Biol221 Final study guide
What are the adaptations that allowed for the success of amphibians?
(1) Amphibians: frogs, toads, and salamanders, caecilians (figures 34.21-34.23). These were the first terrestrial vertebrates arising about 365 million years ago. The major adaptations that allowed for the successful invasion of land were (1) legs for support and movement, (2) lungs to extract oxygen from the air, (3) a redesigned heart, and (4) mechanisms to prevent drying out. Although there are only about 6,000 extant species, the Carboniferous was considered to be the Age of the Amphibians.
What is an amniote egg and why is it important? What are other adaptations that allowed reptiles to colonize drier areas?
(2) Reptiles include lizards, snakes, turtles, crocodilians, and birds (figures 34.24-34.35). Along with mammals, the reptiles make up the amniote animals. The amniotic egg allowed for independence from water for reproduction. (figure 34.24). The amniotic egg has a tough shell and extra embryonic membranes and in general is laid on land. Fertilization is internal. In addition reptiles have waterproof skin (scales with keratin) and use thoracic breathing (unlike the buccal breathing of amphibians); no cutaneous respiration except for some turtles using moist surfaces of the cloaca. The earliest amniotes lived about 320 mya. Most are oviparous but some are viviparous. They have internal fertilization (snakes and lizards have two penises called hemipenes). They are ectotherms like fish and amphibians, but some species behaviorally thermoregulate.
What are the sources of variation and why are they important?
. Sources of variation necessary for evolution by natural selection. Read pp. 482-483 1. mutation occurs constantly and is the result of mistakes made during DNA replication. 2. independent assortment during Meiosis. We will talk about this in more detail later, but basically in a diploid organism, we would not expect all of the chromosomes from the mom to end up in a gamete or all of the chromosomes from the dad to end up in another gamete. Instead there is a combination of mom and dad chromosomes within any given gamete. 3. crossing over during meiosis. Chromosomes swap pieces of DNA during Meiosis (more later) 4. sexual reproduction 5. rapid reproduction 8. altering gene number or position
Briefly describe the three pieces of evidence suggesting that choanoflagellates are the closest relatives of animals.
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Describe in detail how living organisms end up where they do.
1. Dispersal or inability to disperse to an area: For example, the cattle egret migrated to northeastern South American from Africa in the 1930s and since then has spread south and north (see figure 52.17) 2. Other factors include: a. Behavior e.g., habitat selection b. Biotic e.g., interspecific competition, the influence of keystone predators, predator-prey interactions. Read the Inquiry Figure 52.18. c. Abiotic e.g., temperature, water availability, salinity sunlight, soil makeup. d. Climate, the prevailing weather conditions of an area, is influenced by temperature, water availability, sunlight, and wind. e. Read and answer the questions from the Scientific Skills Exercise on page 1181. 3. Unfortunately humans have facilitated the dispersals of some species that have had negative or even catastrophic effects (e.g., European starlings to North America, Africanized honeybees to South America, and zebra mussels and spotted knapweed to North America).
Discuss Mendel's Laws in detail and his four ideas involving the Law of Segregation.
1. Four ideas of Mendel involving the Law of Segregation a. Alternate versions of genes (different alleles) account for variations in inherited characteristics. b. For each character, an organism inherits two alleles (one from each parent) c. If the two alleles differ, then one, the dominant allele is fully expressed in the organism's appearance, the other, the recessive allele, has no noticeable effect on the organism's appearance. d. The two alleles for each character segregate (separate) during gamete production.
What are the common characteristics of non-vascular plants? Be able to discuss each one.
A. Bryophytes (be sure to distinguish this term from the formal Phylum Bryophyta that includes the mosses) 1. These are small herbaceous plants. There are more than 24,000 species. Few of these plants are greater than one cm. tall. The gametophytes are photosynthetic and the sporophytes are dependent (at least for some amount of time) on the gametophytes for nutrition. 2. They are non-vascular; diffusion is important for the transport of water and nutrients and thus, the plants are only up to a few cells thick. 3. Of the two phases: gametophyte and sporophyte, the gametophyte is the dominant phase. The dominant phase of a plant life cycle is the photosynthetic form and in many plants it is the largest part of the plant. See the life cycle of a moss figure 29.6. The gametophyte is composed of one or more gametophores and a protonema. The sporophyte may be green when first formed but later will turn brown and can produce millions of haploid spores. 4. Rhizoids are small delicate structures that anchor the gametophytes of bryophytes to the ground (no roots). 5. Phyla (figure 29.7) a. Phylum Hepatophyta (liverworts). In about 20% of these plants, the gametophytes are flattened and lobed (resembling a liver). b. Phylum Anthocerophyta (hornworts). These may be representative of the earliest land plants c. Phylum Bryophyta (mosses). The gametophytes are small with leaf like structures that are arranged spirally or alternating around the stem-like axis. They are anchored by rhizoids. In moss archegonia (female gametotangia) and antheridia (male gametangia) are present and sperm are flagellated. Mosses are the most abundant plants of the Arctic and Antarctic. Note that in some bryophytes that there are tissues present allowing for the conduction of substances and it is not known if these are homologous with the xylem and phloem of vascular plants. Hornwort - author Jason Hollinger and Liverwort- author Eric Guinther
What are the derived characteristics of vertebrates?
A. Derived Characteristics 1. unique genes compared to invertebrate chordates 2. vertebral column that replaces the notochord and that provides support and functions as a strong, jointed strut that gives leverage to swimming muscles. In a few vertebrates the vertebrae are little more than small prongs of cartilage along the notochord
Discuss pleiotropy, epistasis, polygenic inheritance (continuous variation), incomplete dominance, and codominance.
A. Pleiotropy is the influence of a single gene on unrelated traits. B. Epistasis (p. 279 and figure 14.12) is where two alleles of a gene mask the alleles of another gene and as a consequence, the expected phenotypes associated with the latter are not present. Notice that the ratio is not the 9:3:3:1 expected ratio seen in the example of independent assortment C. Polygenic inheritance or continuous variation (figure 14.13 pp. 2274) occurs when multiple genes act jointly to determine a trait such as height or weight and thus it is difficult to determine the contribution of an individual gene. D. Incomplete dominance involves the ability of two alleles to produce a heterozygous phenotype that is different from either homozygous phenotype. See figure 14.10 page 272 E. Codominance is a situation where both alleles are expressed.
