Monthly Archives: August 2009

Plant Reproduction

red flower

Photo Source

This bright red flower shows clearly the stamens with anthers attached, where the pollen is distributed from. As insects don’t see colours in the red-orange spectrum, this flower is more likely to be pollinated by birds or mammals (such as possums, bats or small rodents). Wind pollinated plants (such as grasses and conifers) produce large amounts of very small-grained, lightweight pollen. Most flowering plants produce smaller amounts of pollen that is transfered by vectors. They attract vectors with bright colours, alluring aromas or sweet or protein-rich nectar.

If you have access to YouTube, there are some incredible time-lapse photography vidoes showing corn seed and sunflower seed germination (geotropism) at http://www.youtube.com/watch?v=iFCdAgeMGOA&feature=player_embedded Top 10 Amazing Biology Videos: http://www.wired.com/wiredscience/2008/11/top-10-amazin-1/ 

Top 10 Time-lapse videos here: http://www.wired.com/wiredscience/2009/03/tenlapse/

Reproductive behaviours

lyrebird display

Over the next two weeks we will be studying the various reproductive strategies of plants and animals, ranging from the broadcast spawning of coral polyps and boxfish (r-strategy) to the K-strategy of whales and other mammals, in which much energy is expended in gestation and caring for the offspring. The prominent tail feathers of the male lyrebird serve to attract passing females. The male does not put energy into producing eggs or caring for offspring, but puts much energy into growing long tail feathers and putting on reproductive displays.

Quiz on reproductive strategies:

Click here for full screen version

Plant Symbioses

lichens

Photo Source

Lichens are extraordinary symbiotic organisms that survive where each of their composite species wouldn’t survive on their own. The dominant species is a fungus – a consumer or decomposer organism – that partners with algae or cyanobacteria (sometimes both). Most lichens grow very, very slowly – often less than a millimeter per year, and some lichens are thought to be among the oldest living things on Earth. This article has more information about lichens: Lichen biology

Another type of symbiosis has recently been discivered between cacti and bacteria, that enables the cactus to survive in some of the earth’s harshest environments. These cacti can colonise sheer rock faces due to the presence of bacteria that release rock-dissolving chemicals.
How cacti become rock busters

Plant Hormones

germinating beans2

This photograph shows our geotropism experiment, in which we pinned germinating broad bean seeds onto plastic cards with different orientations. No matter which way the beans were orientated, they all showed root growth towards gravity and shoot growth in the opposite direction. They were kept in the dark, so light was not a stimulus. Three more jars were set up with beans that had root-tips removed, shoot-tips removed and both root and shoot-tips removed. We will check these results after the weekend, to determine if the plant root-tip and shoot-tip removal has an effect on growth. More information about plant chemicals (including hormones, alkaloids, flavanoids and tannins) here:

Growth and Plant Hormones from Biology On-line

Plant Hormones

Plant Alkaloids

Tannins and tannins.

Trip to Melbourne Zoo

emerald tree boa
Photo Source

Year 11 Biology students are looking forward to their excursion to Melbourne Zoo in a couple of weeks. As part of our study of Adaptations of organisms – including structural, functional and behavioural adaptations and reproductive strategies of organisms, we will be spending the day in Melbourne.

Zoos Victoria have produced a range of learning resources for VCE classes, including Reproduction, Survival Behaviour and Hot, Wet and Wild. We will use these in our self-guided tour of the Zoo.

Animal Enrichment in Zoos

animal enrichment2

Photo Source

Environmental enrichment improves or enhances zoo environments for animals, stimulating them to investigate and interact with their surroundings. Zookeepers enrich animal environments by making changes to structures in their enclosures, presenting novel objects and smells for them to investigate and explore, and by changing how they present food to them. Doing all of these things alleviates boredom by giving animals more choice of activity. It encourages them to forage, hunt and handle their food in ways that are natural to them in the wild.  The traditional method of feeding zoo animals out of a feed pan does little to stimulate complex feeding behaviors.  Enrichment keeps zoo animals active and interested in their environment.

Find out more about Animal Enrichment at the Honolulu Zoo site, Animal Enrichment and Zoos Victoria.

Plant adaptations

Pseudopanax crassifolius

Pseudopanax crassifolius

I’ll admit to be really fascinated by plant adaptations – the enormous variety of structural and functional forms that enable plants to spread their pollen and seeds; germinate and survive extremes of temperature, wind, flood, fire and being eaten. I have been especially intrigued by the way that some animals and plants co-evolve, such as the orchids with flowers that mimic their pollinators and the plants that are stimulated by insect larvae to produce hormones which cause the plant to grow a home for the pest, resulting in leaf galls. Many of the wonderful foods, drinks, herbs and spices we enjoy are as a result of plants producing alkaloids to resist predation – bitter coffee flavours, tea tannins, pungent nutmeg, pepper and cloves as well as curry leaves and cinnamon bark could be examples.

This unusual-looking plant is a native of New Zealand and exhibits some features that demonstrate adaptations to being eaten by giant flightless birds. While Australia and New Zealand are geographically close to each other, they have vastly different habitats and species. Unlike Australia, New Zealand has no natural mammals, so the giant flightless birds were the major plant predators. Birds feed in very different ways to mammals, hence the differnet appearance of plants, such as the Lancewood. Note the narrow, serrated leaves and the unusual dark colour of the plant. “A classic example of a plant that’s trying to protect itself from bird predation, the Lancewood has long, hard, narrow leaves. It also has a dark brown colour; the theory being that brown is actually quite difficult for birds to perceive. It has a strange form and it grows in a single trunk so that it’s not wasting time branching out low down where it’s offering the birds something to eat.

This plant will last for about ten years before it suddenly changes into a completely different form. When these plants were first discovered, the juvenile form and the adult form were thought to be different species. Instead of having something that looks like a whole pile of stick insects, you end up with a plant that has a tall slender trunk, and all the lower leaves have dropped off so it’s well above the height that a moa could reach. The foliage is shortened and it’s also become greener and it’s standing up more so the plant can better photosynthesise.”

From Gardening Australia

Interesting BBC article: “Giant ‘meat-eating’ plant found“.

Survival behaviours

Yabby at Sydney Aquarium

Image Source

The yabbies in our school aquarium make suitable subjects for a study of animal behaviour. Can you classify yabby behaviour according the following:

  • feeding
  • maintenance
  • territorial
  • agressive
  • defensive
  • co-operative
  • reproductive
  • parenting

Which are learned behaviours and which are innate? How are each of these behaviours important to the survival of the yabby as a species? How do you think the behaviour of the yabby is modified by being confined to an aquarium? Can you observe yabbies communicating with each other?

 Department of Primary Industries Aquaculture fact sheet:  “Biology of Yabbies (Cherax destructor)”

Animal behaviour experiment with yabbies: “Agonistic behaviour in Crayfish”

Behavioural Adaptations

bird migration

Photo Source

Animals display many types of behaviour that enable them to survive changes in their environment and pressures from predators, parasites and disease. Bird migration is an obvious example that allows birds to find food and/or partners and raise their chicks. Winter hibernation in cold climates (bears, for example) allows animals to conserve energy in the harsh winter, when food is scarce, and mate and raise their offspring during the spring and summer when food is plentiful. Another interesting example is the reproductive behaviour of marsupials – the red kangaroo can control the length of the gestation period, so that the joey is not born into a drought, but when the mother has plenty of food available and is producing enough milk. She can also produce different types of milk at the same time to nourish joeys of different ages. Can you think of any examples of behvioural adaptations in insects, reptiles and fish?