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Cells, Algae, and Fungi Lesson for Middle School Biology

Updated on May 18, 2019
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I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 8.

Cells, Algae, and Fungi Lesson for Middle School Biology
Cells, Algae, and Fungi Lesson for Middle School Biology

This is the 28th lesson in a series of 32 hands-on lessons covering middle school biology from a Christian perspective. This lesson focuses on cells, algae, and fungi. Extra DNA, eat algae (ice cream), watch yeast inflate a balloon, dissect fungi (mushrooms), and more! I used this plan while teaching a 55 minute middle school biology class. Each lesson plan includes homework assignments and a variety of hands-on activities to make each lesson engaging & memorable. Use these fun lessons with your classroom, homeschool, after-school program, or co-op!

These lessons are written for a class that meets once a week. If your class meets 5 days a week, simply do this lesson one day a week and use the homework assignments (at the bottom of the page) for the work for the other days of the week.

Two 3-D models of a cell created by the students
Two 3-D models of a cell created by the students

Homework Review

1. Pass out tickets to students who did their homework and who did the extra credit.

2. Find out which student found the most items containing seaweed. (I gave them an extra ticket and candy as a prize.) Ask the class which types of items they were able to most frequently find seaweed in the ingredients.

3. Allow students who created a 3-D model of a cell to show their model. (If students brought an edible model for us to eat, they can also pass it out at this time.)

4. Go over the homework questions from the book. (I give out tickets for students who volunteer to answer the questions.)

Preparing Bottles, Balloons, and Budding Activity
Preparing Bottles, Balloons, and Budding Activity

Preparing Bottles, Balloons, and Budding Activity

5. Begin the Bottles, Balloons, and Budding Activity from p. 395, though we made some changes to the directions in the book. I asked for volunteers to help measure and pour the ingredients.

  • Lay out 3 identical bottles. Use a marker to label each bottle. One will be cold. One will be warm. One will be hot.
  • In each bottle place 1 tsp. baker's yeast and 1/4 tsp. sugar. (We used a funnel.)
  • Now we will add the variable. What is a variable? (The one aspect in the experiment that is different.)
  • In the cold bottle, pour 120 mL (about 1/2 cup) of ice cold water.
  • In the warm bottle, pour 120 mL (about 1/2 cup) of warm water (about 105 F), which was the temperature of the warm water from the tap.
  • In the hot bottle, pour 120 mL (about 1/2 cup) of boiling hot water.
  • Place a deflated balloon (which has already been stretched out) over the mouth of each bottle.
  • Gently swirl each mixture.
  • Let's create a hypothesis. What is a hypothesis? (an educated guess) Raise your hand if you think the balloon over the cold water will inflate the most. the warm water? the hot water?
  • Set bottles aside in a location the students can see. It will take about 30 minutes for the balloons to reach their full capacity.

You will need:

  • 3 identical bottles. (We used empty Brisk Tea plastic bottles.)
  • sharpie marker
  • 3 funnels (or 1 can be shared)
  • 3 measuring teaspoons (or 1 can be shared)
  • 3 tsp. baker's yeast (The kind in the glass jar works better than the yeast in the packets.)
  • 1 tsp. sugar
  • 3 liquid measuring cups (or other holder for the water)
  • 120 mL (about 1/2 cup) of ice cold water
  • 120 mL (about 1/2 cup) of warm water (about 105 F), which was the temperature of the warm water from the tap
  • 120 mL (about 1/2 cup) of boiling hot water. (We boiled it in the microwave.)
  • 3 balloons (that have been stretched out already & then had the air released)

Cell parts as a factory analogy
Cell parts as a factory analogy

Cell Parts

6. Review the parts of the cell and how they are like a factory.

  • Which part of the cell regulates what enters or leaves the cell? (cell membrane) It is analogous to the shipping and receiving department of a factory.
  • Which part makes the decisions and controls all the cell activity? (nucleus) The nucleus is like the executive department runs the cell factory.
  • What's the jellylike substance that holds all the organelles or cell parts? (cytoplasm) The cytoplasm is similar to the factory floor that holds all the workers, machines, and equipment.
  • Which part do you think would be like the workers in the assembly line who are responsible for building the goods in the factory? (ribosomes) The ribosomes build the proteins in the cells.
  • Which part is like the assembly line where workers do their work as items move along on a conveyor belt to different parts of the factory? (endoplasmic reticulum). The ER is where the ribosomes do their work, and the ER moves the proteins to different parts of the cell.
  • Which part is like the packaging department who puts the created items in their boxes to ship them? (golgi apparatus). The golgi apparatus prepares proteins for use or export.
  • Which part would be the janitors or maintenance crew? (lysosomes) The lysosomes are responsible for breaking down and absorbing materials taken in by the cell.
  • Finally, what is the power plant for the company? (mitochondria) The mitochondria is the cell’s power plant is of the cell and produces the cell's energy.

