Classroom Lab Work. 8th Grade. Sense of Touch

Hey there everybody. Share with you lab report of "Sense of Touch" laboratory work which you do at classroom. Enjoy!
Just to keep in Mind:

• Lab report of yours has to be in PAST tense
• Conclusion explains methods of how you've done exact lab work by comparing and contrasting PURPOSE and RESULT stages
• Your lab report has to be absolutely clean and easy to read if you want to get THE BEST grade

Title: Sense of touch

Purpose: To identify different sensitivity of skin on different parts of the body. To improve verification skills by negotiation with classmates.

Equipment: 3 cups labeled A, B, C; marbles; a blindfold to cover the eyes of the person; sharp wooden rods.

Background: Skin consists of two layers, the epidermis and the dermis. The upper layer of the epidermis is composed of nonliving cells containing keratin. The dermis provides structural support for the epidermis and a matrix for the many nerve endings, muscles and specialised cells located within the skin.

Procedure:

A. What is hot? What is cold?

1. Pour water at different temperatures in each of the 3 beakers:

Beaker A: about 10°C

Beaker B: about 25°C

Beaker C: about 45°C

2. Place the fingers of your left hand into beaker A and the fingers of your right hand into beaker C. Keep your fingers in the water for about 30 seconds.

3. Remove both hands at the same time and put them into beaker B.

4. Explain what you feel and why.

B. What do you feel with the tips of your fingers?

1. Cross your fingers and roll a marble as teacher shows you. You can touch the tip of your nose instead of the marble.
2. Explain what you feel.

C. Does your brain control your fingers?

1. Work in pairs. One will perform the experiment, the other will be the subject of the experiment.
2. Turn your palms out, cross your arms, intertwine your fingers, and bend your elbows without separating your hands, as teacher shows you.
3. The student performing the experiment points to one finger of the subject person without touching it. The subject should immediately try to move that finger. Repeat two or more times.
4. What has happened? Explain.

D. Sense of Touch.

1. Cover the eyes of the student who is the subject of the experiment.
2. Touch him with wooden rods. He should indicate whether you touched him with one or both points of the rods by saying, “one”, “two”, or “I don’t know”. Find the shortest distance at which person feels two points by changing the distance between these two points. Occasionally touch with one rod instead of two.
3. Investigate sensitivity in three different parts of the body:

1. Forehead
2. Fingertip
3. Outer surface of the upper arm

4. Fill the table.
5. Explain the anatomic reason for having different sensitivities in different parts of the body.
6. Why do babies put everything into their mouths?

Part of the body	The shortest distance at which person feels two points
Forehead
Fingertip
Outer part of the upper arm

Result:

Conclusion: Write usual conclusion and answer questions:

1. What are the receptors found in the skin and their functions?
2. Why is there misperception in the sense of touch?

8th Grade's Skin Lesson

Hey there, everyone. Here is the new (yes!) lesson and module which we begin today. Enjoy!

PDF doc for the lesson

Small quiz for the lesson

Evolution Quiz. 9th Grade

 Join and Enjoy!

8th Grade Classroom Lab Work "Identifying Tissue Types"

Microscopic view of a histologic specimen of human lung tissue stained with hematoxylin and eosin (From english wikipedia).

Hey there everybody. This post is all about identifying human tissue using samples which you get in the class. Enjoy!
Title: Identifying Tissue Types
Purpose: to learn how to distinguish human tissues on from another. To get familiar with anatomical features of different tissues.
Equipment:

Procedure:
A. Does the tissue have a free surface? In other words, is there a continuous sheet of cells which is bounded by other cell tissue on only one side?

No: connective tissue, muscle tissue or nervous tissue (go to B)

Yes: epithelium (continue below)

1. Is there a single, clear layer of cells?

No: pseudostratified or stratified epithelium (go to 2)

Yes: simple epithelium (continue below)

a. Do the cells appear flat, with little cytoplasm around the nucleus?

No: simple cuboidal or simple columnar epithelium (go to b)

Yes: simple squamous epithelium

b. Do the cells appear square, with a round nucleus near the center?

No: simple columnar epithelium (go to c)

Yes: simple cuboidal epithelium

c. Do the cells appear rectangular, with an oval nucleus near the middle or toward the side furthest from the free surface? (Note: the nuclei of nearby cells should be at about the same height.)

