Exit Level Science TAKS Study Guide

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1 Exit Level Science TAKS Study Guide Science TAKS Objective Number of Questions on the Exit Level TAKS Objective 1: Nature of Science 17 Objective 2: Organization of Living Systems 8 Objective 3: Interdependence of Organisms 8 Objective 4: Structures and Properties of Matter 11 Objective 5: Motion, Forces, and Energy 11 Total 55 Objective 3: Interdependence of Organisms (8 questions) Bio 4.C compare the structures and functions of viruses to cells and describe the role of viruses in causing diseases and conditions such as acquired immune deficiency syndrome, common colds, smallpox, influenza, and warts; and Bio 4.D identify and describe the role of bacteria in maintaining health such as in digestion and in causing diseases such as in streptococcus infections and diphtheria. Bio 7.A identify evidence of change in species using fossils, DNA sequences, anatomical similarities, physiological similarities, and embryology; and Bio 7.B illustrate the results of natural selection in speciation, diversity, phylogeny, adaptation, behavior, and extinction. Bio 9.D analyze the flow of matter and energy through different tropic levels and between organisms and the physical environment. Bio 12.B interpret interactions among organisms exhibiting predation, parasitism, commensalism, and mutualism; and Bio 12.E investigate and explain the interactions in an ecosystem including food chains, food webs, and food pyramids. Bio 13.A evaluate the significance of structural and physiological adaptations of plants to their environments. Highlights of Objective 3: Students should be aware that bacteria are not always harmful. The majority of bacteria have no direct effect on humans. Many times bacteria play a beneficial role in organisms and the environment. Students should learn about some of the plant and animal diseases caused by bacteria and viruses. However, students are not expected to be aware of all of them. Items that address this issue will be designed to provide background information on the specific disease used in the item. Evolution is change over time. Students must understand natural selection as a mechanism for evolution, not as a term synonymous with evolution. Students should be able to examine evidence of evolution, such as DNA sequences and homologous structures, to determine the relationship between organisms. Embryology will not be included as evidence of evolution. Students should know that solar energy drives ecosystems. Food chains combine to make more complex food webs, and these webs are limited by the amount of energy that can be transferred between levels. Students need to understand the concept of biomass and relate it to food chains, webs, and pyramids. Students should know that the arrows in a food web or chain point in the direction of energy flow through the system. The cycling of nutrients is essential to maintaining the ecosystem. An understanding of this concept helps students realize why Earth s resources may be limited. Students should be familiar with the water, carbon, and nitrogen cycles. They should be able to analyze how changes, caused by either humans or natural occurrences, affect the availability of these resources. Students should know the significance of the structures and adaptations of plants, such as the variety of leaf structures, methods of dispersing offspring, and methods of obtaining nutrients. The study of plant structures and adaptations helps students better understand the connection between plants and the survival of other life, including human life. Compiled by Mindy Harmison, Vistas High School Program Page 1 of 10

2 Viruses: non-living particles do not carry out respiration or grow or move can reproduce (or make copies of itself) only inside a living host o the host cell is destroyed in the process vary in size and shape all have similar structure - an inner core of DNA or RNA surrounded by one or two protein coats A few diseases caused by viruses: o Acquired Immunodeficiency Syndrome (AIDS) o Common Cold o Small Pox o Influenza (the flu) o Warts Viruses can be prevented with vaccines, but the vaccine must be given before an infection begins Viruses cannot be treated - only the symptoms of viruses can be treated o Antibiotics do not work on viruses Viruses versus Living Cells: Characteristic Virus Living Cell Structure Reproduction DNA or RNA core and a protein coat (capsid) Only within a host cell Genetic Code DNA or RNA DNA Growth and Development No Obtain and Use Energy No Yes Evolve Yes Yes Response to Environment No Yes Cell membrane, cytoplasm, eukaryotic, etc. Independent cell division (asexual or sexual) Yes - increase in number and differentiation Bacteria: living cells prokaryotes (lack a membrane bound nucleus) Bacteria can cause illnesses, however 90% of all bacteria are helpful, not harmful. Benefits of Bacteria: o E. coli live in our intestines and produce vitamins for us o act as decomposers o fix nitrogen in the soil for plants o used to make foods and beverages (cheese, ice cream, etc.) o used in industry (oil eaters clean oil spills) o remove waste products/poisons from water (used in sewage treatment plants) o used to make medicines and chemicals through genetic engineering A few disease causing bacteria: o Streptococcus ( strep throat ) - releases toxins into blood which can cause scarlet fever (rash) o Diptheria - infects tissues of the throat, releasing toxins into blood where they destroy tissues leading to breathing problems, heart failure, paralysis, and/or death Prevention and Treatment: o vaccines stimulate the immune system to produce antibodies o antibiotics can block the growth and development of bacteria Controlling bacteria: o sterilization by heat o disinfectants o proper food storage and processing- refrigeration/freezing and cooking/canning correctly Compiled by Mindy Harmison, Vistas High School Program Page 2 of 10

