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he following questions: • What are the basic types of ecosystems on Earth? • What are methods that ecologists use to study ecosystem structure and dynamics? • What are the different methods of ecosystem modeling? • What is the difference between a food chain and a food web, and what is the importance of each? 1684 Chap...
hic level. Depending on their role as producers or consumers, species or groups of species can be assigned to various trophic levels. In many ecosystems, the bottom of the food chain consists of photosynthetic organisms (plants and/or phytoplankton), which are called primary producers. The organisms that consume the pr...
However, this type of study is limited by time and expense, as well as the fact that it is neither feasible nor ethical to do experiments on large natural ecosystems. To quantify all different species in an ecosystem and the dynamics in their habitat is difficult, especially when studying large habitats such as the Am...
estions: • How do organisms acquire energy in a food web and associated food chains? • How does the efficiency of energy transfer between trophic levels affect ecosystem structure and dynamics? • What are the characteristics of each trophic level in an ecosystem, and how can ecological pyramids be used to model them? C...
cientists have to observe the ecosystem. In other words, some ecosystems are more difficult to study than others, and sometimes the quantification of energy transfers has to be estimated. Another main parameter that is important in characterizing energy flow within an ecosystem is the net production efficiency. Net pro...
ccumulation of mercury in their body over time. c. Larger animals consume many small organisms, which leads to accumulation of hydrogen in their body over time. d. Larger animals consume many small organisms, which leads to accumulation of polyglucose in their body over time. Lab Investigation AP® Biology Investigation...
osystem. d. Humans utilize water from oceans, which is the rarest ecosystem. Rain and surface runoff are major ways in which minerals, including carbon, nitrogen, phosphorus, and sulfur, are cycled from land to water. The environmental effects of runoff will be discussed later as these cycles are described. Figure 37.1...
ng it to re-enter the atmosphere. +) by certain bacteria and fungi. Second, the ammonium is converted to nitrites (NO2 This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 37 \| Ecosystems 1709 Figure 37.18 Nitrogen enters the living world from the atmosphere via nitrogen-fixing bacter...
Cycle Sulfur is an essential element for the macromolecules of living things. As a part of the amino acid cysteine, it is involved in the formation of disulfide bonds within proteins, which help to determine their 3-D folding patterns, and hence their functions. As shown in Figure 37.21, sulfur cycles between the ocean...
behaviors and eating habits of warm-blooded versus cold-blooded animals. Modeling of ecosystem energy is best done with ecological pyramids of energy, although other ecological pyramids provide other vital information about ecosystem structure. 37.3 Biogeochemical Cycles Mineral nutrients are cycled through ecosystems...
etic whereas those of grazing food webs are decomposers. Both primary producers support different components of the ecosystem. c. The primary producers of detrital food webs are decomposers whereas those of grazing food webs are photosynthetic. Both primary producers support different components of the ecosystem. d. Th...
. Herbivores from another region may have entered the ecosystem and consumed the primary producers, causing death of the original herbivores species. d. Overeating by herbivores could have caused depletion of the primary producers, leaving the herbivores without enough food. 45. Although producers are essential for ene...
ugh speciation of a phylogenetic tree into many closely related species; typically, the species “radiate” into different habitats and niches. The Galápagos finches are an example of a modest adaptive radiation with 15 species. The cichlids of Lake Victoria are an example of a spectacular adaptive radiation that include...
World, 2nd ed. (Canberra, AU: Australian Biological Resources Study, 2009). http://www.environment.gov.au/biodiversity/abrs/publications/other/species-numbers/2009/pubs/nlsaw-2nd-complete.pdf. 3. Brian Groombridge and Martin D. Jenkins. World Atlas of Biodiversity: Earth’s Living Resources in the 21st Century. Berkeley...
and volcanic eruptions have been argued. The extinction event occurred just before the breakup of the supercontinent Pangaea, although recent scholarship suggests that the extinctions may have occurred more gradually throughout the Triassic. The causes of the end-Cretaceous extinction event are the ones that are best ...