Discuss the work of Thomas Hunt Morgan including Figure 15.4. What was the importance of his studies?
A. The first scientist to provide us with evidence in support of the association of a specific gene with a specific chromosome was Thomas Hunt Morgan (see pp. 294-295). Like Mendel, Morgan's choice of species worked to his advantage. Morgan worked with a species of fruit fly (Drosophila) that has a relatively short generation time (about two weeks), produces many offspring, is small and easy to keep in the lab, and has only four pairs of chromosomes. Unlike Mendel, Morgan had to breed lots of flies to get the different variations in a phenotype for his studies. After breeding flies for a couple of years, Morgan obtained a white-eyed male fly (the others were red-eyed). He bred this male to a female with red eyes, and the resulting offspring were all red-eyed (which would be expected if the female was homozygous dominant). When he bred F1 offspring with each other, the resulting F2 offspring showed the phenotypic ratio of 3 red eyed: 1 white eyed. But only male offspring had white eyes. Like humans, sex determination in fruit flies is based on females having two X chromosomes and males having an X and a Y. Thus Morgan concluded that the mutant allele for white eyes is on the X chromosome and a male with only one X chromosome would have white eyes if that was the only allele he inherited. The importance of this research is that this was the first gene that was linked to a specific chromosome. See and know the information in Figure 15.4.
Discuss IN DETAIL the three most important reproductive adaptations of seed plants (include everything in the notes). How are these adaptations related to moisture availability?
A. The three most important reproductive adaptations of seed plants 1. Recall that the gametophyte is the dominant phase in bryophytes, but the sporophyte dominates in seedless vascular plants. In seed producing plants, the gametophyte is further reduced in size (to the point of being microscopic). Because the spores of seed plants are not released and are retained in sporangia, the gametophyte develops, is dependent on the sporophyte, and is protected from environmental stresses such as UV light and desiccation. 2. Although spores can withstand harsh conditions and can be dispersed into a new area, seeds are better adapted to both. a. Spores are single-celled structures, but seeds are multicellular and contain an embryo and its food supply b. All seed plants are heterosporous. c. layers of sporophyte tissue (the integument) envelop the megasporangium. Integument + megasporangium + megaspore = ovule d. Inside the megaspore, a female gametophyte develops that produces one or more egg cells. e. If fertilization occurs, the zygote develops into a sporophyte embryo and the entire ovule develops into a seed. f. A seed can remain dormant for long periods of time (up to years in some cases). It germinates if and when conditions are favorable. 3. Pollen allowed an independence from water for fertilization. a. Pollen grains develop from microspores. They form the male gametophytes. Because the male gametophyte is enclosed within the pollen grain it is not accurate to call the pollen grain the male gametophyte b. Pollen grains are protected by tough coats containing sporopollenin and can be dispersed over long distances by wind or animals after they are released from the microsporangium. c. Pollination is the transfer of pollen to the ovules. d. Only a few gymnosperms have flagellated sperm (unlike the seedless plants) and the most common gymnosperms and all angiosperms lack these structures. Seed plants have reduced gametophytes, are better adapted to harsh environments, and have an independence from water for fertilization. All these adaptations relate to their independence of water availability in terms of how they reproduce. Typically, in seedless vascular and non-vascular plants, they rely on flagellated sperm to swim through films of water to reach the egg for fertilization. In seed plants, pollen grains can be dispersed over long distances by wind or animals, which eliminates that dependence for standing water and sperm transport. This adaptation increases colonization and dispersion of their species, contributing to their success and adaptation to dry habitats making them almost ubiquitous.
Know the different types of reproductive structures in fungi and to which phyla these are common.
A. Types of reproductive structures that occur in fungi include: 1. sporangia that are involved in the formation of spores 2. gametangia that are structures within which gametes form 3. conidiophores that produce conidia (multinucleate asexual spores)
For human genetics, know all of the diseases or conditions that are covered in the notes related to autosomal recessive and autosomal dominant inheritance. Be able to determine phenotypic ratios.
B. In humans, the sex chromosomes differ between males and females, with females having two X chromosomes and males having one X and one Y. Since females have only X chromosomes, all ova have one X chromosome (that came from the maternal grandmother or the maternal grandfather). However, sperm contain either an X or a Y chromosome, so the sex of a person is determined by which sex chromosome is present in the sperm. A gene on the Y chromosome is required for the development of testes, if it is absent ovaries develop in the fetus. But the biochemical, physiological and anatomical differences in males and females is complex and there are other genes involved in the development of these traits. C. Other chromosomal system for sex determination include: 1. The X-O system of some insects like grasshoppers. The females have two X chromosomes and the males have one X chromosome. The sperm contains either an X (resulting in a female) or no sex chromosome (resulting in a male with his single X from his mother). 2. The Z-W system of birds, some fishes, and some insects. There are sex chromosomes in the egg but not in the sperm. Females are ZW and males are ZZ. 3. The haplo-diploid system of bees and ants. There are no sex chromosomes, and females develop from fertilized eggs and are diploid while males develop from unfertilized eggs and are haploid. 4. Temperature dependent sex determination of most turtles and all crocodilians. D. Sex-linked inheritance in humans. This involves situations where a recessive allele is expressed in males even though the male possesses only one copy of the allele. This occurs because the allele is present on the X chromosome and the Y chromosome does not have a complimentary allele (and thus there is no dominant or possibility of a dominant allele to mask the recessive allele). The XX/XY sex determination is not common to all animals.
Discuss the different ways that population size can be determined or estimated (include the mark-recapture method in detail).
B. Population size (N) is the number of individuals that make up the population and the density is the number of individuals per unit area or volume. 1. For sessile organisms or large slow moving organisms in a relatively small area, the density can be determined by counting them. However, if the size of the area is large, the individuals present in smaller plots can be counted and then the density can be estimated for the entire area. 2. For mobile organisms, populations are usually estimated since counting could be difficult (try counting fish in an aquarium). A common technique that is used is the mark-recapture method. Read Research Method (Figure 53.2). The equation is: x (marked recaptures) / n (total in second sample) = s (marked initially) / N (total pop. size). This can be rearranged to solve for N: N = s times n divided by x
What are the general characteristics of seedless vascular plants? Detail required.