No: reconsider the previous options

Yes: simple columnar epithelium (continue below)

(1) Are there cilia at the apical surface?

No: simple columnar epithelium

Yes: ciliated simple columnar epithelium

2. Do the cells appear to be predominantly columnar, but adjacent cells are of different height with nuclei staggered up and down (i.e. some cells do not reach the surface)?

No: stratified epithelium (go to 3)

Yes: pseudostratified columnar epithelium (continue below)

(1) Are there hairs at the top surface?

No: pseudostratified columnar epithelium

Yes: ciliated pseudostratified columnar epithelium

3. Given that you are looking at stratified epithelium,

a. Do the cells at the top (free) surface appear flat, with little cytoplasm around the nucleus or with no visible nucleus?

No: stratified cuboidal or stratified columnar epithelium (go to b)

Yes: stratified squamous epithelium (continue below)

(1) Do the cells at the top surface contain nuclei?

No: nonkeratinized stratified squamous epithelium

Yes: keratinized stratified squamous epithelium

b. Do the cells at the top surface appear square, with a round nucleus near the center?

No: stratified columnar epithelium (go to c)

Yes: stratified cuboidal epithelium (Note: this tissue is typically two cell layers thick.)

c. Do the cells at the top surface appear rectangular, with an oval nucleus near the middle or toward the side furthest from the free surface?

No: transitional epithelium (go to d)

Yes: stratified columnar epithelium (continue below)

(1) Are there cilia at the apical surface?

No: stratified columnar epithelium

Yes: ciliated stratified columnar epithelium

d. Do the cells at the top surface appear dome-shaped (or as a mixture of flat- and dome-shaped)?

No: reconsider the previous options

Yes: transitional epithelium

B. Do you see few cells (nuclei) that appear to be separated by extracellular material? In other words, are neraby cells separated by other material or by a gap?

No: muscle tissue or nervous tissue (go to C)

Yes: connective tissue or nervous tissue (continue below)

1. Do you see a large cell shaped like a many-pointed star surrounded by many smaller cells

No: connective tissue (go to 2)

Yes: nervous tissue (i.e. you are looking at the cell body of a neuron surrounded by supporting cells)

2. Do you see concave (or bi-concave) cells with no seen nucleus?

No: connective tissue proper, cartilage or bone (go to 3)

Yes: blood (i.e. you are looking at red blood cells; it may be possible to identify white blood cells nearby)

3. Are there lacunae (small cavities within the tissue)? There may be cells visible within the lacunae.

No: connective tissue proper (go to 4)

Yes: cartilage or bone (continue below)

a. Are the lacunae arranged in concentric rings (like a target or rings of a tree trunk)?

No: cartilage (go to b)

Yes: bone (or osseous tissue) (i.e. compact bone)

b. Given that, you are looking at cartilage,

(1) Are fibers visible in the matrix?

No: hyaline cartilage (Note: this tissue is also distinguished by a high density of lacunae.)

Yes: elastic cartilage or fibrocartilage (go to (2))

(2) Are the fibers fairly organized with a low density of lacunae?

No: elastic cartilage (Note: this tissue is also distinguished by a high density of lacunae and a ‘‘hairy’’ appearance.)

Yes: fibrocartilage

4. Are there large, round cells with their nuclei pushed to the outside?

No: areolar, reticular or dense connective tissue (go to 5)

Yes: adipose (a form of loose connective tissue made up of fat cells)

5. Are the extracellular fibers packed freely? In other words, is there a visible amount of space between nearby fibers?

No: dense connective tissue (go to 6)

Yes: areolar or reticular connective tissue (continue below)

a. Do the fibers form a wide-meshed network, like a fishing net?

No: areolar connective tissue (many overlapping fibers)

Yes: reticular connective tissue

6. Are the extracellular fibers running parallel to one another?

No: dense irregular connective tissue (packets of collagen fibers running in several directions)

Yes: dense regular connective tissue

C. Do there appear to be hot dog bun-shaped structures lined up end to end?

No: muscle (go to D)

Yes: nervous tissue (i.e. you are looking at a myelinated axon of a neuron)

D. Do the cells haven't striations?

No: skeletal or cardiac muscle (go to 1)

Yes: smooth muscle (cells should be spindle- or football-shaped with a large nucleus in the thickest portion, when viewed in longitudinal section)

1. Do you see intercalated discs? In other words, are the striations occasionally interrupted by a thick ‘‘striation’’ running perpendicular to the length of the cell?