tudies have shown that the number of species present increases as the size of the island increases. This phenomenon has also been shown to hold true in other habitats as well. Turning this relationship around, if the habitat area is reduced, the number of species living there will also decline. Estimates of extinction ...
world. The ability to create new crop varieties relies on the diversity of varieties available and the accessibility of wild forms related to the crop plant. These wild forms are often the source of new gene variants that can be bred with existing varieties to create varieties with new attributes. Loss of wild species...
ng Objective Big Idea 4 Enduring Understanding 4.B Essential Knowledge Science Practice Learning Objective 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models. 4.16 The student is able to predict the effects of a change of matter or energy availability on comm...
sity Explore a U.S. Fish & Wildlife Service interactive map (http://openstaxcollege.org/l/habitat_map) of critical habitat for endangered and threatened species in the United States. To begin, select “Visit the online mapper.” For the most part, fishery extinction is not equivalent to biological extinction—the last fis...
the likely magnitude of the effects, with extinction rate estimates ranging from 15 percent to 40 percent of species committed to extinction by 2050. Scientists do agree, however, that climate change will alter regional climates, including rainfall and snowfall patterns, making habitats less hospitable to the species ...
eir situation. More fundamentally, the approach to protecting individual species rather than entire ecosystems is both inefficient and focuses efforts on a few highly visible and often charismatic species, perhaps at the expense of other species that go unprotected. At the same time, the Act has a critical habitat prov...
about individual protected areas by location or study statistics on protected areas by country or region. Access the website in this link and answer the following question.Which country has the largest percentage of its land protected? a. Costa Rica b. Madagascar c. United States d. Germany Habitat Restoration Habitat ...
maintenance of biodiversity. 38.3 Threats to Biodiversity The core threats to biodiversity are human population growth and unsustainable resource use. To date, the most significant causes of extinctions are habitat loss, introduction of exotic species, and overharvesting. Climate change is predicted to be a significant...
field c. introduction of an invasive ornamental plant in a new ecosystem d. emission of greenhouse gases increasing the average temperatures of an area 16. Which of the following activities will result in major habitat loss? 1764 Chapter 38 \| Conservation Biology and Biodiversity a. the fact that suitable primers for ...
inked to it like the honey and jam preparation industries. 35. Many chemical pesticides can be found in the bark and leaves of tropical plants. What is a difference in tropical This OpenStax book is available for free at http://cnx.org/content/col12078/1.6 Chapter 38 \| Conservation Biology and Biodiversity 1767 plants ...
The mass extinction that took place at the Cretaceous-Paleogene boundaries led to a loss of diversity, seen by fewer shapes of pollen grains. 49. 48. The average temperatures varied during the Pleistocene as glaciation periods were followed by warm intervals. Using the graph above and your existing knowledge, discuss ...
ehavioral biology, 1649 behavioral isolation, 747 benthic realm, 1575 beta cell, 1240 beta-pleated sheet (β-pleated), 130 − ) ion, 1338 bicarbonate (HCO3 bicarbonate buffer system, 1338 bicuspid valve, 1377 bile, 1090 binary (prokaryotic) fission, 430 binary fission, 434 binomial nomenclature, 836 biochemistry, 32, 35 ...
on factor-2 (eIF-2), 658, 664 euploid, 528, 535 eutrophication, 1715 Evaluate, 846, 847, 848 evaporation, 63, 77 eversion, 1299 evolution, 28, 35 evolutionary fitness, 792 excitatory postsynaptic potential (EPSP), 1151 exergonic, 268 exergonic reactions, 246 Exocytosis, 223 exocytosis, 225 exon, 622 exons, 612 exoskele...
life history, 1650 life science, 35 life sciences, 12 life table, 1650 ligand, 367, 393 ligase, 564, 575 light harvesting complex, 355 light microscope, 183 light microscopes, 148 light-dependent reaction, 355 light-dependent reactions, 334 light-harvesting complex, 343 light-independent reaction, 355 light-independen...
ositive gravitropism, 992 positive polarity, 876 positive regulator, 642, 664 Possible answers:, 0 post-transcriptional, 637, 664 post-translational, 637, 665 posterior pituitary, 1242 postzygotic barrier, 747 potential energy, 244, 268 potocytosis, 221, 226 precapillary sphincter, 1378 predator, 1576 predict, 804, 804...