B. Seedless Vascular Plants (Pteridophytes) 1. These plants evolved modifications that allowed them to be larger (some extinct species were very large): roots and vascular tissue. However, they were and are still dependent on damp habitats for the movement of the flagellated sperm and for survival of the small, and fragile gametophyte phase. 2. The life cycles of these plants are different from the bryophytes in that the sporophyte phase becomes the dominant phase and the gametophyte is much reduced (figure 29.11). The sporophyte is much more complex than the sporophytes of the byrophytes 3. These plants can be separated into two categories: homosporous and heterosporous. See page 625. a. Homosporous plants produce a single type of spore that produces a bisexual gametophyte that subsequently produces eggs and sperm. b. The sporophytes of heterosporous plants produce two types of spores (1) the megaspore produces the female gametophyte that produces eggs. (2) the microspore produces the male gametophyte that produces sperm.
What are the possible units of selection? Know examples and the relative likelihood of each one.
B. Units of selection. This is not to be confused with the unit of evolution. The unit of evolution is the population. Individuals do not evolve, populations do. What level does natural selection act upon? Possibilities include: 1. Gene selection or natural selection acting on individual genes that are contained within an individual would most likely be rare since genes do not exist as individual units. Gene selection would be more likely in species that have very few genes so that the impact of a single gene would have a greater overall effect on survival and reproduction. Reading http://bitesizebio.com/1344/selfish-genes-and-gene-centered-evolution/ 2. Whereas, individual selection seems to be the most likely unit of selection since it is the individual that survives or doesn't and reproduces or fails to reproduce. Recall that emergent properties are those that arise in higher levels of organization. According to Sinervo, gene selection is less likely due to the complexity that arises from the emergent properties at higher levels such as the organism itself. 3. Kin selection is also a viable unit of selection in situations where kin recognition occurs and where there is a benefit to altruistic behavior. Examples: a. related female wasps working together to raise one female's offspring or bees where one queen and her offspring display eusociality. The hymenopterans are a special case due to haplodiploidy (males are haploid and females are diploid). As a result sisters can share up to 75% of their genes whereas in most diploid organisms the sharing is limited to no more than 50%. b. In Belding's ground squirrels, there are individuals who will serve as sentinels. These individuals watch for predators and when a predator is spotted than emit warning calls so that other members of the group can escape to underground burrows. This puts the callers are greater risk of predation. This actually looks like a case of group selection (see below), one individual potentially sacrificing its life for the good of the group. But, research has shown the groups consist of related females (mothers, sisters, aunts, nieces) and unrelated males (except to their own offspring) and in general the individuals who do the calling are the females. c. There are many examples in the literature of kin selection in various species of animals. However, empirical studies are necessary to gain an understanding of the relative importance of kin selection (Griffin and West, 2002). 4. Group selection is supported by a few scientists. However, what appears to be an example of group selection, adult chimps killing offspring (supposedly to save resources for the other's in the troop), is actually individual selection where new dominant males kill the young shortly after the takeover so that they can breed with the females who no longer have delayed estrus due to nursing an infant. Reading: http://www.scq.ubc.ca/the-controversy-of-group-selection-theory/
Define Biology.
Biology is the study of the nature of life. There are many sub-disciplines within the overall discipline of Biology. Most Biologists narrow the scope of their study of biology to some sub-discipline. This is part of what makes the study of Biology so challenging. In this first course in the Biology Majors' Series, you will learn some basics of Biology in general, and then focus on Ecology, Genetics, Evolution, and Biodiversity.
Discuss the four ways of sex determination that are covered in your notes and textbook.
C. Other chromosomal system for sex determination include: 1. The X-O system of some insects like grasshoppers. The females have two X chromosomes and the males have one X chromosome. The sperm contains either an X (resulting in a female) or no sex chromosome (resulting in a male with his single X from his mother). 2. The Z-W system of birds, some fishes, and some insects. There are sex chromosomes in the egg but not in the sperm. Females are ZW and males are ZZ. 3. The haplo-diploid system of bees and ants. There are no sex chromosomes, and females develop from fertilized eggs and are diploid while males develop from unfertilized eggs and are haploid. 4. Temperature dependent sex determination of most turtles and all crocodilians.
Know a typical cell cycle in detail (include the phases: G1, S, G2, M, C, and G0).
Cell Cycle. In the text M phase = M+C (Figure 12.6). Note that some cells are non-dividing cells and a G0 phase occurs during which the cell is metabolically active. Diagram showing the common stages of the cell cycle. The mitotic phase usually takes up about 10% of the time. M = mitosis, C = cytokinesis, G1 = gap phase 1, S = synthesis phase, G2 = gap phase 2. A. Each cell goes through a cell cycle like the one shown above. The majority of the time, the cell is in Interphase (including the G1, S, and G2 phases). During this phase the cell grows larger, the chromosomes are spread out and are not visible using a compound light microscope. The nucleus and nucleolus or nucleoli (one or more denser and darker staining areas in the nucleus) are also visible 1. G1 is the First Gap phase. A new cell has just formed from a previous cell's division into two daughter cells. The cell is also metabolically active during this time. 2. S is the Synthesis phase. During this phase, DNA replication occurs. 3. G2 is the Second Gap phase. The cell is also metabolically active during this time. B. During the M phase, Mitosis occurs (see below). C. During C phase, Mitosis is almost complete and in general the parent cell divides into two identical daughter cells.
What are the primary factors that increase and decrease population size?
Changes in population density and number are affected by (see figure 53.3): 1. Birth rate and death rate 2. Immigration and Emigration
What factors influence the distribution of the terrestrial biomes.
Climate Temperature Precipitation
Discuss sex-linked inheritance and include the diseases covered in the notes (be able to use Punnett squares to determine the probability that male and female offspring will inherit a given sex-linked condition).
