Unit 4: Evolution & Classification Flashcards

Question

Evolution * Overview * Levels of evolution

Answer 1

* A change in heritable traits within a population over many generations * Results in improved adaptation to an environment & new species * AKA _descent with modification_ * All living things are descended from a common ancestor, but they have become modified to adapt to a certain way of life * Example: humans & fish * both are descended from a common ancestor, but humans have become adapted for life on land & fish in water * Levels of evolution * _Microevolution_: small genetic changes in a species * _Macroevolution_: major changes in life forms due to accumulation of major genetic changes; leads to new species

Answer 2

* **Anatomical** * The concept of common descent * Explanation for anatomical similarities among organisms * **Biochemical** * Similarities in the nucleotide sequence of genes & the amino acid sequence of proteins between living things * **Biogeography** * Related forms evolved in one locale and then spread to accessible regions * 6 regions; each having characteristic life forms * **Fossils** * Remains of past life forms often found embedded in sedimentary rock * Show transitional life forms; a link between two groups of organisms * Allowed the creation of a _geological time scale of Earth_, which divides history into eras, periods and epochs

Answer 3

Measured by the number of fertile offspring produced throughout an organism's lifetime

Answer 4

* Occurs when a few individuals form a new colony, and only a fraction of the total genetic diversity of the original gene pool is represented in these individuals * The particular alleles carried by the founders are dictated by chance alone * A founder event is the same as a bottleneck, except that in a founder event, the original population still exists

Answer 5

* Causes a change in allele frequencies due to migration of individuals * Mixes genetic diversity and keeps the gene pools of populations similar * Example * Plants are not able to migrate, but their pollen is often blown by the wind or carried by insects into different populations

Answer 6

The alleles of all genes in all individuals in a population

Answer 7

* A change in allele frequencies due to _random chance_ * Natural selection or environmental influences are not involved * 2 types * _Founder effect_: * allele frequencies change when a new settlement is founded by a small number of individuals * the founding population does not have all the alleles possible for the species * _Bottleneck effect_: * allele frequencies change when a population is reduced to near extinction

Answer 8

* **Precambrian**: where life began. This era is not divided into periods. By end of this era, soft bodied invertebrates appeared * **Paleozoic era**: by end of this era, all major groups of animals & plants appeared and land dwellers appeared * **Mesozoic**: known as the "age of reptiles". Dinosaurs appeared & become extinct by the end of this era. Jurassic period is when dinosaurs flourished. Placental mammals appeared at the end of this era * **Cenozoic**: modern day. Is the only era divided into epochs. Primates appeared here and humans appeared at the end of this era

Answer 9

* Only present in animals that have the tissue or organ level of organization * Types * **Diploblastic**: have two layers (most primitive) * **Triploblastic**: have three layers (most advanced)

Answer 10

* Only alleles that are expressed (cause a _phenotypic difference_) are subject to natural selection * This makes the heterozygote a potential protector of recessive alleles that might otherwise be weeded out of the gene pool by natural selection

Answer 11

* Descent from a common ancestor * Living things have changed to become adapted to different ways of life * Example: forelimbs have a similar structure because the structure was a feature inherited from a common ancestor

Answer 12

* Proven by the Miller-Urey experiment * Experiment simulated primitive conditions * Resulted in small organic molecules being formed * Gave rise to the first true cell to be formed, the _protocell_ (prokaryotic cell) * Once formed, evolution could take place

Answer 13

* A change in the nucleotide sequence of a gene may change the... * amino acid sequence * protein structure * protein function * traits of an organism

Answer 14

* Shows descent from a common ancestor * Sequences are similar because they are descended from a common prokaryotic ancestor

Answer 15

* Uneven distribution of species around the world * Related organisms are found in similar parts of the world. This is because they are all descendants of a common regional ancestor * Some species were able to spread to other regions as geography & continental drift predicts

Answer 16

* Fossils show that living things have... * _changed over time_ (ie horses have changed over time) * _become more complex_ (ie older fossils show more primitive life forms while newer fossils show more complex ones) * _transitional life forms_ (ie the transitional life form is extinct but the two groups of organisms it links together are not)