80, 184 tissue, 36 tissues, 26 to construct a cladogram, 848 tonic activity, 1198 Tonicity, 209 tonicity, 226 Topoisomerase, 564 topoisomerase, 575 torpor, 1047 total lung capacity (TLC), 1340 trabecula, 1047 trabeculae, 1301 trachea, 1340 tracheid, 993 tragedy of the commons, 1760 trait, 473, 506 trans, 168 trans fat,...
n Area III. Organisms and Populations Topic 9: Five-Kingdom Survey Topic 10: Plants Topic 11: Animal Structure and Function Topic 12: Animal Reproduction and Development Topic 13: Animal Behavior Topic 14: Ecology 25% 7% 6% 4% 4% 4% 25% 8% 9% 8% 50% 8% 12% 10% 6% 4% 10% In order to make your review as easy as possible,...
u write is Nobel-Prize quality. 5. Budget your time. You have 90 minutes for four questions, about 23 minutes each. Just as it’s most important to answer all parts of a question, it’s best to respond to all the essay questions rather than to answer two or even three of them extremely well, with no response on the last ...
ole, near that atom. The area around the atom with the weaker pull on the electrons produces a positive pole. In a molecule of water (H2O), for example, electrons are shared between the oxygen atom and each hydrogen atom. Oxygen, with a greater electronegativity, exerts a stronger pull on the shared electrons than does...
eletons of insects, other arthropods, and mollusks. The α-glucose in starch and the β-glucose in cellulose illustrate the dramatic chemical changes that can arise from subtle molecular changes: the bonds in starch (specifically, the α-glycosidic linkages) can easily be broken down (digested) by humans and other animals...
ons can occur spontaneously, the presence of a catalyst accelerates the rate of the reaction because it lowers the activation energy required for the reaction to take place. A catalyst is any substance that accelerates a reaction but does not undergo a chemical change itself. Since the catalyst is not changed by the re...
olipids orient themselves into two layers, with the hydrophobic tails pointing to the inside of the “sandwich.” 2. C. When product E is no longer consumed by other reactions, it is available to inactivate enzyme D'. As quantities of product E accumulate, more and more of D' will be inactivated. As a result, the rate of...
. It is not likely that living things, as we know them, could be maintained in such an environment. The cohesion of water molecules allows water to flow through small openings. Water movement through plant vessels and animal capillaries is possible because of this characteristic. The movement of water to the upper part...
out aerobic respiration, a process in which energy (in the form of ATP) is obtained from carbohydrates. 35 06_097649 ch03.qxd 6/13/07 8:54 PM Page 36 Part I: Subject Area Reviews 8. Chloroplasts carry out photosynthesis, the plant process of incorporating energy from sunlight into carbohydrates. 9. Microtubules, inter...
olecules may be moving against the gradient and some molecules may be moving down the gradient (remember, the motion is random), the word “net” is used to indicate the overall, eventual result of the movement. Ultimately, a state of equilibrium is attained where molecules are uniformly distributed but continue to move ...
es or centrioles (microtubule organizing centers, or MTOCs), not from the plasma membrane. 6. E. Fats usually originate from smooth ER; proteins originate from ribosomes or rough ER; polysaccharides have various origins; answer D would be appropriate for mitochondria. 7. C. Since mitochondria produce ATP, they are ofte...
oduct of glycolysis. Although the Krebs cycle is described for 1 pyruvate, remember that glycolysis produces 2 pyruvate. In Figure 4-1, the “× 2” next to the pyruvate and the Krebs cycle is a reminder to multiply the products of this cycle by 2 to account for the products of a single glucose. 1. Pyruvate to acetyl CoA....
like NADH is removed and put into the formation of ethanol, essentially a waste product that eventually kills the yeast (and other organisms) that produce it. The goal of this pathway, however, does not really concern ethanol, but the task of freeing NAD+ to allow glycolysis to continue. Recall that in the absence of O...
or they might consist of parts that require you to assemble information from diverse areas of biology. The questions that follow are typical of either an entire AP exam question or merely that part of a question that is related to this section. Directions: Answer the questions below as completely and as thoroughly as ...
