Nikimmit CHAPTER 4 ECOLOGY A. Definition of Ec logy. Organisms depend on each other and on their environment. No organism or group of organisms can exist without influencing or being influenced by the environment and by other living things. The study of the relationship between living things and the environment is called ecology. 2. All the populations livingtin a particular area make up a fitr V.(\-(-1/1 1-1 3. A living community and the nonliving environment together make up a(n) 4. The portion of theearth in which life exists is the r$ 1. Ecology is the study or---it)e. 1) 1(/ It ----th 5., 5 2. Living thin-4 are influenced by and LTTlrr/ B. Environmental Relationships. In their studies of ecology, scientists divide organisms into the following groups: 1. Populations. All organisms of the same kind (all members of the same species) living in a 'certain area make up a population. For example, all the ants living in a particular field make up a population of ants. 2. Communities. All the populations living in the same area make up a community. 3. Ecosystems. A community (all the living things in a particular area) plus the nonliving environment in which the community exists make up an ecosystem. 4. Biosphere. The portion of the earth in which life exists is called the biosphere. The biosphere is made up of many ecosystems. 1. All members of a species living in a certain area make up a ptr i. C. Limiting Factors. Living things need space, water, air, food, light, proper temperature, and a 1% constant supply of energy. If organisms do not (--t4 have enough of any one of these factors, their A.umbers will be limited. These nonliving parts of the environment are called limiting factors because they limit the numbers and kinds of organisms that can exist in an area. For example, the shortage of water and the hot temperatures of the desert determine the kinds of plant and animal life that can survive. Temperature and water supply are limiting factors in a desert environment. 1. Define the term "limiting factor", If elf ht rt't I) ) 64.,\ 4t ( ree limiting factors are and D. Natural Communities. Natural communities may be classified according to the physical characteristics of their environment, such as aquatic (water) or terrestrial (land). Communities are also classified by the dominant (most common) kind of plant life in the area. Plant communities are usually determined by the climate of the area. Table 4 gives the characteristics of the major kinds of plant communities. 14
Table 4. The Major Plant Communities. Community Characteristics Plant Life Tundra Taiga Deciduous forest Rain Forest Grassland Desert Subsoil frozen all year Long, cold winters; summers with thawing subsoil Moderate rainfall; cold winters, warm summers Warm all year; heavy rainfall Much variation in rainfall and temperature Little rainfall; extreme changes in temperature daily Lichens, mosses Conifers firs, spruce, pines Trees that shed their leaves in winter Many kinds of broad-leaved plants and vines Grasses Cacti; shrubs that need little water or that store water 1. An aquatic community is a community 2. "Terrestial" means "NO( 3 Four major kinds of plant communities are. r and cf,voct-,-ici 4. Plant communities are determined by ej munity. The existing community changes the environment in such a way that it becomes suitable for a new kind of community and unsuitable for the existing community Figure 15 shows a typical succession in a northeast state. LICHENS GRASSES SHRUBS 5. An area with little rainfall and extr me daily temperature changes is a d t; t 6. A community that is warm throughout the ear and has heavy rainfall is a rain A('''t 6' 1 7. Trees ttlat lose the leafs in the winter are found in tit'l(ittd.triattber4ii-nunities. 8. Lichens and mosses are found in the tt ji 9. A community that is made up of pines, spruce, and firs is the it t ( A ROCK B MATURE TREES C SHADE TREES E. Biological Succession. Over long periods of time, natural communities change from one kind to another. This orderly and predictable change is known as biological succession. As a result of succession, a new kind of community replaces the existing community The new community is quite different from the original community Succession is caused by changes in growing conditions brought about by the existing corn- FIGURE 15. ECOLOGICAL SUCCESSION. 1. The process by which one kind of community is replaced by another Isind of community is called (7)f t (i:)4 Cif ct 2. Succession ie caused by le tct 7CA kv (" 15
F. Balance in an Ecosystem. The balance in an ecosystem is the result of complex interactions between living things and the environment Within a balanced ecosystem, there is a constant flow of energy and materials between organisms and the environment. 1. Energy Flow. Energy enters an ecosystem when producers (green plants and algae) capture light energy during photosynthesis. Plants use some of the energy for their own life processes, and some energy is stored in food substances produced by the plants. The energy in the food is transferred to consumers (animals) when the plants are eaten. Whenever energy is transferred from one organism to another, some energy is lost. The flow of energy through an ecosystem is in one direction. Energy must constantly be supplied to the ecosystem if organisms are to survive. Energy flow through an ecosystem is represented by food chains and food pyramids (Figure 16). In both food chains and food pyramids, the greatest amount of energy is present at the producer level. web is made up of many food chains, and re resents the path of energy flow, in a communit (Figure 17). HAWK SNAKE -Nue- FROG GREEN PLANTS "C MOUSE FIGURE 17. FOOD WEB. GRASSHOPPER 3. Materials Cycles. In a balanced ecosysterr materials are cycled between the living organ isms and the nonliving environment. Throug these cycles, the same materials are used ow and over again. Materials that are recycled i ecosystems include oxygen, carbon, nitroger and water (Figure 18). OXYGEN FIRST LEVEL CONSUMER THIRD LEVEL CONSUMER -PRODUCER SECOND LEVEL CONSUMER CARBON DIOXIDE FIGURE 18. CARBON-OXYGEN CYCLE FIGURE 16. (TOP) SIMPLE FOOD CHAIN. (BOTTOM) FOOD PYRAMID. 2. Food Webs. In a natural community the flow of energy and materials is very complex. A food 1. Energy enters an ecosystem, as a result c ((a t,.i (V. ṈA- L. 2. The interconnect d food chains in a corn munity form alktnr 16
