Table of Contents

Table of Contents – pages iv-v Unit 1:What is Biology? Unit 2:Ecology Unit 3:The Life of a Cell Unit 4:Genetics Unit 5:Change Through Time Unit 6:Viruses, Bacteria, Protists, and Fungi Unit 7:Plants Unit 8:Invertebrates Unit 9:Vertebrates Unit 10:The Human Body

Table of Contents – pages iv-v Unit 1: What is Biology? Chapter 1:Biology: The Study of Life Unit 2: Ecology Chapter 2:Principles of Ecology Chapter 3:Communities and Biomes Chapter 4:Population Biology Chapter 5:Biological Diversity and Conservation Unit 3:The Life of a Cell Chapter 6:The Chemistry of Life Chapter 7:A View of the Cell Chapter 8:Cellular Transport and the Cell Cycle Chapter 9:Energy in a Cell

Unit 4: Genetics Chapter 10:Mendel and Meiosis Chapter 11:DNA and Genes Chapter 12:Patterns of Heredity and Human Genetics Chapter 13:Genetic Technology Unit 5: Change Through Time Chapter 14:The History of Life Chapter 15:The Theory of Evolution Chapter 16:Primate Evolution Chapter 17:Organizing Life’s Diversity Table of Contents – pages iv-v

Unit 6: Viruses, Bacteria, Protists, and Fungi Chapter 18:Viruses and Bacteria Chapter 19:Protists Chapter 20:Fungi Unit 7: Plants Chapter 21:What Is a Plant? Chapter 22:The Diversity of Plants Chapter 23:Plant Structure and Function Chapter 24:Reproduction in Plants Table of Contents – pages iv-v

Table of Contents – pages iv-v Unit 8: Invertebrates Chapter 25:What Is an Animal? Chapter 26:Sponges, Cnidarians, Flatworms, and Roundworms Chapter 27:Mollusks and Segmented Worms Chapter 28:Arthropods Chapter 29:Echinoderms and Invertebrate Chordates

Table of Contents – pages iv-v Unit 9: Vertebrates Chapter 30:Fishes and Amphibians Chapter 31:Reptiles and Birds Chapter 32:Mammals Chapter 33:Animal Behavior Unit 10: The Human Body Chapter 34:Protection, Support, and Locomotion Chapter 35:The Digestive and Endocrine Systems Chapter 36:The Nervous System Chapter 37:Respiration, Circulation, and Excretion Chapter 38:Reproduction and Development Chapter 39:Immunity from Disease

Unit Overview – pages 32-33 Ecology Principles of ecology Communities and Biomes Population Biology Biological Diversity and Conservation

Chapter Contents – page vii Chapter 4Population Biology 4.1:Population Dynamics 4.1:Section Check 4.2:Human Population 4.2:Section Check Chapter 4Summary Chapter 4Assessment

Chapter Intro-page 90 What You’ll Learn You will explain how populations grow. You will identify factors that inhibit the growth of populations. You will summarize issues in human population growth.

4.1 Section Objectives – page 91 Section Objectives: • Compare and contrast exponential and linear population growth. • Relate the reproductive patterns of different populations of organisms to models of population growth. • Predict effects of environmental factors on population growth.

Principles of Population Growth Section 4.1 Summary – pages 91-99 • Population dynamics – This refers to the fact that populations are constantly changing. • A population is a group of organisms, all of the same species, that live in a specific area. • A healthy population will grow and die at a steady rate unless it runs out of food or space, or is attacked in some way by disease or predators. • Scientists study changes in populations in a variety of ways.

Principles of Population Growth Section 4.1 Summary – pages 91-99 • Population Growth- This is the change in the size of a population over time. A. One method involves introducing organisms into an environment that contains abundant resources and then watching how the organisms react. B. Another method involves the growth of bacteria or yeast in a culture.

Section 4.1 Summary – pages 91-99 Principles of Population Growth • Studies of populations of larger organisms, such as an elk population in a national park, require methods such as the use of radio monitors.

