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Unit 2 District Assessment on December 19/20, 2011
Teacher:
Unit :
Assignment:
Ms Gandla
Ecology
Unit Review
Name___________________
Date_______________
Unit 2 Review
3.1 What Is Ecology?
Lesson Objectives
Describe the study of ecology.
Explain how biotic and abiotic factors influence an ecosystem.
Lesson Summary
Studying Our Living Planet Ecology is the scientific study of interactions among organisms and
between organisms and their environment.
Earth’s organisms live in the biosphere. The biosphere consists of the parts of the planet in which all
life exists.
Ecologists may study different levels of ecological organization:
 Individual organism
 An assemblage of individuals that belong to the same species and live in the same area is called a
population.
 An assemblage of different populations that live together in an area is referred to as a community.
 An ecosystem includes all the organisms that live in a particular place, together with their physical
environment.
 A group of ecosystems that have similar climates and organisms is called a biome.
Biotic and Abiotic Factors Ecosystems include biotic and abiotic factors.
A biotic factor is any living part of an environment.
An abiotic factor is any nonliving part of an environment.
Studying Our Living Planet
1. What is ecology?
2. Label each level of organization on the diagram.
Use the diagram to answer Questions 4–5
Unit 2 District Assessment on December 19/20, 2011
3.
What does the biosphere contain?
______________________________________________________________________________________
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Biotic and Abiotic Factors
6. Use the terms in the box to fill in the Venn diagram. List parts of the environment that consist of biotic
factors, abiotic factors, and some components that are a mixture of both.
air
animals
bacteria
heat
mushrooms
plants
precipitation
soil
sunlight
Both
iotic
Factors
Abiotic
Factors
3.2 Energy, Producers, and Consumers
Lesson Objectives
Define primary producers.
Describe how consumers obtain energy and nutrients.
Lesson Summary
Primary Producers Sunlight is the main energy source for life on Earth. Organisms that can capture
energy from sunlight or chemicals and use that energy to produce food are called autotrophs, or primary
producers.
The process in which autotrophs capture light energy and use it to convert carbon dioxide and water
into oxygen and sugars is called photosynthesis.
The process in which autotrophs use chemical energy to produce carbohydrates is called
chemosynthesis.
Consumers Organisms that rely on other organisms for their energy and food are called heterotrophs.
Heterotrophs are also referred to as consumers. There are many different types of heterotrophs:
Herbivores, such as cows, obtain energy by eating only plants.
Carnivores, such as snakes, eat only animals.
Omnivores, such as humans, eat both plants and animals.
Detritivores, such as earthworms, feed on dead matter.
Decomposers, such as fungi, break down organic matter.
Scavengers, such as vultures, consume the carcasses of other animals.
Unit 2 District Assessment on December 19/20, 2011
Primary Producers
1. What do autotrophs do during photosynthesis?
2. Can some organisms survive without energy from the sun? Explain your answer.
3. Can organisms create their own energy? Explain your answer.
Consumers
4. Complete the table about types of heterotrophs.
Types of Heterotrophs
Type
Definition
Herbivore
Examples
cows, rabbits
Heterotroph that eats animals
humans, bears, pigs
Omnivore
Detritivore
Decomposer
Heterotroph that consumes the carcasses of dead
animals but does not typically kill them itself
5. What is a consumer?
4.2 Niches and Community Interactions
Lesson Objectives
Define niche.
Describe the role competition plays in shaping communities.
Unit 2 District Assessment on December 19/20, 2011
Describe the role predation and herbivory play in shaping communities.
Identify the three types of symbiotic relationships in nature.
Lesson Summary
The Niche Every species has its own tolerance, or a range of conditions under which it can grow and
reproduce. A species’ tolerance determines its habitat, the place where it lives.
A niche consists of all the physical and biological conditions in which a species lives and the way the
species obtains what it needs to survive and reproduce.
An organism’s niche must contain all of the resources an organism needs to survive. A resource is any
necessity of life, such as water, nutrients, light, food, or space.
Competition Competition occurs when organisms try to use the same limited resources.
Direct competition between species often results in one species dying out. This is the basis of the
competitive exclusion principle. This principle states that no two species can occupy exactly the same
niche in exactly the same habitat at the same time.
Competition helps to determine the number and type of species in a community.
Predation, Herbivory, and Keystone Species Predator-prey and herbivore-plant interactions help
shape communities.