Answer 17

* The replacement model: * Modern humans originated in Africa * After migrating into Europe and Asia they replaced the other homo species (including Neandertals and Denisovans)

Answer 18

The members of a population differ from one another

Answer 19

* Proposed the _theory of evolution_ in 1801 * Mechanism of evolution: _Inheritance of Acquired Characteristics_ * Life has changed over time * Characteristics of an organism changed through "use" or "disuse" * No extinction

Answer 20

1. **Single-celled, prokaryotic organisms** that lived in the ocean (Domains: Bacteria & Archae) 2. **Singled celled eukaryotic** **organisms** that lived in the ocean (Kingdom: Protist) 3. **Multicelled eukaryotic organisms** that lived in the ocean (Kingdom Fungi & invertebrate animals from the Animal kingdom) 4. **Vertebrate animals appear**. Ocean-dwelling, jawless fish 5. **Organisms inhabit land & primitive plants appear**. Amphibians, reptiles, & insects 6. **Mammals & birds appear**. Reptiles gave rise to both mammals & birds 7. **Primates appear**. The common ancestor primates was a "shrew like" creature 8. **Humans appear**

Answer 21

* Warm blooded * Mammary glands to produce milk * Body hair

Answer 22

* **Monotremes** * Features: Egg laying (embryo develops in an egg) * Where they evolved: Australia * Examples: Only two species; platypus, spiny anteater * **Marsupials** * Features: Pouched (embryo develops in a pouch) * Where they evolved: Australia * Examples: Kangaroo, koala bear * **Eutheria or Placental** * Features: Placental (embryo develops in uterus & is nourished by placenta) * Where they evolved: Everywhere except Australia * Examples: Humans and most other mammals

Answer 23

* Extinction is the death of every member of a species * During mass extinctions, a large percentage of species become extinct within a relatively short period of time

Answer 24

* Experiment that simulated Earth's primitive atmosphere conditions and resulted in small organic molecules being formed * Significant for two reasons * Demonstrated that biomolecules can form under ancient Earth-like conditions * Transformed speculation that life may have emerged from chemistry into a testable science * Led to a new field of research known as _prebiotic chemistry_

Answer 25

* Different than Lamark & Darwin's theories * _Emphasizes genes_ * The variation in a population is due to different alleles * Evolution causes a change in the frequency of alleles in a population * _Natural selection is not the only mechanism of genetic change_ * Agrees with Darwin's idea of natural selection, but there are other processes besides natural selection that cause genetic change * Mechanisms of genetic change * Genetic drift * Gene flow * Mutations * Natural selection * Non-random mating

Answer 26

* A random change in the nucleotide sequence of a gene * Since mutations create new alleles, they are the basis for which the other mechanisms in the Modern Theory work * **"****_Raw material of evolution_****"** because mutations cause the variation necessary in a population for evolution to occur

Answer 27

* Allows some individuals with an advantage over others to produce more offspring * Causes change in allele frequencies due to the environment. The environment determines which alleles are favorable and which are not * Modern examples * Glucose hating roaches: Bate traps were bated with poisoned glucose. One roach had an aversion to glucose & didn't take the bait--this roach was more fit. It reproduced more & passed on the gene to hate glucose. Over time, roaches evolved to hate glucose * Insecticide resistant bugs * Antibiotic-resistant bacteria

Answer 28

* Differential reproductive success * Individual variation * Inheritance * Overproduction

Answer 29

* **Directional selection** * When an extreme phenotype is favored and the distribution curve shifts in that direction * Can occur when a population is adapting to a changing environment * Example: antibiotic resistance * **Disruptive selection** * When 2+ extreme phenotypes are favored over any intermediate phenotype * Example * British land snails (grasslands vs forested areas) * **Stabilizing selection** * Extreme phenotypes are selected against, and individuals near the average are favored * Can improve adaptation of the population to those aspects of the environment that remain constant

Answer 30

* Individuals are selective about choosing a mate with a preferred trait * Because most sexually reproducing organisms select their mates based on some trait, random mating is never observed in natural populations * Decreases genetic variation * Example: inbreeding

Answer 31

Individuals in a population are engaged in a struggle for existence because breeding individuals in a population tend to produce more offspring than the environment can support.

