Science as Process

What goes into Good Science?

Start with a question. Do background research. Develop your hypothesis. Determine what the variables are and how you will measure them quantitatively (with numbers). Identify your control (if applicable). Write your procedure. Prepare data tables. Collect data (perform experimentation). Graph data. Analyze and discuss data. Was your hypothesis true?

Variable – values in an experiment that can change Control – group in an experiment where all variables are kept the same with no changes; typically this is the “normal” condition Controls are used so that you can compare normal and experimental groups

Independent variable – the variable that scientists purposefully change; the variable that is being “tested” or “questioned” Dependent variable – the responding variable; the variable that changes as a result of the independent variable The changes in the dependent variable are caused by the independent variable.

Question: Which color of light makes plants grow the highest in length: red, green, or white? What is the independent variable? What is the dependent variable? Use the following sentence to figure out the variables. The ____________ changes the _____________. Independent variable Dependent variable

They….. have multiple trials (typically requires finding averages). have quantitative data (numerical). test only one independent variable and one dependent variable. should be able to be repeated by other scientists.

Independent variable goes in the X-axis. (remember Index) Dependent variable goes in the Y-axis. Label both axes and include units. Give the graph a descriptive title. Use a key or legend if needed. Scale must include all data points. The scale on an axis must have equal intervals.

Label the columns and rows. Include units. Give the table a descriptive title.

Hypothesis - a proposed, scientifically testable explanation for an observed event. Example: Red light will make plants grow 50% taller than green light and 25% taller than white light. Inference - a conclusion based on observations, knowledge, and scientifically tested hypotheses Example: After collecting data it was found that white light caused plants to grow taller than red or green lights.

Law or principle- an explanation of scientific events that can be explained using mathematics and is observed to be the same throughout the universe Example: First Law of Thermodynamics - energy cannot be created nor destroyed… Example: Principle of segregation – describes how genes separate in forming sperm and eggs Theory - a widely tested and accepted explanation of science ideas based on observation, measurement, and logic Example: Cell theory – all life is made up of cells…

Cells and the Organization of Life

All living things: 1. Are made of one or more cells 2. Reproduce 3. Are based on a universal genetic code 4. Grow and develop

5. Take in materials and energy and get rid of waste 6. Respond to their environment 7. Maintain a constant internal environment. 8. Change over time (evolve).

Cell Theory 1. All living things are made up of cells. 2. Cells are the basic units of both structure and function in living things. 3. New cells are made only from existing cells.

All cells have: Plasma membrane (cell membrane) – thin layer that surrounds cells Cytoplasm – gel like material inside cells (the “juice”) Genetic material (DNA and/or RNA) Ribosome – organelle where proteins are made

Some cells have: Cell wall – a more rigid structure on the outside of some plasma membranes Nucleus – a membrane-bound organelle that contains genetic material (brain of the cell) Mitochondria – a membrane-bound organelle where energy is released (respiration)

Chloroplasts – a membrane-bound organelle (a type of plastid) where glucose is made (photosythesis) Rough endoplasmic reticulum – a membrane-bound organelle that transports proteins Golgi apparatus – a membrane- bound organelle that packages and processes proteins Vacuole – a membrane-bound organelle that stores water and nutrients

All cells fall into two categories of cells: 1. Prokaryotes Includes bacteria and Archaea 2. Eukaryotes Includes animals, plants, fungi, and protists (like amoebas and paramecium)

Very basic structure Unicellular No membrane-bound organelles (“little organs” in cells) No nucleus, mitochondria, or chloroplasts Do Have DNA, ribosomes, cytoplasm, plasma membrane, and cell wall First living things on the planet. Fossil evidence shows that bacteria have been on the earth for over 3.5 billion years

Microbial Family Tree

Plasma membrane Cytoplasm Cytoskeleton Ribosomes Organelles that are membrane bound (ex. mitochondria and chloroplasts) Fossil evidence shows that eukaryotic cells have been on the earth for approximately 1 billion years. Can be unicellular or multicellular

We need to look at ecosystem to biosphere more closely.

Cell – basic unit of structure and function (ex. nerve) Tissue – groups of cells that work together to perform a common function (ex. spinal cord or muscle cell) Organ – groups of tissues that work together to perform a common function (ex. brain or heart) Organ systems – groups of organs that work together to perform a common function (ex. cardiovascular or nervous system) Body – groups of organ systems

What LOBO would each of these fall into?