Monthly Archives: November 2013

Human Impact on Ocean Fisheries

Cod fisherman with their haul, courtesy of Wikipedia.

Cod fisherman with their haul, courtesy of Wikipedia.

The article linked below outlines the impact of human population growth on global marine fisheries. It has been well-established through scientific research that as people become wealthier, they consume more protein. And as Earth’s human population continues to grow, the pressure on fisheries becomes two-fold: not only are there more people fishing (population growth), but those people are becoming wealthier (economic growth) and eating more seafood per person. This article ties in brilliantly to ESS Topic 3 – Human Populations, Resource Use, and Carrying Capacity.

Click here for the full article.

One last revision note before the test…

Here’s the last part of revision for the test coming up at the end of this week. I’ve saved the Keynote from class as a PDF, which you can view and download below.

A New Approach to Bring Affordable Solar Energy to Rural Africa

This article from Scientific American outlines a recent idea sweeping across much of East Africa, including several projects and start-up companies here in Tanzania.

Rural solar electrification. Image credit: www.greenbiosolar.com

Rural solar electrification. Image credit: www.greenbiosolar.com

The idea is quite simple, actually: Rural families who can’t afford the high costs in setting up a traditional solar electricity system are able to pre-pay for a certain amount of electricity generated by the solar kit. Once they’ve used the electricity paid for, the kit shuts off access until they make another payment – just like the scratch-off cards for mobile phone vouchers we use here in Dar es Salaam – and payments can be made via M-Pesa or similar services. When they have the cash, they buy more electricity, and once they’ve paid for the full kit, it continues to generate electricity for them for free!

Published on the same day was this article from Mary Ellen Harte at the Huffington Post, outlining current and future developments in the field of renewable energy. She focuses specifically on solar energy, with some discussion of wind, wave, and geothermal power as well.

Both of these articles fit nicely within our ESS Topic 3.3.3 – “Outline the factors that affect the choice of energy sources adopted by different societies.”

Grade 9 Biology Test Update

Here’s a little more information about the upcoming unit test.

Topics:

  • Cell structure and function
  • Cell Theory
  • Biological molecules
  • Energy flow through ecosystems
  • Nutrient cycles within ecosystems
  • Photosynthesis and respiration
  • Levels of organization
  • Food webs
  • Trophic levels

Assessment Criteria (max 6 marks each):

  • B1 – Science Vocabulary
  • B2 – Communicating Effectively
  • C1 – Recalling and Explaining Concepts
  • C3 – Evaluating Information
  • E3 – Describing Trends
  • E4 – Concluding

ESS Test – Mark Scheme Published

Below is the recent test on ESS Topics 1, 7, and 2.1 – 2.3. The original test and the mark scheme are included as a single document and consist of real IB questions from past papers.

The red ovals highlight the key words in the questions, and the blue rectangles identify the parts of the responses which earn marks from the examiners. Please use this test as a study guide for future tests, such as this year’s final exam and next year’s mock exam.

What’s on the 9th-Grade Biology Test?

We are 1 week from the summative unit test in grade 9 science, which means it’s time to start revising. Here’s a list of the major topics you’re likely to find on the test.

  • Cell structure and function
  • Plant vs animal
  • Biological molecules
  • Energy flow through ecosystems
  • Nutrient cycles within ecosystems
  • Photosynthesis and respiration
  • Food webs
  • Levels of organization
  • Trophic levels

There will be several skills assessed on the test: recalling scientific facts (vocabulary and definitions, labeling diagrams), explaining scientific concepts, analyzing results, and evaluating trends in experimental data. Make sure you know this stuff well!

Measuring Biomass and Diversity in Ecosystems

Even the snakes at my house are curious! (Image credit: Brad Kremer)

Even the snakes at my house are curious! (Image credit: Brad Kremer)

Environmental scientists, national park wardens, reserve managers, and conservation officers are the people making the decisions about Tanzania’s abundant wildlife resources. Many of the choices they make about the areas and organisms they protect are based on political and/or economic considerations, but most of those decisions will have at least some foundation in scientific knowledge.

How do we know which living resources are present in a national park or reserve? How do we know the number of elephants or eland or egrets in a wildlife management area? These are some essential questions for anyone charged with sustainably managing a country’s natural resources. Luckily for all of us, science has some answers!

The Lincoln Index is a tool used to estimate populations of mobile organisms in an ecosystem. The Lincoln index answers the question, “How many?” There are 4 key steps to properly conducting a Lincoln Index survey:

  1. Capture: systematically catch organisms without harming them

    Lincoln Index formula. See the syllabus for a further explanation on its use.

    Lincoln Index formula. See the syllabus for a further explanation on its use.

  2. Mark: mark the organisms in a way that does not harm them
  3. Release: let them return to their natural habitat
  4. Recapture: catch another

These 4 steps will provide some key data points, which can be plugged into a mathematical formula, shown at right, which estimates the total size of the population in the area sampled.

Another highly useful tool for measuring biotic components of ecosystems is the Simpson Index, or the Simpson Reciprocal Index. The Simpson Index measures the diversity of an ecosystem. Simpson accounts for both aspects of diversity, as defined in our ESS syllabus: species richness (the total number of species present) and species evenness (the number of individuals of each species present). The process for calculating Simpson’s D-value is a little more complicated than that for calculating Lincoln, but not much. Please check the ESS syllabus for details.

Simpson's Diversity Index. See the syllabus for further details on its use.

Simpson’s Diversity Index. See the syllabus for further details on its use.

We’ll be simulating 3 different ecosystems in class over the next couple of days, so you should have plenty of opportunity to test out these formulae and manipulate some of the variables within them. Both of these procedures will help you tremendously on the ESP week of field work in Zanzibar. (Hint, Hint)