D. Sex-linked inheritance in humans. This involves situations where a recessive allele is expressed in males even though the male possesses only one copy of the allele. This occurs because the allele is present on the X chromosome and the Y chromosome does not have a complimentary allele (and thus there is no dominant or possibility of a dominant allele to mask the recessive allele). The XX/XY sex determination is not common to all animals. 1. Classic hemophilia results from a Factor VIII deficiency. The frequency is 1/10,000 Caucasian (generally males). Females can be carriers 2. Muscular dystrophy (Duchenne) is associated with a degeneration of muscle tissue that results from the degradation of myelin coating of nerves that stimulate muscles (1/3,500). Life expectancy is relatively short with these individuals rarely living past age 20.
What is X activation in females? When does it occur? How does it occur and what does it produce? What is a mosaic and how does that occur? Does inactivation ever occur? Explain.
D. X Inactivation in Female Animals that possess two X chromosomes (figure 15.8). In each cell of a female with two X chromosomes, one of those X chromosomes is inactivated during early embryonic development. The inactive X chromosomes condenses into a Barr body and most of its genes are not expressed. But this raises the question of what happens during oogenesis and why are there two X chromosomes in primary oocytes? The answer- in the ovaries, the Barr bodies are reactivated. Another neat feature is that X chromosome inactivation is random in the fetal cells, so that in some cells the X chromosome from the female's mother is inactivated and in other cells the X chromosome from the female's father is inactivated. So the selection of the chromosome that will form the Barr body is random and independent in the different cells and about half of the cells have an active X from the female's mother and the other half have an active X from the female's father. Thus females consist of a mosaic of the two types of cells.
What are the derived characteristics of seedless vascular plants compared to non-vascular plants? What made seedless vascular plants better adapted to a terrestrial environment than non-vascular plants and what was the result of that adaptation by seedless vascular plants?
Derived characteristics of these plants (compared to bryophytes) include: a. the presence of vascular tissue (xylem and phloem) b. roots c. leaves- the lycophytes (oldest vascular plants) have microphylls (one vein, small, mostly spine-shaped leaves) while the other vascular plants mostly have megaphylls (branched vascular system) d. sporophylls- modified leaves that bear sporangia
What is a dihybrid cross, be able to do the types of dihybrid crosses that we covered in class (determine Phenotypic ratios)
Dihybrid crosses are those that involve two distinct characteristics.
Define dispersal and explain what is meant by a species' range.
Dispersal is the movement of organisms away from areas of high population density or the area of origin. The ranges (areas where the species occurs) are expanded by dispersal. Some species disperse more easily than others. A. A few species have wide distributions (e.g., humans) but most of the species of living organisms occur in relatively limited geographic ranges. Biogeography is the study of the distributions of species.
Define dispersion and know the different patterns and what those patterns might "tell" about the species that display them.
Dispersion (the pattern of spacing among individuals within the boundaries of the population). These patterns are important characteristics for ecologists because they provide insight into the environmental associations and social interactions of the members of that population. The patterns are: 1. Clumped (the most common) where the members of the population aggregate in patches.. This decreases the probability that a given individual will be taken as prey. It also makes finding mates easier. Social species (regardless of the reason) are most often found in clumps. 2. Uniform where they are evenly spaced. This may be due to territoriality which involves site tenacity, and defense of the territory. 3. Random or unpredictable spacing where the position of an individual is independent of the other members of the population.
Define genes, gene expression. Know the order of gene expression
Each DNA molecule contains several hundred to a few thousand genes. Genes are portions of DNA molecules that contain genetic information that directs protein synthesis The process whereby genes direct protein synthesis is called gene expression. The order of this process is DNA is transcribed to RNA (specifically mRNA or messenger RNA) is translated into proteins
Define evolution (see the three definitions in your notes).
Evolution can be simply defined as change over time. Darwin defined evolution as descent with modification. But the following definition is more narrow and states that evolution is the change in allele frequencies in a population over time, where alleles are defined as alternative states of genes [e.g., in fruit flies, Drosophila, there is a gene for eye color (each individual will have two, one from its mother and one from its father), but there are alternative states, or different alleles, of this eye color gene (e.g., red and white). 1. Recall that evolution is one of the unifying concepts of biology 2. Evolution can be viewed in two ways a. Pattern. This can be seen in various disciplines of science with biology being one of them. Patterns can be observed. b. Process. These are the mechanisms of evolution or how it occurs. 3. I found this cite for you to skim over http://dc37.dawsoncollege.qc.ca/humanities/gabriel/DTP/origin.htm
What are the factors that are necessary for Natural Selection to occur? Why would that be so?
Factors that are necessary for Natural Selection to work, units of selection, sources of variation, and modes of selection A. Factors 1. characteristics must be inherited (but see figure 23.4 page 482 for an example of non-heritable variation) 2. there must be variation in these characters. Why: Because if there is no variation, there is no survival of the fittest. if all organisms are the same, it makes no difference which ones are killed, the gene pool stays the same 3. there must be an excess of offspring produced 4. differential reproductive success of those offspring must occur.
Define phylogeny and list the factors that phylogenies are based upon.
I. Introduction to Phylogeny and Systematics A. Phylogeny is the evolutionary history of a species or group of species. Phylogenies are based on: 1. fossil records 2. morphological homologies 3. molecular homologies (homologies are similarities that are due to shared ancestry whereas analogies are similarities that are due to convergent evolution instead of shared ancestry; see figure 26.7).
What are the general characteristics of fungi?
II. Characteristics of fungi A. Fungi are eukaryotic chemoheterotrophs. B. They acquire nutrients by absorption from the environment. Because only relatively small molecules (e.g., glucose) can be transported into fungal cells, they secrete external digestive enzymes that break down larger molecules into those that can be absorbed into the organism (external digestion). C. Some fungi are decomposers (digest their food from wastes of organisms, or dead plants and animals), some are parasites (these cause disease in other organisms like plants and animals) and some are mutualists (that absorb nutrients from other living organisms but also provide some other necessary component to the other organism making the interaction a net positive one). D. Fungi produce spores that at times outnumber the number of pollen grains in the air.