Predation occurs when one organism (the predator) captures and eats another (the prey).
Herbivory is an interaction that occurs when an animal (the herbivore) feeds on producers (such as
plants).
Sometimes changes in the population of a single species, often called a keystone species, can cause
dramatic changes in the structure of a community.
Symbioses Symbiosis occurs when two species live closely together in one of three ways: mutualism,
commensalism, or parasitism.
In mutualism, both species benefit from the relation ship.
In parasitism, one species benefits by living in or on the other and the other is harmed.
In commensalism, one species benefits and the other is neither helped nor harmed.
The Niche
1. What is a niche?
2. Give an example of resources a squirrel might need.
3. Three different warbler species live in the same tree. One species feeds at the top of the tree, the second
species feeds in the middle part of the tree, and the third species feeds at the bottom of the tree. Do all
three species occupy the same niche? Explain.
Unit 2 District Assessment on December 19/20, 2011
Competition
For Questions 4–8, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
4. Competition occurs when organisms attempt to use the same resources.
5. Competition between members of the same species is known as interspecific
competition.
6. The competitive exclusion principle states that no two organisms can occupy
exactly the same niche in exactly the same habitat at exactly the same time.
7. If two species of bacteria are grown in the same culture, one species will always
outcompete the other.
8. Members of the same species tend to divide resources instead of competing over
them.
Predation, Herbivory, and Keystone Species
Write the letter of the correct answer on the line at the left.
9. A lion eating a zebra is an example of
A. herbivory.
B. habitat destruction.
10. A cow eating grass is an example of
A. herbivory.
B. predation.
C. predation.
D. a keystone species.
C. habitat destruction.
D. a keystone species.
11. A keystone species is one that
A. eats a mixture of plants and animals.
B. is introduced into a community after a major disturbance.
C. causes the amount of diversity in a community to decrease.
D. helps to stabilize the populations of other species in the community.
Lesson Objectives
Describe and compare the characteristics of the major land biomes.
Identify the areas that are not classified into a major biome.
Lesson Summary
The Major Biomes A biome is a group of terrestrial regional climate communities that
covers a large area and is characterized by soil type, climate, and plant and animal life.
In tropical rain forests, the tops of tall trees form a covering called the canopy. Shorter
trees and vines form another layer called the understory. It is hot and wet all year.
Tropical dry forests are found in areas with alternating wet and dry seasons. The trees in
these forests may be deciduous, meaning they shed their leaves during a particular
season.
In a tropical grassland, grassy areas are spotted with isolated trees.
Deserts have less than 25 centimeters of precipitation annually.
Temperate grasslands have warm summers, cold winters, and deep soil.
Unit 2 District Assessment on December 19/20, 2011
Temperate woodlands and shrublands are large areas of grasses and wildflowers such as
poppies interspersed with trees or shrubs.
Temperate forests are made up of deciduous and evergreen coniferous trees. Coniferous
trees produce seed-bearing cones and most have waxy needles. Temperate forests have
soils rich in humus, which forms from decaying leaves and makes soil fertile.
Northwestern coniferous forests have mild temperatures with cool, dry summers and
abundant precipitation in fall, winter, and spring.
Boreal forests, or taiga, are dense forests of coniferous evergreens.
Tundra is characterized by permafrost, a layer of permanently frozen subsoil.
Other Land Areas Some areas, such as mountains and polar ice caps, do not fall neatly
into the major biomes.
5.1 How Populations Grow
Lesson Objectives
List the characteristics used to describe a population.
Identify factors that affect population growth.
Describe exponential growth.
Describe logistic growth.
Lesson Summary
Describing Populations Researchers study five important characteristics of a population:
Geographic range is the area in which a population lives.
Population density is the number of individuals per unit area.
Population distribution is how individuals are spaced out in their range.
Growth rate determines whether a population grows, shrinks, or stays the same size.
Age structure is the number of males and females of each age in a population.
Population Growth Populations can grow, shrink, or stay the same size.
Factors that increase population size include births and immigration, which is the movement of
individuals into an area.
Factors that decrease population size include deaths and emigration, which is the movement of
individuals out of an area.
Exponential Growth When conditions are ideal, the larger a population gets, the faster it grows. When a
population’s numbers grow larger with each generation, exponential growth is occurring. Ideal conditions
include unlimited resources and absence of predation and disease.
