Answers to Practice Items

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1 nswers to Practice Items Question 1 TEKS 11 Human development of land inherently displaces the former habitat, so there is definitely an effect. The displacement of a habitat for another can only be destructive. The development of land for human purposes decreases the carrying capacity of the former habitat. This is the correct The redevelopment of a habitat for another will not increase the carrying capacity of that habitat. Question 2 TEKS 11 The disappearance of jerboa actually would decrease competition for food in that stratus of the food web. Rattlesnakes are likely to decrease as they eat jerboa. Rattlesnake, badger, and lizards as predators of jerboa indeed would decrease. This is the correct The disappearance of jerboa will decrease rattlesnakes, badgers, and lizards, and thus, coyotes and raptors also will decrease. Question 3 TEKS 11 It s clear from the data that the birds decrease when the snake is present. The round dots describe the effect of the snake on the bird population. The line clearly trends downward. This is the correct mutualistic relationship would result in an increase in the population of both. Neither line shows the bird population increasing. Question 4 TEKS 11 Increasing a predator population is likely to put pressure on the prey population. The result is a decrease in both until stasis is reached. This is the correct arrying capacity depends on balance between organisms. Increasing one will have an effect on the other. The carrying capacity will only increase once the source of imbalance is removed. This question does not indicate that. Increasing a predator will put pressure on the prey population, likely decreasing its numbers.

2 Question 5 TEKS 11 Parasites cause disease and infection, and decrease the ability to survive. irth rate likely would decrease. Parasites would inhibit survival and reproduction and would decrease growth rate. Growth rate for the reasons outlined above would decrease. isease and infection caused by parasites would likely cause an increase in the death rate. This is the correct Question 6 TEKS 11 Plants are autotrophs. Fungi as decomposers are heterotrophs. Fungi serve as decomposers and help bring nutrients back into the environment. This is the correct Tertiary consumers are at the top of the food chain and rely on other consumers for food. Primary producers are photosynthetic plants or other organisms. Question 7 TEKS 11 Two important roles for bacteria are nitrogen fixation and decomposing dead matter. This is the correct Fungi recycle nutrients, and plants produce oxyten. Plants are photosynthetic, and not all fungi produce antibiotics. While some bacteria can fix nitrogen, bacteria decompose matter, not preserve it. Question 8 TEKS 11 Growth occurs because of special stem cells in our bones. efense of our body is coordinated by the immune system. acteria inhabit our intestine, aiding in digestion. This is the correct Respiration occurs in the mitochondria. Question 9 TEKS 11 ntibiotics kill most bacteria in our body, even the beneficial species in our gut. This is the correct ntibiotics are not converted into stomach acid. ntibiotics do not have a water drawing affect in our gut. ntibiotics do not cause physical damage to our digestive tract.

3 Question 10 TEKS 11 acteria cause disease by destroying the tissues they infect and releasing toxins. This is the correct racks in our skin that allow dirt to enter will bring bacteria into our system. However, not all bacteria enter our system in this way. Heat generated through bacterial infection occurs because of disruptions in our systems which maintain homeostasis. Viruses integrate into host cell N. acteria do not. Question 11 TEKS 11 acteria are prokaryotes and therefore have no nucleus. ntibiotics do not affect the endoplasmic reticulum. Otherwise, all cells would be affected. ntibiotics work by inhibiting the bacterium cell from creating a cell wall. This is the correct gain, bacteria are prokaryotes and have no nucleus. Question 12 TEKS 11 ntigens from the vaccine don t inactivate the virus. That occurs later by cells from the immune system. Hormones don t play a role in immune response in this way. Hormones help cells communicate with each other. Enzymes from platelets aid in the blood forming clots. The first interaction of a vaccine in the body is that antigens from the body induce the production of antibodies that will recognize the virus for destruction. This is the correct Question 13 TEKS 11 Lichen are composed of photosynthetic algae and decomposing fungi. This makes them able to survive on both the food they produce and the decomposition of matter already there. This is the correct Lichens are not food sources, but they do help prepare the environment for other food sources to take root. Lichens do require light for the photosynthetic aspect of the organism. Lichens are decomposers, but that s not all they do.