Explain exponential population growth IN DETAIL (everything from the notes)
II. Exponential Growth: maximum population growth rate (no limitations). Read pages 1190-1192 A. Equation dN/dt = rinstN where: d = the change in, N = the number of individuals in a population, t = time, and rinst = the instantaneous per capita rate of increase. B. Species that experience periods of exponential growth are called r-selected species. They tend to: 1. Reproduce at a young age 2. Produce many small young 3. Offer little parental care C. Figure (see figures 53.8-53.9) D. Realism. Over the long term, exponential growth cannot be sustained, instead new populations (due to a founder event), rebounding populations may show a period of exponential growth (see also Figure 53.9 for the exponential growth of an elephant population once hunting was prohibited). Also, short "bursts" of exponential growth can occur in r-selected species (when many offspring are present).
What are the general characteristics of gymnosperms?
II. Gymnosperms (naked seeds) A. These plants lack ovaries and thus the seeds develop on the surfaces of sporophylls, specialized leaves. B. The gymnosperms preceded the angiosperms (see below) C. About the same time that the reptiles were increasing in diversity & amphibians undergoing a decline, the gymnosperms were replacing the seedless vascular plants.
Describe the two theories explaining the evolution of eukaryotes from prokaryotes.
II. How did these first eukaryotes evolve? See Figure 28.3 and Scientific Skills Exercise page 589 A. Autogenous model - eukaryotes arose from prokaryotes that showed a specialization of membranes (derived from the infoldings of the plasma membrane). B. Endosymbiotic model - small prokaryotes lived symbiotically within larger prokaryotes. Evidence in support of this includes: the existence of endosymbiots, similarities between bacteria and mitochondria and chloroplasts (similar cell sizes between mitochondria, chloroplasts, and average bacterium, all reproduce by binary fission, similar ribosomal components, one of the algal-like protists, Cyanophora, looks like a chloroplast, and circular DNA).
What are linked genes? Be able to explain Morgan's experiment from Figure 15.3
II. Linked genes are those that are located near each other on the same chromosome that tend to be inherited together. Linked genes would result in unexpected phenotypic ratios than the expected with a dihybrid cross (see figure 15.9 and read about it on pp. 299-300). If you are interested in learning more about linked genes, genetic recombination and mapping the distance between genes read pp. 300-304.
Describe Mendel and his work in detail (include history, hypotheses, choice of Pisum sativum, and how Mendel performed his experiments).
II. Mendel's Laws are based on his work with garden peas, Pisum sativum (why garden peas? earlier studies had shown that hybrids could be produced, large numbers of true breeding varieties were available, they are small and easy to grow, and they have a short generation time). Mendel grew up on a farm and in school learned about agriculture. In 1843, he entered an Augustinian monastery. He later studied at the University of Vienna (1851-1853) where he was influenced by two scientists: Doppler (a physicist) encouraged his students to learn science through experimentation and also trained Mendel to use mathematics to help explain natural phenomena; Unger (a botanist) aroused Mendel's interest in the causes of variation in plants. Mendel then returned to the monastery and around 1857 began his studies. Two hypotheses were favored before Mendels' work (blending inheritance-traits observed in parents blend together to form traits in offspring, and the inheritance of acquired characteristics- traits present in parents are modified, through use and passed on to offspring in the modified form). Mendel set out address the question: what are the basic patterns in the transmission of traits from parents to offspring. See the results of Mendel's F1 crosses in Table 14.1, Figure 14.2 (for how Mendel performed the crosses between two plants) and Figure 14.3 (for the F1 results for flower color). Read Concept 14.1 pp. 268-274
Define allopatric speciation, and sympatric speciation (both types).
II. Speciation or the origin of new species is the outcome of isolation and divergence. Isolation is created by reductions in gene flow and divergence is created when mutation, genetic drift, and selection act on the separated populations There are two possible modes of speciation (the first is the most likely; figure 24.5). (4) Define speciation. In allopatric speciation a population (consisting of members of the same species) becomes geographically separated and gene flow is interrupted (see figures 24.6-24.8), then as selection pressures change for the two populations or genetic drift occurs, there are changes in allele frequency that can ultimately (over a very long period of time) lead to formation of organisms that are different in allele frequencies with genetic divergence ultimately resulting in the evolution of reproductive isolation.. The geographic features that lead to interrupted gene flow and isolated populations vary depending on species. For some species, something as minor as a decrease in water level causing one lake to be separated into two smaller lakes would be enough. But for other species that can move over relatively great distances (e.g., water fowl), the split lake would not result in isolation of populations since the birds can easily fly from one separated lake to another. Read about Gambusia and allopatric speciation (also see figure 24.6). Additional evidence from both laboratory experiments (figure 24.7) and from data collected on species in natural environments (figure 24.8) support allopatric speciation. Also read and complete the Scientific Skills Exercise on page 507. In sympatric speciation (figures 24.9-24.11) a new species arises without any geographic separation of a population. It is less common that allopatric species, but reproductive isolation can occur when gene flow is interrupted by polyploidy, sexual selection, and habitat differentiation.
What are the general characteristics of Angiosperms (Phylum Anthophyta)? KNOW THIS IN DETAIL.
III. Angiosperms: the flowering plants A. This is the most diverse taxon of plants. There are about 250,000 species. B. In the past, these were divided into two categories: monocots and dicots. New analyses show that the monocots are indeed a clade, but the dicots are multiple clades with most of them in what is termed the eudicots. The other lineages of the dicots are the Basal Angiosperms (water lilies, star anise, and Amborella) and the Magnoliids (about 8,000 species). C. These plants are so successful because of better adaptations related to vascular tissue and because of flowers and fruits.
Discuss chromosomal abnormalities due to non-disjunction and changes in chromosome structure.
