Biology Test 1 Study Set

Science

Aims to understand the natural world through the natural world through observation and reasoning. Science is both descriptive and hypothesis-driven. Science is a constant state of change as new data, methods and ideas arise.

Descriptive Science

Classifying and describing life in a given habitat.

Which type of science is associated with the "Scientific Method"?

Hypothesis-Driven science

Deductive reasoning

Uses general principles to make specific predictions

Inductive Reasoning

Uses specific observations to develop general conclusions

Example of Deductive Reasoning:

Natural selection used to explain changes in populations

Examples of Inductive Reasoning:

Fossils show that life has change on Earth over time.

Steps of the Scientific Methods

Observation--\> question --\> hypothesis --\> prediction --\> conclusion

Hypothesis

Possible explanation for observation, makes a prediction that can be tested, retained until disproven, always subject to further rejection

Experiment

Tests hypothesis must be carefully designed to only test one variable at a time(independent variable), and consists of both a control and test experiment.

Can a hypothesis be proven?

No, it can be supported or disproven

What is the purpose of a control experiment?

To allow comparison to an experimental group

What is the purpose of a test experiment?

To determine if the independent variable is changed.

What is the difference between an independent variable and a dependent variable?

The dependent variable will vary depending on the independent variable.

What is pseudoscience?

It describes the claims, beliefs, or practices that purport to be science BUT does not use accepted scientific methods to draw conclusions and the claims or beliefs often can't be tested.

What is the difference between a hypothesis and a scientific theory?

In scientific reasoning, a hypothesis is constructed before any applicable research has been done. A theory, on the other hand, is supported by evidence

Reductionism

Breaks a complex process down to its individual component parts and has advanced understanding in many areas.

Systems Bio

Focuses on how components work together, relies heavily on modeling of biological processes, may allow prediction of emergent properties.

emergent properties

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.

What is the ultimate source of energy for life on Earth?

The sun

Living organisms are the most \________ \_________ on Earth.

complex chemical

Characteristics of living systems:

1. consist of cells

2. store and process information

3. transform energy

4. grow and reproduce

5. adapt and evolve

Genotype

genetic makeup of an organism

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

What determines an organisms phenotype?

The proteins produced as the result of gene expression, which is influenced by intra- and extracellular environmental factors.

What can we conclude about the relationship between all living organisms today?

All organisms are related to each other and descend from a common ancestor.

What features may be used to classify organisms?

appearance, reproduction, mobility, and functionality

Why is it important to classify organisms?

it facilitates the study of life, facilitates communication between biologists, has been heavily influenced by phenotypic comparisons

What are the three domains of life?

Bacteria, Archaea, Eukarya

Which two domains are most closely related to each other?

Archaea and Eukarya

What are the tenants of Cell Theory?

1. All organisms are composed of cells

2. Cells are the smallest living things

3. Cells arise only from pre-existing cells

How are current cells and organisms connected to the first living cell?

All cells today represent a continuous line of descent from the 1st living cell

Emergent properties

result from the interaction of components and cannot be deduced by looking at the parts themselves and "life" is an emergent property.

Element

pure substance that consists entirely of one type of atom

Atomic number

number of protons in an atom that defines type of element

Mass

amount of substance

Weight

Force exerted by gravity on a substance

Atomic mass

sum of masses of protons and neutrons in an atom

Isoptope

Atoms of the same element that have different number of neutrons

The Octet Rule

Atoms tend to completely fill outer energy levels

Which element is the basis for most biological molecules and what term is applied to such molecules?

carbon, organic

What determines an atom's chemical behavior?

Electrons

What are valence electrons?

Electrons in the outermost level

What is the difference between a cation and an anion?

Cations have more protons than electrons therefore positive charge and anions have more electrons than protons and therefore they have a negative charge.

How are covalent bonds formed?

sharing of electrons

What is the significance of valence electrons for the formation of covalent bonds?

atoms can fill up their outer electron shell and gain stability.