4 Question 14 TEKS 11 lava flow is likely to wipe an area clean. In this case, primary succession would take place in the new environment. well-established ecosystem is called a climax community. Previously forested areas destroyed by fire are prime candidates for secondary succession. This is the correct Rock ledges exposed by melting glaciers are places where primary succession would occur. Question 15 TEKS 11 Human development of land, as in farming, affects the habitats that were previously there. The effect of planting crops on previously undeveloped land actually decreases the diversity of life that once was there. Human development is destructive to the habitats it replaces. This is the correct nswer is correct. Question 16 TEKS 11 The process of succession is the reestablishment of an ecosystem. Former inhabitants will try to repopulate the area. Since succession is the reestablishment of an ecosystem, the diversity of species will increase as the ecosystem grows. This is the correct Succession in the increase in diversity after an ecological disruption. nswer is correct. Question 17 TEKS 11 Human cultivation destroys habitat. ense shrubs are one of the steps on the way to a climax community. Plants get their carbon dioxide from the atomosphere. Pioneer and early species serve the purpose of preparing the environment and making it more fertile for sustained growth. This is the correct Question 18 TEKS 11 rrange the pictures in order of increasing density. So, 2 should go first and 1 should come last. 2 represents the recently fire ravaged forest, and 1 represents the eventual climax community. This is the correct This order would be correct if a climax community (1) were shown first followed by the forest fire and then repeated the climax community in the end again. Order the pictures from least dense to most dense.

5 Question 19 TEKS 12 Reproduction at different times doesn t necessarily the species won t compete for the same resources. Whether they eat more or less doesn t affect whether they will compete for those resources. The environment will simply allow more species to survive if they eat less. Species can t occupy the same habitat if they move away. Occupying different niches means they don t compete for the same resources, habitat, and don t put environmental pressure on each other. This is the correct Question 20 TEKS 12 ommensalism is a symbiotic relationship in which one species benefits and the other species neither benefits nor suffers. Mutualism is a symbiotic relationship in which both species benefit. Parasitism results in harm being done to a species. Predation is a hunter eating another species for food. This is the correct Question 21 TEKS 12 No information can be gathered as to whether a species is a consumer. Parasites would increase in population over time, forcing the other to decrease. Parasites would also succeed those they infect. If species is a predator, the increase in its population eventually will cause both species to die out. This is the correct ecomposers would succeed scavengers. Question 22 TEKS 12 ommensalism is a symbiotic relationship in which one species benefits and the other species neither benefits nor suffers. Mutualism is a symbiotic relationship in which both species benefit. Parasitism results in harm being done to a species. This is the correct Predation is a hunter eating another species for food. Question 23 TEKS 12 Mutualism is a symbiotic relationship in which both species benefit. Parasitism results in harm being done to a species. ommensalism is a symbiotic relationship in which one species benefits and the other species neither benefits nor suffers. This is the correct Predation is a hunter eating another species for food. This is the correct

6 Question 24 TEKS 12 Insects play an important role in the reproductive process of a plant, and flowers provide food for insects. This is the correct If the insects then harmed the flower after taking the nectar, then this would be parasitism. Flowers benefit from the process of pollination. Insects benefit from the food source. The act of insects taking nectar as food from the flower doesn t destroy the flower. Question 25 TEKS 12 Mutualism is a symbiotic relationship in which both species benefit. This is the correct answer because the bacteria fix nitrogen for the plant, and the plant provides shelter for the bacteria. Parasitism results in harm being done to a species. ommensalism is a symbiotic relationship in which one species benefits and the other species neither benefits nor suffers. Predation is a hunter eating another species for food. This is the correct Question 26 TEKS 12 Herbivores only obtain energy from producers. ecomposers obtain energy from the remains of all organisms. This is the correct Producers depend on no other organisms as a food source. arnivores depend on other animals as a food source. Question 27 TEKS 12 Hawks are predators; insect-eating birds are carnivores. Mice are primary consumers; flower seeds are the products of producers. mountain lion is a predator; bark beetles are herbivores. This is the correct Grasshoppers are herbivores; grass is an autotroph. Question 28 TEKS 12 Rabbits only eat grass and are therefore just primary consumers. Grasshoppers only eat grass and are therefore just primary consumers. Mice eat both grasshoppers and grass and are therefore both primary and secondary consumers. This is the correct l Spiders eat grasshoppers and are only secondary consumers.

7 Question 29 TEKS 12 Reproduction is a life process and is counted in the energy used by the organism. The creation of body tissue is a life process and is counted in the energy used by the organism. Fat storage is a life process and is counted in the energy used by the organism. Whatever energy that is not used by the organism or passed up to the next trophic level is lost as heat to the environment. This is the correct Question 30 TEKS 12 Osprey use redfish as a food source and would decrease if redfish were eliminated. The disappearance of redfish would increase the clam population, likely having a negative effect on amphipods. The clam worm population would increase because of the disappearance of its predator, the redfish. This is the correct If redfish disappear, clam worms increase, eating more of their food and causing a decrease of phytoplankton. Question 31 TEKS 12 Frogs are likely to increase because of an impacted increase in its resources. The disappearance of rabbits would increase grass, thereby providing an avenue for crickets to increase. Grass will increase since it serves as food for rabbits. Mountain lions, as predators of rabbits, would experience a food shortage and decrease in numbers. This is the correct Question 32 TEKS 12 The mountain lions prey was rabbit and deer. They will increase. This is the correct Snakes are not prey to the mountain lion. Mice are not prey to any of the mountain lions prey. Hawks are not prey to the mountain lion. dditionally, mice are not prey to any of the mountain lions prey.