Onion skin under a microscope
Onion skin under a microscope

7. (Optional) Allow students to observe an onion skin under a microscope. They can see the cell walls, cell membranes, nuclei (big dots), and vacuoles (tiny dots).

You will need:

  • microscope
  • prepared slide of an onion skin

DNA is like a cookbook
DNA is like a cookbook

DNA is like a cookbook

8. Point to any clothing item someone is wearing.

  • Quickly ask, “How was this made? What is it made from? What are some of the parts of it and what do they do?” [example: sleeves keep your arms warm, hole in the head allows you to pull it over your head, etc.]
  • Just like this sweater/jacket/etc. was knit/sewn/etc. from wool/yarn/etc. with each part having a purpose, our bodies were knit together by God and each part of our bodies has a specific purpose.
  • In Psalm 139:13-14, David wrote about God, "For You formed my inward parts; You wove me in my mother’s womb. I will give thanks to You, for I am fearfully and wonderfully made."
  • Each of you are fearfully and wonderfully made by God! God didn’t use yarn to make our bodies. He used cells and DNA.

9. Our DNA is like a cookbook, containing recipes for each cell. Every cell has the entire cookbook. It has all the recipes or information for all the cells, but God made them so that they know which one recipe to use in each cell.

  • If I had flour, sugar, butter, and eggs, what could I make? (sugar cookies, pound cake, bread, pancakes, candy, etc.) I have the same 4 ingredients, but I could make lots of things, couldn't I?
  • Every cell in your body contains a cookbook for you called DNA that tells it what is should do. DNA stands for DeoxyriboNucleic Acid. Say that with me, “Deoxy...ribo…Nucleic…Acid.” DNA sure is easier to say, isn't it?
  • Even though our DNA uses recipes to make all our body parts (from our skin to our hearts to our brains to our bones), DNA is made up of building blocks called genes. Each gene contains a sugar and a phosphate as well as one of four types of ingredients or base molecules: adenine, guanine, cytosine and thymine.
  • Our bodies are made up of about 100 trillion cells! How many cells make up our body? (100 trillion)
  • Each cell is an amazing self-contained unit, and yet they all work together to make up one “you.” We began with one cell. Within that one cell was all the information to make you. Your height, eye and hair color, if you can roll your tongue, and much more. God wrote it within your cells. Your cell began to divide and multiply, and they began to specialize. Some cells became your lungs, others became your hands, others became your heart, and so on.
  • From hair color, to ear shape, to whether or not we will have dimples, God included the directions in our DNA. Every cell has the entire cookbook. It has all the recipes or information for all the cells, but God made them so that they know which one recipe to use in each cell. The DNA only uses the part needed to make the particular type of cell it is.

You will need:

  • a cookbook

How to See DNA

10. Demonstrate the length and width of a strand of DNA.

  • Where do you think the DNA is found in a cell? Within the nucleus of each cell is the recipe, or DNA, for that cell.
  • All the DNA is squished tightly together in the nucleus of each cell. If it were stretched from end to end, it would reach from the earth to the sun, not one time but 800 times!
  • One strand of our DNA is about 1 meter (3.28 feet).
  • Quickly have 2 students stand at one end of the room and hold out a thin piece of thread that is about 1 meter (3.28 feet). (They should be far enough away so that the other children can't see the thread.)
  • This thread is about the same length of a strand of our DNA, which is about 1 meter or 3 1/4 feet. Can you see it?. The thread is like DNA. Normally we can only see it with a microscope because it is so thin.
  • Tell one of the students to crumple up the thread and hold it in the palm of his/her hand. Can you see the thread now? We are going to do something similar to the DNA in our strawberries so that we will be able to actually see it!