No: skeletal muscle (should have distinct striations and no branching)

Yes: cardiac muscle (cells branch; striations may be difficult to see)

Result:
Conclusion:

Main information obtained from “Dichotomous Key for Histology by Ryan Bavis, Cassie Shigeoka, and Jerred Seveyka”, American Teachers Publishing.

BYOD 9th Grade. ERAS

Hey there. Here is the a little bit different lesson on ERAS of Life on Earth, a little bit controversial but still worth studying.

Geological Eras

Learning outcomes: to be able to explain main events in plant’s and animal’s changes during life on Earth.

1. Step one (individual work): Circle the right words or phrases in italics to create grammatically correct questions.

Questions	Answers
1. How many years/old is the Earth?
2. What possibly could/might have created proto-continents?
3. When multicellular life could have possibly evolve/evolved?
4. Is it true/Is true that life on Earth began with single-celled prokaryotic cells?

Step 2 (individual work): Match the following correct answers to the questions above. There are two extra answers that cannot be used.

1. Yes, it is true. The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such as bacteria.
2. Yes, there are.
3. Erosion, sedimentation and volcanic activity - possibly assisted by more meteor impacts - eventually created small proto-continents which grew until they reached roughly their current size 2.5 billion years ago.
4. There are 67000 of them.
5. The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billion-year-old zircon crystals.
6. Multicellular life evolved over a 1.5 billion years ago.

2. Step 1 (individual work): Read the text and circle words that you don’t  know.

Its earliest times were geologically violent, and it suffered constant bombardment from meteorites. When this ended, the Earth cooled and its surface solidified to a crust - the first solid rocks. There were no continents as yet, just a global ocean peppered with small islands. The continents have since repeatedly collided and been torn apart, so maps of Earth in the distant past are quite different to today's.

It's only in the last 570 million years that the kind of life forms we are familiar with began to evolve, starting with arthropods, followed by fish 530 million years ago (Ma), land plants 475Ma and forests 385Ma. Mammals didn't evolve until 200Ma and our own species, Homo sapiens, maybe only 200,000 years ago. So humans hypothetically have been around for a mere 0.004% of the Earth's history.

Step 2 (team work): Assemble the puzzle by matching time with what could happen at that time.

BYOD. Darwin's Birthday. 9th Grade

Hey hi. Today you have to fill out table with correct answers. Enjoy!

Use this text for the activity.

Darwin's Birthday - Text A

Charles Darwin was born on 12th February two hundred years ago. He hated school, especially learning Latin, but he loved reading and studying the details of the natural world. He had a famous grandfather who was a radical thinker. Erasmus Darwin was the doctor of George III, an inventor of engines and very interested in natural philosophy. In fact, Erasmus had influenced the ideas of Mary Shelley who wrote Frankenstein. His mother, Susannah, was the daughter of Josiah Wedgewood. The Wedgewood pottery was very advanced for its time. The Wedgewoods were radical, technological minded business people.

Charles Darwin went first to Edinburgh to study medicine. He met a lot of radical thinkers. He also met a freed slave who taught him to stuff birds. His father thought he was lazy, and sent him to study theology in Cambridge. He might then have become a clergyman, and spent a quiet life studying natural history. However, he was invited to travel around the world on a government survey ship called the Beagle as a companion for the captain. He thought he was going to be away for two years, but he was away for five years. Everywhere he went he collected specimens. He collected rocks and fossils.

He collected plants and animals. He wrote lots of notes and made lots of drawings. He also met a wide variety of human beings. He saw slaves in Brazil, and was very shocked and angry. He strongly disagreed with Captain Fitzroy who thought that slaves were an inferior family of humans who had to be controlled.

After he came back to England, he married another Wedgewood, and moved to Kent. He continued to study plants and animals, and think about how forms of life were linked to each other. He was worried about publishing his ideas, because he thought many people would be angry about them. Only when he heard that someone else was going to publish similar ideas he published "The Origin of the Species" in 1859. This book was about natural selection in animals, but he decided not to write about humans. When others put forward the theory that there were eight different races of men that had evolved separately he decided to publish "The Descent of Man" in 1871. He put all the races in one family and undermined the arguments for slavery. Many thousands of copies of the book were published. It was quickly translated into many languages. His ideas were taken up by sociologists, psychologists, biologists, politicians and philosophers. Many people were worried that his ideas were dangerous.

