Division table from 2 to 10

Multiplication and Division table from 2 to 10

MYTH The British helped the Jews displace the native Arab population of Palestine. FACT Herbert Samuel, a British Jew who served as the first High Commissioner of Palestine, placed restrictions on Jewish immigration “in the ‘interests of the present population’ and the ‘absorptive capacity’ of the country.”1 The influx of Jewish settlers was said to force the Arab fellahin (native peasants) from their land. This was when less than a million people lived in an area that now supports more than nine million. The British limited the absorptive capacity of Palestine when, in 1921, Colonial Secretary Winston Churchill severed nearly four-fifths of Palestine—some thirty-five thousand square miles—to create a new Arab entity, Transjordan. As a consolation prize for the Hejaz and Arabia (which are both now Saudi Arabia) going to the Saud family, Churchill rewarded Sharif Hussein’s son Abdullah for his contribution to the war against Turkey by installing him as Transjordan’s emir. The British went further and placed restrictions on Jewish land purchases in what remained of Palestine. By 1949, the British had allotted 87,500 acres of the 187,500 acres of cultivable land to Arabs and only 4,250 acres to Jews. This contradicted Article 6 of the Mandate which stated that “the Administration of Palestine…shall encourage, in cooperation with the Jewish Agency…close settlement by Jews on the land, including State lands and waste lands not acquired for public purposes.”2 Ultimately, the British admitted that the argument about the country’s absorptive capacity was specious. The Peel Commission said, “The heavy immigration in the years 1933–36 would seem to show that the Jews have been able to enlarge the absorptive capacity of the country for Jews.”3 MYTH The British allowed Jews to flood Palestine while Arab immigration was tightly controlled. FACT The British response to Jewish immigration set a precedent of appeasing the Arabs, which was followed for the duration of the Mandate. The British restricted Jewish immigration while allowing Arabs to enter the country freely. Apparently, London did not feel that a flood of Arab immigrants would affect the country’s “absorptive capacity.” During World War I, the Jewish population in Palestine declined because of the war, famine, disease, and expulsion by the Turks. In 1915, approximately 83,000 Jews lived in Palestine among 590,000 Muslim and Christian Arabs. According to the 1922 census, the Jewish population was 83,000, while the Arabs numbered 643,000.4 Thus, the Arab population grew exponentially while that of the Jews stagnated. In the mid-1920s, Jewish immigration to Palestine increased primarily because of anti-Jewish economic legislation in Poland and Washington’s imposition of restrictive quotas.5 The record number of immigrants in 1935 (see table) was a response to the growing persecution of Jews in Nazi Germany. The British administration considered this number too large, however, so the Jewish Agency was informed that less than one-third of the quota it asked for would be approved in 1936.6 The British gave in further to Arab demands by announcing in the 1939 White Paper that an independent Arab state would be created within ten years and that Jewish immigration was to be limited to 75,000 for the next five years, after which it was to cease altogether. It also forbade land sales to Jews in 95% of the territory of Palestine. The Arabs, nevertheless, rejected the proposal. Jewish Immigration to Palestine7 1919 1,806 1931 4,075 1920 8,223 1932 12,533 1921 8,294 1933 37,337 1922 8,685 1934 45,267 1923 8,175 1935 66,472 1924 13,892 1936 29,595 1925 34,386 1937 10,629 1926 13,855 1938 14,675 1927 3,034 1939 31,195 1928 2,178 1940 10,643 1929 5,249 1941 4,592 1930 4,944 By contrast, throughout the Mandatory period, Arab immigration was unrestricted. In 1930, the Hope Simpson Commission, sent from London to investigate the 1929 Arab riots, said the British practice of ignoring the uncontrolled illegal Arab immigration from Egypt, Transjordan, and Syria had the effect of displacing the prospective Jewish immigrants.8 The British governor of the Sinai from 1922 to 1936 observed, “This illegal immigration was not only going on from the Sinai, but also from Transjordan and Syria, and it is very difficult to make a case out for the misery of the Arabs if at the same time their compatriots from adjoining states could not be kept from going in to share that misery.”9 The Peel Commission reported in 1937 that the “shortfall of land is…due less to the amount of land acquired