What is the difference between polar covalent bonds and nonpolar covalent bonds?

Polar covalent bonds result when electrons are unequally shared between atoms, while nonpolar covalent bonds result when electrons are more equally shared between atoms.

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons

Electronegativity of hydrogen

21

Electronegativity of carbon

25

Electronegativity of nitrogen

30

Electronegativity of oxygen

35

Ionic bonds

Formed when one or more electrons are transferred from one atom to another

Covalent bonds

Bonds created by sharing electrons with other atoms.

True or False: The atoms that form water are connected by H bonds but the interactions between different water molecules represent covalent bonds.

False

True or False: Unlike polar molecules, nonpolar molecules cannot form hydrogen bonds with water and therefore are not soluble in water.

True

Cohesion

Attraction between molecules of the same substance

Adhesion

An attraction between molecules of different substances

What chemical ability of water accounts for essentially all these properties?

Solid water is less dense than liquid water

Solute

A substance that is dissolved in a solution.

Solvent

the substance in which the solute dissolves

Hydration shell

Prevent the solute from interacting with other solute molecules

Amphipathic molecules

have both hydrophilic and hydrophobic properties and associate into highly organized structures of water

Ionization

any process that results in the formation of an ion

What is produced by the ionization of water?

a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻).

Ph Scale

(Partial Hydrogen) measures hydrogen ion concentration

What is the relationship between pH value and proton concentration?

"Low pH" corresponds to a very high concentration of protons. "High pH" corresponds to a very low concentration of protons

Acid

A substance that increases the hydrogen ion concentration of a solution.

Base

A substance that decreases the hydrogen ion concentration in a solution.

Buffer

compound that prevents sharp, sudden changes in pH

What element forms the framework for most biological molecules?

Carbon

What is a macromolecule?

a molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer.

Carbohydrates

Broken down to glucose to provide energy.(energy storage and structural support)

Proteins

Nutrients the body uses to build and maintain its cells and tissues(enzymes and structural support)

Nucleic acids

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus(storage and depression of genetic information)

Lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.(Energy storage, membrane structure and cell communication)

Which macromolecules are assembled from subunits?

Proteins-amino acid subunits

What is the chemical composition of a monosaccharide and where is the energy stored in a monosacchardie?

Simple sugar, contains C, H, O in a 1: 2: 1 ratio, bonds store energy, and typically has 3-6 carbons.

Isomers

molecules that have the same molecular formula but different structures

Dehydration reaction

removal of a water molecule each time a subunits added to the end of a growing polymer

What are the three components of a nucleotide?

nitrogenous base, a pentose sugar, and phosphate.

What determines which end of the DNA strand is 5'and which is 3'?

"5 prime end" has a free hydroxyl (or phosphate) on a 5' carbon and the "3 prime end" has a free hydroxyl (or phosphate) on a 3' carbon

What are phosphodiester bonds?

Bonds that are responsible for the polymerization of nucleic acids by linking sugars and phosphates of adjacent nucleotides

Which bases are purines and which are pyrimidines?

Purines: Adenine and Guanine

Pyrimidines: Thymine and Cytosine

What are the distinguishing features of DNA vs RNA?

DNA the sugar is two prime deoxyribose and in RNA the sugar is ribose which contains a hydroxyl group

protein primary structure

linear sequence of amino acids

protein secondary structure

The folding of the primary structure of a protein. This folding is caused principally by hydrogen bonds. The result is beta-sheets, alpha-helices, and random coils.

protein tertiary structure

Generated by interactions between amino acids far apart in sequence.

protein quaternary structure

Interaction between two or more polypeptides. Generated by same type of bonds that produce tertiary structure.

What are alpha-helices and beta sheets?

Alpha-helices are like a spiral wave while the beta-sheet is like a small wave.

What does it mean when a protein is denatured?

It loses its structure and function (it unfolds)

What may cause protein denaturation?

chemical action, heat or agitation

Organelles

Discrete internal macromolecular structures specialized for a particular function.