Biology as a Science

I designed an experiment to see if the amount of water affected the height of the grass. I gave plot A 1 gallon of water per week. I gave plot B 2 gallons of water per After 4 weeks, the grass in plot B was taller than in plot A Can I say for sure that water affects the height of grass? A B

Video Video Is this a good experiment? Is there something they could improve upon? Can you tell for sure if elephants are afraid of mice?

Parts of a Controlled Experiment 1. Testable Question Def: This is a question that can be answered by an experiment Usually only one factor at a time is investigated Good examples: ***Does the amount of fertilizer affect the number of flowers on a plant? Is a person’s heart rate affected by 5 hour energy? Bad example: Why is the sky blue? What happens after you die?

Parts of a Controlled Experiment 2. Hypothesis Def: A hypothesis is an explanation or prediction that can be tested

Good examples: Bad example: Does the amount of fertilizer affect the number of flowers on a plant? ***I think adding fertilizer will cause a plant to produce more flowers Is a person’s heart rate affected by 5 hour energy? I think 5 hour energy does not affect a person’s heart rate Bad example: Why is the sky blue? I think blue is pretty What happens after you die? I think I’ll be reincarnated as a unicorn

Parts of a Controlled Experiment 3. Independent Variable Def: This is what you are changing on purpose to see if it has an effect on whatever you’re testing Does the amount of fertilizer affect the number of flowers on a plant? ***The independent variable would be the amount of fertilizer 4. Dependent Variable Def: This is what you are measuring or observing as a result Does the amount of fertilizer affect the number of flowers on a plant? ***The dependent variable would be the number of flowers that grow on the plant 5. Controls Def: The things that are the same for all experimental groups Ex: ***water, sunlight, temp.

Parts of a Controlled Experiment 6. Procedure Def: Step by step instructions Why is it important to write a good procedure? Your experiment needs to be able to be repeated so that someone else can see if they get the same results that you did 7. Data Information you collect (with units) in a table and/or graph

Good bar graphs Title Depend. Variable Independent Variable Start at 0

Parts of a Controlled Experiment 8. Conclusion Includes: What does your data tell you? Example: Because all of the plants produced the same number of flowers, that must mean that fertilizer does not affect the number of flowers on a plant.

What did we learn yesterday? Diapers hold more plain water than urine Temperature and color don’t make a difference in how much liquid a diaper can hold Saltiness does make a difference in how much liquid a diaper can hold Diapers hold less when there is salt in the water

Today’s Experiment Group 1 & 2 Group 3&4 Group 5&6 0% salt 5% salt 10% salt We want to see if the amount of salt affects the amount of liquid a diaper can hold What is the only thing that should be different group to group? What are we measuring? What needs to be the same group to group? At least 2 people at every lab table

What makes something absorbent? Absorb means to take in or soak up The more something can absorb, the more absorbent it is Cellulose sponges are more absorbent than natural ones How absorbent something is depends on a wide variety of factors

Why are diapers so absorbent? The crotch of the diapers is filled with a special polymer A polymer is a long chain of molecules A molecule is one or more elements put together A molecule of water is 2 hydrogens and 1 oxygen

Why are diapers so absorbent? The crotch of the diaper is filled with a special polymer called sodium polyacrylate When it is dry, it’s all curled up in coils

Why are diapers so absorbent? When it touches water, it uncoils and leaves certain molecules exposed

Why are diapers so absorbent? These molecules are like magnets They attract (absorb) water

Why can’t they absorb as much salt water as distilled water? The salt takes up some of the “spaces” on the polymer so the water has nowhere to “park”

What does this teach us about babies and diapers? Diapers will be more absorbent when the baby’s urine is less concentrated

All living things …..

Have DNA that is copied and passed from parent to offspring

Are made of one or more cells

Grow and develop by adding more cells and/or making the cells look different from each other

Respond to a stimulus in their environment

Evolve over long periods of time (as a group)

Take in materials and energy and builds up or breaks down the materials through metabolism

Obtain homeostasis by keeping their internal environment stable

Reproduce to make offspring, either sexually or asexually

Living or non-living?

Characteristics of Living Things Can you name at least 5 of them? Can you tell me whether something is living or non living and use the characteristics to explain why/why not? How many do you have to have to be considered living?