Living Environment Regents Exam Review - Unit 7

Unit 7 Review

fossils

• oldest fossils are found at the bottom

• more complex fossils are found near the top

comparative cytology

• compare cell structures of different kingdoms

comparative biochemistry

• compare chemicals such as DNA and proteins (enzymes and hormones)

comparative anatomy

• compare bone structures

• ex. human arm vs. bat wing vs. whale flipper

homologous structures

• same basic structure but different functions

vestigial structures

• structures that do not have any use, but are the remains of structures that were once functional

• ex. whale leg bones, snake hind (back) limbs, human tailbone, human appendix

comparative embryology

• when members of two or more different species share a number of characteristics, it provides evidence that they share a common ancestor - they have an evolutionary relationship

• the more traits in common, the more recent the ancestor/the more closely related they are

Lamarck

• he was WRONG ABOUT EVERYTHING

• claimed theory of use and disuse - organisms develop certain organs because of need

• claimed inheritance of acquired characteristics - that characteristics developed by an organism during their lifetime are then passed along to their children

Darwin

• theory of natural selection - where nature selects those who are best adapted

• came up with the theories of overproduction, competition, survival of the fittest, reproduction, and time/speciation

• could not explain what caused variations though

overproduction (Darwin)

• more offspring are produced than can survive

competition “struggle for existence” (Darwin)

• organisms compete for food, water, shelter, etc.

survival of the fittest “natural selection” (Darwin)

• organisms who have variations that have variations that make them best adapted will survive while those without those variations will die

reproduction (Darwin)

• the best adapted will pass on their variations to their offspring

time/speciation (Darwin)

• origin of new species

• variations accumulate and new species emerge - the variations that are good are passed on to children and once enough children are born with that variation, then a new species is officially made

causes of variation

• affected by sexual reproductions (gene recombination & crossing over) and mutations

selecting agent

• something in nature that chooses who is best adapted

• ex. available food, predators, etc.

the modern theory of evolution

• combines Darwin’s theory of natural selection with the study of genetics

• each trait is controlled by a different gene (selection of DNA on a chromosome)

• you are BORN WITH the combination of genes that determine your unique set of traits

• if you have traits that help you survive in your environment, you will be able to live and reproduce which means your genes are passed onto the next generation so then the organisms in that generation will have traits that have ADAPTIVE VALUE in their environment

gene coding

• the genes coding for useful (adapted) traits will INCREASE in the population

• the genes coding for less useful (adapted) traits will DECREASE in the population

• it is the relative numbers of these genes within a species that drives the change in that population over time

adaptive radiation

• a single population splits into groups having different traits which leads to a new

• ex. Darwin’s finches

geographic isolation

• isolation of members of a species by a geographic barrier

• ex. mountain, desert, lake, river, etc.

• leads to reproductive isolation (can only reproduce with the organisms stuck in the same spot as them) and eventually a new species (speciation)

punctuated equilibrium

• long periods of stability followed by short periods of change

gradualistic equilibrium

• changes occur slowly over time

microevolution

• ex. insecticide resistant insects, antibiotic resistant bacteria, industrial melanism (peppered moth)

genetic variation

• more genetic variation in a species = more likely the species will survive the changes in the environment

• a species will remain unchanged for long periods of time if it has some genetic variation and the environment remains stable

heterotroph hypothesis

• 1st organisms on earth were simple unicellular heterotrophs

• organisms have evolved into becoming more complex over time