Chapter: Interactions of Life

Table of ContentsTable of Contents

Section 3: Interactions Within Communities

Section 1: Living Earth

Section 2: Populations

• Biosphere - part of Earth that supports life is The Biosphere11

Living EarthLiving Earth

• Different environments = different organisms

The Biosphere11Living EarthLiving Earth

• Earth - just right for life.

• Mercury - too hot during the day and too cold at night

Life on Earth 11

Living EarthLiving Earth

• Venus – too hot

• Mars - colder than Earth

• farther from Sun

• thinner atmosphere.

• Ecosystem - all the living and nonliving parts of an environment

Ecosystems 11Living EarthLiving Earth

11Living EarthLiving Earth

• Ecology - study of interactions between organisms and their environments.

• Ecologists - scientists who study Ecology

Ecosystems

• Population - all organisms of the same species that live in an area at the same time.

Populations11Living EarthLiving Earth

• Community - all the populations of species living in an ecosystem.

11Living EarthLiving Earth

Populations

11Living EarthLiving Earth

11Living EarthLiving Earth

• Habitat - place where an organism lives

• Provides:

• Food

• Shelter

• Temperature

• Moisture

Question 111

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Earth’s _____ includes the top part of Earth’s crust, all the waters covering Earth’s surface, and the atmosphere surrounding Earth.

A. biosphere B. carrying capacity C. ecosystemD. limiting factor

11

The correct answer is A. The biosphere is defined as the part of Earth that supports life and living things.

Answer

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11

This illustration can be used to represent a forest community because it _______.

Question 2

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A. shows birds gathering twigs to make nests.B. shows clouds representing rainfall.C. shows deer grazing on grass.D. shows many different populations living together.

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The correct answer is D. A community includes the populations of all species that live in a particular ecosystem. The illustration shows populations of deer, blue birds, and various species of plants.

Answer

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11

What kind of scientist would study how bison grazing on prairie grass affect the grasshoppers that lived in the prairie?

Ecologists study interactions that occur among organisms and their environment.

Question 3

Answer

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22PopulationsPopulations

• Competition occurs when two or more organisms seek the same resource at the same time.

Food, Water, and Space

• Competition limits population size

22PopulationsPopulations

Growth Limits

• Can occur between the same species or different species

• Population density - number of individuals of one species per a specific area.

22PopulationsPopulations

Population Size

Measuring Populations 22PopulationsPopulations

• 1 method - trap-mark-release.

• Use sample counts to estimate the sizes of large populations

Sample Counts 22

PopulationsPopulations

22PopulationsPopulations

• Limiting factor - anything that restricts the number of individuals in a population.

• Carrying capacity - largest number of individuals of one species that an ecosystem can support over time

22PopulationsPopulations

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• Biotic potential - highest rate of reproduction under ideal conditions

22PopulationsPopulations

• Birth Increases population22PopulationsPopulations

• Death Decreases population

22PopulationsPopulations

• Immigration Increases population

• Emmigration Decreases population

22PopulationsPopulations

22PopulationsPopulations

• Exponential growth - the larger a population gets, the faster it grows.

22PopulationsPopulations

22PopulationsPopulations

22PopulationsPopulations

• Carrying capacity influenced by infectious diseases

Question 1 22

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How might competition with the owl and woodpecker limit the growth of the population of the lizards shown in this illustration?

22

A. there would be more competition for food B. there would be more competition for nesting spaces C. there would be more competition for sunlightD. there would be more competition for water

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The correct answer is B. All three animals use the cactus for nesting spaces. If nesting spaces are limited, the lizards may not be able to raise young and their population size will be limited.

Answer

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Question 2 22

An ecologist measured 10 square meters of beach and counted 50 crabs. The scientist then multiplied 50 by 10 and estimated that there were 500 crabs on 100 square meters of beach. What tool was the ecologist using?

A. biotic count B. capacity count

C. limiting countD. sample count

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22

The correct answer is D. Sample counts are used to estimate the sizes of large populations.

Answer

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Question 3 22

Which has the highest biotic potential, a fish that can produce 4000 eggs a year or one that can produce 20 eggs a year?

The fish that can produce 4000 eggs a year has the highest biotic potential. Biotic potential is the highest rate of reproduction under ideal conditions.

Answer

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Organisms Need Energy33Interactions Within CommunitiesInteractions Within Communities

• Sun - source of energy for most life on earth

• Producers - Organisms that use an outside energy source to make energy-rich molecules

33Interactions Within CommunitiesInteractions Within Communities

• Most contain chlorophyll

• Consumers - organisms that cannot make their own energy-rich molecules

33Interactions Within CommunitiesInteractions Within Communities

• Obtain energy by eating other organisms

• Herbivores – eat plants

33Interactions Within CommunitiesInteractions Within Communities

Consumers

• Omnivores - eat plants and animals.

33Interactions Within CommunitiesInteractions Within Communities

• Carnivores - eat other animals

33Interactions Within CommunitiesInteractions Within Communities

• Decomposers - consume wastes and dead organisms.

• Food chain - model of the feeding relationships in an ecosystem

33Interactions Within CommunitiesInteractions Within Communities

33Interactions Within CommunitiesInteractions Within Communities

• Symbiosis - close relationship between species

33Interactions Within CommunitiesInteractions Within Communities

• Mutualism - symbiotic relationship in which both species benefit

• Commensalism – 1 organism benefits and the other is not affected

33Interactions Within CommunitiesInteractions Within Communities

• Roundworms, are common in puppies.

Parasitism 33Interactions Within CommunitiesInteractions Within Communities

• The roundworm attaches itself to the inside of the puppy’s intestine and feeds on nutrients in the puppy’s blood.

33Interactions Within CommunitiesInteractions Within Communities

• Parasitism - 1 organism benefits but the other is harmed

33Interactions Within CommunitiesInteractions Within Communities

• Niche – organism’s role in its environment

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33Interactions Within CommunitiesInteractions Within Communities

• Predator - consumers that capture and eat other consumers

• Prey - the organism that is captured by the predator

Question 133

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Fleas often live on dogs or cats and bite them for a meal of blood. This can be harmful to the cat or dog that is bitten. What type of symbiotic relationship is this?

This is an example of parasitism. In this type of relationship, one organism is harmed, while the other benefits.

Answer

Question 233

How do producers that contain chlorophyll make energy rich molecules?

A. they use chemosynthesis B. they use commensalismC. they use mutualismD. they use photosynthesis

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Answer33

The correct answer is D. Green plants contain chlorophyll so that they can use the energy of the Sun for photosynthesis.

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Question 333

Which describes how predators affect an ecosystem?

A. decrease the number of niches in the ecosystem B. decrease the number of species in the ecosystemC. increase competition among speciesD. limit the size of the prey population

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Answer33

The correct answer is D. Because predators limit the prey populations, food and other resources are less likely to become scarce and competition between species is reduced.

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