Lab Exam One

Objectives of Lab #1

- Learn about the steps of the scientific method

- Practice using the Scientific Method

- Develop a testable hypothesis

- Make conclusions based on data collected

What is the scientific method?

The scientific method is a systematic technique of acquiring what is known about a subject or disciple

Four steps of the scientific method

1. Observation

2. Hypothesis

3. Experimentation

4. Analysis / Conclusion

Observation

Something that you observe and find out

Hypothesis

A reasonable explanation of an observed phenomena - an educated guess

Experiment

Testing and figuring out if a hypothesis is correct

Analysis / Conclusion

Accept or reject the hypothesis and decide if further research is necessary

Materials from Lab #1

- Termites

- White Paper

- Pencil

- Ink Pens

- Black Sharpie

- Tray

- Paint Brushes

Procedure of Lab #1

1. Observe the termites

2. Make a hypothesis about the termites

3. Experiment your hypothesis

4. Accept or reject the hypothesis you created

Lab #1 Experiment

Part 1

- Get 3 termites together

- Circle them in with red pen

- Time how long it takes them to leave the circle

- Repeat that process 3 times and record data

- Record data and get an average time

Part 2

- Get 3 termites

- Circle them in with a black sharpie

- Time how long it takes them to leave the circle

- Repeat that process 3 times and record data

- Record data and get an average time

What two qualities are necessary to have a good hypothesis?

- Testable and Falsifiable

Explain the difference between a hypothesis & theory?

- Hypothesis - an observation that you're testing to see if it's true

- Theory - An observation that has been studied many times and is "proven" to be true

How many times does an experiment need to be repeated?

At least 3 times, because this way it allows for there to be an outlier. This will still keep the information accurate instead of wrong information.

What is a control?

The group that receives no treatment at all. You need it to compare if the treatment actually did anything at all

What was the purpose of lab #1?

To learn how to think about and use the scientific method and experiment with it.

Objectives of Lab #2

- Learn basic terminology associated with microscope usage

- Learn the structures of a compound light microscope

- Practice correctly using a microscope

- Practice making a wet mount slide

- Compare and observe different types of cells

Contrast

The ability to distinguish parts of an object from each other

Dissecting Microscope

Magnification - 10x & 20x

Light Source - Top, bottom, or both

Image produced - Real Image

Movement of organism - Identical to actual motion

Compound Microscope

Magnification - 40x, 100x, & 430x

Light Source - Bottom

Image Produced - Virtual image (inverted & reversed)

Movement of Organisms - Opposite of actual motion

Magnification

the ratio of an object's image size to its real size

Resolution

describes the ability of a microscope to distinguish detail

base of the microscope

The part that sits on the bench or table

Light source

In the base and has a switch to turn the light on and off

Voltage Control Knob

Regulates light intensity

- Helps regulate light intensity which can help with seeing the specimen

arm of the microscope

Comes off the base and supports the stage, lens system, and control mechanisms

Stage

Flat surface on which the slide is placed and sits

Stage clips

The silver clips that hold the slide into place

Condenser

Helps concentrate the light on the object - has iris diaphragm built into it

Iris Diaphragm

A lever that helps you control how much light enters into the lens

Body tube

Part that comes off the arm and holds the lens

Ocular Lenses

The lens that you look into to see the specimen (there can be one or two depending on the kind of microscope)

Revolving nosepiece

Coming off of the body tube it holds and turns the objectives into viewing position

Objective lenses

these are found on the nosepiece and range from low to high power - 4x, 10x, & 43x

Scanning objective

Has a magnification of 4x - Shortest

Low-power objective

Has a magnification of 10x - Medium / Middle one

High-power objective

Has a magnification of 43x - Longest

Coarse focusing knob

The bigger of the 2 control knobs that moves the stage up and down

Fine focusing knob

The smaller of the 2 control knobs that you use to make an object clearer in focus

Versatile generalists

Species that are able to thrive in many different types of environments

Metabolism

A variety of chemical changes

Homeostasis

Maintaining a dynamic steady-state

Diffusion

Movement of molecules from a higher concentration to a lower concentration

Pseudopodia

Temporary extensions of the protoplasm

Cilia

Short hair-like projections that extend from the surface of some protozoans

Flagella

whiplike tails found in one-celled organisms to aid in movement

Phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Materials used for Lab #2

- Compound light microscope

- Blank slide

- Cover slip

- Letter "e" slide

- Prepared protozoan slides

- Amoeba model

- Protozoan video

Lab #2 Protocol / Experiment

1. Observe the prepared slides of amoeba, paramecium, volvox and sketch each

2. Observe live protist

- Make a wet mount of the mixed culture

- Using the key, identify as many organisms as you can and record their names on the datasheet

- Next to the organism, briefly describe their activities

What are the two lenses on a compound light microscope

- Ocular & objective lens

What objective should be facing down when you begin and end using your microscope?

- Scanning objective

Briefly explain (in your own words) how to properly focus the microscope

...

What is the magnification of the ocular lens?

10x

How is resolution different from magnification in reference to microscopes?

Magnification - The ability to make smaller objects seem larger

Resolution - The ability to distinguish tow objects from each other (Makes the view clearer and let's you be able to tell what you're looking at)

As magnification increases what happens to the field of view?

It decreases

Explain how protista are generalists

They are able to thrive in live in most environments

What is homeostasis?