3 Evolution - a change in a species over time Natural Selection - a mechanism by which evolution may take place within a population of organisms o individuals within the same species are not identical o the environment presents many different challenges to an individual s ability to survive and reproduce o organisms tend to produce more offspring than their environment can support and, therefore, individuals of a species often compete with one another to survive o individuals within a population that are better able to cope with the challenges of their environment tend to leave more offspring than those less suited to the environment o therefore, the traits of those better-suited for their environment tend to increase o Example of Natural Selection: A species of fish will lay thousands, sometimes millions, or eggs. In this population of eggs, individuals will exhibit slight variations. Fishes may differ slightly in color, fin and tail size, and speed. An egg that grows to be a fast fish with a skin color that allows it to blend in better with its surroundings is more likely to survive to reproductive age than a slow fish with more obvious coloring. These adaptations carried over several generations will produce a change in the species. Evidence of Evolution: o DNA Sequences: by comparing the DNA sequences of two organisms, scientists can determine whether or not they are related example: dogs are close relatives to bears relationships between organisms can be used to trace evolutionary pathways o Fossils: fossil records can be used to study life forms of the past and date them relative to one another (older fossils are found in lower rock layers) scientists have found that many simpler life forms existed early in Earth s history and became more complex over time o Anatomical Similarities: example: the forearms of a crocodile, a bat, and a bird are used for different functions, but the bones are arranged very similar to one another (homologous structures) example: thorns of rosebushes and spines of sea urchins are both structural adaptations that protect the organism from predation example: functionless structures, such as the eye of a blind cave fish, demonstrate structural change over time o Physiological similarities: example: bacteria building up a resistance to certain antibiotics and insects building up a resistance to certain pesticides o Embryology: the pattern of development of the embryos of fish, reptiles, birds, and mammals indicate evolutionary relationships among the species Interactions among Organisms: predation: a relationship on which one organism preys on another as a source of food o example: an owl hunting a field mouse mutualism: a relationship between two different species in which both species benefit o example: A hummingbird receives nectar from a flower and the flower has its pollen spread to other flowers by the hummingbird. The hummingbird gets food and the flower is more likely to reproduce. o example: Sharks are cleaned by a little fish known as a Remora. The shark never eats them since they clean bacteria off of the shark. The Remora get food and the shark gets cleaned. parasitism: a relationship between two different species in which one species benefits and the other is harmed o example: A good example is a tape worm. It intercepts all of the host s food, causing the host to starve to death. commensalism: a relationship between two different species in which one benefits and the other neither benefits nor is harmed o example: Orchids live high in tree-tops on the branches of large trees. They do not harm the tree, but they are helped by being raised up into the sunshine and receiving water. Compiled by Mindy Harmison, Vistas High School Program Page 3 of 10

4 Tropic Levels and Energy Pyramids: All of the organisms in an ecosystem fall into one of several tropic levels. The tropic level of an organism is based on its position in a food chain. o Primary Producers: autotrophs autotrophs - organisms who are able to produce their own chemical energy green plants, algae, and certain bacteria green plants and algae convert solar energy into chemical energy through photosynthesis some bacteria convert inorganic chemicals into chemical energy o Primary Consumers: herbivorous heterotrophs heterotrophs - organisms who must consume autotrophs or other heterotrophs in order to obtain chemical energy herbivores - organisms which eat only plants to obtain chemical energy cows, sheep, rabbits, squirrels, grasshoppers o Secondary Consumers: small carnivorous heterotrophs heterotrophs small carnivores - generally consume primary consumers carnivores - organisms which primarily eat meat to obtain chemical energy snakes, some birds, some toads, bats o Tertiary Consumers: large carnivorous heterotrophs heterotrophs large carnivores - generally consume tertiary consumers lions, wolves, bears, hawks, people Solar energy is the driving force behind all food chains and, therefore, the tropic levels. Energy flows through the tropic levels from the Sun, to the producers, to the primary consumers, to the secondary consumers, etc. o The most energy is available at the producer level. o At each tropic level, there is less available energy than at the level before. o In general, only about 10 percent of the energy at one level of a food web is transferred to the next, higher, level. The other 90 percent of the energy is used for the organism's life processes or is lost as heat to the environment. o The tropic levels are usually represented as an energy pyramid to show the decrease in available energy as you more from one level to the next. Food Chains and Webs Food chains and webs show how plants and animals are all interconnected within an ecosystem Food chains are used to show part of the complex way in which energy is transferred in ecosystems. Organisms seldom eat just one kind of plant or animal. The many interactions of plants and animals in food chains, when connected, form a food web. You should be able to identify several different food chains within a food web. The arrows of food chains and food webs always point in the direction of energy flow. Examples of Food Chains: Compiled by Mindy Harmison, Vistas High School Program Page 4 of 10