by Jews than to the increase in the Arab population.”10 MYTH The British changed their policy to allow Holocaust survivors to settle in Palestine. FACT The gates of Palestine remained closed for the duration of the war, stranding hundreds of thousands of Jews in Europe, many of whom became victims of Hitler’s “Final Solution.” After the war, the British refused to allow the survivors of the Nazi nightmare to find sanctuary in Palestine. On June 6, 1946, President Truman urged the British government to relieve the suffering of the Jews confined to displaced persons camps in Europe by immediately accepting 100,000 Jewish immigrants. Britain’s foreign minister Ernest Bevin replied sarcastically that the United States wanted displaced Jews to immigrate to Palestine “because they did not want too many of them in New York.”11 Some Jews reached Palestine, many smuggled in on dilapidated ships organized by the Haganah. Between August 1945 and the establishment of the State of Israel in May 1948, sixty-five “illegal” immigrant ships, carrying 69,878 people, arrived from European shores. In August 1946, however, the British began to intern those they caught in camps on Cyprus. Approximately 50,000 people were detained in the camps, and 28,000 remained imprisoned when Israel declared independence.12 MYTH As the Jewish population grew, the plight of the Palestinian Arabs worsened. FACT In July 1921, Hasan Shukri, the mayor of Haifa and president of the Muslim National Associations, sent a telegram to the British government in reaction to a delegation of Palestinians that went to London to try to stop the implementation of the Balfour Declaration. Shukri wrote: We are certain that without Jewish immigration and financial assistance there will be no future development of our country as may be judged from the fact that the towns inhabited in part by Jews such as Jerusalem, Jaffa, Haifa, and Tiberias are making steady progress while Nablus, Acre, and Nazareth where no Jews reside are steadily declining.13 The Jewish population increased by 470,000 between World War I and World War II, while the non-Jewish population rose by 588,000.14 The permanent Arab population increased by 120% between 1922 and 1947.15 This rapid growth of the Arab population was a result of several factors. One was immigration from neighboring states—constituting 37% of the total immigration to pre-state Israel—by Arabs who wanted to take advantage of the higher standard of living the Jews had made possible.16 The Arab population also grew because of the improved living conditions created by the Jews as they drained malarial swamps and brought improved sanitation and health care to the region. Thus, for example, the Muslim infant mortality rate fell from 201 per thousand in 1925 to 94 per thousand in 1945, and life expectancy rose from 37 years in 1926 to 49 in 1943.17 The Arab population increased the most in cities where large Jewish populations had created new economic opportunities. From 1922–1947, the non-Jewish population increased by 290% in Haifa, 131% in Jerusalem, and 158% in Jaffa. The growth in Arab towns was more modest: 42% in Nablus, 78% in Jenin, and 37% in Bethlehem.18 MYTH Jews stole Arab land. FACT Despite the growth in their population, the Arabs continued to assert they were being displaced. From the beginning of World War I, however, part of Palestine’s land was owned by absentee landlords who lived in Cairo, Damascus, and Beirut. About 80% of the Palestinian Arabs were debt-ridden peasants, semi-nomads, and Bedouins.19 Jews went out of their way to avoid purchasing land in areas where Arabs might be displaced. They sought land that was largely uncultivated, swampy, cheap, and—most important—without tenants. In 1920, Labor Zionist leader David Ben-Gurion expressed his concern about the Arab fellahin, whom he viewed as “the most important asset of the native population.” He insisted that “under no circumstances must we touch land belonging to fellahs or worked by them.” Instead, he advocated helping liberate them from their oppressors. “Only if a fellah leaves his place of settlement,” Ben-Gurion added, “should we offer to buy his land, at an appropriate price.”20 Jews only began to purchase cultivated land after buying all the uncultivated territory. Many Arabs were willing to sell because of the migration to coastal towns and because they needed money to invest in the citrus industry.21 When John Hope Simpson arrived in Palestine in May 1930, he observed, “They [the Jews] paid high prices for the land and, in addition, they paid to certain of the occupants of those lands a considerable amount