11+Population+and+Community

Group 11 Aldric Ng, 1-B; Antonio Go II, 1-C; Mark Cheng, 1-D

factors that limit the population

Population and Community

I. Population - a group of organisms of the same kind - characteristics of population: 1) size --- number of organisms of the same kind living in a certain place at a certain time 2) density --- number of a certain organism per square kilometer of land/water area 3) distribution --- how the population is distributed/arranged in their habitat --- clumped, random, or uniform 4) sex --- depends on the number of males and females in a population --- male or female 5) age --- depends on the number of youth and elderly in a population --- old or young - factors that pertain to population growth: 1) birth rate --- average number of births for a certain organism per year 2) death rate --- average number of deaths for a certain organism per year 3) rate of increase/decrease --- rate of increase or decrease in the population's number based on birth and death rates 4) life expectancy --- average life span of the organisms in the population -factors that limit the population ---The vagaries of the physical environment ex. floods, forest fires, hurricane, drought etc. ---Lack of food supply ---Lethal diseases II. Community - different populations organisms living together in the same habitat - interactions in a community: 1) Competition --- happens when two kinds of organisms need the same thing to survive --- the two organisms must compete with one another in order to get this resource --- usually, one benefits (the winner), while the other is not able to get the resource and may die (the loser) --- sometimes, both organisms will lose due to intense competition --- ex. Both the lion and the cheetah need to eat antelope to survive. They compete with each other. Since the cheetah is faster, it is able to reach and catch the antelope before the lion. The lion does not get anything at all. 2) Predation --- one species (called predator) get their food from other organisms who are hunted and eaten (called prey) --- ex. The bird eats caterpillars to survive. The bird is the predator, while the catepillar is the prey. --- prey defenses: --- i. camouflage --- prey may try to hide itself or blend in with the background --- ex. Zebras have stripes in order to camouflage with tall grass in the savannah. --- ii. chemicals --- prey may try to release chemicals to ward off predators --- can be odors, repellers, or poisons --- ex. A skunk may shoot out bad-smelling odors in order to ward off predators. --- iii. warning coloration and mimicry --- prey with toxic stings usually have special colors --- other prey have "mimicry" colors that make them look like their toxic counterparts --- ex. Some bees may have mimicry colors that makethem look like a poisonous wasp. --- iv. special movements --- some prey may make sudden movements like spreading their wings out to look bigger --- other prey may "play dead" in order to fool predators 3) Symbiotic Relationships --- a close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member --- kinds: --- i. Commensalism -- one species benefits -- the other is neither helped nor harmed -- ex. An orchid grows on the trunk or on the branch of trees. The orchid can get enough sunlight from its high position. The tree is not affected at all by this. --- ii. Mutualism -- both species benefit -- neither species can live without the other -- ex. The yucca moth's primary source of food is the nectar of the yucca plant. The yucca plant depends exclusively on the yucca moth to pollinate it. --- iii Protocooperation both species can live without each other ex. Some plants do not need the help of pollinators in order to reproduce, thus their relationship with pollinators is facultive mutualism. --- iv. Parasitism -- one species benefits by getting the nutrients off of another species (called parasite) -- the other species is not killed, but is affected negatively (called host) -- ex. Fleas feed off of dogs' blood to survive. The fleas are parasites. The dogs are harmed, but not killed. They are hosts. --- v. Amensalism -- one species is harmed -- the other is not affected at all -- ex. Penicillium creates a chemical, Penicillin that kills bacteria.

III. Issues - Overpopulation of human beings -- Nowadays, the human population has been growing at an alarming rate. -- Each one of us contributes more to the pollution in the world. -- The pollution is slowly causing the population of other species to dteriorate. -- Habitats of animals are being destroyed, as deforestation and water pollution destroy the homes of animals. -- Pollution also kills animals because of the garbage and the toxic wastes.

IV. Questions (sorry this is late, cher) 1) Fill in the chart (3 points) || Effect on One Species ||  Effect on the Other Species || Ex. Mutualism ||  + (positive effect) ||  + (positive effect) || Ex. Parasitism ||  + (positive effect) ||  - (negative effect) || Competition ||  ||  || Commensalism ||  ||  || Protocooperation ||  ||  || Amensalism ||  ||  || Predation ||  ||  || 2)







competition predation symbiotic rel : mutualism, protocooperation, commensalism, amensalism, parasitism

V. Sources 1) "Biology: The Unity and Diversity of Life." Cecie Starr and Ralph Taggart. Wadsworth Publishing Company, Inc. 1978. 2) "Science Matters Volume A." Joan Fong, Lam Peng Kwan, Eric Lam, Christine Lee,and Loo Poh Lim. Marshall Cavendish Education. 2008. 3) "Exploring and Protecting Our World Grade 6." Carmelita Coronel, Thelma Mingoa, Alicia Padua, Miliza Romero, Melvin Mingoa, and Lilia Rabago. VIBAL Publishing House, Inc. 2006. 4) 5) [] 6) []