Environmental science: Population power of doubling
Power of Doubling
If you were offered a choice between one million dollars and a penny on the first day of the month, two pennies on the second day, four pennies on the third, and so
forth for 30 days, which would you choose If you calculate this, you will find that the second choice would give you somewhat more than one million dollars! Each
day you are doubling a larger number, and although the number of pennies increases slowly at first, it soon reaches over one million dollars. That is the power of
doubling, or exponential growth.
Growth is defined as exponential when the increase of a quantity is proportional to the size of the quantity. The quantity may be numbers, as in the numbers of
individuals in a population, or some other measure, such as amount of energy consumed. Exponential growth is very slow in the early stages, but quickly accelerates.
A frequent measure of exponential growth is doubling time, that is, the amount of time required for the quantity to double. The shorter the doubling time, the faster
is the rate of growth.
The human population, like all populations of organisms, grows exponentially when unchecked. Although it took 130 years, from 1800 to 1930 for the world population to
double, it doubled again by 1975, a mere 45 years. At this rate the world population of 5.5 billion in 1993 would be expected to reach 11 billion by 2035. Different
areas of the world, however, have vastly different doubling times. While the doubling time for developed areas in 1993 was 162 years, that for the less developed
areas was 35 years.
In this activity, you will demonstrate exponential growth and determine the doubling time and growth rate of a simulated population.
MATERIALS:
2 pennies
approximately 200 dried beans (or dry macaroni)
2 8-oz. Paper cups
graph paper
1 larger paper cup marking pen
PROCEDURE:
1) Label one small paper cup, ���Parents���, and the other one ���Offspring���. Label the large cup, ���Bean Pot���. Place 10 beans in the ���Parents��� cup and the rest in the
���Bean Pot���. Each bean represents an individual in a population.
2) Toss the two pennies. If both pennies show heads, toss again. If both pennies show tails, one member of the population has died and you should remove a bean
from the ���Parents��� cup and put it into the ���Bean Pot���. If one head and one tail show, a member of the population has had a child. To simulate the birth, take one
bean from the ���Parents��� cup and one from the ���Bean Pot��� and place them in the cup marked ���Offspring���.
3) Continue tossing until there are no longer any beans in the ���Parents��� cup. Count the number of beans in the ���Offspring��� cup and record the number in Data Table A.
The ���Offspring��� now become the parents, so move all of the beans from the ���Offspring��� cup into the ���Parents��� cup.
4) Repeat steps #2 and #3 until you have completed 10 generations.
5) Make a graph of your data, with generation number on the horizontal axis and population size on the vertical axis.
DATA TABLE A:
Generation # Population Size
0
1
2
3
4
5
6
7
8
9
10
6) Repeat the activity, only this time assume that when a head shows to the right of a tail, the individual decides not to have a child. In that case, place one bean
from the ���Parents��� cup into the ���Offspring��� cup, but do not add a bean from the ���Bean Pot���. If, on the other hand, the head shows to the left of the tail, proceed as
you did before, taking one bean from the ���Parents��� cup and one from the ���Bean Pot��� and placing them in the ���Offspring��� cup. Record your data in DATA TABLE B. When
you have finished 10 generations, graph your data on the same graph in a different color.
DATA TABLE B:
Generation # Population Size
0 10
1
2
3
4
5
6
7
8
9
10
FOLLOWUP:
1) On average, how should the birth rate of this population compare with the death rate
How do you know this
2) From your graph, determine the doubling times for the population at the beginning, the middle, and the end of the graph. Are they all the same Explain why.
3) Assume that a generation is equal to 20 years. Use the doubling time from your graph to calculate the growth rate of the population, using the formula below:
annual growth rate (%) = 70/doubling time (yrs.)
4) Calculate the doubling time and growth rate for the second set of data as you did for the first. Compare the two data sets.
5) Write a short paragraph explaining the implications of this activity for the human population.
Demographic Variable Country Data
Birth Rate (annual number of births per 1,000 total population) World 22
More Developed 11
Less Developed 24
Less Developed (Excl. China) 28
Africa 38
Death Rate (annual number of deaths per 1,000 total population World 9
More Developed 10
Less Developed 8
Less Developed (Excl. China) 9
Africa 14
GNI PPP Per Capita, 2001 (US$) World $7,160
More Developed $22,030
Less Developed $3,660
Less Developed (Excl. China) $3,570
Africa $2,120
Population 2025 (projected) World 7,907,000,000
More Developed 1,260,000,000
Less Developed 6,647,000,000
Less Developed (Excl. China) 5,192,000,000
Africa 1,289,000,000
Population 2050 (projected) World 9,198,000,000
More Developed 1,257,000,000
Less Developed 7,940,000,000
Less Developed (Excl. China) 6,547,000,000
Africa 1,883,000,000
Our Service Charter
-
Excellent Quality / 100% Plagiarism-Free
We employ a number of measures to ensure top quality essays. The papers go through a system of quality control prior to delivery. We run plagiarism checks on each paper to ensure that they will be 100% plagiarism-free. So, only clean copies hit customers’ emails. We also never resell the papers completed by our writers. So, once it is checked using a plagiarism checker, the paper will be unique. Speaking of the academic writing standards, we will stick to the assignment brief given by the customer and assign the perfect writer. By saying “the perfect writer” we mean the one having an academic degree in the customer’s study field and positive feedback from other customers. -
Free Revisions
We keep the quality bar of all papers high. But in case you need some extra brilliance to the paper, here’s what to do. First of all, you can choose a top writer. It means that we will assign an expert with a degree in your subject. And secondly, you can rely on our editing services. Our editors will revise your papers, checking whether or not they comply with high standards of academic writing. In addition, editing entails adjusting content if it’s off the topic, adding more sources, refining the language style, and making sure the referencing style is followed. -
Confidentiality / 100% No Disclosure
We make sure that clients’ personal data remains confidential and is not exploited for any purposes beyond those related to our services. We only ask you to provide us with the information that is required to produce the paper according to your writing needs. Please note that the payment info is protected as well. Feel free to refer to the support team for more information about our payment methods. The fact that you used our service is kept secret due to the advanced security standards. So, you can be sure that no one will find out that you got a paper from our writing service. -
Money Back Guarantee
If the writer doesn’t address all the questions on your assignment brief or the delivered paper appears to be off the topic, you can ask for a refund. Or, if it is applicable, you can opt in for free revision within 14-30 days, depending on your paper’s length. The revision or refund request should be sent within 14 days after delivery. The customer gets 100% money-back in case they haven't downloaded the paper. All approved refunds will be returned to the customer’s credit card or Bonus Balance in a form of store credit. Take a note that we will send an extra compensation if the customers goes with a store credit. -
24/7 Customer Support
We have a support team working 24/7 ready to give your issue concerning the order their immediate attention. If you have any questions about the ordering process, communication with the writer, payment options, feel free to join live chat. Be sure to get a fast response. They can also give you the exact price quote, taking into account the timing, desired academic level of the paper, and the number of pages.