of money which they were not legally bound to pay.”22 In 1931, Lewis French conducted a survey of landlessness for the British government and offered new plots to any Arabs who had been “dispossessed.” British officials received more than 3,000 applications, of which 80% were ruled invalid by the government’s legal adviser because the applicants were not landless Arabs. This left only about 600 landless Arabs, 100 of whom accepted the government land offer.23 In April 1936, a new outbreak of Arab attacks on Jews was instigated by local Palestinian leaders who were later joined by Arab volunteers led by a Syrian guerrilla named Fawzi al-Qawuqji, the commander of the Arab Liberation Army. By November, when the British finally sent a new commission headed by Lord Peel to investigate, 89 Jews had been killed and more than 300 wounded.24 The Peel Commission’s report found that Arab complaints about Jewish land acquisition were baseless. It pointed out that “much of the land now carrying orange groves was sand dunes or swamp and uncultivated when it was purchased…There was at the time of the earlier sales little evidence that the owners possessed either the resources or training needed to develop the land.”25 Moreover, the Commission found the shortage was “due less to the amount of land acquired by Jews than to the increase in the Arab population.” The report concluded that the presence of Jews in Palestine, along with the work of the British administration, had resulted in higher wages, an improved standard of living, and ample employment opportunities.26 It is made quite clear to all, both by the map drawn up by the Simpson Commission and by another compiled by the Peel Commission, that the Arabs are as prodigal in selling their land as they are in useless wailing and weeping (emphasis in the original). —Transjordan’s king Abdullah27 Even at the height of the Arab revolt in 1938 (which began in April 1936 with the murder of two Jews by Arabs and the subsequent murder of two Arab workers by members of the Jewish underground28), the British high commissioner to Palestine believed the Arab landowners were complaining about sales to Jews to drive up prices for lands they wished to sell. Many Arab landowners had been so terrorized by Arab rebels they decided to leave Palestine and sell their property to the Jews.29 The Jews paid exorbitant prices to wealthy landowners for small tracts of arid land. “In 1944, Jews paid between $1,000 and $1,100 per acre in Palestine, mostly for arid or semiarid land; in the same year, rich black soil in Iowa was selling for about $110 per acre.”30 By 1947, Jewish holdings in Palestine amounted to about 463,000 acres. Approximately 45,000 were acquired from the mandatory government, 30,000 were bought from various churches, and 387,500 were purchased from Arabs. Analyses of land purchases from 1880 to 1948 show that 73% of Jewish plots were purchased from large landowners, not poor fellahin.31 Many leaders of the Arab nationalist movement, including members of the Muslim Supreme Council, and the mayors of Gaza, Jerusalem, and s sold land to the Jews. As’ad el-Shuqeiri, a Muslim religious scholar and father of Palestine Liberation Organization chairman Ahmed Shuqeiri, took Jewish money for his land. Even King Abdullah leased land to the Jews.32 MYTH The British helped the Palestinians to live peacefully with the Jews. FACT In 1921, Haj Amin el-Husseini first began to organize fedayeen (“one who sacrifices himself”) to terrorize Jews. El-Husseini hoped to duplicate the success of Kemal Atatürk in Turkey by driving the Jews out of Palestine just as Kemal had driven the invading Greeks from his country.33 Arab radicals gained influence because the British administration was unwilling to take effective action against them until they began a revolt against British rule. Colonel Richard Meinertzhagen, former head of British military intelligence in Cairo, and later chief political officer for Palestine and Syria, wrote in his diary that British officials “incline towards the exclusion of Zionism in Palestine.” The British encouraged the Palestinians to attack the Jews. According to Meinertzhagen, Col. Bertie Harry Waters-Taylor (financial adviser to the military administration in Palestine 1919–23) met with el-Husseini in 1920, a few days before Easter, and told him that “he had a great opportunity at Easter to show the world…that Zionism was unpopular not only with the Palestine administration but in Whitehall.” He added that “if disturbances of sufficient violence occurred in Jerusalem at Easter, both General [Louis] Bols [chief administrator in