8 Question 33 TEKS 12 While you can get a general sense of biomass at each trophic level, the underlying reasons for the organization of a pyramid have much more to do with energy than they do with mass. Energy is indeed lost to the environment as one goes up levels in a pyramid. Thus, less mass can be supported at higher levels. This is the correct Remains of organisms are decomposed and reintroduced at the lowest level. They don t necessarily sink down because lower levels may not use the remains of higher levels as food. Organisms at higher levels tend to live longer lives than those at lower levels. Question 34 TEKS 12 acteria are not consumers of protozoa. There must be a direct link between organisms. Look for the producers to start a pyramid. They are always at the bottom. lgae, even though it is depicted at the top, actually are the source of all arrows. So, algae, then snails, then diving beetles are the correct sequence. This is the correct acteria consume dead organisms, not the other way around as suggested by this pyramid. mphipods are eaten by catfish, not the other way around as suggested by this pyramid. Question 35 TEKS % passing of energy occurs between the producer and the fifth level consumer. Jumping two levels in a pyramid passes only 1% of available energy. This would occur between the producer and the secondary consumer. This is the correct Jumping only one level in a pyramid passes 10% of the available energy. This would be from producer to primary consumer or from primary consumer to secondary consumer. 100% of the energy is available at any trophic level for that trophic level. Question 36 TEKS 12 Not all species need sunlight to stay warm. Resources are constantly changing. species ability to adapt to those changes determines whether the species will survive in the long term. This is the correct Many stationary species survive for long periods of time. Not all species need to be able to perform photosynthesis.

9 Question 37 TEKS 12 n inability to secure resources because of consumption by competing or invasive species is a common reason why species go extinct. Pollution will sicken animals and make them less likely to reproduce. The consumption of the eggs and habitat make the species unlikely to reproduce. ll of these answers are correct. Question 38 TEKS 12E Erosion occurs because of water flow. There s nothing to indicate a change or alteration of water flow in this problem. The plants play an important role in the nitrogen cycle. Removing the plants would disrupt this process. This is the correct answere. Herbicides kill plants. Photosynthesis only occurs in plants. There s nothing in this problem to indicate disruptions of the water cycle. Question 39 TEKS 12E Water is not involved in the nitrogen cycle in this way. Nitrogen-fixing bacteria and lightning are the two most important contributors to the nitrogen cycle. This is the correct Mobility of consumers has no effect on this cycle. Transpiration releases water, which contributes to the water cycle. Question 40 TEKS 12E Ozone is not mentioned as part of the carbon cycle. The arrows coming from the plant indicate that the factory releases carbon into the atmosphere. The arrows coming from the plant only go from the factory. It does not absorb carbon. The factory definitely releases carbon. This is the correct Question 41 TEKS 12E Plants absorb carbon through the process of photosynthesis. Plants conduct both photosynthesis and respiration. This is the correct ecause they conduct both photosynthesis and respiration, plants are key players in the carbon cycle. Plants contribute carbon through respiration, too!

10 Question 42 TEKS 12F The variable in this problem is the size of the environment. Looking at the number of offspring shows that more offspring are able to survive in larger environments. This means that the population density is probably pretty constant. This is the correct The initial larger numbers of offspring taper off, suggesting that the fleas produce less offspring when crowded. The large increase in the number of offspring suggest that they produce more offspring when thinly populated. Reproduction rates actually decreased at about 20 days. Question 43 TEKS 12F ny invasive species will compete for the resources of the plants and animals already in the established ecosystem. This is the correct This would only be true if the nonnative plant were desirable food for the animals. If it isn t, it would crowd out the desirable food and animals would decrease. This would only be true if the insects liked living in the new species. It s possible they won t. Fish need oxygen, so this won t kill fish. Overproduction of oxygen would lead to algal bloom, clogging the water and making it difficult for the fish to breathe. However, there will be plenty of oxygen. Question 44 TEKS 12F Sheep are not represented in the graph, so no conclusion can be drawn about them. The peaks and valleys of the rabbit and coyote populations suggest that they are linked. The coyotes actually contributed to the homeostasis of the ecosystem. This is the correct Sheep are not represented in the graph, so no conclusion can be drawn about them. Rabbit population actually increases greatly when coyote populations drop. Question 45 TEKS 12F s sewage waste increases, walleye population actually drops. s sewage waste increases, carp populations definitely benefit. This is the correct s sewage waste increases, trout and whitefish populations are the first to go. s sewage waste increases, carp populations actually increase.