Place value to 1000

Numbers to 1000 place value lesson 1

Place value, ordering and comparing numbers from 0 to 1000

Place Value to 1,000

Numbers to 10000(place values)

Figure 18-11 represents the amount of energy stored as organic material in each trophic level in an ecosystem. The pyramid shape of the diagram indicates the low percentage of energy transfer from one level to the next. On average, 10 percent of the total energy consumed in one trophic level is incor- porated into the organisms in the next. Why is the percentage of energy transfer so low? One reason is that some of the organisms in a trophic level escape being eaten. They eventually die and become food for decomposers, but the energy contained in their bodies does not pass to a higher trophic level. Even when an organism is eaten, some of the molecules in its body will be in a form that the consumer cannot break down and use. For example, a cougar cannot extract energy from the antlers, hooves, and hair of a deer. Also, the energy used by prey for cellu- lar respiration cannot be used by predators to synthesize new bio- mass. Finally, no transformation or transfer of energy is 100 percent efficient. Every time energy is transformed, such as during the reactions of metabolism, some energy is lost as heat. Limitations of Trophic Levels The low rate of energy transfer between trophic levels explains why ecosystems rarely contain more than a few trophic levels. Because only about 10 percent of the energy available at one trophic level is transferred to the next trophic level, there is not enough energy in the top trophic level to support more levels. Organisms at the lowest trophic level are usually much more abundant than organisms at the highest level. In Africa, for exam- ple, you will see about 1,000 zebras, gazelles, and other herbivores for every lion or leopard you see, and there are far more grasses and shrubs than there are herbivores. Higher trophic levels con- tain less energy, so, they can support fewer individuals.A population is a group of organisms that belong to the same species and live in a particular place at the same time. All of the bass living in a pond during a certain period of time make up a pop- ulation because they are isolated in the pond and do not interact with bass living in other ponds. The boundaries of a population may be imposed by a feature of the environment, such as a lake shore, or they can be arbitrarily chosen to simplify a study of the population. The humans shown in Figure 19-1 are part of the pop- ulation of a city. The properties of populations differ from those of individuals. An individual may be born, it may reproduce, or it may die. A population study focuses on a population as a whole—how many individuals are born, how many die, and so on. Population Size A population’s size is the number of individuals that the population contains. Size is a fundamental and important population property but can be difficult to measure directly. If a population is small and composed of immobile organisms, such as plants, its size can be determined simply by counting individuals. Often, though, individ- uals are too abundant, too widespread, or too mobile to be counted easily, and scientists must estimate the number of individuals in the population. Suppose that a scientist wants to know how many oak trees live in a 10 km2 patch of forest. Instead of searching the entire patch of forest and counting all the oak trees, the scientist could count the trees in a smaller section of the forest, such as a 1 km2 area. The scientist could then use this value to estimate the population of the larger area. SECTION 1 OBJECTIVES ● Describe the main properties that scientists measure when they study populations. ● Compare the three general patterns of population dispersion. ● Identify the measurements used to describe changing populations. ● Compare the three general types of survivorship curves. VOCABULARY population population density dispersion birth rate death rate life expectancy age structure survivorship curve FIGURE 19-1 A population can be widely distributed, as Earth’s human population is, or confined to a small area, as species of fish in a lake are. Copyright © by Holt, Rinehart and Winston. All rights reserved. 382 CHAPTER 19 If the small patch contains 25 oaks, an area 10 times larger would likely contain 10 times as many oak trees. A similar kind of sampling technique might be used to estimate the size of the pop- ulation shown in Figure 19-2. To use this kind of estimate, the sci- entist must assume that the distribution of individuals in the entire population is the same as that in the sampled group. Estimates of population size are based on many such assumptions, so all esti- mates have the potential for error. Population Density Population density measures how crowded a population is. This measurement is always expressed as the number of individuals per unit of area or volume. For example, the population density of humans in the United States is about 30 people per square kilome- ter. Table 19-1 shows the population sizes and densities of humans in several countries in 2003. These estimates are calculated for the total land area. Some areas of a country may be sparsely popu- lated, while other areas are very densely populated. Dispersion A third population property is dispersion (di-SPUHR-zhuhn). Dispersion is the spatial distribution of individuals within the popu- lation. In a clumped distribution, individuals are clustered together. In a uniform distribution, individuals are separated by a fairly con- sistent distance. In a random distribution, each individual’s location is independent of the locations of other individuals in the popula- tion. Figure 19-3 illustrates the three possible patterns of dispersion. Clumped distributions often occur when resources such as food or living space are clumped. Clumped distributions may also occur because of a species’ social behavior, such as when animals gather into herds or flocks. Uniform distributions may result from social behavior in which individuals within the same habitat stay as far away from each other as possible. For example, a bird may locate its nest so as to maximize the distance from the nests of other birds. These migrating wildebeests in East Africa are too numerous and mobile to be counted. Scientists must use sampling methods at several locations to monitor changes in the population size of the animals. FIGURE 19-2 TABLE 19-1 Population Size and Density of Some Countries Population size Population density Country (in millions) (in individuals/km2) China 1,289 135 India 1,069 325 United States 292 30 Russia 146 8 Japan 128 337 Mexico 105 54 Kenya 32 54 Australia 20 3 dispersion from the Latin dis-, meaning “out,” and spargere, meaning “to scatter” Word Roots and Origins Copyright © by Holt, Rinehart and Winston. All rights reserved. POPULATIONS 383 The social interactions of birds called gannets, which are shown in Figure 19-3b, result in a uniform distribution. Each gannet chooses a small nesting area on the coast and defends it from other gannets. In this way, each gannet tries to maximize its distance from all of its neighbors, which causes a uniform distribution of individuals. Few populations are truly randomly dispersed. Rather, they show degrees of clumping or uniformity. The dispersion pattern of a population sometimes depends on the scale at which the popu- lation is observed. The gannets shown in Figure 19-3b are uni- formly distributed on a scale of a few meters. However, if the entire island on which the gannets live is observed, the distribution appears clumped because the birds live only near the shore. POPULATION DYNAMICS All populations are dynamic—they change in size and composition over time. To understand these changes, scientists must know more than the population’s size, density, and dispersion. One important measure is the birth rate, the number of births occur- ring in a period of time. In the United States, for example, there are about 4 million births per year. A second important measure is the death rate, or mortality rate, which is the number of deaths in a

