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bio 106 exam 1
First bio exam
| Question | Answer |
|---|---|
| What captures Aristotles ideas? | Species are permanent and arranged on a ladder of increasing complexity. |
| What is an adaptation? | Traits that enhance organisms survival and reproduction. |
| Can individuals evolve? | Individuals do not evolve. |
| What captures Linnaeus' ideas? | - Developed a binomial system for naming species. - Adopted a nested classification system, grouping similar species in increasingly general categories. - Related species in a pattern of creation as opposed to evolutionary - Darwin did NOT agree |
| What captures Cuvier's ideas? | - Developed a big part of paleontology. - Older striatum = more dissimilar fossils than what we see today. - Some fossils stayed in sediment while other disappeared due to horrific events but were repopulated - Extinction exists but denies evolution. |
| What captures Lyell's ideas? | Physical evidence proves that the earth is older than 1000 years. |
| What captures Lamarck's ideas? | - Life changes over time through: - Use and disuse: body parts frequently used become larger and stronger. Unused body parts deteriorate. - Inheritance of acquired characteristics: organisms pass body modifications onto offspring, enhances them more |
| What did Lamarck overall realize? | Overall recognized that evolutionary change leads to adaptation to environment. |
| Why are limited resources a key part of natural selection? | It may cause a modification that will allow a species to live longer. |
| Why is heritable variation a key part of natural selection? | It can positively influence not only performance but also how well offspring will cope with environmental challenges. This can allow offspring to survive and reproduce. |
| Individuals experience natural selection, but do not evolve. Where is the evolutionary impact of natural selection seen ? | At the population level |
| What is a mutation? | A change in the nucleotide sequence of an organisms DNA. |
| What is adaptive evolution? | A process in which traits that enhance survival or reproduction tend to increase in frequency over time. |
| What is intERsexual selection? | Individuals of one sex (usually females) are choosy in selecting their mates from the other sex. |
| What is intRAsexual selection? | Individuals of one sex compete directly for mates of the opposite sex (often happens in males) |
| What is genetic variation? | Differences among individuals in the composition of their genes or other DNA sequences. |
| What are the two things that determine phenotype? | An inherited genotype and environmental influences. |
| A “heterozygote” has one dominant allele and one hidden (recessive) allele. How does heterozygote protection relate to evolution? | It maintains a huge pool of alleles that might not be favored under present conditions but that could be beneficial if the environment changes. (enhances reproductive success) |
| Which mutations can be passed to offspring (and therefore, are relevant to natural selection)? | Only mutations in cell lines that produce gametes can be passed onto offspring. |
| What is the combined effect of the three mechanisms that contribute to shuffling alleles? | These mechanisms ensure that sexual reproduction rearranges existing alleles into fresh combinations each generation. This provides much of the genetic variation that makes evolution possible. |
| What are the three mechanisms that contribute to shuffling alleles? | Crossing over, independent assortment of chromosomes, abd fertilization. |
| What is genetic drift? | When chance events cause alleles frequencies to fluctuate unpredictably from one generation to another, especially in small populations. |
| What is the founder effect? | Genetic drift that occurs when a few individuals become isolated from a larger population whose gene pool composition is not reflective of that of the original population. |
| What is the bottleneck effect? | a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts |
| Is natural selection random? | No, it consistently increases the frequencies of alleles that provide reproductive advantage. Leads to adaptive evolution. |
| What is “relative fitness”? | The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals. |
| What is favored in directional selection? | Favors variants that are at one extreme of the distribution. |
| What is favored in disruptive selection? | Favors variants at both ends of the distribution. |
| What is favored in stabilizing selection? | Favors immediate types of variants and removes extreme ones. |
| What two scenarios can prevent natural selection from reducing genetic variation? | Heterozygote advantage and frequency-dependent selection. |
| Why can't natural selection fashion perfect organisms? | - Selection can act only on existing variations - Evolution is limited by historical constraints - adaptations are often compromises - Change, natural selection, and the environment interact |
| What does reproductive isolation mean? | The existence of biological factors that impede members of two species from interbreeding and producing viable, fertile offspring |
| List each of the 5 prezygotic mechanisms of reproductive isolation. | Habitat isolation, Temporal isolation, Behavioral isolation, Mechanical isolation, Genetic isolation. |
| What are the limitations to the Biological Species Concept? | The # of species to which this concept can be applied to is limited. Does not apply to asexually reproducing organisms. Species here are designated by the absence of gene flow. Pairs of species can be extinct + still have gene flow occur between them. |
| What other alternative species concepts are out there? | Ecological species concept and morphological species concept. |
| How does the biological species concept define a species? | A group of populations whose members have the potential to interbreed in nature and produce viable/ fertile offspring but do not produce offspring with members of other groups. (reproductively compatible. |
| What is a prezygotic reproductive barrier? | (before the zygote) a reproductive barrier that impedes mating between species or hinders fertilization in interspecific mating occurs |