½ O + - 2 ATP 2 O2 -2e CALVIN CYCLE (C carbon reactions) 3 12 PGA 1 rubisco CO2 6 CO2 6 RuBP 6 ADP 12 ATP 12 ADP 2 12 NADPH 12 NADP + 12 G3P 3 4 6 ATP 10 G3P 2 G3P glucose Figure 5-1 5. Photosystem I. The electron transport chain terminates with PS I (with P700). Here the electrons are again energized by sunlight and ...
P do not lead to the production of useful, energy-rich molecules like glucose. Instead, specialized cellular organelles, the peroxisomes, are found near chloroplasts, where they function to break down photorespiration products. Thus, considerable effort is made by plants to rid the cell of the products of photorespirat...
and most of the enzymes for the light reactions are found in the thylakoid membranes. There are several kinds of chlorophyll, including chlorophyll a and b (and c and d in certain algae). P700 and P680 are special chlorophyll a molecules differing from other chlorophyll a molecules because of their special arrangement ...
hus, the efficiency of photosynthesis increases and photorespiration is avoided. In addition, by increasing the efficiency of photosynthesis, stomata need not remain open as long and, as a result, water is conserved. For CAM, discuss the temporal separation of CO2—how CO2, in the form of malic acid, is transported to t...
ny species begin cytokinesis and form cleavage furrows or cell plates. In other species, cytokinesis is delayed until after meiosis II. Also, a short interphase II may begin. In any case, no replication of chromosomes occurs during this period. Instead, part II of meiosis begins in both daughter nuclei. 5. In prophase ...
occurring during metaphase, ensures that microtubules are properly attached to all kineto- chores at the metaphase plate before division continues with anaphase. 80 09_097649 ch06.qxd 6/13/07 8:55 PM Page 81 Cell Division 2. Cyclin-dependent kinases (Cdk’s). Cdk enzymes activate proteins that regulate the cell cycle b...
omatid. The entire cell cycle includes both mitosis and interphase. Interphase is a period of growth and is divided into three stages, identified G1, S, and G2. The G1 phase describes the first period of growth following mitosis. During the S phase, a second DNA molecule (chromatid) is replicated from each chromosome. ...
normal convention to write a pair of alleles with the dominant allele first). In this condition, only the dominant allele is expressed. 7. The phenotype is the actual expression of a gene. Purple flowers, blue eyes, and brown hair each represent the phenotype of their respective genes. On the other hand, the genotype r...
e recessive trait (white flowers). So the cross is P ___ × pp. Since you do not know the second allele for the first individual, represent it with an underscore, leaving a blank space for the unknown allele. The next step is to perform both possible crosses, PP × pp and Pp × pp. For the first cross, all F1 will be purp...
ack-vestigial, bbvv) would be 1⁄4 BbVv, 1⁄4 bbvv, 1⁄4 Bbvv, and 1⁄4 bbVv (Figure 7-6). However, since the two genes are on the same chromosome and cannot assort independently, the graynormal fly produces only two kinds of gametes, BV and bv. Bv and bV gametes are not produced. Taking linkage into consideration, the exp...
n a segment of a chromosome is moved to another chromosome. For example, Down syndrome ordinarily occurs when an individual inherits an extra chromosome 21 (as a result of nondisjunction). However, Down syndrome can also occur after a translocation of a chromosome segment from chromosome 21 to chromosome 14. An individ...
could be BB × BB, BB × Bb, BB × bb, or Bb × Bb. Thus, there is no one single genotype for either parent. Answer choice E is incorrect because although one parent would always be black, you cannot be certain whether the second parent is black or white. 7. E. In the CCSS × ccss cross, CCSS produces only CS gametes, and ...
