Exam 1 Study Guide Flashcards
What is Biology?
Biology is the scientific study of life
List and describe the characteristics of life.
1) Presence of cells
2) Order: biological hierarchy
3) Response to the physical environment
4) Energy processing
5) Evolution
Describe how energy flows through an ecosystem. Where does the energy come from, how is it processed, and how in what form does it leave?
Energy flows through an ecosystem, usually entering as light and exiting as heat
- The “light” mentioned here is sunlight
- When you move, some of that energy is released as heat, thats how we regulate our body temperature
What characteristics do eukaryotic and prokaryotic cells have in common? How do they differ?
All cells have a plasma membrane, ribosomes, cytoplasm, and DNA. The primary distinction between these two types of organisms is that eukaryotic cells have a membrane-bound nucleus and prokaryotic cells do not.
What are the taxonomic groups that we use to classify living organisms? Which group is more general? Which is least general?
(most general to more specific): Domain, Kingdom, Phylum, Class, Order, Family, Genus, species
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How is taxonomy used in the study of evolution?
It helps identify biological specimens
State the three domains of life.
1) Bacteria
2) Archaea
3) Eukarya
Describe the role that DNA plays in the growth, development, and reproduction.
DNA contains the instructions needed for an organism to develop, survive and reproduce.
Compare positive and negative feedback.
Negative feedback: as more of a product accumulates, the process that creates it slows, and less of the product is produced
Positive feedback: as more of a product accumulates, the process that creates it speeds up and more of the product is produced
State and describe the steps of the scientific method.
The scientific process includes:
- Making observations
- Forming logical hypotheses
- Testing hypotheses through experimentation
What does it mean that a hypothesis must be testable and falsifiable?
A hypothesis is called falsifiable if it is possible to conceive of an experimental observation that disproves the idea in question.
Describe what Darwin meant by “descent with modification” and “natural selection.”
Descent with modification: Organisms are modified descendants of common ancestors
Natural selection:
- Individuals in a population vary in their traits, many of which are heritable
- More offspring are produced than survive, and competition is inevitable
- Species generally suit their environment
Can traits acquired over the course of an organism’s life be passed on to its offspring?
Acquired traits are not coded in the DNA of an individual and therefore most scientists believe they cannot be passed down to offspring during reproduction.
How are evolutionary trees used to describe the evolutionary history of organisms?
The branches themselves connect up in a way that represents the evolutionary history of the species—that is, how we think they evolved from a common ancestor through a series of divergence (splitting-in-two) events.
Nutrient cycling
a cyclic process that encompasses the movement of nutrients from the physical environment to living organisms and back to the environment.
chromosome
A carrier of genetic information that is found inside the nucleus of a cell
gene
the basic physical and functional unit of heredity.
theory
- Broader and more general in scope than a hypothesis
- Supported by a large body of evidence in comparison to a hypothesis and can lead to new testable hypotheses
hypothesis
A hypothesis is a tentative answer to a well-framed question
- A scientific hypothesis leads to predictions that can be tested by observation or experimentation
What is matter?
anything that takes up space and has mass
What is an atom?
the smallest unit of matter that still has chemical characteristics
What is an element?
a pure substance that cannot be broken down to other substances by chemical reactions
Which four elements make up 96% of human body mass?
carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)
What is a compound?
A material made up of two or more parts or elements
What is a molecule?
a group of atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance.
Describe these subatomic particles of the atom: proton; neutron, electron.
Proton: a positively charged particle that resides in the nucleus of an atom
Neutron: an uncharged elementary particle that has a mass nearly equal to that of the proton
Electron: a stable atomic particle that has a negative charge
If a normal atom of an element has 6 protons: a) which element is it? b) how many electrons will it usually have? c) how many neutrons will it usually have?
a) carbon
b) 6 electrons
c) 6 electrons
What is a Dalton?
unit used to express molecular mass
- Neutron mass and proton mass are measured in daltons
How are an element’s atomic number and atomic mass determined?
An element’s atomic number = # of protons in its nucleus
An element’s mass number = protons + neutrons in the nucleus
If Cl has 17 electrons, 17 protons, and 18 neutrons, what is its mass number?
mass number = 35
What are valence electrons? How do they affect the bonding potential of an element?
Valence electrons are those in the outermost shell, or valence shell.
Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms
Calculate the valence of the following elements: C, O, H, N.
carbon: 4
oxygen: 6
hydrogen: 1
nitrogen: 5
What are isotopes? Describe how scientists can use radioactive isotopes.
Isotopes are two atoms of an element that differ in the number of neutrons.
Radioactive isotopes decay spontaneously, giving off particles and energy; have applications in biological research
- Dating fossils
- Diagnosing medical disorders
Describe covalent bonds. What do you call compounds that form from covalent bonds?
A covalent bond is the sharing of a pair of valence electrons by two atoms
Molecular compounds form from covalent bonds
What is electronegativity?
a measure of an atom’s ability to attract shared electrons to itself.
Are the shared electrons distributed evenly between the atoms in a covalent bond?
In pure covalent bonds, the electrons are shared equally.
What is a polar versus nonpolar covalent bond? How do the properties of polar and nonpolar molecules differ?
nonpolar: electrons are shared equally. polar: electron sharing is unequal.
Polar molecules have positive and negative ends which nonpolar do not.
What is an ionic compound? How do ionic bonds form?
An ionic bond is formed by the complete transfer of some electrons from one atom to another.
What is an ion? What do you call an ion with a positive charge? What do you call an ion with a negative charge?
A charged atom (or molecule) is called an ion.
Negative ion: anion; positive ion: cation
What is a hydrogen bond? How does it form? Is it weaker or stronger than a covalent bond?
A hydrogen bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.
It is weaker than a covalent bond
What is a chemical reaction? Describe a reversible reaction? What happens when the relative amounts of product and reactants stabilize?
Chemical reactions make or break chemical bonds
- Chemical reactions start with materials called reactants and produce materials called products
All chemical reactions are theoretically reversible
The products of the forward reaction become the reactants for the reverse reaction
trace elements
Trace elements are those required by an organism in minute quantities
orbital
Electron orbitals are three-dimensional representations of the space in which an electron is likely to be found.
single bond
single bond: shares one pair of valence electrons
double bond
Double bond: shares two pairs of valence electrons
Describe the four emergent properties of water that contribute to Earth’s fitness for life.
1) Cohesive behavior
- water sticks to itself
2) ability to moderate temperature
- keeps things from becoming too cold or too hot
3) expansion upon freezing
4) versatility as a solvent
- universal solvent of life
What properties of water do plants use to move water against gravity?
adhesion and cohesion
What type of energy is temperature used to measure? How do fluctuations of temperature affect the movement of molecules?
heat energy
Temperature change in water will first break hydrogen bonds before heat is absorbed by the water molecules, leading to evaporation