Maintaining a stable internal environment

What are three ways in which protist move?

Pseudopods, Cilia, Flagella

Objectives of Lab #3

- Practice using the microscope

- Compare and observe different types of cells

- Use stains in order to see cellular features

Prokaryotic Cells

Smaller, simpler cells

Eukaryotic Cells

Larger, more complex cells

Plasma Membrane

Surrounds the outside of the cells and hold the cells intact and surrounds the cytoplasm of the cell

Cytoplasm

The fluid and all of the structures within the cell

Chromosomes in prokaryotes

Circular and are localized to a particular region of the cell called the nucleoid

Nucleoid

Area of a bacterial cell where the circular bacterial chromosome is located. There is NO membrane at the edge of this area that distinguishes it from a nucleus of a eukaryotic cell

Ribosomes

Small structures in which proteins are made

Nucleus

An organelle with double membranes that contain the DNA of eukaryotic cells, often referred to as the control center of the cells

Organelles

A tiny cell structure that carries out a specific function within the cell

Endoplasmic Reticulum

System of membraneous channels used for internal transport inside the cytoplasm. If it has no ribosomes associated with it, then it is referred to the as smooth endoplasmic reticulum. If it has ribosomes attached to it then it is referred to as the rough endoplasmic reticulum.

Vesicle

A bag of membrane used to store or separate materials inside a cell

Golgi complex

A series of flattened pancake type membranous vesicles where materials are secreted and packed. Proteins have sugars added to them here. Lysosomes are made here.

Lysosomes

Vesicles of strongly lytic enzymes that can digest cell contents, the 'suicide bags' of the cell that destroy cells when they are injured or no longer needed

Mitochondria

A cell organelle with a double external membrane used to package energy released by breaking chemical bonds into small units of the energy-storing molecule adenosine triphosphate (ATP). Often referred to as the 'powerhouse' of the cell.

Chloroplast

A cell organelle with a double external membrane used to convert light energy in the process of photosynthesis which makes sugar from carbon dioxide and water releases oxygen as a side product. The organelle contains the green pigment chlorophyll.

Microtubule

One of the components of the cytoskeleton made of the protein tubulin arranged in a small hollow tube

Cytoskeleton

Supports structures inside of a cell that keeps organelles in position. Made of microtubules, microfilaments, intermediate filaments

Cell Wall

A support structure made of cellulose found outside the plasma membrane of plant cells

Central Vacuole

A large vesicle filled with water and salts found in the center of most plant cells

Materials used for Lab #3

- Compound light microscope

- Blank slide

- Cover slide

- Elodea

- Toothpick

- Saline solution

- Water with dropper

- Animal cell model

- Plant cell model

- Lens paper

- Dropper bottle with saline solution

- Dropper bottle with water

- Onion

- Potato

- Iodine

- Neutral red

- Methylene blue

Onion procedure on Lab #3

- Prepare a slide with a drop of water and have a coverslip ready at hand

- Cut or peel off a very thin piece of the onion

- Put the onion on the slide in the water and cover it with a slip

- Sketch the onion with no stain

- After sketching it with no stain get a drop or two of neutral red and stain the onion

- Sketch the onion with the stain

What did we use to stain the onion?

Neutral Red

Potato procedure for Lab #3

- Prepare a slide with a drop of water and have a coverslip ready at hand

- Cut off a very small slice of potato

- Put the potato on the slide in the water and cover it with a slip

- Sketch the potato with no stain

- After sketching it with no stain get a drop or two of iodine and stain the potato

- Sketch the potato with the stain

What did we use to dye the potato?

Iodine

Fresh Elodea procedure from Lab #3

- Prepare a slide with a drop of water and have a coverslip ready at hand

- Take a piece of fresh elodea and put it on the slide, and cover it with the coverslip

- Observe what you see and sketch it

- (this one had the chloroplast that you could see)

What could you see from the fresh elodea in Lab #3?

Chloroplast

Stained cheek cells procedure from Lab #3

- Get the prepared slide from Mrs. Bostrom

- Bring it back and view it on the microscope

- Sketch what you see

What is the basic unit of life?

Cells

What type of cells lack chloroplast and cell walls?

Animal cells

What does it mean to have an eccentric nucleus?

That the nucleus is often off-center

What is cytokinesis?

the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells

Which type of cell divides by forming a cleavage furrow?

Animal Cells

Which type of cells has a large water vacuole in the center?

Plant cells

What is the purpose of staining cells?

increase contrast

What is the appearance of air bubbles as seen under the microscope?

Perfect circles

What is the process of cyclosis in Elodea cells?

Fluid cytoplasm in the cells are moved around in the currents and carry the nutrients, proteins, & organelles through the cell

Plants

- Have cell wall

- Have chloroplast (autotroph)

- Nucleus is often off-center (eccentric)

- Often large water-filled vacuoles

- Cytokinesis occurs with the formation of cell plate

Animals

- Lack cell wall

- Lack chloroplast (heterotroph)

- Nucleus often centered (concentric)

- Small scattered vacuoles

- Cytokinesis occurs with the formation of a cleavage furrow

Cyclosis

The process by which the fluid cytoplasm inside a given cell is moved around in currents, carrying nutrients, proteins, and organelles through the cell

Objectives of Lab #4

- Measure the amount of energy in different food sources

- Develop an experiment to compare calories in two different food sources

Energy

The ability to do work