Unit B Lesson B8 Diffusion and Osmosis
Completion requirements
Lesson B8: The Effect of Diffusion and Osmosis on Cells
Video Lesson
How do the processes of diffusion and osmosis affect cells? Watch this video to learn more.
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Diffusion and Osmosis Review
You learned about diffusion and osmosis in grade 7 science. If you need to refresh your memory on diffusion and osmosis, watch the following video.
You learned about diffusion and osmosis in grade 7 science. If you need to refresh your memory on diffusion and osmosis, watch the following video.
Lesson B8: The Effect of Diffusion and Osmosis on Cells
Figure B.2.8.1 – Secondhand smoke can cause health problems like asthma.
Figure B.2.8.2 – E-cigarettes still produce harmful secondhand smoke.
Figure B.2.8.3 – Smoking causes diseases like lung cancer.
Reading and Materials for This Lesson
Science in Action 8
Reading: Pages 115–119
Materials:
Water, 2 glasses, 3 raw eggs, spoon, vinegar, corn syrup
Secondhand Smoke
Cigarette smoking causes many negative health effects, in both smokers and the people around them. Cigarette smoke contains many toxic chemicals. Smoke diffuses from a cigarette into the surrounding area. Anyone nearby breathes in the diffused cigarette smoke, also known as secondhand smoke. Breathing in secondhand smoke is almost as dangerous as smoking itself.
The lungs are the main body organ affected by cigarette smoke. Gases diffuse from the lungs into blood vessels that surround the lungs. These blood vessels then transport the gases around the body. Harmful gases from cigarettes diffuse from the lungs into the blood. Cigarettes produce carbon monoxide gas, which blocks oxygen from reaching all parts of the body. Nicotine is an addictive drug in cigarettes. Nicotine also diffuses from the lungs into the blood.
Cigarette smoking causes many negative health effects, in both smokers and the people around them. Cigarette smoke contains many toxic chemicals. Smoke diffuses from a cigarette into the surrounding area. Anyone nearby breathes in the diffused cigarette smoke, also known as secondhand smoke. Breathing in secondhand smoke is almost as dangerous as smoking itself.
The lungs are the main body organ affected by cigarette smoke. Gases diffuse from the lungs into blood vessels that surround the lungs. These blood vessels then transport the gases around the body. Harmful gases from cigarettes diffuse from the lungs into the blood. Cigarettes produce carbon monoxide gas, which blocks oxygen from reaching all parts of the body. Nicotine is an addictive drug in cigarettes. Nicotine also diffuses from the lungs into the blood.
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Smoking Affects Us All
Watch these videos to learn more about the dangers of secondhand smoke.
Watch these videos to learn more about the dangers of secondhand smoke.
Some people smoke e-cigarettes, also called vaping. However, smoke from e-cigarettes is still harmful. Watch this video to find out more.
Think • Interpret • Decide
Diffusion
This video shows an experiment using food colouring in water to test the effect of concentration on diffusion.
This video shows an experiment using food colouring in water to test the effect of concentration on diffusion.
Questions:
After you have finished watching the video, carefully consider the following questions. Then click on each question to reveal an answer.
After you have finished watching the video, carefully consider the following questions. Then click on each question to reveal an answer.
Think: What’s the point? Do you understand the results of this experiment? If not, watch it again.
In this experiment, the higher concentration of food colouring diffused, or spread out faster into the water, compared to the lower concentration of food colouring.
As concentration of a substance increases, it diffuses faster. As concentration of a substance decreases, it diffuses slower.
Diffusion occurs when particles move from an area of high concentration to an area of low concentration. Particles in a solution try to spread out as quickly as possible, to create an equal concentration everywhere in the solution. A high concentration
of particles moves faster to spread out in the solution, compared to a lower concentration of particles.
Figure B.2.8.4 – Altitude sickness caused by hypoxia makes hikers feel nauseous and weak.
Figure B.2.8.5– People climbing high mountains risk getting altitude sickness.
Figure B.2.8.6 – Sometimes people need to carry oxygen at high mountain altitudes.
Altitude Sickness
Oxygen is necessary in all living cells. Cells use oxygen to produce energy to stay alive. Oxygen initially enters the body through the lungs. In the lungs, oxygen gas diffuses into blood vessels surrounding the lungs. The blood then carries oxygen to all cells in the body.
At high altitudes, such as on very high mountains, there are lower amounts of oxygen in the air. Lower amounts of available oxygen means that less oxygen diffuses into people’s lungs and blood. A lack of oxygen in the body can cause a condition called hypoxia, which is also known as altitude sickness. Symptoms of altitude sickness include exhaustion and nausea.
Oxygen is necessary in all living cells. Cells use oxygen to produce energy to stay alive. Oxygen initially enters the body through the lungs. In the lungs, oxygen gas diffuses into blood vessels surrounding the lungs. The blood then carries oxygen to all cells in the body.
At high altitudes, such as on very high mountains, there are lower amounts of oxygen in the air. Lower amounts of available oxygen means that less oxygen diffuses into people’s lungs and blood. A lack of oxygen in the body can cause a condition called hypoxia, which is also known as altitude sickness. Symptoms of altitude sickness include exhaustion and nausea.
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The View is Amazing! My Stomach, Not So Much.
Watch this video to learn more about the symptoms and treatment of altitude sickness.
Watch this video to learn more about the symptoms and treatment of altitude sickness.
Try It!
Egg Osmosis
Try this experiment to observe osmosis in eggs. This experiment will take two days to complete.
Materials:
Try this experiment to observe osmosis in eggs. This experiment will take two days to complete.
Materials:
- Water
- 2 glasses
- 3 raw eggs
- Spoon
- Vinegar
- Corn syrup
Instructions:
- Fill both glasses two-thirds full with vinegar.