3. Three substances that are recycled in nature are ), -t 4-), 4. Food chains and food pyramids represent the flow of L. rfitl in a community 5. In food chains and food pyramids, the greatest açnountfof energy is present at the Li k level.. In an ecosystem, materials are c twee, n living organisms and the 7. cled be- is not recycled in an ecosystem. 4. Upsets in Ecosystems. The natural balance in an ecosystem may be disturbed by natural events or by human activity Major natural disturbances include floods, fires, earthquakes, climate changes, and disease. Human activities that disturb the balance of ecosystems include cutting down forests, clearing land, and building dams. These changes may cause erosion, floods, and loss of wildlife. rat1 1. To "conserve" means to 2. Three renewable resources atra,and 3. Three nonrenewable resources are I piriyicpac,, and (A) a. 'lam meat CHAPTER 1. All the plant and animal species living in a particular area make up (1) a population a community (3) an ecosystem (4) a biosphere 2. Groups of organisms interacting with each other and with the nonliving environ ent make up (1) a population (2) a community 3) an ecosystem (4) a biosphere. Base your answers to questions 3 and 4 on the diagram below. 1. The natural balance pf qn ecosystem may b upset by ftifvcitt ekle_filrer mi AM' 2. Some human activities that upset the balance of osystems lude and G. Conservation of Resources. Humans are faced with serious shortages of natural resources. We must learn to conserve (save) our natural resources. Soil, trees, and water are classified as renewable resources. They are replaced by natural processes overtime. Nonrenewable resources, such as minerals and oil, are not replaced by natural processes. Our supplies of these resources will eventually run out, even through some are recycled in the ecosystem. 3. The diagram illustrates a kind of community The kinds of plants that can live in this area are limited by a lack of (1) air (2) minerals (3) animals (4) temperature 4. The community illustrated in the diagram is (1) tundra a taiga (3) tropical rain forest (4) deciduous forest 5. Natural communities change in an orderly and predictable sequence. This process of change is known as (1) migration (2) hibernationesuccession (4) life cycle 17
6. The diagram below represents a (1) cycle (2) succession (3) food web (4) food chain 7. Which organism is the producer in the diagram of a food pyramid below? (1) frog (2) cricket (3) mouse 4) een plant 8. Th diagram below represents a (1) food chain food web (3) material cycle (4) life cycle 2 4 6 8 Number of Generations 10. If the relationship between the food supr and population increase continues as shown c the graph, what would probably happen to tl population? (1) Nothing will change. 2 The po ulation will run out of food. (3) The rood supp will increase. (4) The population will increase size. Base your answers to questions 11 and 12 ( the diagram below. OWLS FOXES t...-----" SNAKES,.- MICE '"*......' RABBITS PLANTS INSECTS I I I I" 11 '11'111 I 11. The owls shown in the diagram are(1) con sumers (2) producers (3) decomposers (4) func. 12. Which of the following food pyramids be: represents the diagram above? (1) 1 (2) 2 (3) (4) 4 9. Which of the following statements about conservation is true? (1) Humans have little effect on the environment. (2) The Earth will never run out of raw materials. (3) The natural balance of an ecosystem is never disturbed. 6) Humans are faced with serious shortages of natural resources. Base your answer to question 10 on the graph top of next column which shows the relationship between increasing populations and food supply. 18 (3)
Base your answers to questions 13 through 16 on the diagram below, which shows certain relationships among living things. 18. Which of the following resources is no! renewable? (1) soil (2) plants (3) water (4)minerals 19. Which of the following organisms act as decomposers in a food chain? 1 bacterii green plants (3) corn (4) foxes 20. What is the approximate length of the leaf shown below from the beginning of the petiole (P) to the tip of the blade (B)? bacteria Molds 13. Which of the following statements about living things is represented by this diagram? (1) All living things come from other living things. 0. )Living things are dependent on one another and on their environment. (3)All living things respond to stimuli in their environment. (4) Reproduction provides for the continuation of life by producing new individuals. 14. Molds are examples of organisms that ar (1) producers (2) consumers (3) predators decomposers 15. What gas produced by the tree is used by the frog for respiration? (1) carbon dioxide (2) nitrogen 03 oxygen (4) hydrogen 16. The diagram best iilustrate41ia food chain (2) a plant community (3) a popu ation (4) a life cycle 17. In the diagram of a food chain below, which organism is a producer? A (2) B (3) C (4) D 14,111%.0 I 111111111 (1) 9 in. (2).9 in 9 cm. (4) 10 cm. 21. Using a complete sentence, describe a laboratory activity during which a person should wear safety glasses or safety goggles. A, 6 ko&-ec dy 0 1,6 It (,:4 'eni vi Ca- --'. ) tj 4 ve --(01 Tit 22. Four pieces Of ladoratory equipment are shown below. Which piece of equipment would be used to measure the temperature' of water? A (2) B (3) C (4) D 0 C A 19 tgel -"Vrtis7147PtEr ' 4N-I -T77.