Palestine, 1919–20] and General [Edmund] Allenby [commander of the Egyptian force, 1917–19, then high commissioner of Egypt] would advocate the abandonment of the Jewish Home. Waters-Taylor explained that freedom could only be attained through violence.”34 El-Husseini took the colonel’s advice and instigated a riot. The British withdrew their troops and the Jewish police from Jerusalem, allowing the Arab mob to attack Jews and loot their shops. Because of el-Husseini’s overt role in instigating the pogrom, the British decided to arrest him. He escaped, however, and was sentenced to ten years in absentia. A year later, some British Arabists convinced High Commissioner Herbert Samuel to pardon el-Husseini and to appoint him Mufti (a cleric in charge of Jerusalem’s Islamic holy places). By contrast, Vladimir Jabotinsky and several followers, who had formed a Jewish defense organization during the unrest, were sentenced to 15 years. They were released a few months later.35 Samuel met with el-Husseini on April 11, 1921, and was assured “that the influences of his family and himself would be devoted to tranquility.” Three weeks later, riots in Jaffa and elsewhere left forty-three Jews dead.36 El-Husseini consolidated his power and took control of all Muslim religious funds in Palestine. He used his authority to gain control over the mosques, the schools, and the courts. No Arab could reach an influential position without being loyal to the Mufti. His power was so absolute that “no Muslim in Palestine could be born or die without being beholden to Haj Amin.”37 The Mufti’s henchmen also ensured he would have no opposition by systematically killing Palestinians who discussed cooperation with the Jews from rival clans. As the spokesman for Palestinian Arabs, el-Husseini did not ask that Britain grant them independence. On the contrary, in a letter to Churchill in 1921, he demanded that Palestine be reunited with Syria and Transjordan.38 The Arabs found rioting an effective political tool because of the lax British response toward violence against Jews. In handling each riot, the British prevented Jews from protecting themselves but made little effort to prevent the Arabs from attacking them. After each outbreak, a British commission of inquiry would try to establish the cause of the violence. The conclusion was always the same: The Arabs feared being displaced by the Jews. To stop the rioting, the commissions would recommend that restrictions be placed on Jewish immigration. Thus, the Arabs learned they could always stop the influx of Jews by staging riots. This cycle began after a series of riots in May 1921. After failing to protect the Jewish community from Arab mobs, the British appointed the Haycraft Commission to investigate the cause of the violence. Although the panel concluded the Arabs had been the aggressors, it rationalized the cause of the attack: “The fundamental cause of the riots was a feeling among the Arabs of discontent with, and hostility to, the Jews, due to political and economic causes, and connected with Jewish immigration, and with their conception of Zionist policy.”39 One consequence of the violence was the institution of a temporary ban on Jewish immigration. The Arab fear of being “displaced” or “dominated” was an excuse for their attacks on Jewish settlers. Note, too, that these riots were not inspired by nationalistic fervor—nationalists would have rebelled against their British overlords—they were motivated by economics, the radical Islamic views of the Mufti, and misunderstanding. In 1929, Arab provocateurs convinced the masses that the Jews had designs on the Temple Mount (a tactic still used today to incite violence). A Jewish religious observance at the Western Wall, which forms a part of the Temple Mount, served as a pretext for rioting by Arabs against Jews, which spilled out of Jerusalem into other villages and towns, including Safed and Hebron. Again, the British administration made no effort to prevent the violence, and, after it began, the British did nothing to protect the Jewish population. After six days of mayhem, the British finally brought troops in to quell the disturbance. By this time, most of Hebron’s Jews had fled or been killed. In all, 133 Jews were killed and 399 wounded in the pogroms.40 After the riots, the British ordered an investigation, resulting in the Passfield White Paper. It said the “immigration, land purchase and settlement policies of the Zionist Organization were already or were likely to become, prejudicial to Arab interests. It understood the mandatory government’s obligation to the non-Jewish community to mean that