hromosomes (Mendel’s law of independent assortment). B. When two genes are linked, they are on the same chromosome. If they are on the same chromosome, they migrate together to either pole (unless crossing over occurs). Thus, they violate Mendel’s law of independent assortment and are inherited together as if they were...
ki segment and works backward toward the earlier segment (5' → 3') to fill the space left by the RNA primer. A special situation occurs, however, at the ends, or telomeres, of eukaryotic chromosomes. 109 11_097649 ch08.qxd 6/13/07 8:56 PM Page 110 Part I: Subject Area Reviews Two problems can occur when replication rea...
ing for a different protein product. A A-AA- 1 TATA box terminator 3 NUCLEUS DNA 3' 5' 3' -A -A-A A ---- A poly-A tail - A - A A N D emt p la te newRNA C U G A s tra d n G C A T onxe e xon - - - A -A- in t r o n snRNP complex RNA Polymerase 2 intr o n 3' 5' Transcription (Steps 1, 2, 3, 4) 4 5' intron 5' cap P P P G 5'...
the virus is DNA or RNA, double-stranded or single-stranded. Some important variations follow. • For most DNA viruses, the DNA is replicated to form new viral DNA and the DNA is transcribed to produce viral proteins. The DNA and proteins are assembled into new viruses. • For some RNA viruses, the RNA serves as mRNA or ...
rocess, DNA fragments of different lengths are separated as they diffuse through a gelatinous material under the influence of an electric field. Since DNA is negatively charged (because of the phosphate groups), it moves toward the positive electrode. Shorter fragments migrate further through the gel than longer, heavi...
is caused by the replacement of one amino acid by another in two chains of the hemoglobin protein, severely reducing the effectiveness of hemoglobin in carrying oxygen. However, a frameshift in the mRNA coding for hemoglobin would certainly make it entirely ineffective. 9. D. In a DNA double helix, thymine base-pairs w...
that appear from one generation to the next. These traits are represented by alleles for genes that modify morphology (form or structure), physiology, or behavior. Thus, evolution is changes in allele frequencies in populations over time. There are two areas of evolutionary study, as follows: 1. Microevolution describ...
to distinct changes in the allele frequencies of the population. • Insecticide resistance occurs as a result of directional selection. Because traits of individuals vary in a population, some individuals may possess some degree of resistance to the insecticide. These few individuals survive and produce offspring, most...
e very strong and can dramatically influence evolution. • An analogy of genetic drift can be made with the chances associated with flipping a coin. If a coin is flipped 100 times, the number of heads obtained would approach the expected probability of 1⁄2. However, if the coin is flipped only 5 times (analogous to a sm...
). The mule, a sterile offspring of a donkey and a horse, is a sterile hybrid. 8. Hybrid breakdown occurs when hybrids produce offspring that have reduced viability or fertility. Patterns of Evolution The evolution of species is often categorized into the following four patterns (Figure 9-3): 1. Divergent evolution des...
mbranes of cyanobacteria. 140 12_097649 ch09.qxd 6/13/07 8:57 PM Page 141 Evolution Sample Questions and Answers Multiple-Choice Questions Directions: Each of the following questions or statements is followed by five possible answers or sentence completions. Choose the one best answer or sentence completion. 1. Which o...
raction with the environment. As Darwin stated, natural selection is the survival of the fittest. Since there is considerable variation in traits among individuals in a population, individuals who possess advantageous traits survive and leave more offspring. Evolution occurs because alleles will increase in frequencies...
eny, or evolutionary relationships. Thus, by knowing the characteristics that define organisms within a taxon, you are aware of the evolutionary relationships among these organisms. The study of the evolutionary relationships among organisms is called systematics. All living things consist of one or more cells. All cel...
to move in response to light. 151 13_097649 ch10.qxd 6/13/07 8:57 PM Page 152 Part I: Subject Area Reviews 2. Dinoflagellates have two flagella. One flagellum is posterior, while the second flagellum is transverse and rests in an encircling mid groove perpendicular to the first flagellum. Some of these are bioluminesc...