Answer 32

1. **Level of organization**: cellular, tissue, organs 2. **Digestive system**: incomplete, complete 3. **Body cavity**: acoelom, pseudocoelom, coelom 4. **Body plan** (symmetry): asymmetry, radial, bilateral 5. **Repetition of body parts**: not segmented, segmented

Answer 33

* Not segmented * Cnidaria * Mollusca * Nematoda (Roundworms) * Platyhelminthes (Flatworms) * Porifera * Segmented * Annelida (Segmented worms) * Arthropoda * Chordata * Echinodermata

Answer 34

* Mutations that can cause a malfunctioning protein to be harmful to an organism * Called "silent" if it does not result in a change to the function of the protein encoded by the gene * A change in a single nucleotide in a gene

Answer 35

* All members of a single species that occupy a particular area at the same time and that interbreed and exchange genes

Answer 36

1. Adapted to an **_arboreal_** life 2. Limbs are **_mobile**_ with _**5_** digits each (allows for grasping ability) 3. Opposable **_big toe**_ and _**thumb_** (allows for grasping ability) 4. Have nails instead of claws (allows for grasping ability) 5. A shortened snout which allows for the **_eyes**_ to be located to the _**front**_ of the head. This also allows for _**stereoscopic_** vision (able to see in three dimensions and have depth perception) and also binocular vision (able to view an object with both eyes. 6. A **_larger**_ and more _**complex_** brain 7. They give birth to **_one_** offspring at a time

Answer 37

* Name of the first cell formed by organic molecules * It gave rise to the first true cell which was prokaryotic * Once the true cell formed, evolution could take place

Answer 38

* States that long periods of stasis, or no visible change, are followed by rapid periods of speciation * Speciation often occurs relatively rapidly, and this can explain why few transitional links are found. Mass extinction events are often followed by rapid periods of speciation

Answer 39

* When one species gives rise to two species, each of which continues on its own evolutionary pathway * Occurs whenever reproductive isolation develops between two formerly interbreeding groups or population * Types * **Allopatric speciation** * Occurs when populations become separated by a geographic barrier and gene flow is no longer possible * Example: Salamanders in California * **Sympatric speciation** * Found among plants, where the multiplication of the chromosome number in one plant prevents it from successfully reproducing with others of its kind * Self-reproduction can maintain such a new plant species

Answer 40

* A group of organisms capable of interbreeding that are isolated reproductively from other organisms * If organisms cannot mate and produce offspring in nature, or if their offspring are sterile, they are defined as different species

Answer 41

* Placing organisms into categories * Categories show 1. Similarities between organisms 2. Differences between organisms 3. Evolutionary relationships * Taxons = general name for organisms that exhibit a set of shared traits

Answer 42

* All living things are descended from a common ancestor, thus they are all related * Organisms have changed over time to become better adapted to their environment or way of life * Evolution produces more complex, better adapted organisms * If a species cannot adapt, it becomes extinct

Answer 43

An inherited characteristic. Can be physical or physiological.

Answer 44

* Not used to classify phyla * Types * **Hydrostatic** (most primitive): a skeleton based on the pressure of fluid in the organisms body * **Exoskeleton**: a skeleton on the outside of the body (externally) * **Endoskeleton** (most advanced): a skeleton made of cartilage and/or bone located internally

Answer 45

* Agnatha (jawless fish) * Amphibia * Aves (birds) * Cephalochordata (lancelets) * Chondrichthyes (cartilaginous fish) * Mammalia * Osteichthyes (bony fish) * Reptilia * Urochordata (tunicates)

Answer 46

* Anatomical features that are fully developed in one group of organisms but that are reduced and may have no function in similar groups * Occur because organisms inherit their anatomy from their ancestors * Example * Most birds have wings for flight, but ostriches have greatly reduced wings and cannot fly

Answer 47

* Organisms become better adapted to their environment or way of life * New species develop

Answer 48

* Genes & alleles

Answer 49

* Individual organisms do not evolve * Populations of organisms evolve

Unit 4: Evolution & Classification Flashcards

(75 cards)