Palestine’s resources must be primarily reserved for the growing Arab economy.”41 This meant it was necessary to restrict Jewish immigration and land purchases. MYTH The Mufti was not a Nazi collaborator. FACT In 1941, Haj Amin al-Husseini, the Mufti of Jerusalem, fled to Germany and met with Adolf Hitler, Heinrich Himmler, Joachim Von Ribbentrop, and other Nazi leaders. He wanted to persuade them to extend the Nazis’ anti-Jewish program to the Arab world. The Mufti sent Hitler fifteen drafts of declarations he wanted Germany and Italy to make concerning the Middle East. One called on the two countries to declare the illegality of the Jewish home in Palestine. He also asked the Axis powers to “accord to Palestine and to other Arab countries the right to solve the problem of the Jewish elements in Palestine and other Arab countries in accordance with the interest of the Arabs, and by the same method that the question is now being settled in the Axis countries.”42 In November 1941, the Mufti met with Hitler, who told him the Jews were his foremost enemy. The Nazi dictator rebuffed the Mufti’s requests for a declaration in support of the Arabs, however, telling him the time was not right. The Mufti offered Hitler his “thanks for the sympathy which he had always shown for the Arab and especially Palestinian cause, and to which he had given clear expression in his public speeches.” He added, “The Arabs were Germany’s natural friends because they had the same enemies as had Germany, namely…the Jews.” Hitler told the Mufti he opposed the creation of a Jewish state and that Germany’s objective was destroying the Jewish element in the Arab sphere.43 In 1945, Yugoslavia sought to indict the Mufti as a war criminal for his role in recruiting twenty thousand Muslim volunteers for the SS, who participated in the killing of Jews in Croatia and Hungary. He escaped French detention in 1946, however, and continued his fight against the Jews from Cairo and later Beirut where he died in 1974. MYTH The bombing of the King David Hotel was part of a deliberate terror campaign against civilians. FACT British troops seized the Jewish Agency compound on June 29, 1946, and confiscated large quantities of documents. At about the same time, more than 2,500 Jews from all over Palestine were arrested. A week later, news of a massacre of 40 Jews in a pogrom in Poland reminded the Jews of Palestine how Britain’s restrictive immigration policy had condemned thousands to death. In response to the British provocations, and a desire to demonstrate that the Jews’ spirit could not be broken, the United Resistance Movement planned to bomb the King David Hotel, which housed the British military command and the Criminal Investigation Division in addition to hotel guests. The Haganah pulled out of the plot and left it up to the Irgun. Irgun leader Menachem Begin stressed his desire to avoid civilian casualties and the plan was to warn the British so they would evacuate the building before it was blown up. Three telephone calls were placed on July 22, 1946, one to the hotel, another to the French Consulate, and a third to the Palestine Post warning that explosives in the King David Hotel would soon be detonated. The call to the hotel was received and ignored. Begin quotes one British official who supposedly refused to evacuate the building, saying, “We don’t take orders from the Jews.”44 As a result, when the bombs exploded, the casualty toll was high: 91 killed and 45 injured. Among the casualties were 15 Jews. Few people in the main part of the hotel were injured.45 For decades, the British denied they had been warned. In 1979, however, a member of the British Parliament provided the testimony of a British officer who heard other officers in the King David Hotel bar joking about a Zionist threat to the headquarters. The officer who overheard the conversation immediately left the hotel and survived.46 In contrast to Arab attacks against Jews, which Arab leaders hailed as heroic actions, the Jewish National Council denounced the bombing of the King David.47 1 Aharon Cohen, Israel and the Arab World, (NY: Funk and Wagnalls, 1970), p. 172

