Monthly Archives: July 2010

Play and Learn – CellCraft

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cellcraft screen shot

Image Source

I would have liked to have known about this game last semester, when we were doing Unit 1: Cells. CellCraft is a free, on-line, educational game where you can build a cell by adding cell organelles, collecting glucose, making ATP and then fight off viruses. This game was made possible by a grant from the Digital Media & Learning Competition. The goal was to make a truly educational game that was also genuinely fun to play. The game will soon have an open forum and eventually downloadable teacher materials.

When you play the game however, be aware that it does not model evolutionary processes – cell organelles did not just ‘appear’ when they were required by the cell. Modelling evolutionary processes would involve a far more complex and time-consuming program. The game helps you to learn and remember the names and functions of various cell organelles. There is a long and somewhat interesting discussion about creationism vs evolution with reference to this game on the Geek Dad blog. In my opinion, the game has achieved it’s goal of assisting students to understand cellular structures and processes in an engaging and student-friendly way.

Physiological Adaptations to cold temperatures

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wood_frog

Image Source – Cold-tolerant Wood Frog

Wood frogs (Rana sylvatica) are found in the northern parts of North America where the temperature can get very cold. When the wood frog experiences chilly conditions, a chemical signal is sent through it’s boy which prepares the frog to be frozen. The frog can remain frozen solid for the whole winter. The frog’s heart stops beating during this time also. It feels rock hard and looks dead but is not. When the weather starts to get warmer in the spring, the frog thaws out just in time for mating season. The frog can stay frozen without dying because of the way it stores glucose, which lowers the freezing point of water. The frog is able to build up the concentration of glucose in it’s cells, so that the cytoplasm doesn’t freeze, even when the interstitial water freezes.  Two-thirds of the water in the frog’s body can freeze into ice crystals.

(Student post from an article in “Scientriffic” by Priyanka Shewpersad)

winter_vegetables

Image Source – Winter vegetable garden

Winter vegetables, such as broccoli, cabbage, cauliflower and brussel sprouts, are also frost-tolerant. These plants have genes that allow “antifreeze proteins” to be produced, which prevent the plant cells from being damaged by frost.

Physiological adaptations for Survival

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budgerigars2

Budgerigars – Melopsittacus undulatus

The following posts are by students, about the structual, functional and behavioural features of vertebrates that live in arid environments, that enable them to balance their water requirements.

Structural

-Small size of the budgie means that the water requirements are minimal.

-Budgerigars save water by excreting thier waste as nitrogenous waste.

Behavioural

– the budgies will huddle together in dry weather to reduce water loss by reducing thier movement and loss of water through sweat glands.

-they eats seeds with a high water content

Functional

– the budgies excrete most of their nitrogenous waste as uric acid which can be contolled as to how dry or wet it is depending on water availability

Euro or wallaroo

Euro or wallaroo – Macropus robustus

Structural

  • have bare muzzles
  • have large ears

Functional

  • can obtain all necessary water from food during dry spells

Behaviour

flounder

Flounder – Platichthys flesus

Structural features of the flounder

  • The flouder has a a minute body cavity that helps the flouder stay on the bottom of the ocean.
  • Lack of air bladder helps the flouder to stay on the bottom of the ocean.
  • Eyes on the up side of their body helps to spot pray and predators.
  • The top side of the flouders is dark and the bottom side is light.
  • They have strong teeth and jaw.
  • They have a large mouth.
  • Pusterior fin flatter and broader to swim faster and helps to swim on side

Functional features of the flounder

  • tolerance for low salinity
  • has diluted urine in fresh water
  • concntrated urine in salt water

behavioural features of  flounder

  • Change color of skin to match surroundings to hide from predators
  • bury themselves in the sand to hide from predators or to catch pray
  • change shape to help find food
  • go from river to sea

Measuring Biodiversity

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dead fox fence

Dead foxes on a fence

The study of any species requires an estimate of their density in different habitats. Scientists use many different methods of measuring density, depending on the size, abundance, behaviour and habitat of the species. Sometimes a line transect and quadrats are used to measure the abundance and cover of different floral species in a grassland reserve. Other methods to measure relative density include:

  1. Aerial photographs (eg. whales, herds of moose or other hoofed mammals during migration, flamingos)
  2. Capture-recapture (or mark and release)
  3. Traps (eg. Elliot traps for small mammals, pit-fall traps for reptiles, light traps for insects, harp traps for bats)
  4. Number of fecal pellets
  5. Vocalisation frequency
  6. Pelt records
  7. Catch per unit fishing effort
  8. Number of artifacts (nests, pupal cases, burrows etc.)
  9. Questionnaires (of hunters and trappers for example)
  10. Cover (of plants)
  11. Feeding capacity (amount of bait taken)
  12. Roadside counts

Each method has it’s advantages and disadvantages and is most valubale when used as an adjunct to more direct methods.This article from the CSIRO, “Estimating whale numbers in the Southern Ocean” explains how scientists go about estimating the abundance and population structure of minke whales.

This activity, Counting Smarties, from Maths by Email, models the “Mark and Recapture” or “Tag and Release” methods using smarties.

Reference: Charles J. Krebs (1985) “Ecology – The Experimental Analysis of Distribution and Abundance” Harper International, New York.