- Place one raw egg in each glass. Make sure the eggs are completely covered with vinegar. Leave the eggs for 24 hours.
- Carefully remove the eggs from the glasses with a spoon. Rinse them with water. The vinegar will have removed the eggshells.
- Rinse the glasses and put one egg back in each glass.
- To one glass, add enough pure water to completely cover the egg.
- To the other glass, add enough corn syrup to completely cover the egg.
- Leave the eggs again for 24 hours.
- Carefully remove the eggs from the glasses with a spoon. Rinse them with water.
- Compare both eggs to an untouched raw egg. What do you observe?

- Watch this video to see this experiment and its results:
Questions:
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
Removing the eggshells exposed the egg’s outer membrane, so water could enter and leave the egg.
Osmosis occurs when water moves from an area of higher concentration to an area of lower concentration. There was a higher concentration of water inside the egg compared to the concentration of water in the corn syrup, so water moved out of
the egg into the corn syrup.
Osmosis occurs when water moves from an area of higher concentration to an area of lower concentration. There was a higher concentration of water outside the egg compared to the concentration of water inside the egg, so water moved into the
egg.
Figure B.2.8.7 – Cholera is caused by bacteria.
Figure B.2.8.8 – Cholera bacteria spread through food and water supplies. Flies can also spread the disease.
Figure B.2.8.9 – Cholera causes severe diarrhea and dehydration.
Cholera
In a healthy person, osmosis occurs in the intestines. Water diffuses from a high concentration in the intestines to a lower concentration in the blood. This is how water is transported to all body cells.
Cholera is a bacterial disease that disrupts osmosis in the intestines. Cholera bacteria make a toxin that interferes with the osmosis of water into the body. This toxin decreases the concentration of water outside body cells. As a results, water moves by osmosis from a higher concentration inside cells to a lower concentration outside cells. This extra water exits the body, resulting in the cholera symptoms of severe dehydration and watery diarrhea.
In a healthy person, osmosis occurs in the intestines. Water diffuses from a high concentration in the intestines to a lower concentration in the blood. This is how water is transported to all body cells.
Cholera is a bacterial disease that disrupts osmosis in the intestines. Cholera bacteria make a toxin that interferes with the osmosis of water into the body. This toxin decreases the concentration of water outside body cells. As a results, water moves by osmosis from a higher concentration inside cells to a lower concentration outside cells. This extra water exits the body, resulting in the cholera symptoms of severe dehydration and watery diarrhea.
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Funky Fluids
Cholera easily spreads in places with contaminated drinking water. Watch this video to learn more about the symptoms and treatment of cholera.
Cholera easily spreads in places with contaminated drinking water. Watch this video to learn more about the symptoms and treatment of cholera.
Figure B.2.8.10 – Cured meats are often hung in markets for shoppers to buy.
Figure B.2.8.11 – Salt was once used as money.
Figure B.2.8.12 – Salami is a type of sausage cured with salt.
Salt-Cured Meat
Today salt is inexpensive and easily obtained. However, salt used to be very valuable because it was difficult to produce. Salt was valuable because it was used to preserve food, especially meat, when people did not have refrigerators and freezers.
Salt preserves meat through the process of osmosis. The muscle and fat cells of fresh meat contain lots of water. Bacteria that rot meat grow well in wet conditions. Taking the water out of meat prevents rotting. To get water out of meat cells, the meat is surrounded with salt. This makes the concentration of water higher inside the meat cells compared to outside the cells. Water then moves out of the meat by osmosis. The tissues left behind are dry, which prevents bacterial growth.
The process of preserving meat with salt is also referred to as curing. We still eat salt-cured meat today, because it tastes delicious! Ham, bacon, corned beef, salami, and jerky are all examples of salt-cured meat.
Today salt is inexpensive and easily obtained. However, salt used to be very valuable because it was difficult to produce. Salt was valuable because it was used to preserve food, especially meat, when people did not have refrigerators and freezers.
Salt preserves meat through the process of osmosis. The muscle and fat cells of fresh meat contain lots of water. Bacteria that rot meat grow well in wet conditions. Taking the water out of meat prevents rotting. To get water out of meat cells, the meat is surrounded with salt. This makes the concentration of water higher inside the meat cells compared to outside the cells. Water then moves out of the meat by osmosis. The tissues left behind are dry, which prevents bacterial growth.
The process of preserving meat with salt is also referred to as curing. We still eat salt-cured meat today, because it tastes delicious! Ham, bacon, corned beef, salami, and jerky are all examples of salt-cured meat.
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Saltiness vs Sickness
Watch this video to learn more about how salt cures, or preserves, meat.
Watch this video to learn more about how salt cures, or preserves, meat.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.
Unit B Lesson 8 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
-
REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
-
CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher.
To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Be a Self-Check
Superhero!
Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
Fluid with a similar concentration to blood prevents blood cells from shrivelling or bursting due to osmosis. If pure water is added to blood, water will quickly enter blood cells and cause them to burst. If the IV salt solution is more concentrated
than blood, water will leave blood cells and cause them to shrivel. When the IV line has a similar concentration to blood, the blood cells remain unaffected.
Limp celery has lost water from its cells. When you put celery into water, osmosis causes water to enter the celery cells, making it crisp again.
Water will move from the blood into salty cells because water, via osmosis, moves to where there is less water. This results in cells with more fluid in them than normal, which is why people will often report feeling "bloated" after eating too
much salt.
Extra salt in the body creates a lower concentration of water outside cells compared to inside cells. This causes water to move out of cells and into the blood by osmosis. An increased amount of water in the blood creates more pressure on blood
vessels, which have a limited ability to expand.
A lack of water causes body cells to shrivel, and as a result, they can’t function properly.