Many advances in science—the development of genetics after Darwin’s death, for example, have greatly increased our thinking about evolution. Even with our new knowledge of genes and DNA, the theory of evolution still persists today much as Darwin first described it, and is universally accepted by scientists.

Darwin's Birthday - Text B

Some ideas in science are difficult to understand, because our intuitions don't like them very much. Some scientists argue that this may be because our brains have not evolved fast enough, and are better designed to work for small groups of hunter/gatherers. This is what most of us were doing four to five thousand years ago. So, for instance, we think we have a good chance of winning the National Lottery, we see significance in coincidences and we read astrology predictions and only remember when they come true.

We have trouble in comprehending very large and very small things. We have trouble comprending the distance to the sun and other stars and galaxies. We have trouble getting our heads around the age of the earth.

Sometimes analogy, metaphor and even poetry can help our understanding. Imagine you are lying in the bath looking at your big toe poking up out of the water. Imagine you are the size of the toe, and you are lying in a smaller bath looking at your big toe. How many times would you need to do this to be the size of a cell? A molecule?

The earth is about 4.5 billion years old, and life on earth is much shorter than that: 4,000 million years. Stretch out your arms. From the beginning of life at your left hand fingertips, there is nothing except bacteria until well beyond your right shoulder. Invertebrates turn up at your right elbow and dinosaurs in the palm of your right hand. Dinosaurs go extinct in the last joint of your big finger. A thin nail clipping represents the time 200,000 years ago since homo sapiens appeared. You would brush off the whole of recorded history (5000 years) with one brush of a nail file.

Richard Dawkins, who works hard to make science comprehensible to non-scientists, has an analogy to help to explain evolution throught natural selection and the mutations of genes. Imagine a mountain five miles high with a vertical precipice on one side and a gentle slope (4 thousand million miles long) on the other. When we look at a squid (500 million years old) it is difficult to imagine how it evolved into a monkey. It is difficult even to comprehend the five million year journey from chimpanzee to human being. The slope at the back of the mountain is so gentle that you would probably have to pedal down it on a bicycle. Animals have evolved up this gentle slope through natural selection and mutation. The changes have not been steady. They go in spurts for a thousand years or so and then nothing much happens for a few thousand more.

Darwin's Birthday - Text C

Before Darwin was born, most people in England thought that species were not linked in a single “family tree.” They were unconnected, unrelated and unchanged since the moment of their creation. Earth itself was thought to be 6,000 years old. There would not have been time for species to change. People were not part of the natural world; they were above and outside it. They had been created to rule over the animals. Many also believed that there were superior races created to rule over inferior races. Before 1800, only a handful of naturalists in England and France had given the idea of evolution serious consideration. And even they couldn’t see how there could have been enough time for evolution to occur.

After Darwin returned from his trip around the world, he began to think about all the different animals and plants he had found. Darwin relied on his notebooks. In them, he jotted private ideas, questions and fragments of conversations related to his thinking on “transmutation”; what we now call “evolution.” The notebooks reveal a great mind homing in on a great idea: plants and animals are not fixed and unchanging. Instead, all species are related through common ancestry, and they change over time. By the late summer of 1842 Darwin felt ready to commit an outline of his theory to paper. The main points were clear: plants and animals with useful variations were likely to live longer. That meant they could leave more offspring, some of which would carry the new variation. Over time, species could change through this process of natural selection.

Darwin did not rush to publish. He lived on inherited wealth and was part of the establishment. The world was full of reform and revolution. The 1848 revolutions in France, the 1867 Reform Bills giving richer working classes the vote, the American Civil War, the Fenian uprisings in Ireland created unease. As a young man he wanted to see the end of slavery, but later he showed racial prejudice against the Irish. He did not always agee with social reform. His books when published cost the same as a working man's weekly wage. When Annie Besant and Charles Bradlaugh were accused of obscenity by publishing a birth contral leaflet, Darwin refused to support their case.