5 Examples of Food Webs: The Oxygen, Carbon, Nitrogen, and Water Cycles The Oxygen Cycle: o The two parts of the oxygen cycle are photosynthesis, during which green plants take in water and carbon dioxide and give off oxygen, and respiration, during which plants and animals use oxygen and give off carbon dioxide and water. The products of photosynthesis are utilized by autotrophs and heterotrophs during cellular respiration. The products of cellular respiration are utilized by autotrophs during photosynthesis. respiration photosynthesis Compiled by Mindy Harmison, Vistas High School Program Page 5 of 10

6 The Carbon Cycle: o Background: The concentration of carbon in living matter (18%) is almost 100 times greater than its concentration in the earth (0.19%). Living things extract carbon from their nonliving environment. For life to continue, this carbon must be recycled. o Description: Carbon is released into the atmosphere by: burning fossil fuels volcanic activity cellular respiration of plants, animals, and decomposers (converting food energy into usable energy in the mitochondria of cells) Carbon is taken out of the atmosphere through photosynthesis Animals obtain carbon by eating plants Animal waste and decaying plants and animals place carbon into the soil Carbon in the soil forms fossil fuels We burn fossil fuels, releasing carbon into the air The Nitrogen Cycle: o Background: All life requires nitrogen-compounds such as proteins and nucleic acids. Air, which is 79% nitrogen gas, is the major reservoir of nitrogen, but most organisms cannot use nitrogen in this form. Plants must secure their nitrogen in "fixed" form. Animals secure their nitrogen (and all other) compounds from plants (or animals that have fed on plants). o Description: Nitrogen in the air is fixed into the soil by lightening and nitrogen in the soil is fixed by bacteria. Fixing nitrogen enables it to be used by plants. Plants take in nitrogen through their roots. Animals obtain nitrogen by eating plants. Animal waste products and decaying plants and animals add nitrogen back into the soil. Bacteria fix the nitrogen in the soil so that it can be used by plants Compiled by Mindy Harmison, Vistas High School Program Page 6 of 10

7 The Water Cycle: o Liquid water on the Earth s surface is heated by the Sun and evaporates, turning into water vapor in the air. o Water vapor in the air rises into the atmosphere where cooler temperatures cause it to condense, turning into liquid water droplets that form clouds. o Air currents move clouds around the globe causing water droplets to collide, grow, and fall out of the sky as precipitation. o The precipitation falls back into the oceans or onto land, where it flows over the ground as surface runoff or into the ground as groundwater Plant Adaptations Adaptations Pictures Benefits long roots Trees and plants with long roots are better able to collect water as it falls and provide good support for the organism. tap roots/storage roots Trees and plants with taproots are able to access deep water and to store larger amounts of water and food. Compiled by Mindy Harmison, Vistas High School Program Page 7 of 10

8 Adaptations Pictures Benefits spines/thorns Spines and thorns deter predators and provide shade for the plant (like a lattice). cactus shape Many cacti are barrel-shaped so that they can store large quantities of water. The ribs on the cacti allow them to expand and contract without damage to the plant as they gain and lose water. stoma cells Stoma cells are openings in a leaf that allow for the exchange of gases, including water vapor, between the leaf and its environment. Stoma cells stay closed during the warmest parts of the day to prevent water loss. thick cuticle This protective layer on the leaf prevents water loss and deters predation. tall trees and shrubs The leaves of tall trees and shrubs have more access to sunlight, allowing them to produce more food due to photosynthesis. Compiled by Mindy Harmison, Vistas High School Program Page 8 of 10

9 Adaptations Pictures Benefits big leaves Bigger leaves have more access to sunlight, allowing them to produce more food due to photosynthesis. tendrils allow vines to climb Higher climbing vines have more access to sunlight allowing, them to produce more food due to photosynthesis. seed dispersal Some seeds have wings or lightweight hairs that allow them to catch the wind like a kite and be distributed far distances via the wind. Pollen is light and can also be distributed long distances via the wind. Some seeds are sticky or have thorns so that they are transferred from one location to another as they attach to the fur of animals or the clothes/shoes of humans. Animals which eat fruit eventually deposit the seeds elsewhere. Compiled by Mindy Harmison, Vistas High School Program Page 9 of 10

10 Adaptations Pictures Benefits insect traps The Venus Flytrap is a photosynthetic, carnivorous plant that lives in swampy habitats where there is little nitrogen. As a result, the flytrap has evolved to obtain nitrogen from insects it traps. The plant has two leaves that resemble jaws, and when the insect lands on the plant, the leaves close on the insect. The plant then digests it. Insect traps allow plants living in nitrogen-poor soil to obtain the nitrogen needed for survival. flowers that attract pollinators As birds and insects eat the nectar of flowers, the pollen adheres to them. They then transfer the pollen to other flowers (cross-pollination). This allows for greater genetic diversity, making plants more likely to adapt to their environments. Sources: Glencoe McGraw-Hill TAKS Science Quick Review Handbook ml community.seas.columbia.edu/.../fuse.php?id= Compiled by Mindy Harmison, Vistas High School Program Page 10 of 10