How dense is your population


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How dense is your population

  1. 1. How dense is your population? 8SCIENCE: Tues. Oct. 26
  2. 2. Population density REVIEW: What are the characteristics of a population? (3) – Population Size – Population Spacing – Population Density - What is population density? - Number of individual organisms living in a certain area
  3. 3. Population density examples • # individuals = population density area 1) If 2500 grasshoppers live in an area of 1 km², what is the population density? – 2500 grasshoppers/km² 2) If there are 23 students in our class, and the area of this room is 46km², what is the population density? – 2 students/km² 3) If 15 cows live in an area of 60km², what is the population density? – 4 cows/km²
  4. 4. Population density activity: Quick activity: your group will be given a garbage bag and ruler 1) Take the garbage bag at your table and measure the length and width - What is the area of the bag? 2) Place it on the floor and all members in your group should try to stand on it – both feet should be on the bag. - How many people are in your group? What is the population density on the bag? 3) Now take the garbage bag and fold in half – what is the area? - Can all of your group stand on the bag? - What is the new population density? 4) Repeat step 3 by folding the bag one more time. - Why wasn’t everyone able to stand on the bag? - What were you competing for?
  5. 5. More characteristics of populations REVIEW: • What do living things need to grow and reproduce? – Can these populations grow forever? – Why not? LIMITING FACTORS • Another characteristic of populations is called carrying capacity • Imagine a population of rabbits increases each year. Is there a limit to the supply of resources in that environment? • YES: after some time the environment will not have enough resources for the rabbits to survive or reproduce and the population will stop increasing
  6. 6. Carrying Capacity • (17– 9 pg. 490) – This means the environment has reached the CARRYING CAPACITY – Carrying capacity is the largest number of individuals an environment can support and keep healthy for a period of time – What do you think happens when the population becomes higher than the carrying capacity?
  7. 7. Human growth • What are some limiting factors to human population growth? – Water – Food – Living space – Pollution – Disease • To measure our human impact on nature, we measure our ecological footprint (eco-footprint)
  8. 8. Eco-footprint • How do we impact the earth and create our footprint? – Food – Energy use – Transportation • If everyone on Earth lived the way the AVERAGE person in North America did, we would need 3.8 Earths to support all of the people
  9. 9. Homework questions to answer about Ecological Footprint: • To calculate your eco-footprint: 07/ QUESTIONS: 1) What is the size of your Ecological Footprint? How many planets would we need if everyone in the world had your Ecological Footprint? 2) How does your Footprint compare with those of people in other countries in the world? 3) What parts of your lifestyle do you think contributed the most to the size of your Footprint? 4) What changes to your lifestyle can you make to reduce your ecological footprint? You should have one change for food, water use, energy use, and transportation. **PLEASE answer in full sentences and HAND THIS IN CLASS THURSDAY, OCTOBER 28TH**