The tension between scientific theory and social change still exists. The current atheist buses are an example. Even nowadays, atheism is viewed by many as immoral and destructive. The Humanist Society is national charity supporting and representing people who seek to live good lives without religious or superstitious beliefs. Their vision is of a world without religious privilege or discrimination, where people are free to live good lives on the basis of reason, experience and shared human values. They want 12th February to become Darwin Day. Our increasing knowledge of evolution puts us in the strong position of being able to counteract the worse effects of natural selection.

Darwin's Birthday - Text D

Natural selection is a simple mechanism that causes populations of living things to change over time. In fact, it is so simple that it can be broken down into five basic steps: V.I.S.T.A.: Variation, Inheritance, Selection, Time and Adaptation. Members of any given species are seldom exactly the same, either inside or outside. Organisms can vary in size, colour, ability to fight off diseases and countless other traits. These traits arise from spontaneous mutation and enable the organism to survive and pass them to future generations.

DNA contains a set of instructions for building bodies. When organisms reproduce, they pass on their DNA. The traits are encoded in the DNA and offspring often inherit the variations of their parents. Tall people, for example, tend to have tall children.

Overwhelming evidence shows us that all species are related — that is, that they are all descended from a common ancestor. One hundred and fifty years ago, Darwin saw evidence of these relationships in striking anatomical similarities between diverse species, both living and extinct. Today, we realize that most such resemblances, in both physical structure and embryonic development, are expressions of shared DNA, the direct outcome of a common ancestry.

Cave-dwelling tetra fish are blind; they have small vestigial eyes that do not work. Then why have them at all? Biologists have long struggled to explain, how natural selection could fully account for such degenerations, and recently they have found another possible answer: genetic mutations that hamper eye development also may increase the number of taste buds. Thus, mutations that happened to give the fish an advantage in tasting and smelling, a huge benefit in a dark environment, might also have caused the degeneration of their eyes. Humans also have vestigial features, evidence of our own evolutionary history. The appendix, for instance, is believed to be a remnant of a larger, plant-digesting structure found in our ancestors.

influenza viruses can evolve very rapidly by frequent mutation. Each year scientists study flu viruses from around the world in order to find out how they have evolved. They then create a vaccine designed to help the body’s immune system ward off the most dangerous of the upcoming year’s mutants. This process has saved countless lives. Any one vaccine can help immune systems fight only some varieties of flu. The viruses newly evolved survive and reproduce . New flu vaccines are needed every year to fight newly evolved or re-emergent varieties of the virus. This shows how mutations in viruses help them to survive, but humans suffer.

Cell Model Samples

 

11th Grade E-cology Overall

 Link for the whole presentation

Science. Lessons 1-2. 10th Grade

 

Hey everyone. At last we have lessons. Hooray!

Materials for this lesson. Enjoy!

Evolution 3. Maybe there is something

 Learning outcomes

Content: to be able to explain microevolution using examples.

Language: to be able to use specific vocabulary to explain microevolution.

1 step one (individual work). This is the key vocabulary for the Evolution topic. Do you know meaning of these words and phrases? Use a dictionary to match the words with their translation.

to stretch

complexity

to paddle

depigmented

to spin

whirlpool

velocity

implication

step two (individual work). Write notes about the video while watching it

2 Step one (individual work). Circle the right words or phrases in italics to create grammatically correct questions.

Questions	Answers
1. What is the scientist’s/scientists hypothesis regarding the diversity of fish in the Lower Congo River?
2. What data was/were collected about the river?
3. What did they discover about how the hydrology of the Lower Congo River is affecting/affected fish species that live there?
4. What did the genetic testing of the fish species show/showed?

Step two (individual work). Match the following correct answers to the questions above. There are two extra answers that cannot be used.

1. Scientists investigated whether the rapids and whirlpools were just on the surface. They wanted to know how deep the river was under those rapids and whirlpools. They also collected data about the velocity of the river and the direction of the river’s flow.
2. They posed a hypothesis, collected data about the hydrology of the river, collected fish from various parts of the river and did genetic testing. They analysed the data and used it to support their hypothesis.
3. Because of the river’s topography, the fish are isolated in their various niches. They are unable, for example, to swim from one side of the river to the other.
4. While fish species on opposite sides of the river appeared to be the same species, they were genetically different.
5. The complexity of the river’s hydrology is key to understanding why there are so many different species of fish there.
6. The river’s features set up natural barriers that isolate species, which then diversify.

