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Chapter%205:%20Populations%20and%20Communities

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Title: Chapter 9: Introduction to Genetics Author: RCulnen Last modified by: Bryan Rescigno Created Date: 2/27/2008 1:31:46 PM Document presentation format – PowerPoint PPT presentation

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Title: Chapter%205:%20Populations%20and%20Communities


1
Chapter 5 Populations and Communities
2
Useful Definitions
  • Population Group of organisms that all belong
    to the same species and live in a specific area.
  • Steady State Growth rate is zero
  • Population remains stable

3
Exponential Growth
  • Ideal conditions for growth and reproduction.
  • Rapid increase in a population.

4
Logistic Growth Page 1034
  • Most populations go through a number of growth
    phases.
  • Carrying Capacity - of individuals that can be
    supported in a given environment.

5
Factors that Control Population Growth
  • Density-Dependent Limiting Factors
  • Affect large populations more strongly than small
    populations
  • 1. number of births
  • 2. number of deaths
  • 3. number of individuals that enter / leave
    population
  • Immigration increases population size
  • Emigration decreases population size

6
Predator/Prey Relationships
  • Almost every animal serves as a food source for
    another one.
  • These species have coexisted for many years.
  • Accustomed to each others strengths and
  • weaknesses.
  • Defense vs.
  • Counterdefense

7
The Best Defense is a Good Defense
  • Prey Predator
  • Shells, poisonous skin, Stronger jaws, digestive
  • Barbs, Camouflage enzymes, keen eyesight,
  • venom
  • Natural Selection.
  • Adaptations that allow individuals to best
    survive and reproduce in their natural
    environments.

8
Section 3 Interactions Among Communities
  • Populations within a community interact with one
    another in many ways.
  • Plants compete for water, nutrients, and
    sunlight.
  • Herbivores compete for food and space.
  • Carnivores compete for herbivores and other prey

9
Interactions
  • 1. Commensalism One
  • organism benefits
    and the
  • other is unharmed.
  • 2. Mutualism Two
    species live
  • together that
    benefit both
  • organisms.

10
DO NOW May 22
  • Draw a graph to represent logistic growth.
  • Label the axes and the area of the graph that
    represents carrying capacity.

11
Interactions between Ecosystems
  • Consider a pond in a forest.
  • The pond supports a whole range of plant and
    animal life.
  • Water enters the pond from a nearby stream.
  • Water runoff feeds a different stream or marsh.
  • Animals in the forest rely on the pond for food
    and water.
  • Even birds that travel many miles benefit from
    this pond.

12
Chapter 6 People and the Biosphere
  • Humans affect the environments they inhabit.
  • Massive number of trees cut down.
  • Destroyed plants that did not provide benefits.
  • Dangerous/Wild animals were hunted and killed to
    protect humans and domesticated animals.

Logging around the world continues to threaten
and destroy many native species of plants and
animals.
13
Factors that Determine Population Growth
  • Humans create enormous demands on the natural
    resources of planet Earth.
  • Birthrate versus Deathrate
  • Earths population continues to increase
    threatening to use up many of its natural
    resources to meet the basic needs of life.
  • Earths population will double in the next half
    century at the current rates.
  • High birthrate
  • Low deathrate
  • Longer life-span

14
Human Population Growth Curve
15
Pollution
  • Biodegradeable organic wastes such as sewage and
    food scraps can be broken down into essential
    nutrients
  • Nonbiodegradeable ones cannot be broken down
    through natural processes (glass, chemicals,
    plastics.)

Garbage dump site in Mexico City, Mexico.
16
Pollution
  • Industrial chemicals, sewage waste, and the
    thermal pollution (burning of fossil fuels)
  • The Greenhouse Effect (Carbon dioxide)
  • Destruction of the Ozone Layer (Chloroflurocarbons
    are now banned)
  • Extinction of Plant and Animal Species
    (Destruction of natural habitats)

17
Saving the Earth
  • Going Green
  • Conservation of land.
  • Protecting oceans and other bodies of water.
  • Using more biodegradeable products.
  • Breeding endangered species in safe environments.
  • Banning the hunting of a species for sport.
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