7:24pm

Parent: This was a fun one in that I ended up teaching Lauren something as well as her teaching me something. I knew the meaning of some of the words. She taught me the others. She talked about freshwater fish having kidneys and they pee. They are also hypotonic. Saltwater fish do not have kidneys and they poop. They are hypertonic. I questioned salmon as they live in both types of water and she told me about anadromous fish.

Student: My mom knew something. She knew what cyto, exo, endo, and pino meant. I tried to explain that phago meant engulf and she was able to help me understand the definitions more. I explained that fish in freshwater pee while fish in saltwater no not pee. She was interested in how salmon can live in both. I told her that salmon are anadromous fish.

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