Considerations in the Study of Criminal Justice Inequilty in Canada A key feature of Can Society is inequity, particularly income inequity Top 1% earns 39.1% of income One million children live in low-income households Gender inequality in the workplace costs Canada $150 billion/year Women working full-time earn 74.2 cents for every dollar that full-time male workers make Racism, Prejudice and Discrimination Prejudice: unsubtitled, negative prejudgment of individuals/groups based on ethnicity, religion or race Discrimination: action/decision treats a person/group negatively Racism: prejudice, discrimination or antagonism based on belief that one’s race is superior Racial Profiling: action that relies on stereotypes about race, colour, ethnicity, ancestry, religion, place of origin rather than on reasonable suspicion Racial Profiling Experiences of Women Women- UNiqu experiences within CJS Higher education than ever before Self-report violent victimization is higher among women (85% per 100,000 women versus 67% per 100,000 for men) Experiences of Indigenous Persons Disproportionately represented as both victims and offenders at all stages of the criminal justice system Violent victimization is more than double that of non-indigenous persons (160 vs. 74/1,000) 27% homicide victims in 2009 were indigenous The Legacy of Colonization Many indigenous people live on the margins of Canadian society Pervasive poverty High rates of unemployment Low levels of formal education High death rates (accidents/violence) Often much worse off than non-indigenous persons Residential school system operated by federal government -1880s-1990 150,000 Indigenous children sent to residential schools “60s schoop” Intergenerational impact - residential schools - Truth and Reconciliation Commission Additional Considerations Escalating Costs of the CJS CJS expenditures have increased despite the overall decline in crime rates across the country Rise of the Surveillance Society Life in early 21st century- the pervasiveness of technology, surveillance technology Most citizens do not realize that every day their activities are recorded by video camera while shopping, when standing at a bus stop, even while driving Needs of Crime Victims Physically, Psychologically, emotionally, financially and social Victims can feel worse because of re-victimization Re-victimization: the negative impact on victims of crimes casued by the decisions and actions of criminal justice personnel Canadian Victims Bills of Rights, 2015. Summary Inequality, racism, prejudice and discriantion were intriduced as features of Canadian Society These are often manifested in racial profliing and the racialization of gropus and individuals Addtional consideration in the study of teh criminal juscitce system are The escalating costs of criminal jusicte The question as to whether the Canadian public is getting the “value of money,” The changing boundaries of criminal justice agencies as reflected in the development of multi agency partnerships Additional Consideration in the study of the criminal Justice system are The challenges posed by teh rise of teh surveillance society due to the pervasiveness of technology The challenges faced by crime victims Concerns for the health and wellness of offenders criminal justice professionals and The lack of diversity among crimina

Place Value to Tens of Millions - Starter Quiz

Place Value to Millions

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