Science Fundamentals: Key Concepts and Definitions
Science Fundamentals: Key Concepts
Science is a body of knowledge and a process for generating that knowledge.
The Scientific Method
What is science and the scientific method based on? Evidence
An observation is a description, measurement, or record of any object or scientific phenomenon.
After it has been supported by a predictable experimental outcome, a scientific hypothesis still cannot be considered to have been proven true.
In a controlled experiment, which variable is manipulated? Independent variable
Basic Units of Life
What is the smallest and most basic unit of life? Cell
Change in the overall genetic characteristics of a group of organisms from generation to generation is the definition of biological evolution.
Atoms and Molecules
The smallest unit of a chemical element that displays the properties of that element is an atom.
Which of the following components of an atom is NOT found in the nucleus? Electron
If an atom of Nitrogen has 7 protons, 7 electrons, and 8 neutrons, what is its atomic mass? 15 AMU
In which type of bond are one or more pairs of electrons shared between two atoms? Covalent
How many different elements would be needed to construct a molecule of C6H12O6? 3
In the following chemical equation, the burning of rocket fuel, how many molecules of H2O are produced by burning 2 molecules of O2? – 2H2 + O2 → 2H2O + Energy 4
Acids and Bases
For Questions 15-17 consider the following substances and their pH: Tomatoes (4.5), Baking Soda (8.3), Oranges (3.5), Human Blood (7.4)
Which substance is the most basic? Baking Soda
Which substance has the highest hydrogen (H+) ion concentration? Oranges
How many hydrogen (H+) ions are there in tomatoes compared to oranges? Oranges have 10X more H+ ions than tomatoes
Chemical Reactions
When two monosaccharides are combined to form a disaccharide, water is produced. What is this type of reaction called?
Monosaccharide + Monosaccharide → Disaccharide + H2O Dehydration reaction
A saturated fatty acid is saturated with hydrogen because it does not have a double bond.
Cell Structure and Function
A cell is a self-contained structure that can replicate itself and use energy to maintain its complex organization.
The plasma membrane is made of a double layer of lipids called the phospholipid bilayer.
Which component of a eukaryotic cell contains the cell’s DNA? Nucleus
Which organelle creates energy for the cell in the form of ATP using glucose? Mitochondria
Which organelle is only found in plant cells and creates glucose from Water, CO2 and sunlight? Chloroplast
One major function of the plasma membrane is to control what enters and leaves the cell.
The fragrance of bread baking in a kitchen spreads to other rooms by diffusion.
As a biological process, osmosis is a type of passive transport.
The concentration of glucose inside a cell is higher than the concentration outside the cell, yet glucose continues to enter the cell. This is an example of active transport.
Characteristics of Living Organisms
List three characteristics of living organisms:
- Composed of one or more cells
- Reproduce using DNA
- Obtain energy from the environment to support metabolism
- Sense their environment and respond to it
- Maintain a constant internal environment (homeostasis)
- Can evolve as groups
Matter and Elements
Define “Matter” – Anything that has mass and volume
What are the four elements of life? – Carbon, Hydrogen, Oxygen, and Nitrogen (CHON)
Properties of Water
List two of the special properties of water:
- Polar Molecule
- Water is the solvent of life
- Solid water (ice) is less dense than liquid water
- Water moderates temperature swings
Chemical Reactions: Reactants and Products
Identify the reactants and products in the following chemical reaction: 6CO2 + 6H2O → C6H12O6 + 6O2
Reactants: 6CO2 + 6H2O (6 Carbon Dioxide + 6 Water)
Products: C6H12O6 + 6O2 (1 glucose + 6 Molecular Oxygen)
Nucleotide Structure
What are two of the three parts that make up the structure of a Nucleotide? – Sugar, phosphate, nitrogenous base
Cell Components
Write the name of the cell component with its description:
Cytoplasm: Everything within the plasma membrane – the contents of the cell.
Cytosol: The thick fluid that surrounds all of the structures within the cell.
Cell membrane (plasma membrane): The boundary between the cell and the outside environment
Cytoskeleton Functions
List 3 functions of the cytoskeleton:
- A collection of cylinders and filaments
- Organizes the interior of the cell
- Supports movement of vesicles
- Gives the cell shape
- Allows some cells to move
Membrane Transport
Name one type of membrane transport which requires energy, and one type which does not:
Requires energy: Active carrier proteins, endocytosis, exocytosis.
Does not require energy: Simple diffusion, facilitated diffusion, osmosis.
Scientific Fact vs. Scientific Theory
Explain the difference between a Scientific Fact and a Scientific Theory:
A scientific fact is a direct and repeatable observation of the natural world (ex: when you let go of something it falls, grass is green, etc.). A theory is a major explanation of a scientific phenomenon which has been supported through extensive testing by many different scientists.
Macromolecules
Name two of the four classes of macromolecules. What is the monomer and polymer of each? What are the functions of these classes of macromolecules?
Carbohydrates: monomer= monosaccharide (ex: glucose), polymer= polysaccharide (ex: starch), function= energy storage
Proteins: monomer= amino acid, polymer= polypeptide, function= catalyst for chemical reactions, membrane transport, etc
Lipids: monomer= fatty acid, polymer= triglyceride, phospholipid, etc, function= energy storage, chemical signals, etc
Nucleic acids: monomer= nucleotide, polymer= nucleic acid (DNA, RNA, ATP), function= genetic information (DNA/RNA), cellular energy (ATP)
Cell Size and Efficiency
The 4mm cell can exchange the most materials with its environment because it has the largest surface area. The 1mm cube is the most efficient because it has the largest surface area to volume ratio.
Prokaryotic vs. Eukaryotic Cells
What are three differences between prokaryotic and eukaryotic cells?
Prokaryotic:
- Smaller
- Single celled organisms only
- DNA in cytoplasm
- No organelles
Eukaryotic:
- Larger
- Single celled and multicellular organisms
- DNA in nucleus
- Membrane-bound organelles
Passive vs. Active Transport
How is passive transport different from active transport by biological membranes? Provide an example of each.
Passive transport moves materials from areas of high concentration to low concentration (with the concentration gradient), and does not require energy to do so. Ex: Simple diffusion, facilitated diffusion, osmosis.
Active transport moves materials from areas of low concentration to high concentration (against the concentration gradient) and requires energy to do so. Ex: Active carrier transport, endocytosis, exocytosis)
Hypotonic Solutions
If a cell is placed into a hypotonic solution, in which direction will the water flow? What will happen to the cell if it is a plant cell? If it is an animal cell?
If a cell is placed into a hypotonic solution, water will move into the cell. A plant cell will swell and stretch to the cell wall. Plant cells function best in this type of environment. An animal cell will swell and eventually burst, causing the cell to die.