3 (individual work). Sort the words and phrases below into two columns.

Words and phrases: fossils, evolution explains the origin of life, biogeography, evolution is just a theory, individuals evolve, organisms evolve on purpose, anatomy and embryology, molecular biology.

Evidence	Misconceptions

4 (team work): Explain why the statement that a monkey is more evolved than a mouse is incorrect.

5 Step one (individual work): Match the words after reading the text below.

Adaptation is a heritable trait or behaviour in an organism that aids in its survival and reproduction in its present environment. Convergency is the process by which groups of organisms independently evolve to similar forms. Divergency is the process by which groups of organisms evolve in different directions from a common point. Natural selection is the reproduction of individuals with favourable genetic traits that survive environmental change because of those traits, leading to changes. Idioadaptation is the modification which involves progressive specialisation that results in more perfect adaptation of an organism to a particular environment. Aromorphosis is the biological change marked by general increase in degree of organisation without sharp specialisation. Degeneration is the worsening of a tissue or an organ in which its function is less or its structure is reduced.

Step two (individual work): Match the given words with the numbers on the picture:

1. Idioadaptation
2. Idioadaptation
3. Idioadaptation
4. Degeneration
5. Aromorphosis
6. Aromorphosis
   
   
   

Cell Organelles. Different lesson

Human Cell Organelles

Learning outcomes

Content: to be able to name 8 eukaryotic cell organelles;

to be able to distinguish different organelles one from another depending on their functions.

Language: to be able to describe concisely and precisely functions of the organelles using the appropriate terminology.

Key Vocabulary: 

to recover - 

to store - 

network - 

to sort - 

to engulf - 

to perplex - 

enzyme - 

spindle -

Exercise 1. (individual work). Fill in the blanks after listening the CELL SONG

Cell Song Scrypt

I went into a cell, to get out of the rain,

And there was the gatekeeper, the (A)___________

I went into a cell, and what did I see?

The (B)___________, it's the energy factory.

I went into a cell, and said "who drives this bus?"

And found myself talking to the boss, the (C)___________

I went into a cell, to recover from a spasm,

And found myself swimming in some clear (D)___________

I went into the nucleus to ask how to get home,

And got genetic info, stored in a (E)___________

I went into a cell, and stretching o' so far,

Was a thin and wavy network, it's called the (F)___________

I went into a cell, trying not to be perplexed,

By the packaging and sorting in the (G)___________

I went into a cell, and said "who makes proteins here?"

And somebody responded "it's the (H)___________, my dear."

I went into a cell, and was feeling pretty fine,

‘Til a (I)___________ engulfed me, and dissolved me in enzymes.

I went into a cell, and was feeling pretty nimble,

‘Til a (J)___________  lassoed me, tying me up in a spindle.

I went into a plant cell to see how trees get so tall,

And all around the outside was a (K)___________

I went into a plant cell, "why's it so green I asked?"

"'Cause I make food from sunlight," said a (L)___________

I went into a plant cell to see how plant cells store food,

When a (M)___________  informed me that he was the storage dude.

So when you go inside a cell, remember what you see,

There's over a trillion cells in both you and me.

Just sing this song if you ever feel confusion,

And remember active transport is the opposite of (N)___________

Exercise 2. Step one (individual work). This is the key vocabulary for the CELL ORGANELLES video. Do you know meaning of these words and phrases? Use a dictionary to match the words with their translation.

strand

to survive

flux

resilience

mosaic

to attract

to repel

studded

carbohydrates

to anchor

Step two (individual work). Answer questions after watching the video (https://goo.gl/qyH7AF).

1. Which are the primary molecules making up plasma membranes in cells?
2. Cell membranes are selectively permeable, meaning they let some things in but keep others out. Why might a cell want to do this? What kind of things would a cell want to keep out?
3. What are some of the cellular functions that a cell membrane participates in?

Exercise 3. Step one (individual work). Complete the following table by writing names of organelles and their functions. Extract only main ideas. Do it using pages 29-35 in your book. Cytoskeleton is not the organelle!

Organelle	Function
Cell Membrane	separates the inner side of a cell from its outer environment protects the cell regulates which materials can pass in or out

Exercise 3. Step two (team work). Discuss your answers with the team.

BRING THE PLASTICINE NEXT LESSON!