III. Chromosomal Abnormalities result from non-disjunction during meiotic divisions. This means that one gamete gets zero of a chromosome and the other gets both members of the pair. Although non-disjunction is more common in the gametes of older women, it can also occur in younger women or in males of any age. When an egg or sperm that is missing a chromosome forms a zygote, the embryo often fails to develop. When an egg or a sperm that has both members of a pair form a zygote, the embryo may fail to develop or in other cases, the offspring develops but is born with three of that chromosome (trisomy). A. Down syndrome (trisomy 21) 1/750 births overall, but the frequency increases for older women because their eggs have been arrested in Meiosis longer and the spindles can be faulty. For women over 45, the risk is as high as 1/16 B. When X chromosomes fail to separate, some gametes have 2 Xs and some have 0 Xs. Thus an offspring can be XXX (sterile but otherwise normal), X0 (sterile, short stature, webbed neck, Turner's syndrome), XXY (male, sterile with many female secondary sex characteristics, Klinefelter's syndrome). C. The Y chromosome can also be present in two copies in the sperm. XYY males are fertile, but may be more aggressive or antisocial. D. Changes in the structure of chromosomes also occur [deletions (cri-du-chat), inversions and translocations (a form of cancer), and duplications (FMR g
Explain Human population growth IN DETAIL (everything from the notes and readings).
III. Human Population Growth A. The current population stands at about 7.4 billion. B. Recently the human population has experienced exponential or near exponential growth (see figure 53.22). Notice that the human population grew slowly until relatively recently and then began to increase rapidly. Read pages 1201-1205 http://www.census.gov/popclock - World and U. S. population clocks. C. Even though developed nations have lower birth rates (replacement level fertility in some cases), these nations do contribute to the environmental problems by the high per capita resource consumption that occurs. The average American uses 20-40 times more resources than a citizen of a developing country and has 20 to 40 times more of an environmental impact.
Describe mitosis
III. Mitosis. See figures 12.7, 12.8, and 12.11 for mitosis. Mitosis can be divided into phases based on the appearance of the chromosomes through a compound light microscope. A. Prophase - 1. The chromosomes shorten and thicken and become visible using a compound light microscope (however, they are not as condensed as they will be during the next phase). The sister chromatids (the duplicated chromosomes that are the result of DNA replication) are attached at the centromeres. 2. The nucleolus or nucleoli disappear 3. The assembly of the spindles begins in the centrosomes that are non-membranous organelles that function throughout the cell cycle to organize the cell's microtubules. Centrosomes are also known as microtubule-organizing centers. In animals, a pair of centrioles is located at the center of the centrosome. Interestingly the centrioles do not have an essential function in mitosis or cytokinesis. Most plant centrosomes lack centrioles. These centrosomes, like other organelles are replicated during interphase. The mitotic spindle (consisting of centrosomes, microtubules that extend from them (sometimes called spindle fibers) and radial arrays of shorter microtubules, asters, that extend from the centrosomes (like a starburst) begins to form. 4. The two centrosomes begin to separate due to the lengthening of the microtubules (spindle fibers) between them. B. Prometaphase 1. The nuclear membrane breaks down 2. The sister chromatids become more condensed. 3. Some spindle fibers attach to kinetochores of the centromeres C. Metaphase 1. The chromosomes line up at the equator (or metaphase plate) of the cell (note the arrangement and compare it to Metaphase I and Metaphase II of meiosis) 2. The spindles are complete and the centrosomes are at the opposite poles of the cell. 3. For each sister chromatid, the kinetochores are attached to spindles coming from opposite poles of the cell. D. Anaphase 1. The centromeres separate because the cohesion proteins holding the sister chromatids together break apart and the kinetochore microtubules shorten. 2. The sister chromatids (now called chromosomes) separate and are pulled toward the opposite poles 3. The polar microtubules elongate preparing the cell for cytokinesis E. Telophase 1. The chromosomes are now separated. 2. The nuclear membranes form around each set of chromosomes and the nucleolus (or nucleoli) reappear 3. The nucleolus or nucleoli reform 4. In most cases, the cytoplasm begins to divide 5. The chromosomes become less tightly coiled. 6. The microtubules are broken down F. Cytokinesis 1. This stage often overlaps with Telophase and is usually nearly complete by the end of telophase. 2. In animal cells a cleavage furrow occurs, then deepens and the parent cell divides into two new daughter cells, while in plant cells a cell plate forms between what will be the two new daughter cells.
What are invasive species? Why are they such a problem?
Invasive species: a species, often introduced by humans, that takes hold outside its native range Cause environmental harm, economic harm, or impact human health
Explain logistic population growth IN DETAIL (everything from the notes)
Logistic growth takes into account the factors that regulate population growth and the concept of a carrying capacity (K) or the population size at which stabilization occurs. See pp. 1192-1194 A. Equation dN/dt = riN(K-N/K) clarification K-N divided by K where K = carrying capacity, see above for other variables B. Species that show a stabilization of N are called K-selected. They tend to: 1. Reproduce later in life 2. Produce fewer, larger, and more developed offspring. 3. Provide a great deal of parental care Note: Obviously there is a continuum between r-selected and K-selected. (4) True or False. Citizens of underdeveloped countries contribute more to environmental problems. C. Figure (see figure 53.11). D. Realism. For most populations, this is more realistic. Rather than the population reaching and remaining exactly at K, the numbers fluctuate. E. See the Scientific Skills Exercise on page 1194 and answer the questions
Describe meiosis
Meiosis. Like mitosis, meiosis can also be divided into phases, but it is more complex than mitosis. Meiosis involves two cell divisions. See figure 13.8 pp. 254-255. A. Prophase I (lasts longer and is more complex than prophase of mitosis) 1. The chromosomes shorten and thicken and become visible using a compound light microscope 2. The nuclear membrane breaks down 3. In animals, the centrioles move to the opposite ends of the cell 4. The mitotic spindle forms 5. The homologues pair up (remember these are not the same as sister chromatids which are already paired up). A synaptonemal complex attaches the homologues tightly together all along their length. Crossing over and synapsis occurs (see figure 13.9). The homologues crisscross at various places (the crossings are called chiasmata, singular chiasma). This process involves the swapping of DNA between the homologues. It is an important source of variation. When the synaptonemal complex disappears (late prophase), each homologous pair becomes visible as a tetrad (a cluster of four chromosomes) B. Metaphase I 1. The chromosomes line up at the equator of the cell, but the homologues not the sister chromatids are arranged toward the opposite ends of the cell. 2. The spindles are attached to the kinetochores of the homologues 3. Independent assortment of chromosomes occurs where the homologue arrangement is random (see figure 13.11; if the figure is confusing, please read the section about Independent Assortment p. 263). C. Anaphase I 1. The chromosomes begin to separate 2. But, the homologues, not the sister chromatids are pulled apart D. Telophase I 1. Now the homologues are positioned at the opposite ends of the cell 2. In some organisms, nuclear membranes reform E. Cytokinesis F. Prophase II If the chromsomes lengthened, after cytokinesis they now shorten again and the spindle apparatus forms G. Metaphase II 1. Spindles form and attach 2. the chromosomes line up. Note the arrangement H. Anaphase II Now the sister chromatids separate I. Telophase II 1. Now the sister chromatids of half of the original number of chromosomes are present in each of the haploid nuclei 2. Nuclear membranes form
Be able to do the types of monohybrid crosses that we covered in class (determine Genotypic and Phenotypic ratios).