| What is a Postzygotic reproductive barrier? | (after the zygote) prevents hybrid zygotes produced by two different species from developing into viable, fertile adults. |
| List the 3 postzygotic barriers. | reduced hybrid viability: hybrids do not complete development reduced hybrid fertility: less likely to reproduce hybrid breakdown: offspring is sterile |
| What conditions are associated with allopatric speciation? | Geographical isolation, genetic drift, natural selection, and sexual selection. |
| What can happen in allopatric species that leads to speciation? | - individuals colonizing to a remote area - descendents become geographically isolated from the parent population - reproductive barriers |
| What conditions are associated with sympatric speciation? | Speciation occurs in populations that live in the same geographical areas. |
| What is habitat differentiation? | - a mechanism that can lead to sympatric speciation - when a subpopulation exploits a habitat or resource not used by the parent population. |
| What is sexual selection? | - a mechanism that can lead to sympatric speciation - mate choice based on male breeding coloration can act as a reproductive barrier that keeps the gene pool of these two species separate. |
| What is a ‘hybrid zone’? | A region which members of different species meet and mate, producing at least some offspring of mixed ancestry |
| In a hybrid zone, what is ‘reinforcement’ with respect to the speciation process? | Natural selection occurs for strengthened prezygotic barriers to reproduction. - reduces unfit hybrids *strengthening of reproductive barrier |
| In a hybrid zone, what is ‘fusion’ with respect to the speciation process? | The specialization process reverses, eventually causing the two hybridizing species to fuse into a single species. *weakening of reproductive barriers |
| In a hybrid zone, what is ‘stability’ with respect to the speciation process? | Stable hybrid zones have been observed in cases where the hybrids are selected against (an unexpected result) *continued production of hybrid individuals |
| What do branch points on cladograms represent? | Often matches how taxonomists have classified groups of organisms nested within more inclusive groups. |
| Define a clade. | A group of species that includes an ancestral species and all of its descendants. |
| Which group is a true clade? | Only monophyletic as it is equivalent to a clade. |
| What does someone who studies/uses systematics do? | -These individuals study all kinds of living organisms (fungi, bacteria, plants, animals, fossils of extinct animals) and human uses of plants and animals -Gather much information about the morphology, genes, and biochemistry of the relevant organisms. |
| What are the two components of a species name and what are the rules about writing them? | - genus: A taxonomic category above the species level, designated by the first word of a species’ two part scientific name. - specific epithet: unique for each species within the genus (ex. The scientific name for a leopard is Panthera pardus) |
| Taxonomic ranks of the hierarchical classification system in order from least to most inclusive | Species, Genus, Family, Order, Class, Phylum, Kingdom, and Domain |
| What do branch points on cladograms represent? | Often matches how taxonomists have classified groups of organisms nested within more inclusive groups. |
| What are the three key points to keep in mind when interpreting phylogenetic trees? | - The diagrams should only be interpreted in terms of patterns of descent. NOT time - Represents common ancestor not evolutionary traits - Lineages have evolved at different rates. |
| Explain what “homology” is. | Phenotypic and genetic similarity due to shared ancestry. |
| Explain what “analogy” is and be sure to indicate how it is different from homology. | An analogy is similarity between organisms. This is due to convergent evolution rather than ancestral traits that are phenotypic and genetic. - Another way to distinguish between homology and analogy is the complexity of the characters being compared. |
| What is a Monophyletic group? | pertaining to a group of taxa that consists of a common ancestor and ALL of its decedents. * Equivalent to a clade |
| What is a Paraphyletic group? | pertaining to a group of taxa that consists of a COMMON ancestor and SOME, but NOT all, of its descendants. |
| What is a Polyphyletic group? | pertaining to a group of taxa that includes distantly related organisms but does NOT include their most common ancestor. |
| What is an “outgroup” and how is it used to infer phylogenies? | A species or group of species from an evolutionary lineage that is closely related to but not part of the group of species being studied. Used to represent genetic change. (used as a point of comparison) |
| What is convergent evolution ? | occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages. |
| Name the three basic plant organs. | Roots, Stems, Leaves |
| What are the functions of the plant root? | - Anchors a vascular plant in the soil - Absorbs mineral and water - Often stores carbohydrates |
| What is a taproot system? | - penetrates the soil deeply, helps prevent the plant from toppling. - energetically expensive to make, allows the plant to be taller, gives plant more access to favorable light conditions, can put the plant at an advantage for pollen and seed dispersal |
| What is a fibrous root system? | roots that are thin and interweaving, spread out below the soil surface. primary root that emerges from the germinating seed dies early on. Many small roots emerge from the stem. Creates a thick sheet of adventitious roots. |
| Define adventitious | a plant organ that grows from an unusual source. |
| Describe the most important role of root hairs. | Allow for the plant to absorb water and minerals. Also increase the surface area of the root enormously. |
| What are the functions of the stem? | -Bears the leaves and buds. - Elongates and orients the shoot in a way that maximizes photosynthesis by the leaves. - elevates reproductive structures, facilitating the dispersal of pollen and fruit. - may perform a small amount of photosynthesis |