tion of all plants is the diploid sporophyte generation. A diploid structure is more apt to survive genetic damage because two copies of each chromosome allow recessive mutations to be masked. 2. All plants possess a cuticle, a waxy covering on aerial parts that reduces desiccation. 3. The development of a vascular sys...
loid nucleus. The triploid nucleus divides by mitosis to produce the endosperm, which provides nourishment for subsequent development of the embryo and seedling. The fertilization of the egg and the polar nuclei each by a separate sperm nucleus is called double fertilization. Other evolutionary advancements among the a...
tes, the nerve cord becomes the brain and spinal cord. • Pharyngeal gill slits provide channels across the pharynx (a muscular structure at the beginning of the digestive tract) to the outside of the body. In some chordates, the slits become gills for oxygen exchange or filter feeding, while in others, the slits disapp...
the phylum Chordata have notochords. Roundworms are in the phylum Nematoda. 19. A. Pharyngeal gill slits appear only in chordates. All eumetazoa possess three germ layers and develop an archenteron. A true coelom is shared with other phyla, such as Echinodermata and Arthropoda. Not all chordates have vertebrae (only th...
s of cells that differ mostly by the nature of their cell walls. • Parenchyma cells, the most common component of ground tissue, have thin walls and serve various functions including storage, photosynthesis, and secretion. • Collenchyma cells, which have thick but flexible cell walls, serve mechanical support functions...
n most cases, however, the endodermis and casparian strips are lacking, as these tissues are specialized for water absorption. Other differences are noted in the following points. Plants Dicot Stem epidermis cortex phloem vascular cambium vascular cylinder xylem pith epidermis cortex xylem phloem pith vascular cylinder...
ater, cohesion results from the polarity of water molecules, which causes hydrogen bonding to occur between adjacent water molecules. As a result, the water molecules within a series of xylem cells (vessels or tracheids) behave as a single, polymerlike molecule. • Bulk flow of water through xylem cells occurs as water ...
ins. Although ABA is named for the process of abscission, its influence on the abscission of leaves, flowers, and fruits is controversial. Plant Responses to Stimuli Since plants are anchored by their roots, they cannot move in response to environmental stimuli. Instead, they change their growth pattern. A growth patte...
ct Area Reviews 10. All of the following are true about growth rings in 13. Ripening of fruit is promoted by trees EXCEPT: A. Growth rings can be used to measure the age of trees in temperate regions. B. Growth rings are caused by variations in the growth of xylem tissue. C. Growth rings in nonwoody plants provide a hi...
by the control center. When the control center determines that conditions have returned to normal, corrective action is discontinued. Thus, in negative feedback, the original condition is canceled, or negated, so that conditions are returned to normal. Compare this with positive feedback, in which an action intensifies...
vessels, the arterioles, and then branch further into the smallest vessels, the capillaries. Gas and nutrient exchange occurs by diffusion across capillary walls into interstitial fluids and into surrounding cells. Wastes and excess interstitial fluids move in the opposite direction as they diffuse into the capillarie...
onsist of a tube and closely associated blood vessels (Figure 12-2). The nephron is strategically positioned in the kidney so that the tube winds from the outer portion of the kidney, the cortex, down through the medulla, then back up into the cortex, then back down through the medulla, draining into the center of the ...
t. • Liver. The liver produces bile, which functions to emulsify fats. Emulsification is the breaking up of fat globules into smaller fat droplets, increasing the surface area upon which fat-digesting enzymes (lipase, for example) can operate. Since bile does not chemically change anything, it is not an enzyme. Bile is...
transmitters are recycled by the presynaptic cell. 195 15_097649 ch12.qxd 6/13/07 8:59 PM Page 196 Part I: Subject Area Reviews Some of the common neurotransmitters and the kind of activity they generate are summarized below: 1. Acetylcholine is commonly secreted at neuromuscular junctions, the gaps between motor neuro...
s a series of nonspecific events that occur in response to pathogens. When skin is damaged, for example, and bacteria or other organisms enter the body, the following events occur: • Histamine is secreted by basophils, white blood cells found in connective tissue. • Vasodilation (dilation of blood vessels), stimulated ...