You will need:

  • a piece of thin thread that is about 1 meter (3 1/4 feet) long

Extracting DNA from a strawberry
Extracting DNA from a strawberry

Extracting DNA from a Strawberry

11. Follow the directions to extract DNA from a strawberry using normal household materials:

  • Give each student or group of students (up to 4 in each group) a strawberry and a plastic sandwich bag. Have the students put the strawberry in the plastic bag and smash it into a pulp. Tell them that by doing this, they are breaking the cell walls of their strawberry.
  • Have a few volunteers assist in creating a class-size amount of the extraction liquid by gently mixing together 225 ml (or 1 cup) of water, 5 g (or 1 1/4 tsp.) salt, and 25 ml (or 5 tsp.) Dawn dish-washing detergent.
  • Each student or group should add 10 mL (or 2 tsp.) of the extraction liquid to their bag of smashed strawberry and then gently smash the liquid together with the strawberry. (They don't want to create suds or bubbles, though.) Explain that the cell membranes are basically made of fat, which is kind of like grease. The dish-washing detergent is going to dissolve the cell and nuclear membranes of the cell just like it cuts through grease in a dirty pan.
  • Have a student in each group wrap a paper towel around their finger and then pull it out so that there is an indention in the paper towel. Have them then put the paper towel in a small, disposable cup. They should pour their smashed strawberry mixture into the indention in the paper towel and allow the liquid to seep through the paper towel into the cup. This will take about a minute. If there is not much liquid, squeeze the juice out from the strawberry mixture inside the paper towel.
  • Have the students throw away the paper towels and then slowly add 3 ml (or 3/4 tsp.) of very cold rubbing alcohol down the side of the cup. Explain that DNA is soluble in water but not in rubbing alcohol. Rubbing alcohol actually makes the DNA clump together just like we did with the thread earlier.
  • Wait a minute or so until you see a milky white blob of DNA.
  • Use a bamboo skewer to fish out the DNA strand. They can touch it if they would like. They can also save it to bring it home with them.
  • If desired, have the students clean their hands and then each eat a strawberry.

You will need:

  • 90% rubbing alcohol that has been in the freezer for at least an hour
  • 1 plastic sandwich bag per student/group,
  • 1 fresh or frozen strawberry per student/group
  • salt
  • Dawn dish-washing detergent
  • paper towel per student/group
  • 1 small disposable cup (like Dixie bathroom cup) per student/group
  • 1 bamboo skewer per student/group
  • strawberry to eat (optional)
  • measuring tools: granulated cylinders or liquid measuring cup and measuring teaspoon

Enjoying ice cream made with algae
Enjoying ice cream made with algae

Eating Algae

12. (Optional) Pass out cups of ice cream. Why are we celebrating with ice cream today? Yes, ice cream is made with algae. Who remembers the name of it? (carrageen, from irish moss, which is a type of red algae)

You will need:

  • ice cream that contains carrageen (we used Walmart's brand of Cookies & Cream)
  • disposable cups or bowls
  • disposable spoons
  • ice cream scoop
  • napkins or paper towels

Observing green algae from a nearby pond
Observing green algae from a nearby pond

Algae Overview

13. Quickly review notes on algae while looking at the pictures in the textbook or on PowerPoint slides.

  • What are the smallest chlorophyll-containing plants found in nearly every body of water called? (algae)
  • In what kingdom are green algae? (plant) Why? (they contain chlorophyll)
  • Algae make up the largest portion of plankton, and marine algae are responsible for 70% of photosynthesis! 70% of that fresh oxygen we're breathing isn't coming from the trees and flowers outside. It's coming from the marine algae in the seas and oceans.

A. Green Algae

  • Most of 8000 species are microscopic, so why can we see them? (because of vast numbers can be seen as green scum on pond or lake)
  • What's one type of green algae? (volvox, filaments, spirogyra)

B. Yellow Algae

  • Why are they called yellow algae? (They contain yellow or brown pigment that masks chlorophyll = appear yellow-green or golden-brown)
  • What is the must abundant life form on earth? (Bacteria! That was tricky, wasn't it?)
  • What is the 2nd most must abundant life form on earth? (diatoms)
  • Who has used diatomaceous earth? What does your family use it for? (It's usually used to keep away insects as it's like cut glass to them.) That's made from the outer cell walls of diatoms. It's also used in toothpaste, insulation, & filters.
  • Diatoms cell wall “shells” made of silica (hard substance in glass & sand) with 2 almost equal halves that fit together like 2 sides of Petri dish – have a variety of shapes & sizes & give diatoms appearance of tiny glass sculptures

C. Brown Algae

  • Who's gone to the beach and seen the brown seaweed that floats to the shore?
  • Almost all live in cool ocean waters & include seaweeds like kelp, rockweed, & gulfweed.
  • Have you seen those little balls on the seaweed? Many equipped with gas-filled gloats to keep near the surface to obtain sunlight for photosynthesis.
  • Kelps are the largest brown algae – in Atlantic & Pacific – grow to over 200 feet – source of algin, gummy substance used to make salad dressings, skin lotions, aspirin, pudding, & ice cream

