1: Biology and the Tree of Life

Question 1

organism

Answer 1

Any living entity that contains one or more cells.

Question 2

theory

Answer 2

An explanation for a broad class of phenomena that is supported by a wide body of evidence. A theory serves as a framework for the development of new hypotheses.

Question 3

cell

Answer 3

A highly organized compartment bounded by a thin, flexible structure (plasma membrane) and containing concentrated chemicals in an aqueous (watery) solution. The basic structural and functional unit of all organisms.

Question 4

cell theory

Answer 4

The theory that all organisms are made of cells and that all cells come from preexisting cells.

Question 5

hypothesis

Answer 5

A testable statement that explains a phenomenon or a set of observations.

Question 6

prediction

Answer 6

A measurable or observable result of an experiment based on a particular hypothesis. A correct prediction provides support for the hypothesis being tested.

Question 7

evolution

Answer 7

(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection and other processes. (2) Any change in the genetic characteristics of a population over time, especially, a change in allele frequencies.

Question 8

natural selection

Answer 8

The process by which individuals with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution.

Question 9

heritable

Answer 9

Referring to traits that can be transmitted from one generation to the next.

Question 10

artificial selection

Answer 10

Deliberate manipulation by humans, as in animal and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits to reproduce.

Question 11

population

Answer 11

A group of individuals of the same species living in the same geographic area at the same time.

Question 12

fitness

Answer 12

The ability of an individual to produce viable offspring relative to others of the same species.

Question 13

adaptation

Answer 13

Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.

Question 14

tree of life

Answer 14

The phylogenetic tree that includes all organisms.

Question 15

phylogeny

Answer 15

the evolutionary history of a group of organisms.

Question 16

phylum

Answer 16

(plural: phyla) In Linnaeus’ system, a taxonomic category above the class level and below the kingdom level. In plants, sometimes called a division.

Question 17

prokaryotes

Answer 17

A member of the domain Bacteria or Archaea; a unicellular organism lacking a nucleus and containing relatively few organelles or cytoskeletal components. Compare with eukaryote.

Question 18

eukaryotes

Answer 18

A member of the domain Eukarya; an organism whose cells contain a nucleus, numerous membrane-bound organelles, and an extensive cytoskeleton. May be unicellular or multicellular. Compare with prokaryote.

Question 19

taxon

Answer 19

(plural: taxa) Any named group of organisms at any level of a classification system.

Question 20

taxonomy

Answer 20

The branch of biology concerned with the classification and naming of organisms.

Question 21

domain

Answer 21

(1) A taxonomic category, based on similarities in basic cellular biochemistry, above the kingdom level. The three recognized domains are Bacteria, Archaea, and Eukarya. (2) A section of a protein that has a distinctive tertiary striation and function.

Question 22

genus

Answer 22

(plural: genera) In Linnaeus’ system, a taxonomic category of closely related species. Always italicized and capitalized to indicate that it is a recognized scientific genus.

Question 23

species

Answer 23

An evolutionarily independent population or group of populations. Generally distinct from other species in appearance, behavior, habitat, ecology, genetic characteristics, and so on.

Question 24

scientific name

Answer 24

The unique, two-part name given to each species, with a genus name followed by a species name – as in Homo sapiens. Scientific names are always italicized, and are also known as Latin names.

Question 25

null hypothesis

Answer 25

A hypothesis that specifies what the results of an experiment will be if the main hypothesis being tested is wrong. Often states that there will be no difference between experimental groups.

Question 26

control

Answer 26

In a scientific experiment, a group of organisms or samples that do not receive the experimental treatment but are otherwise identical to the group that does.