Investigation 3 Microscopic Life

Objectives: I will describe, and compare and contrast single-celled and multi-cellular organisms. I will explain the difference between when a cell is living and when a cell is an organism.

What do paramecia, euglena, and amoeba have in common?

Discuss with your shoulder partner. What do you see when you look at the Elodea? When you focus up and down through the leaf sample, what did you notice? Are the rectangles flat, like designs drawn on the surface of the leaf, or are they three-dimensional? Are the boxes empty? How many layers of these “bricks” do you see?

Elodea Cells-Label your 400x picture. Then copy the info Elodea Cells-Label your 400x picture. Then copy the info. at the bottom on a new page. Label it Inv. 3-Microscopic Life. Copy-The boxes or bricks that you see in the Elodea are cells. Cells are units From which the Elodea leaf are made. They are too small to see with the naked eye.

Cytoplasmic Streaming Did you notice anything else moving inside the cells? What did it look like? Cytoplasmic Streaming Video Cells are filled with a fluid called cytoplasm. Cytoplasm can sometimes Be seen moving inside the cells of living things.

Cell Wall: Protects the cell

Cytoplasm: Fluid inside a cell

Chloroplast: Structure that gives plants their green color

Did you know?? The cell is the basic unit of life. Life happens in cells.

Stop Here!

Paramecia The little “bug” you saw dashing around in the slide with the Elodea is a paramecium (plural, paramecia). Today we will have an opportunity to look at them more closely.

Preparing a Paramecium Wet Mount Video Paramecium Video Conduct the Paramecia Lab

Observations What movements did you observe? What did you see on the outside of the paramecium? How big was it at 100X? At 400X? Are they living or nonliving? What is your evidence? Could you see if it was doing all of the things you have listed in your definition of a living organism? What might we do to see some of these acivities?

Stop!

Similarities and Differences Take a few minutes to construct a Double Bubble Map and fill in what you know. Elodea Leaf Paramecium

Paramecia are single-celled organisms-Copy all notes. Paramecia are not made of cells, because each paramecium itself is a single cell. Just like the individual green “bricks” in the Elodea are individual cells, each paramecia is an individual cell. The Elodea plant is an organism. Elodea is a multicellular organism Because it is made up of many cells. The Paramecium is an organism. Paramecia are single-celled organisms because they are one cell.

Share Ideas Remember, our definition of an organism is any living thing- a plant, an animal, or any other life-form that is free-living (can live independently). An organism is always free-living, that is it is not a part of a larger living organism. Can a single living cell be a living organism? Can a single living cell not be a living organism? Is an Elodea leaf cell a living organism? Is a paramecium cell a living organism?

Important Point in Our Investigation of Life We have been developing our definition of “living” by describing the characteristics of life-the functions (what they do) and requirements (what they need) that are common to all things we consider living.

These things are also characteristics of cells These things are also characteristics of cells. *Some cells live alone and some live with millions of others. Both are alive, and both do all of the things that we recognize as living. HOWEVER….Not all cells are organisms, because not all cells are able to live independently (on their own).

Protist *Paramecia are single-celled organisms in the kingdom of life called Protista (pro-TEES-ta). In Greek, proto means early, and protist means the very first. So single-celled organisms like paramecia are members of a kingdom of life that includes organisms that are similar to some of the very first life-forms on Earth. *Protists are NOT “animals”! Animals are always multicellular. Protista is a separate kingdom whose members are mostly single-celled.

Examples: A kangaroo rat is an multi-cellular organism. It is composed of millions of different cells that are NOT the same. They have bone cells, muscle cells, skin cells, blood cells, brain cells, kidney cells, etc. If an individual rat cell were removed, would it survive? Is it an organism? Its survival depends on its unique environment as part of a complex organism.

Plants Tree limbs are living when they are attached to a tree. But the branch will not survive independently without the rest of the tree. So a tree limb is living, but not an organism. Are amoeba and flagellates organisms?

Characteristics of Life So, should we add anything to our Characteristics of Life?

Cilia: Used for movement The bubbles were water-expelling vesicles. Organelle: Paramecia’s guts

___Use Energy from Food What can a Single- cell Organisms do? What can a Multi-cell organisms do? _____Grow __Eliminate Waste ____Reproduce ___Need Water __Exchange Gases ___Use Energy from Food

Mini pond Hunt

Volvox

Flagellates

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