CHARACTERISTICS OF LIFE The world is filled with familiar objects, such as tables, rocks, plants, pets, and automobiles. Which of these objects are living or were once living? What are the criteria for assigning something to the living world or the nonliving world? Biologists have established that living things share seven characteristics of life. These characteristics are organization and the presence of one or more cells, response to a stimulus (plural, stimuli), homeostasis, metabolism, growth and development, reproduction, and change through time. Organization and Cells Organization is the high degree of order within an organism’s internal and external parts and in its interactions with the living world. For example, compare an owl to a rock. The rock has a spe- cific shape, but that shape is usually irregular. Furthermore, differ- ent rocks, even rocks of the same type, are likely to have different shapes and sizes. In contrast, the owl is an amazingly organized individual, as shown in Figure 1-2. Owls of the same species have the same body parts arranged in nearly the same way and interact with the environment in the same way. Copyright © by Holt, Rinehart and Winston. All rights reserved. ORGANISM (Barn Owl) ORGAN (Owl’s Ear) TISSUE (Nervous Tissue Within the Ear) CELL (Nerve Cell) Every living organism has a level of organization. The different levels of organization for a complex multicellular organism, such as an owl, are shown in the figure below. FIGURE 1-2 THE SCIENCE OF LIFE 7 All living organisms, whether made up of one cell or many cells, have some degree of organization. A cell is the smallest unit that can perform all life’s processes. Some organisms, such as bacteria, are made up of one cell and are called unicellular (YOON-uh-SEL-yoo-luhr) organisms. Other organisms, such as humans or trees, are made up of multiple cells and are called multicellular (MUHL-ti-SEL-yoo-luhr) organisms. Complex multicellular organisms have the level of orga- nization shown in Figure 1-2. In the highest level, the organism is made up of organ systems, or groups of specialized parts that carry out a certain function in the organism. For example, an owl’s ner- vous system is made up of a brain, sense organs, nerve cells, and other parts that sense and respond to the owl’s surroundings. Organ systems are made up of organs. Organs are structures that carry out specialized jobs within an organ system. An owl’s ear is an organ that allows the owl to hear. All organs are made up of tissues. Tissues are groups of cells that have similar abilities and that allow the organ to function. For example, nervous tissue in the ear allows the ear to detect sound. Tissues are made up of cells. A cell must be covered by a membrane, contain all genetic information necessary for replication, and be able to carry out all cell functions. Within each cell are organelles. Organelles are tiny structures that carry out functions necessary for the cell to stay alive. Organelles contain biological molecules, the chemical compounds that provide physical structure and that bring about movement, energy use, and other cellular functions. All biological molecules are made up of atoms. Atoms are the simplest particle of an ele- ment that retains all the properties of a certain element. Response to Stimuli Another characteristic of life is that an organism can respond to a stimulus—a physical or chemical change in the internal or external environment. For example, an owl dilates its pupils to keep the level of light entering the eye constant. Organisms must be able to respond and react to changes in their environment to stay alive. ORGANELLE (Mitochondrion) BIOLOGICAL MOLECULE (Phospholipid) ATOM (Oxygen) cell from the Latin, cella meaning “small room,” or “hut” Word Roots and Origins www.scilinks.org Topic: Characteristics of Life Keyword: HM60257 mb06se_bios01.qxd 5/18/07 10:37 AM Page 7 8 CHAPTER 1 Homeostasis All living things, from single cells to entire organisms, have mecha- nisms that allow them to maintain stable internal conditions. Without these mechanisms, organisms can die. For example, a cell’s water content is closely controlled by the taking in or releas- ing of water. A cell that takes in too much water will rupture and die. A cell that doesn’t get enough water will also shrivel and die. Homeostasis (HOH-mee-OH-STAY-sis) is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Organisms have regulatory systems that maintain internal conditions, such as temperature, water content, and uptake of nutrients by the cell. In fact, multi- cellular organisms usually have more than one way of maintain- ing important aspects of their internal environment. For example, an owl’s temperature is maintained at about 40°C (104°F). To keep a constant temperature, an owl’s cells burn fuel to produce body heat. In addition, an owl’s feathers can fluff up in cold weather. In this way, they trap an insulating layer of air next to the bird’s body to maintain its body temperature. Metabolism Living organisms use energy to power all the life processes, such as repair, movement, and growth. This