Monohybrid crosses are those that involve one characteristic only.
Describe IN DETAIL the factors that influence the structure of communities (abiotic factors, predators, interspecific competition, competitive exclusion principle, and examples).
More about Interspecific Interactions and community structure (the species makeup of the community) A. Note -Abiotic factors play a role in community structure. Amphibians are rare in arid areas due to their moisture requirements. History of the area is important in community structure. The absence of a particular species may not mean that it cannot survive in the area, but that it cannot get there (e.g., a mountain range or some other obstacle keeps it from getting there). In addition, disturbance influences community structure (read pp. 1222-1225). C. Predator-prey interactions. Predators and their prey are obviously interacting. In some cases predators may play a role in the regulation of prey populations. Predation is "good for" the predator but "bad for" the prey. Thus prey species have evolved defenses such as crypsis, fleeing, mechanical barriers, chemical deterrents and mimicry (Batesian: harmless mimic and Mullerian: harmful mimic). See figure 54.5. D. Interspecific Competition occurs when members of different populations and species compete for the sa6)me limited resource(s). 1. Interference involves actual fighting 2. Exploitative involves the use of the resource 3. Competitive Exclusion Principle (by Lotka and Volterra, and then tested by Gause). States that two species with very similar requirements cannot coexist, one will out-compete the other. The results of the interspecific competition include: extinction of the "inferior" species or resource partitioning (see below). However, another outcome of interspecific competition is resource or niche partitioning.
What are the mechanisms of Evolution?
Other mechanisms of evolution include genetic drift (e.g., Founder events and Population bottlenecks), gene flow, and sexual selection. However, Natural Selection is the only mechanism that increases the frequency of beneficial alleles (those that provide the individual with traits that enhance survival and reproductive fitness), and consequently that leads to adaptive evolution.
For Porifera, Cnidaria, Platyhelminthes, Annelids, Mollusks, Nematodes, Arthropods, Echinoderms, and Chordates know information about their tissues, symmetry, number and types of embryonic tissue layers, whether they are protostomes or deuterostomes, and if they are protostomes whether they are lophotrochozoans and ecdysozoans.
Porifera These are sessile, mostly marine organisms that lack symmetry and true tissues No embryonic layers Cnidarian They have radial symmetry, tissues but no organs They are diploblastic and thus have no mesoderm. The ectodermis is the outer layer, the gastrodermis is the inner layer, while the mesoglea is the substance that is located between the 2 layers Platyhelminthes Protostomes (Lophotrochozoa) 3 cell layers: ectoderm, endoderm and mesoderm Bilateral symmetry Annelids Bilateral symmetry Protostomes (Lophotrochozoa) 3 tissue layers: ectoderm, mesoderm and endoderm Mollusks Bilateral symmetry Protostomes (Lophotrochozoa) 2 tissue layers: endoderm and ectoderm Nematodes Bilateral symmetry Protostomes (Ecdysozoa) Triploblastic (ectoderm, mesoderm and endoderm) Arthropods Bilateral symmetry Protostomes (Ecdysozoa) Triploblastic Echinoderms Deuterostomes Adults have radial symmetry, but the larvae have bilateral symmetry Triploblastic Chordates Radial symmetry Adults have radial symmetry, but the larvae have bilateral symmetry Triploblastic
Define ubiquitous and know how the term relates to prokaryotes.
Prokaryotes are the most numerous living organisms (the number of cells in a handful of fertile soil is greater than the number of humans who have ever existed on Earth). They are almost ubiquitous (found almost everywhere) including some of the harshest environments on Earth
Why did scientists change the classification of protists from one kingdom to spread out in four supergroups or clades?
Protista is no longer a valid Kingdom due to the lack of close relationships between the diverse taxa (the taxa are polyphyletic). Genetic and morphological studies have shown that some protists are more closely related to plants, fungi, or animals than they are to other protists. As a result, the kingdom in which all protists once were classified, Protista, has been abandoned. Amd various protist lineages are now recognized as kingdoms in their own right. Most biologists still use the term protist, but only as a convenient way to refer to eukaryotes that are not plants, animals or fungi.
What are sister chromatids? Homologues?
Sister chromatids: the duplicated chromosomes that are the result of DNA replication Homologous: similarity in characteristics resulting from a shared ancestor
Know the Hardy-Weinberg Theorum in detail. Include: equation, variables, assumptions, and the overall importance of the theorem.
The Hardy-Weinberg Equilibrium Equation (read pages 483-487, will be covered in Laboratory Topic 11). This is a mathematical model that tracks the fate of alleles over time. The take home message is that Non-equilibrium supports evolution (see below) A. the equation p2 + 2pq + q2 = 1 where: p = the frequency of the allele A q = the frequency of the allele a and p2 = AA, 2pq = Aa, and q2 = aa B. Assumptions: 1. no mutation 2. large population size 3. isolated populations (no gene flow and thus no migration) 4. sexual reproduction with random mating 5. no selection C. Does this seem realistic? Of course not. Moreover non-equilibrium supports evolution because evolution is the change in allele frequencies (in a population) over time and nonequilibrium is a change in allele frequencies. D. Look over Scientific Skills Exercise page 487.
What are species richness and species abundance? What is H and why is it significant?