D. Red Algae

  • Almost all are marine & live at greater depths & in warmer waters than brown
  • You've been eating something from a type of red algae: Irish moss – source of carrageen, jellylike substance used in production of many foods – gives commercial ice cream smooth, creamy texture & keeps chocolate milk from separating

Dissecting a mushroom
Dissecting a mushroom

Fungi Overview

14. Quickly review notes on fungi while looking at the pictures in the textbook or on PowerPoint slides.

  • Why aren't mushrooms plants? (They're heterotrophs & can’t make their own food)
  • How are many very beneficial to nature? (Most are saprophytes – organisms that obtain nourishment from dead organisms – decomposers = break down complex molecules of plants & animals into simpler ones that can be used by other living organisms.)
  • What is the word for the study of fungi? (mycology)
  • Name a parasite fungi (causing athlete’s foot & ringworm)
  • Name a helpful fungi that you would swallow (mushrooms, baker’s yeast, penicillium = penicillin)
  • What are most fungi made of? (hyphae = threadlike structures, which mass to form mycelium = body of fungus)

15. Allow students to use plastic knives to dissect mushrooms. What do you notice?

You will need:

  • plastic knives per student or pair of students
  • mushrooms (such as the edible ones from the store)

16. As students continue to explore their mushrooms, discuss club fungi.

A. Mushrooms & Toadstools

  • Some are edible & some are very poisonous
  • At reproduction, a stalk of tightly bound hyphae with an umbrella-shaped, spore-forming cap rises quickly out of the ground. Together the stalk & cap make up the fruiting body.
  • Underside of cap has many gills, each containing hundreds of club-shaped basidia (each containing 4 spores = over 1 billion spores released by 1 mushroom)
  • Puffballs known for releasing lots of spores (up to 7 trillion)

B. Bracket fungi (shelf fungi)

  • Grows on trees & rotting logs
  • Grow more slowly than mushrooms & don’t have gills
  • Spores fall from holes on underside of fruiting body & are spread by the wind

C. Crop Destroyers: Rusts & Smuts

Moldy bread I brought next to bread that didn't grow mold from a student's experiment
Moldy bread I brought next to bread that didn't grow mold from a student's experiment

Fungi: Mold

17. For those of you who brought in your moldy bread and cheese from your homework, let's look at them. What do you or did you notice about them?

  • Rhizopus stolonifera = bread mold – shiny, white hyphae spread by dark-colored spores that burst from spore cases & carried by wind – favorable for growth: high humidity, warm temps, & darkness
  • Mold is beneficial in that it helps us to produce what tasty product? (cheese)

You will need:

  • a piece of moldy bread (I found one a few weeks ago and have been saving it for class.)

Final Results of Bottles, Balloons, and Budding Activity
Final Results of Bottles, Balloons, and Budding Activity

Yeast: Bottles, Balloons, and Budding Activity

18. Sac Fungi (yeasts & mildew)

  • Most people think mushrooms are the largest group of fungi, but they're not. What is the largest group of fungi? (sac fungi = yeasts & mildew)
  • They're multicellular except for yeasts which are unicellular

19. What happened to our balloons?

  • Why do you think the warm water produced the most gas?
  • As yeast eats = fermentation = converts sugar into alcohol & carbon dioxide
  • This is why bread dough rises. The alcohol evaporates during baking, but the carbon dioxide becomes temporarily trapped, causing the bread to rise & leaving those bubbles in the dough.

A Beka's Science: Order & Design science textbook
A Beka's Science: Order & Design science textbook

Homework

(Page numbers refer to the pages in A Beka's Science: Order & Design textbook.)

  • Friday: Complete Check it Out from p. 404. Instead of peeling 2 potatoes, you can simply slice 2 slices from a potato. Run all around 1 slice with unwashed hands. Place it in a disposable bowl and cover it with plastic wrap. Then wash your hands thoroughly with soap and water. Rub the second potato and place it in a separate disposable bowl labeled "washed hands." Cover it with plastic wrap. Leave them in a warm place. Observe them next Wednesday. What do you notice? If possible, bring them in for us to see.
  • Monday: Read pp. 396-404. Answer 7 questions of your choice from p. 404.
  • Tuesday: Read pp. 406-409. Answer 3 questions of your choice from p. 409.
  • Wednesday: Read pp. 411-420. Answer 4 questions of your choice from p. 421. Please bring your potatoes to class tomorrow.
  • Extra Credit: Sketch and identify 4 different trees that you find outside. Include the general tree shape, the leaf shape (possibly doing a leaf rubbing), and the bark type (possibly doing a bark rubbing) You can get another extra ticket for doing this for 4 more trees. (8 in total = 2 tickets)

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© 2019 Shannon

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