energy use depends on metabolism (muh-TAB-uh-LIZ-uhm). Metabolism is the sum of all the chemical reactions that take in and transform energy and materials from the environment. For example, plants, algae, and some bacteria use the sun’s energy to generate sugar molecules during a process called photosynthesis. Some organisms depend on obtaining food energy from other organisms. For instance, an owl’s metabolism allows the owl to extract and modify the chemi- cals trapped in its nightly prey and use them as energy to fuel activities and growth. Growth and Development All living things grow and increase in size. Some nonliving things, such as crystals or icicles, grow by accumulating more of the same material of which they are made. In contrast, the growth of living things results from the division and enlargement of cells. Cell division is the formation of two new cells from an existing cell, as shown in Figure 1-3. In unicellular organisms, the primary change that occurs following cell division is cell enlargement. In multi- cellular life, however, organisms mature through cell division, cell enlargement, and development. Development is the process by which an organism becomes a mature adult. Development involves cell division and cell differen- tiation, or specialization. As a result of development, an adult organism is composed of many cells specialized for different func- tions, such as carrying oxygen in the blood or hearing. In fact, the human body is composed of trillions of specialized cells, all of which originated from a single cell, the fertilized egg. This unicellular organism, Escherichia coli, inhabits the human intestines. E. coli reproduces by means of cell division, during which the original cell splits into two identical offspring cells. FIGURE 1-3 Observing Homeostasis Materials 500 mL beakers (3), wax pen, tap water, thermometer, ice, hot water, goldfish, small dip net, watch or clock with a second hand Procedure 1. Use a wax pen to label three 500 mL beakers as follows: 27°C (80°F), 20°C (68°F), 10°C (50°F). Put 250 mL of tap water in each beaker. Use hot water or ice to adjust the tem- perature of the water in each beaker to match the temperature on the label. 2. Put the goldfish in the beaker of 27°C water. Record the number of times the gills move in 1 minute. 3. Move the goldfish to the beaker of 20°C water. Repeat observations. Move the goldfish to the beaker of 10°C. Repeat observations. Analysis What happens to the rate at which gills move when the temp- erature changes? Why? How do gills help fish maintain homeostasis? Quick Lab mb06se_bios01.qxd 5/18/07 10:37 AM Page 8 THE SCIENCE OF LIFE 9 Reproduction All organisms produce new organisms like themselves in a process called reproduction. Reproduction, unlike other characteristics, is not essential to the survival of an individual organism. However, because no organism lives forever, reproduction is essential for the continuation of a species. Glass frogs, as shown in Figure 1-4, lay many eggs in their lifetime. However, only a few of the frogs’ off- spring reach adulthood and successfully reproduce. During reproduction, organisms transmit hereditary informa- tion to their offspring. Hereditary information is encoded in a large molecule called deoxyribonucleic acid, or DNA. A short segment of DNA that contains the instructions for a single trait of an organism is called a gene. DNA is like a large library. It contains all the books—genes—that the cell will ever need for making all the struc- tures and chemicals necessary for life. Hereditary information is transferred to offspring during two kinds of reproduction. In sexual reproduction, hereditary information recombines from two organisms of the same species. The resulting offspring are similar but not identical to their parents. For example, a male frog’s sperm can fertilize a female’s egg and form a single fer- tilized egg cell. The fertilized egg then develops into a new frog. In asexual reproduction, hereditary information from different organisms is not combined; thus the original organism and the new organism are genetically the same. A bacterium, for example, reproduces asexually when it splits into two identical cells. Change Through Time Although individual organisms experience many changes during their lifetime, their basic genetic characteristics do not change. However, populations of living organisms evolve or change through time. The ability of populations of organisms to change over time is important for survival in a changing world. This factor is also impor- tant in explaining the diversity of life-forms we see on Earth today.

