Lesson B5: Studying Cells

Key Ideas     Unit Checklist 

  Video Lesson

When we observe cells under a microscope, we are able to see that cells contain smaller inner structures called organelles. Watch these two videos to learn more about studying cells.

 
 
 
 
 
 

  Lesson B5: Studying Cells

Figure B.2.5.1 – Cells are the building blocks of life.
Figure B.2.5.2 – Plant cells contain chloroplasts.


Figure B.2.5.3 – Glass slides hold microscope samples.
Reading and Materials for This Lesson

Science in Action 8
Reading: Pages 103–109

Materials:
Jello powder, water, electric kettle, bowl, spoon, fridge, small zipper-seal sandwich bag, grape.

Discovering Cells
People didn’t always know about cells. It wasn’t until the 1600’s, when the microscope was invented, that scientists were able to see cells. Our understanding of cells has been developed over many years by many scientists. We are still making new discoveries about cells today!

 Watch More

Living things are made up of... Cells?

Watch this video to learn more about the development of cell theory.

 
 
 
 
Watch this animation to journey inside a human body cell.

 
 

Lesson Activity

Comparing Plant and Animal Cells

Problem:

In this activity, you will make a study tool to compare the similarities and differences between plant and animal cells.

Download:

DOWNLOAD this Venn diagram. A Venn diagram is made of two overlapping circles. Venn diagrams are used to show the similarities and differences between two things. You will make a Venn diagram showing the similarities and differences between a plant cell and an animal cell.

Instructions:

  1. Print the plant cell vs. animal cell Venn diagram you downloaded.

  2. Rewatch the lesson video and try out this interactive website. You may need to activate Adobe Flash on your computer for the website to work. If you can't use the website, skip to step 3 and do your best. Make sure you check the feedback below.

  3. What cell organelles do plant and animal cells have in common? Write down these common cell organelles and their functions in the overlapping part of the circles on your Venn diagram.

  4. What cell organelles are unique to plant cells? Write down these cell organelles and their functions in the “Plant Cells” circle on your Venn diagram.

  5. What cell organelles are unique to animal cells? Write down these cell organelles and their functions in the “Animal Cells” circle on your Venn diagram.


  Try It! 

Cell Model

Try this activity to build a simple model of an animal cell.

Materials: 
  • Jello powder
  • Water
  • Electric kettle
  • Bowl
  • Spoon
  • Fridge
  • Small zipper-seal sandwich bag
  • Grape
 
This activity involves hot fluids. It must be completed with the supervision of an adult. DO NOT attempt this activity by yourself.

Hot fluids and metal can burn you or others if you are not careful.
Take care when pouring and stirring hot fluids.
Instructions:

  1. Make jello dessert according to the instructions on the jello powder package, using jello powder, water, an electric kettle, a bowl, and a spoon.

    WARNING: Do NOT pour the hot jello fluid into the plastic sandwich bag. The bag may melt and hot fluid will spill everywhere. Instead, use a heat-resistant bowl to chill the Jello in the fridge.

  2. The jello bowl will require a few hours to cool and set in the fridge.

  3. Put one grape into a small zipper-seal sandwich bag and seal the bag. The grape represents the nucleus of a cell.

  4. Carefully move the bag in all directions. How does the grape interact with the bag?

  5. Open the bag. Keep the grape in the bag and fill the bag with chilled jello dessert. Seal the bag.

  6. Carefully move the bag in all directions again. How does the grape interact with the jello-filled bag?

Questions: 

Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.


The sandwich bag represented the cell membrane.
The grape in the empty bag collided with the bag walls more often. The grape in the jello-filled bag was more protected and did not collide with the walls as often.
Cytoplasm is thick and gooey. It suspends and holds cell organelles apart from one another, which protects them from colliding with each other easily.

  Connections 

Figure B.2.5.4 – Cell biologists grow and test cells.
Figure B.2.5.5 – Researchers study cells under microscopes.

Connections – Career
>> Cell Biologists

Cell biologists are scientists who grow and study cells. Understanding how cells work allows cell biologists to figure out how diseases and medicines affect cells. Cell biologists also study how different cells interact with each other. One of the most important tools that cell biologists use is the microscope.

 Watch More

Becoming a Cell Biologist

Watch this video to hear a cell biologist talk about his job.

 
 
Figure B.2.5.6 – Plant cell walls contain cellulose.
Figure B.2.5.7 – Tree trunks contain lots of cellulose.
 
Cellulose

Plant cell walls are made from a thick, strong material called cellulose. Cellulose makes cell walls stiff. Cellulose is insoluble in water, which means it doesn’t dissolve when plant cells absorb a lot of water.

Humans eat plants, which means cellulose enters our bodies. However, the human digestive system is not able to break down plant wall cellulose. Instead, cellulose moves through the digestive system as dietary fiber. It helps keeps food moving along through the digestive tract.

Trees are strong, rigid structures. Wood contains a large amount of cellulose in its cell walls. This cellulose provides support to the tree trunk cells. Because paper is made from wood, cellulose fibres are the main component of paper. Cellulose insulation in buildings is made from recycled paper.

 Watch More

Cellulose: For More Than Just Holding Up Trees

Watch this video to see how cellulose insulation is installed in a house attic.

 
 
 
 
Nanocellulose is tiny cellulose fibres from tree cells. Nanocellulose has many interesting applications. Watch this video to learn more about nanocellulose.

 
 

Figure B.2.5.8 – Cows have four stomach compartments.
Figure B.2.5.9 – Giraffes are ruminants.

Ruminants

Figure B.2.5.10 – Camels, like all ruminants, chew their cud as a part of digestion.


Ruminants are plant-eating animals that can digest tough cellulose fibre. Ruminant animals include cows, sheep, deer, and elk.

In order to digest cellulose from plant cell walls, ruminants have four stomach compartments. The first stomach compartment is called the rumen. In the rumen, balls of chewed-up plants called cud are formed. Cuds come back up to the ruminant’s mouth, where they chew them some more. The ruminant swallows the cud again, and eventually cuds move through the other three stomach compartments to break down all the tough cellulose.

 Watch More

How Many Stomachs Does a Cow Have? Let Me Ruminate on That.

Watch this video to learn more about how food passes through a cow’s four stomachs.

 
 
 
 
This video animates food passing through a cow’s digestive system.

 
 



  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 5 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.

  1. DOWNLOAD the self-check quiz by clicking here.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

Plant cells make their own starch and sugar food through photosynthesis. Chloroplasts are the cell organelles where photosynthesis occurs. Animal cells do not make their own food, so they do not need chloroplasts.
If a slide specimen is thick, light cannot shine through it. Thin layers allow light to pass through, illuminating individual cells.
Insoluble dietary fibre is cellulose that is found in plant cell walls. Animal cells in meat do not have a cell wall, so they do not contain cellulose fibre.
Plants have tall rigid structures, like stems and tree trunks. Stiff cell walls help provide support to these tall structures.
Plant cells make their own food in chloroplasts, but they also need to use that food to provide energy to the cell. Mitochondria are the cell organelles where energy is produced. Since all cells need energy, all cells have mitochondria.