Linear Growth The growth of populations is unlike the growth of pay you get from a job, which is linear growth. Money received Hours worked

Section 4.1 Summary – pages 91-99 How fast do populations grow? Populations of organisms, do not experience linear growth. Rather, the graph of a growing population starts out slowly, then begins to resemble a J-shaped curve.

Section 4.1 Summary – pages 91-99 How fast do populations grow? • Growth is slow at first because the number of reproducing individuals is small. • Rapid growth comes later because the total number of individuals that are able to reproduce has increased.

Section 4.1 Summary – pages 91-99 Is growth unlimited? • A J-shaped growth curve illustrates exponential population growth. • Exponentialgrowth means that as a population gets larger, it also grows at a faster rate. • Exponential growth results in unchecked growth or a population explosion.

Section 4.1 Summary – pages 91-99 How fast do populations grow? Population Growth of Houseflies 1 million 500,000 Population size 100 One year

Section 4.1 Summary – pages 91-99 What can limit growth Limits of the Environment • Limiting factors, such as availability of food, disease, predators, or lack of space, will cause population growth to slow. • Under these pressures, the population may stabilize in an S-shaped growth curve.

Section 4.1 Summary – pages 91-99 What can limit growth?

Section 4.1 Summary – pages 91-99 Carrying capacity • The number of organisms of one species that an environment can support indefinitely is its carrying capacity. • When a population overshoots the carrying capacity, then limiting factors may come into effect. Click image to view movie.

Section 4.1 Summary – pages 91-99 Carrying capacity • Deaths begin to exceed births and the population falls below carrying capacity. Carrying capacity

Section 4.1 Summary – pages 91-99 Reproduction Patterns • In nature, animal and plant populations change in size. • Biologists study the factor that determines population growth—an organism’s reproductive pattern, also called its life-history pattern. • A variety of population growth patterns are possible in nature.

Rapid life-history patterns Section 4.1 Summary – pages 91-99 • This pattern is found in organisms that produce many offspring in a short period of time – flies, mosquitos, mice, bacteria • Rapid life-history patterns are common among organisms from changeable or unpredictable environments. • Rapid life-history organisms have a small body size, mature rapidly, reproduce early, and have a short life span, and a short gestation period.

Slow life-history patterns Section 4.1 Summary – pages 91-99 • This pattern is found in organisms that produce fewer offspring over a long period of time – elephants, hippos, whales, some plants • Large species that live in more stable environments usually have slow life-history patterns.

Section 4.1 Summary – pages 91-99 Slow life-history patterns • Slow life-history organisms tend to be larger in size, mature slowly, reproduce later in life, have a longer life span and longer gestation period. They maintain population sizes at or near carrying capacity.

Section 4.1 Summary – pages 91-99 Density factors and population growth • How organisms are dispersed can be important. • Three patterns of dispersal are random, clumped, and uniform. Clumped Uniform Random

Section 4.1 Summary – pages 91-99 Density factors and population growth • Ecologists have identified two kinds of limiting factors that are related to dispersal: density-dependent and density-independent factors. • Population density describes the number of individuals in a given area.

Section 4.1 Summary – pages 91-99 Density factors and population growth • Density-dependent factors are factors that have an increasing effect as populations become more dense. These include disease, competition, predators, parasites, and food. • Disease, for example, can spread more quickly in a population with members that live close together.

Section 4.1 Summary – pages 91-99 Density factors and population growth • Density-independent factors can affect all populations, regardless of their density. • Most density-independent factors are abiotic factors, such as temperature, storms, floods, drought, and major habitat disruption.

Section 4.1 Summary – pages 91-99 Organism Interactions Limit Population Size • Population sizes are limited not only by abiotic factors, but also are controlled by various interactions among organisms that share a community.

Section 4.1 Summary – pages 91-99 Predation affects population size • When a predator consumes prey on a large enough scale, it can have a drastic effect on the size of the prey population. Normally, predations causes populations to fluctuate slightly. • Populations of predators and their prey are known to experience cycles or changes in their numbers over periods of time.