Various communities differ in species diversity consisting of both species richness and relative abundance. A. Species richness is the number of species making up a community B. Relative abundance relates to how many individuals of each species are present in the community (fig. 54.11) C. One of the techniques used to determine species diversity is the Shannon diversity index (more information is presented on page 1216 and figure 54.11) H = -(pAlnpA + pBlnpB + pClnpC +...) Where: A, B, C ... are the species in the community p = relative abundance of each species ln = natural logarithm the higher the value of H, the greater the diversity
Describe the flow of energy through a food chain, include summaries of the processes involved in energy transfer) and the relationships to the first and second laws of thermodynamics. Explain conservation of matter. Is it the same phenomenon as conservation of energy?
There is a limit to the number of trophic levels in a food chain or a food web. This relates to the 2nd Law of Thermodynamics and the loss of energy as heat between each trophic level. These three reactions are consistent with the First and Second Laws of Thermodynamics. The First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another. Sunlight energy is converted into CPE in glucose, then CPE in ATP. The Second Law of Thermodynamics states that during these energy transformations, some (or all) of the energy is converted from more ordered forms to less ordered forms (or entropy increases). During the energy transformation, heat is released as a less ordered form of energy. As a result, only a small percentage of the energy transferred from one trophic or feeding level to another ends up producing biomass in the next level (@ 10%).
What is the unit of evolution? Explain why that is so.
The unit of evolution is the population. -> Individuals do not evolve, populations do. -> The population is the smallest unit where evolution changes is possible
Why are bacteria so successful (include cellular features, mutations and the three ways that they transfer DNA)?
Their success is based on: structures such as cell walls made of peptidoglycan (a glycoprotein unique to prokaryotes) that maintain cell shape, provide protections and prevent lysis in hypotonic environments (figure 27.3) a capsule that protects cells from dehydration, protects the cells from chemicals of the immune systems of hosts, and also helps the cell attach to surfaces or other cells. In addition, many prokaryotes are capable of motility mostly by flagella (see figure 27.7). Prokaryotes mutate rapidly due to short generation times (as little as 20 minutes), the potential for periods of exponential population growth (reproduce by binary fission; however, they cannot sustain exponential growth in a culture due to limiting resources, competition, and waste buildup). They have a great deal of genetic diversity due to their rapid reproduction, higher mutation rates, and genetic recombination between members of the same species but different strains and even between different species by transformation (the uptake of naked DNA from the environment), transduction (transfer of DNA by bacteriophages), conjugation (direct transfer of plasmids, circular extrachromosomal DNA via pili; see figure 27.13). But know the three methods of horizontal gene transfer (cell to cell and in some cases species to species or genera to genera transfer of DNA): conjugation (see above), transduction (the transfer of DNA from one bacterium to another by a bacteriophage or virus that attacks bacteria) and transformation (the transfer of naked DNA from the environment into a bacterial cell- Note this is the process that occurred in the strains of Streptococcus pneumoniae that Griffith used in his experiment that showed that the genetic material could be transferred from one cell to another).
What is a theory? How do theories compare to hypotheses?
Theory: an explanation that is broader in scope than a hypothesis, generates new hypotheses, and is supported by a large body of evidence. Theories compare to hypotheses A scientific theory is much broader in scope than a hypothesis A theory is general enough to spin off many new, specific hypotheses that can be tested A theory is generally supported by much greater body of evidence
What are the characteristics of animals?
There are 1.3 million identified extant species of animals; about 95% of all animals are invertebrates (lacking backbones). They arose about 700 million years ago (read pp. 669-673 Concept 32.2 and be able to outline the evolutionary history of animals. These organisms are very diverse in form. I. What is an animal? Let us look at the characteristics that are consistent with being classified as such. A. A multicellular heterotrophic eukaryotic organism that in general obtains organic materials by ingestion. The nutrients are then digested and absorbed internally (unlike fungi). Food acquisition can be accomplished by various methods: 1. suspension feeders filter they kill them slowly. 2. Deposit feeders eat through their substrate (like earthworm) 3. Parasitic like predator but they may not kill them or kill them slowly 4. Predators capture and eat other animals 5. Herbivores feed on the plant materials and photosynthetic protists (snails, hummingbird) B. Store carbohydrate as glycogen C. Animals do not have cell walls, but have unique intercellular junctions (e.g., tight junctions, desmosomes, and gap junctions). Animals also possess structural proteins that hold cells together. D. Cells are organized into tissues, except in sponges and two of these tissues are unique (nervous and muscle). E. Most reproduce sexually with a dominant diploid stage. In general relatively small sperm fertilize a relatively large ovum or egg (oogamy). Cleavage then occurs (mitotic divisions) resulting in a blastula, then a gastrula forms (during which the three germ layers endoderm, mesoderm and ectoderm also form for most animals). Many animals go through a larval stage and then metamorphose into the adult stage. See figure 32.2 p. 668 F. These organisms inhabit nearly all environments, but most are marine. G. Animals have the ability to move rapidly and in complex ways; this differs from other living organisms. H. Animals are members of the Clades Unikonta and Opisthokonts.
Know how to properly write a scientific name.
Writing scientific names properly. Scientific names include the genus name and the species name. In some cases, the subspecies is included. The scientific name is italicized, the first letter of the genus name is capitalized and the first letter of the species is not capitalized. Examples include Crotalus horridus (the Timber Rattlesnake) and Ginkgo biloba (the Maidenhair tree). Scientific names allow scientists and others to be sure that the living organism that they are talking or writing about are the same organism. I have heard some call a mole a salamander.
What are the general characteristics of arthropods?
a. segmentation with fusion of some segments (early arthropods showed little variation in the segments, but as the arthropods continued to evolve, the segments tended to fuse, decrease in number, and become more specialized. b. rigid exoskeleton made of protein and chitin for protection and attachment. Molting is necessary for growth. c. jointed appendages that are specialized for movement, sensing, feeding, defense, and reproduction. d. good sense organs (e.g., compound eyes in some, olfactory organs of smell, and antennae for tactile and olfactory senses. In addition, cephalization is present and thus the sense organs are concentrated at the anterior end of the animal. e. the systems for gas exchange include gills and trachea f. open circulatory system that probably arose independently of the circulatory system of mollusks and containing sinuses that collect the hemolymph (these sinuses are collectively referred to as the hemocoel). g. molting
