Unknown Material Exam One Flashcards
What is the definition of a cell?
Cells are the basic units of life that use DNA to produce proteins.
What are the five characteristics of life?
- Life is made up of cells and is organized
- Life uses energy to do work
- Life maintains an internal balance or homeostasis
- Life reproduces, grows, and develops using DNA
- Life exists in populations that evolve over time
What are some differences between Prokaryotes and Eukaryotes
- Prokaryotes are only single celled, while Eukaryotes can be either single or multiple
- Prokaryotes are much smaller than eukaryotes
- Prokaryotes don’t have membrane bound organelles, while eukaryotes do
- Prokaryotes have no nucleus, while eukaryotes do
- Prokaryotes likely evolved first
What is the most inclusive taxonomic group?
Domain is the most inclusive followed by Kingdom
What is the most exclusive taxonomic group?
Species is the most exclusive followed by genus
What are the four Kingdoms of the Domain Eukarya?
Fungae
Animalia
Plantae
Protist
In what order did the three Domains originate?
First was Archaea and Bacteria
Second was Eukarya
When did the first life form on earth appear?
4 billion years ago
When did photosynthetic organisms first appear?
2.5 billion years ago
What is the age of land plants and animals?
500 million years ago
What changed in the atmosphere to allow organisms to move onto land?
O2 (oxygen gas) in the atmosphere that was generated during photosynthesis allowed for gradual formation of O3 bonds (ozone layer) which protects organisms from ultra violet rays
What is evolution?
Evolution is decent by modification which results in changes in the genetic information on populations
What is artificial selection?
Artificial selection is selective breeding of plants and animals to obtain desired traits.
What are adaptations?
Adaptations are specific traits that help an organism survive long enough to reproduce
What are the five steps of the scientific method?
- Make an observation
- Ask a question
- Form a hypothesis
- Make predictions about your hypothesis
- Design and conduct an experiment to test predictions
What are the three characteristics of a good hypothesis?
- It is a statement
- It is testable
- It is falsifiable
What is the dependent variable?
The dependent variable is the variable subject to change by the independent variable; it is what is being measured.
What is the independent variable?
The independent variable is the variable that is manipulated by the experimenters.
What is the standardized variable?
Standardized variables are variables in the experiment that are held constant, so interactions between the dependent variable and independent variable.
What is the control group?
The control group is the group that is untreated (devoid of independent variable) that is used for comparison.
What are atoms?
Atom are the smallest pieces of an element and they retain the characteristics of that element.
What are elements?
Elements are pure substances made up of the same type of atom, and they cannot be broken down by chemical means.
What are compounds?
Compounds are substances containing molecules of two or more elements
What is a molecule?
Molecules are stable associations of atoms that can be composed of one or more elements.
What is the weight of one proton or one neutron?
The weight is 1 Atomic Mass Unit
What is the atomic number?
The atomic number is the number of protons in an atom, thereby identifying the element.
What is the atomic weight?
The atomic weight is the average mass of all the isotopes of a particular element.
Example is Nitrogen can be N-14 or N-15, and because of this they have different weights.
What is the mass number?
The mass number is the number of protons and neutrons in an atom’s nucleus.
What is the molecular weight?
The molecular weight is the sum of the atomic weights of all the different atoms in a given molecule.
What is an isotope?
An isotope is element that has the same amount of protons but different number of neutrons.
The same element may have a different mass number.
What is an orbital?
An orbital is the area where electrons spend 90% of their time - orbitals can hold a maximum of two electrons.
What is an electron shell?
The electron shell denotes the energy level. In each shell orbitals are filled in a specific sequence.
First shell holds one orbital and therefore two electrons
Second shell holds 4 orbitals and therefore 8 electrons
What is the valence shell?
The valance shell is the outermost electron shell which determines how atoms will behave.
What is an ionic bond?
An ionic bond is when one atom has a much higher affinity for electrons and completely steals the electrons of another.
This results in two ions, one positive and one negative.
An ionic bond is formed as a result of the electrical attractions of positive and negative ions.
What is a covalent bond?
Covalent bond form when two or more atoms share one or more pairs of electrons to fill their valence shells.
They have the highest bond energy.
What does it mean to have a polar covalent bond?
A polar covalent bond is formed when one atoms electronegativity is slightly higher than that of the other.
This results in electrons being more attracted to the more electronegative nucleus.
What does it mean to have a non-polar covalent bond?
A non-polar covalent bond forms when each atom involved has the same electronegativity so that electrons are shared equally.
What is a hydrogen bond?
A hydrogen bond is the attraction between the partial positive and partial negative side of two molecules
Water is a good example.
What are van der Waal’s forces?
Van der Waal’s forces occur when adjacent come close enough to each other that the electron clouds barely touch.
They are the weakest among the bonds.
What is cohesion?
Cohesion is the tendency of water molecules to stick together because of hydrogen bonds.
Eg. Plants take advantage of this to help water move against gravity
What is adhesion?
Adhesion is the attraction of water molecules to molecules of different type.
Eg. Water adhering to the edges of a cup
Why is water more dense as a liquid than as a solid?
Because when water freezes the space between molecules increases and the movement slows down. When water is in liquid state the molecules are more free to move around and they bond easier.
What is the pH scale based on?
It is a logarithmic scale of the H+ concentration in Moles/Liter
What is a buffer?
A buffer is a weak acid and its corresponding base or vice versa that helps maintain a constant pH
If a strong acid (H+) is added to the buffering solution (HCO3-) not all the H+ ions from the acid remain in the solution and is instead used to form the weak acid (H2CO3) which decreases the acidifying effect of the added acid
What is the importance of buffers?
Buffers are important for maintaining pH. Maintaining pH is paramount to cell function because it influences rates of reactions and can change the 3D structure of molecules and their functions.
What is the law of mass action?
The law of mass action states that addition of a reactant on one side of a reversible system (buffers) drives the system in the direction that uses up that compound.
Eg. addition of an acid drives the reaction in one way, and addition of base drives it in the other.
