Category Archives: Functioning Organisms

Plant Reproduction

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red flower

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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/

Plant Symbioses

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lichens

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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

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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.

The Story of ‘H’ – Helicobacter pylori

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The Story Of H

This is ‘The Story of H’, by Lubomir Panayotov, and it recently won Best Storytelling in the Slideshare, ‘Tell a story in 30 slides or less’ contest. Helicobacter pylori is a bacteria that affects 50% of the population and has been shown to cause stomach ulcers. Australian scientists won the Nobel prize in 2005 for their discovery of this bacteria and it’s role in gastritis and peptic ulcer disease.

Human Reproduction

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This Thursday we are looking at Chapter 7; Activity 7.3 in your practical manual – Human Reproduction. We will be labelling diagrams of the male and female reproductive systems and watching a short video.

Reproduction in other animals, including oviporous, viviporous and ovovivaporous animals.

The Reproductive systems of males and females, including labelled diagrams.

Role of hormones in human reproduction.

Excellent Stages of Meiosis Animation from McGraw Hill

Comparison of Mitosis and Meiosis from McGraw Hill

Random Orientation of Homologous Pairs of chromosomes during meiosis – McGraw Hill.

Meiosis – production of gametes – on Cells Alive!

Another Meiosis Animation from Sinauer Associates

Reproduction in Ferns

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The life cycle of a fern is beautiful and a little complex, but can be learnt with the aid of diagrams. The fern has two life stages – a tiny, haploid phase (the gametophyte – n) and a diploid phase (the sporophyte – 2n), which is the obvious and recognisable plant.

Diagram of the Life Cyle of a Fern and another diagram from David Nelson. Student tutorial about the fern life cycle. Fern life cycle clearly showing haploid and diploid phases.

Print out a Life cycle of a Fern diagram here: life-cycle-of-a-fern-diagram

 

Reproduction – Sexual and Asexual

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This week we are looking at reproduction – by the end of this unit you will understand the concepts of sexual and asexual reproduction and describe how reproduction occurs in unicellular and multicellular organisms. You will learn that prokaryotes reproduce by binary fission and that eukaryotes can also reproduce asexually by mitosis, budding, parthenogenesis or vegetative reproduction (runners, rhizomes, tubers, bulbs and cuttings). More about asexual reproduction here. PowerPoint about Asexual Reproduction at SlideShare. Introduction to Reproduction and asexual reproduction at About Biology.

Sexual reproduction occurs in both plants and animals and involves the production of gametes by meiosis. Fertilization (when male and female gametes meet) can be external, as in many marine and freshwater organisms, or internal, as in most terrestrial vertebrates, such as birds, reptiles and mammals.  

Sexual Reproduction in Animals, more about reproduction and more about meiosis at About Biology.

Reproduction in Flowering Plants

 

Transport in Plants

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Biology 4 Kids: Xylem and phloem

Look through the virtual microscope at xylem and phloem cells.

What Wikipedia says about vascular tissue in plants.

WikiAnswers: What’s the difference between xylem and phloem?

Different types of plant tissues – including good diagrams.

Plant structure, including more good diagrams, photos and microscope images of plant tissues.

Plant Structure II, showing a comparison of monocots and dicots – including arrangement of vascular tissue. Moncotyledons are plants with one seed leaf, parallel venation in their leaves and flowers with petals in multiples of 3 (eg. maize, rye grass). Dicotyledons (such as buttercups, celery and beans) have two seed leaves, reticulate venation and flowers with petals in groups of 4 or 5.

How woody plants grow – why trees develop concentric rings- Vascular tissue animation.

After completing the practical exercise on pages 64 to 66, describe the distribution of vascular bundles in monocot root xs and dicot root xs. How does this distribution compare to the distribution of vascular bundles in stem tissue of moncots and dicots?

How does ring-barking affect trees and why does this occur?

Transport in Animals

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This week we start to look at the circulatory, respiratory and excretory systems of animals and the xylem and phloem cells in plants. We know now how different organisms obtain their nutrients, now we need to know how nutrients and oxygen get to every cell in the body and how wastes are removed from it.

Great animation about how the heart works here. Video of heart and circulatory system here.

Human Anatomy Online – interactive diagrams of all the systems, including nervous, skeletal and reproductive. KLB Science Interactivities have produced a clever quiz on the heart and circulatory system. More great Human Body stuff from National Geographic here. Virtual microscope images of the circulatory system from the Indiana University Bloomington.

Image Source – Note the five different types of white blood cells.

Components of blood

Virtual microscope slide of blood

Virtual microscope images of arteries, veins and capillaries showing tissue types.

RESPIRATORY SYSTEM

Don’t get confused between cellular respiration and breathing! Cellular respiration is the process that converts glucose and oxygen to energy within the cells. Oxygen is supplied to those cells by the red blood cells, which carry oxyhaemoglobin to cells and remove carbon dioxide from cells. The respiratory system includes the lungs, trachea, bronchioles and alveoli, which carry air into and out of the body.

Respiration – University of Melbourne animation of lung structure showing alveoli.

Habits of the Heart – Lung Structure from the Science Museum of Minnesota.

Video of the Respiratory System

Human Anatomy Animations of the respiratory and circulatory sytems from Bioanime. This site includes animations of all the human tissue types, including the different types of white blood cells.