Logistic Growth Resources become less available as a population grows.
Logistic growth occurs when population growth slows and then stops after a period of exponential
growth has occurred.
Population size stabilizes at the carrying capacity, the maximum number of individuals of a given
species that an environment can support.
Describing Populations
For Questions 1–5 complete each statement by writing the correct word or words.
1. The
2. Population density is the
is the area in which a population lives.
of individuals per unit area.
Unit 2 District Assessment on December 19/20, 2011
3. How the individuals are spaced in their range is a population’s
4. Growth rate is how quickly a population
5. To find the
age.
in size.
of a population, count the number of males and females of each
Population Growth
For Questions 6–10, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true
6. If the death rate is less than the birthrate, the population is likely to shrink.
7. Immigration increases population size.
8. Young animals may immigrate from the place where they were born to establish new
territories.
9. A high birthrate and immigration decrease population size.
10. Populations grow if more individuals are born than die in a period of time.
Exponential Growth
12. Describe the conditions in which exponential growth occurs.
13. Can exponential growth occur in a population of organisms that take a long time to reproduce? Why or
why not?
14. Complete the graph by drawing the characteristic shape of exponential population growth.
15. What letter is used to refer to the characteristic shape of an exponential growth curve?
Unit 2 District Assessment on December 19/20, 2011
Logistic Growth
16. Complete the graph by drawing the characteristic shape of logistic population growth.
17. What letter is used to refer to the characteristic shape of the logistic growth curve?
18. When real-world populations of plants and animals are analyzed, why do they most often have the
logistic growth curve?
19. What does the term carrying capacity refer to?
20. Complete the table to name and explain three phases of logistic growth. Use the terms growth rate,
population size, and carrying capacity in your explanations.
Phases of Logistic Growth
Phase
1
2
3
Phase name
Explanation
Unit 2 District Assessment on December 19/20, 2011
Density-Dependent Limiting Factors
7. What is a density-dependent limiting factor?
8. When do density-dependent factors operate most strongly?
9. What are four density-dependent limiting factors?
10. Complete the graphic organizer with examples of density-independent limiting factors.
Population
Size
can be limited by
density-independent
factors such as
5.3 Human Population Growth
Lesson Objectives
Discuss the trend of human population growth.
Explain why population growth rates differ in countries throughout the world.
Lesson Summary
Historical Overview The size of the human population has increased over time.
For most of human existence, limiting factors such as the scarcity of food kept death rates high.
As civilization advanced, agriculture, industry, improved nutrition, sanitation, and medicine reduced
death rates. Birthrates stayed high in most places. This led to exponential growth.
Today, the human population continues to grow exponentially, although the doubling time has slowed.
Patterns of Human Population Growth Demography is the scientific study of human populations.
Demographers try to predict how human populations will change over time.
Over the past century, population growth in developed countries slowed. As death rates dropped,
birthrates dropped also. Demographers call this shift the demographic transition. Most people live in
countries that have not undergone the demographic transition.
An age-structure graph shows how many people of each gender are in each age group in a population.
Demographers use such graphs to predict how a population will change. More people of reproductive
age usually means faster growth.
Unit 2 District Assessment on December 19/20, 2011
Many factors, including disease, will affect human population growth in the twenty-first century.
Current data suggest the human population will grow more slowly over the next 50 years than it did for
the last 50 years.
Historical Overview
For Questions 1–5, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
1. Over the last 1000 years, the size of the human population has decreased.
2. Since the 1800s, human population growth has been logistic.
3. The human population has increased because birthrates have dropped.
4. The combination of low death rates and high birthrates led to exponential growth.
5. Charles Darwin suggested that human populations are regulated by war, famine,
and disease
6. Complete the table below to explain how each factor affected the size and growth rate of the human
population over the last 10,000 years.
Factors That Affected Human Population Growth
Cause
Agriculture
Improved health care and medicine
Improved sanitation
Bubonic plague
Industrial Revolution
Effect
Unit 2 District Assessment on December 19/20, 2011
Use these age structure diagrams to answer Questions 8–11.
8. Which country has gone through the demographic transition? How do you know?
9. Which country do you predict will experience a slow and steady growth rate in the near future? Why?
10. Which country is most likely to grow exponentially in the near future? Why?
11. Suggest three factors that might slow population growth in Rwanda.