ase of tropic hormones produced in the anterior pituitary. Tropic hormones are hormones whose target cells are other endocrine glands. Thus, they regulate hormone production by other glands. Because the pituitary gland controls the production of hormones by many other glands, it is often referred to as the “master glan...
loss of heat. As a result, your body temperature, especially of critical internal organs, will drop. 2. E. Gas exchange in human lungs is not aided by countercurrent exchange. The arteries and veins in the legs of wading birds and in the fins and tails of marine mammals are closely parallel so that heat transfer from ...
his book and involve the following processes: 5. Hormone regulation of the menstrual cycle. 6. Regulation of population size. 7. The rate of an enzyme reaction (through feedback inhibition and allosteric enzymes, for example). 8. Gene regulation by repressible and inducible enzymes. 209 15_097649 ch12.qxd 6/13/07 8:59 ...
s, but they ultimately disintegrate. Concentrating the cytoplasm in one viable secondary oocyte (and at the end of meiosis II, one egg) assures that adequate amounts of stored food, as well as mitochondria, ribosomes, and other cytoplasmic organelles, will be available for the developing embryo. In contrast, the sperm ...
, cleavages are spiral, forming cells on top that are shifted with respect to those below them. • Indeterminate and determinate cleavages. A cleavage is indeterminate if it produces blastomeres that, if separated, can individually complete normal development. In contrast, blastomeres produced by a determinate cleavage ...
ces can be narrowed by each successive cell division, cells are more likely to be determined later in the developmental sequence than earlier. By tracing the fates of cells during development, a lineage map can be built. A complete lineage map has been described for the nematode (roundworm) Caenorhabditis elegans. Ever...
e human chorionic gonadotropin (HCG), which induces the corpus luteum to continue production of progesterone, which, in turn, maintains the endometrium. Both questions 1 and 2 require a discussion of the reproductive processes, but their focuses are different. In answering the first question, you need to state the simi...
iciently. Habituation allows individuals to ignore repetitive events which, from experience, they know are inconsequential. As a result, the animals can remain focused on other, more meaningful events. Observational learning and insight provide a mechanism to learn new behaviors in response to unexpected events without...
ng, the males are driven from the hive and die. In a normal diploid reproductive system, mother and offspring, as well as sisters, are related, on average, by only 50% of their genes. However, because half of the chromosomes of all sister bees are the same (from their haploid father), they share, on average, 75% of the...
9:00 PM Page 236 Part I: Subject Area Reviews over 85 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 35-39 20-24 15-19 10-14 5-9 under % Male % Female Age Structure Figure 15-1 Type I (human Type II (Hydra ) Type III (oyster) Relative age Survivorship Curves Figure 15-2 236 18_097649 ch15.qxd 6/13/07...
ce partitioning, certain characteristics may enable individuals to obtain resources in their partitions more successfully. Selection for these characteristics reduces competition with individuals in other partitions and leads to a divergence of features, or character displacement. • Two species of finches that live on ...
increases with population growth, may be unsuitable to certain species. Succession is often described by the series of plant communities that inhabit a region over time. Animals, too, take up residence in these communities but usually in response to their attraction to the kinds of resident plants, not because of any w...
as NH4 other animals. The stages in the assimilation of nitrogen are as follows: Nitrogen fixation: N2 to NH4 and UV radiation. Nitrification: NH4 + or NO3 NH4 – to organic compounds by plant metabolism. – and NO2 + to NO2 – to NO3 – by various nitrifying bacteria. + by nitrogen-fixing prokaryotes (in soil and root nod...
mimicry E. Müllerian mimicry 8. Burr-bearing seeds that are dispersed by clinging to the fur of certain birds do not harm or help the birds. 9. The monarch and viceroy butterflies both have orange wings with the same distinctive black markings. When the monarch caterpillar feeds on milkweed, a toxic plant, it stores t...
egion. The final, climax community is a stable community that remains unchanged until destroyed by some catastrophic event, such as fire. Then the process begins again. The first community to occupy the lake consists of pioneer species with r-selected characteristics. These characteristics include good dispersal abilit...

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