Biology Exam 1

Scientific method

Observation → Question → Hypothesis → Prediction → Experiment → Analyze results → Report results or revise hypothesis

Observation

The process of noticing or identifying something that leads to a scientific question.

Hypothesis

A suggested explanation for an event that is testable and falsifiable.

Prediction

A specific expected result based on a hypothesis.

Experiment

A test that manipulates a factor to see how it affects an outcome.

Variable

Any part of an experiment that can vary or change.

Control group

The group that has every feature of the experimental group except the experimental manipulation.

Independent variable

The variable the experimenter manipulates or changes.

Dependent variable

The variable being tested and measured; it depends on the independent variable.

Falsifiable

A hypothesis is falsifiable if experimental results can disprove it.

Scientific inquiry

An ongoing cycle involving exploration, testing ideas, community analysis and feedback, and benefits/outcomes.

Peer review

The process where scientists receive feedback from other scientists on their work.

Replication

Repeating scientific research to see whether similar results can be obtained.

Basic science

Science that seeks to expand knowledge regardless of short-term application.

Applied science

Science that uses knowledge to solve real-world problems.

Order

A property of life in which living things are highly organized, structured, and made of cells.

Response to environment

The ability of living organisms to sense and respond to their surroundings.

Reproduction

The ability of living organisms to produce offspring.

Adaptation

A heritable trait that increases survival and reproduction through natural selection.

Growth and development

The increase in size and/or changes that occur as an organism develops.

Homeostasis

The maintenance of a relatively stable internal environment.

Energy processing

The ability of living organisms to obtain and use energy.

Evolution

Change in allele frequencies in a population over time.

Phylogenetic tree

A diagram that illustrates evolutionary relationships between organisms.

Three domains of life

Bacteria, Archaea, and Eukarya.

Prokaryotes

Organisms such as Bacteria and Archaea that lack intracellular organelles.

Levels of organization

Organelles → cells → tissues → organs/organ systems → organisms → populations/communities → ecosystems → biosphere.

Species

An evolutionarily independent population or group of populations.

Biological species concept

Defines species based on reproductive isolation; members do not interbreed or fail to produce viable, fertile offspring.

Morphospecies concept

Defines species based on differences in size, shape, or other morphological features.

Phylogenetic species concept

Defines species based on evolutionary history.

Speciation

A splitting event that creates two or more distinct species from an ancestral species.

Natural selection

The process in which heritable variation leads to differences in reproductive success.

Darwin and Wallace

Scientists who independently proposed natural selection as a mechanism of evolution.

Darwin's first postulate

Individuals in a population vary in their traits.

Darwin's second postulate

Some differences between individuals are heritable and passed to offspring.

Darwin's third postulate

More offspring are produced than can survive.

Darwin's fourth postulate

Individuals with certain heritable traits are more likely to survive and reproduce.

Evolution

A change in the allele frequencies of a population over time.

Biological fitness

The ability of an individual to produce surviving, fertile offspring relative to other individuals in the population.

Adaptation

A heritable trait that increases an individual's fitness in a particular environment.

Selection

Differential reproduction resulting from heritable variation.

Galápagos finches

Finches with different beak forms associated with different types of food use.

Fossil

A trace of an organism that lived in the past.

Fossil record

The many fossils found and described in scientific literature.

Radiometric dating

A method that uses radioactive decay to assign absolute ages to materials.

Earth's age

About 4.6 billion years old according to the study guide.

Extinct species

Species that no longer exist.

Transitional feature

A fossil trait that is intermediate between ancestral and derived species.

Vestigial trait

A reduced or incompletely developed structure with no or reduced function that resembles a functioning structure in a related species.

Natural selection requirements

Heritable variation and differential reproductive success.

Population-level evolution

Evolution occurs when allele frequencies change in a population across generations, not because an individual needs or chooses a trait.

DNA

Deoxyribonucleic acid; stores genetic information in its base sequence.

DNA bases

Adenine (A), guanine (G), cytosine (C), and thymine (T).

DNA nucleotide

A phosphate group + 5-carbon sugar + nitrogenous base.

Purines

Adenine and guanine.

Pyrimidines

Cytosine and thymine.

DNA base pairing

Guanine pairs with cytosine; adenine pairs with thymine.

Antiparallel

DNA's two strands run in opposite directions.

Gene

A stretch of DNA that codes for something.

Allele

A sequence variant of a gene.

Genotype

The allele combination or genetic makeup of an organism.

Phenotype

The characteristics or observable traits of an organism.

Gene-to-protein sequence

DNA → transcription → mRNA → translation → protein → phenotype.

Transcription

The process that produces mRNA from DNA.

Translation

The process in which a ribosome uses mRNA to build a polypeptide/protein.

mRNA

Messenger RNA that carries information from DNA to the ribosome.

tRNA

RNA that brings amino acids to the ribosome during translation.

Codon

A sequence on mRNA that pairs with an anticodon during translation.

Anticodon

A sequence on tRNA that pairs with a codon.

Environmental effect

A change caused by environmental conditions that does not necessarily involve a change in allele frequencies.

Evolution vs environmental change

Evolution involves a change in allele frequencies across generations; environmental effects can change traits without changing allele frequencies.

Chromosome

A strand of DNA packaged with proteins called histones.

Sister chromatids

Two identical copies of one replicated chromosome held together at the centromere.

Centromere

The region where sister chromatids are held together.

Cell cycle

Interphase (G1 + S + G2) followed by M phase.

G1 phase

The first gap phase; chromosomes are unreplicated.

S phase

The DNA synthesis phase; DNA replicates.

G2 phase

The second gap phase; the cell prepares for division.

M phase

The phase containing mitosis and cytokinesis.

Mitosis

Cell division that produces two genetically identical daughter cells in the study guide's model.

Prophase

Chromosomes condense and the spindle apparatus begins to form.

Prometaphase

The nuclear envelope breaks down and microtubules contact chromosomes at kinetochores.

Metaphase

Chromosomes line up at the middle/equator of the cell.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

The nuclear envelope reforms and chromosomes de-condense.

Cytokinesis

The division of the cytoplasm that produces separate daughter cells.

Mitosis outcome

Two genetically identical daughter cells.

Mitosis chromosome number

Mitosis does not reduce chromosome number in the study guide's model.

Ploidy

The number of complete sets of chromosomes in a cell.

Diploid (2N)

A cell with two chromosome sets, one from each parent.

Haploid (N)

A cell with one chromosome set.

Homologous chromosomes

The two copies of a chromosome inherited from the two parents.

Sister chromatids

Two identical copies made when one chromosome replicates.

Meiosis I

The reductional division in which homologous chromosomes separate and chromosome number is reduced.

Meiosis II

The division in which sister chromatids separate.

Prophase I

Chromosomes condense, homologous chromosomes pair, and crossing-over occurs.

Crossing-over

The exchange of genetic material between homologous chromosomes during Prophase I.

Metaphase I

Homologous chromosome pairs line up at the equator.

Anaphase I

Homologous chromosomes separate and move to opposite poles while sister chromatids remain together.