Section 4.1 Summary – pages 91-99 Predation affects population size • The data in this graph reflect the number of hare and lynx pelts sold to the Hudson’s Bay Company in northern Canada from 1845 through 1935. Lynx and Hare Pelts Sold to the Hudson’s Bay Company Lynx Hare Number of organisms(in thousands) Times (in years)

Section 4.1 Summary – pages 91-99 Predation affects population size • In field studies, predation increases the chance that resources will be available for the remaining individuals in a prey population. • Predation keeps natural populations healthy. WHY? • Predators prey on the sick, injured, old, weak – this results in a healthier population.

Section 4.1 Summary – pages 91-99 Competition within a population • Competition is a density-dependent factor. • When only a few individuals compete for resources, no problem arises. • When a population increases to the point at which demand for resources exceeds the supply, the population size decreases because some organisms go w/o food, shelter, etc. and thus die.

Section 4.1 Summary – pages 91-99 The effects of crowding and stress • When populations of certain organisms become crowded, individuals may exhibit symptoms of stress. • As populations increase in size in environments that cannot support increased numbers, individual animals can exhibit a variety of stress symptoms.

Section 4.1 Summary – pages 91-99 The effects of crowding and stress • These include aggression, decrease in parental care, decreased fertility, and decreased resistance to disease. All of these will lead to a population decrease. • They become limiting factors for growth and keep populations below carrying capacity.

Section 1 Check Question 1 Exponential growth means that as a population gets larger, it also _____. A. grows at a slower rate B. grows at a faster rate C. grows at a steady rate D. stabilizes in an S-shaped growth curve

Section 1 Check The answer is B. A J-shaped growth curve illustrates exponential growth. Population Growth of Houseflies 1 million Population size 500,000 100 One year

Section 1 Check Question 2 Which of the following would you expect to observe after a population exceeds its carrying capacity? A. population increases exponentially B. births exceed deaths C. deaths exceed births D. population growth rate is unaffected by limiting factors

Section 1 Check The answer is C. Limiting factors may come into effect after a population exceeds its carrying capacity. Deaths begin to exceed births and the population falls below carrying capacity. Characteristics of Population Growth Exponential growth DISEASE PREDATORS SPACE FOOD Carrying capacity S curve J curve Population 0 Time

Section 1 Check Question 3 Offspring per Individual Life Span Organism mosquito 250 1 month elephant 5 70 years humans 2 77 years oak tree 50 100 years A. grows at a slower rate B. grows at a faster rate C. grows at a steady rate D. stabilizes in an S-shaped growth curve

Section 1 Check The answer is A. Rapid life-history organisms have a small body size, mature rapidly, reproduce early, and have a short life span. Offspring per Individual Life Span Organism mosquito 250 1 month elephant 5 70 years humans 2 77 years oak tree 50 100 years

Section 1 Check Question 4 The number of organisms of one species that an environment can support indefinitely is its _____. A. life-history pattern B. growth rate C. demographic D. carrying capacity

Section 1 Check The answer is D. If population size rises above the carrying capacity, more organisms die than are born and the population drops back below the carrying capacity. Carrying capacity

Section 1 Check Question 5 Compare the terms “density-dependent factors” and “density-independent factors”.

Section 1 Check Both are limiting factors for organisms. Density-dependent factors have an increasing effect as the population increases and include disease, competition, parasites, and food. Density-independent factors can affect all populations regardless of density. Most are abiotic factors such as temperature, rainfall, and major habitat destruction.

4.2 Section objectives– page 100 Section Objectives: • Identify how the birthrate and death rate affect the rate at which a population changes. • Compare the age structure of rapidly growing, slow-growing, and no-growth countries. • Explain the relationship between a population and the environment.

Section 4.2 Summary – page 100-103 World Population • In the United States, a census is taken every ten years. • One of the most useful pieces of data is the rate at which each country’s population is growing or declining. • These figures are the basis for demography, the study of human population size, density and distribution, movement, and its birth and death rates.

Table of Contents – pages iv-v