| What are the functions of leaves? | - main photosynthetic organ - Intercepts light, exchanges gases with the atmosphere, dissipates heat, defends the plant from herbivores and pathogens. |
| What is the function of the dermal layer? | to provide a protective cover for the entire body of the plant. (kinda like our skin) |
| What function does the dermal layer serve? | -First line of defense against physical damage and pathogens |
| What are trichomes and what functions do they serve? | - hair-like outgrowths of the shoot epidermis - Reduces water loss, reflect excess light - Most commonly: they defend against herbivores and pathogens by forming a mechanical barrier or secreting chemicals |
| What is the function of the xylem? | conducts water and dissolved minerals upward from roots into the shoots. |
| What is the function of phloem? | transports sugar (product of photosynthesis) from where they are made (usually the leaves) to where they are needed/ stored (roots and sites of growth like developing leaves and fruits) |
| What are the functions of ground tissue? | The ground tissue may include cells specialized for functions such as storage, photosynthesis, support, or short-distance transport. |
| Where do we find parenchyma cells? | Mainly occur in the dermal and ground tissues. |
| Describe the shape and movement of water in tracheids: | -Long thin cells with tapered ends. -Water moves from cell to cell mainly through the pits, where it does not have to cross thick secondary walls. |
| Describe the shape and movement of water in vessel elements | -Generally wider, shorter thinner walled and less tapered than the tracheids. -The end walls of the vessel elements have perforation plates that enable water to flow freely through the vessels. |
| What features are lacking in sieve-tube elements? | -They lack a nucleus, ribosomes, a distinct vacuole, and cytoskeletal elements. |
| What is the function of companion cells? | -The nucleus and ribosomes serve the cell and the adjacent sieve-tube element. -In some plants, companion cells in leaves also help load sugars into the sieve-tube elements. These then transport the sugars to other parts of the plant. |
| What are the two types of meristems in plants? Where are they found? | Apical: located at the tips, roots and shoots, and in auxiliary buds of shoots Lateral: extend along the length of roots and stems. |
| What is the primary growth? | - growth produced by apical meristems, lengthening stems and roots. - allows roots to extent throughout soil and shoots to increase their exposure to light |
| What is the secondary growth? | - growth produced by lateral meristems, thickening the roots and shoots of woody plants. |
| What happens at the root cap? | Protects the delicate apical meristem as the root pushes through the abrasive soil during primary growth |
| What happens at the zone of cell division? | new root cells are produced, including cells of the root cap. |
| What happens at the zone of elongation? | where most of the growth occurs as root cells elongate (sometimes more than 10x their original length. |
| What happens at the zone of differentation? | (also zone maturation) cells complete their differentiation and become distinct cell types. |
| What structural component of a typical eudicot root matches with the vascular cylinder? | Vascular |
| What structural component of a typical eudicot root matches with the cortex? | Ground |
| What structural component of a typical eudicot root matches with the epidermis? | Dermal |
| What structural component of a typical eudicot root matches with the root hair? | Dermal |
| What are the functions of stomata? | Pores that allow exchange of CO2 and O2 between the surrounding air and the photosynthetic cells inside the leaf. Major avenues for the evaporative loss of water. |
| What is the function of guard cells? | Regulate the opening and closing of the pore. |
| What is the ground tissue of the leaf called? | mesophyll |
| Which structures make up the vascular bundle? | Vascular: Sclerenchyma (fiber cells), Phloem, Xylem, Vascular bundle. Ground: Cortex, Pith, Ground tissue connecting pith to cortex Dermal: Epidermis |
| Describe he difference in how the vascular bundles are arranged here versus in the eudicot. | In monocots, ground tissue is not partitioned into pith and cortex (LM) like in the eudicots. |
| What did the evolution of secondary growth allow plants to create? | This allowed the production of novel plant forms ranging from massive forest trees to woody vines. |
| In woody plants, what is accomplished by primary growth and what is accomplished by secondary growth? | Primary growth: adds leaves and lengthens stems and roots in the younger regions of a plant Secondary growth: increases the diameter of stems and roots in older regions where primary growth has ceased. |
| . What tissue is responsible for the production of secondary vascular tissue and where is it located? | The vascular cambium is located outside the pith and primary xylem and to the inside of the primary phloem and the cortex. |
| What are vascular rays and what is their function? | Radical files of mostly parenchyma cells that connect the secondary xylem and phloem. They move water and nutrients between the secondary xylem and phloem, store carbohydrates and other reserves and aid in wound repair. |
| What is heartwood? | closer to the center of a stem or root. the older layers of secondary xylem that no longer transport water and minerals. |
| What is sapwood | newest/ outer layers of secondary xylem that transport xylem sap. This wood allows a large tree to survive even if the center of its truck is hollow. |
| What is the function of cork? | As these cells mature, they deposit a waxy, hydrophobic material called suberin in their walls and then die. Functions as a barrier to help protect the stem or root from water loss, physical damage, and pathogens. |
| Cork is not the same as bark. What is bark? | Includes all tissues external to the vascular cambium. The main component in this is the secondary phloem. |
Created by:
annette.rosen
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