The cytoskeleton is a network of thin tubes and filaments that crisscrosses the cytosol. The tubes and filaments give shape to the cell from the inside in the same way that tent poles support the shape of a tent. The cytoskeleton also acts as a system of internal tracks, shown in Figure 4-18, on which items move around inside the cell. The cytoskeleton’s functions are based on several struc- tural elements. Three of these are microtubules, microfilaments, and intermediate filaments, shown and described in Table 4-2. Microtubules Microtubules are hollow tubes made of a protein called tubulin. Each tubulin molecule consists of two slightly different subunits. Microtubules radiate outward from a central point called the centrosome near the nucleus. Microtubules hold organelles in place, maintain a cell’s shape, and act as tracks that guide organelles and molecules as they move within the cell. Microfilaments Finer than microtubules, microfilaments are long threads of the beadlike protein actin and are linked end to end and wrapped around each other like two strands of a rope. Microfilaments con- tribute to cell movement, including the crawling of white blood cells and the contraction of muscle cells. Intermediate Filaments Intermediate filaments are rods that anchor the nucleus and some other organelles to their places in the cell. They maintain the inter- nal shape of the nucleus. Hair-follicle cells produce large quantities of intermediate filament proteins. These proteins make up most of the hair shaft. 84 CHAPTER 4 TABLE 4-2 The Structure of the Cytoskeleton Property Microtubules Microfilaments Intermediate filaments Structure hollow tubes made of two strands of intertwined protein fibers coiled into coiled protein protein cables Protein subunits tubulin, with two subunits: å actin one of several types of and ∫ tubulin fibrous proteins Main function maintenance of cell shape; cell maintenance and changing of maintenance of cell shape; motility (in cilia and flagella); cell shape; muscle contraction; anchor nucleus and other chromosome movement; movement of cytoplasm; cell organelles; maintenance of organelle movement motility; cell division shape of nucleus Shape Microtubules provide a path for organelles and molecules as they move throughout the cell. FIGURE 4-18 Microtubules Nucleus Endoplasmic reticulum Mitochondrion Ribosomes Copyright © by Holt, Rinehart and Winston. All rights reserved. Copyright © by Holt, Rinehart and Winston. All rights reserved. CELL STRUCTURE AND FUNCTION 85 1. Explain how the fluid mosaic model describes the plasma membrane. 2. List three cellular functions that occur in the nucleus. 3. Describe the organelles that are found in a eukaryotic cell. 4. Identify two characteristics that make mitochon- dria different from other organelles. 5. Contrast three types of cytoskeletal fibers. CRITICAL THINKING 6. Relating Concepts If a cell has a high energy requirement, would you expect the cell to have many mitochondria or few mitochondria? Why? 7. Analyzing Information How do scientists think that mitochondria originated? Why? 8. Analyzing Statements It is not completely accurate to say that organelles are floating freely in the cytosol. Why not? SECTION 3 REVIEW During cell division, centrioles organize microtubules that pull the chromosomes (orange) apart. The centrioles are at the center of rays of microtubules, which have been stained green with a fluorescent dye. FIGURE 4-20 Cilia and Flagella Cilia (SIL-ee-uh) and flagella (fluh-JEL-uh) are hairlike structures that extend from the surface of the cell, where they assist in movement. Cilia are short and are present in large numbers on certain cells, whereas flagella are longer and are far less numerous on the cells where they occur. Cilia and flagella have a membrane on their outer surface and an internal structure of nine pairs of micro- tubules around two central tubules, as Figure 4-19 shows. Cilia on cells in the inner ear vibrate and help detect sound. Cilia cover the surfaces of many protists and “row” the protists through water like thousands of oars. On other protists, cilia sweep water and food particles into a mouthlike opening. Many kinds of protists use flagella to propel themselves, as do human sperm cells. Centrioles Centrioles consist of two short cylinders of microtubules at right angles to each other and are situated in the cytoplasm near the nuclear envelope. Centrioles occur in animal cells, where they organize the microtubules of the cytoskeleton during cell division, as shown in Figure 4-20. Plant cells lack centrioles. Basal bodies have the same structure that centrioles do. Basal bodies are found at the base of cilia and flagella and appear to organize the devel- opment of cilia and flagella.

Multiplication and division facts on table 5

3.4(K) solve one‐step and two‐step problems involving multiplication and division within 100 using strategies based on objects; pictorial models, including arrays, area models, and equal groups; properties of operations; or recall of facts 3.5(B) represent and solve one‐ and two‐step multiplication and division problems within 100 using arrays, strip diagrams, and equations 3.5(E) represent real‐world relationships using number pairs in a table and verbal descriptions 3.6(C) determine the area of rectangles with whole number side lengths in problems using multiplication related to the number of rows times the number of unit squares in each row

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