Monthly Archives: May 2009

Classification of Living Organisms

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We are all relatively familiar with the five classes of vertebrates (mammals, birds, reptiles, fish and amphibians), but less familiar with species that account for about 97% of all known animal species – the invertebrates – or animals without backbones. The arthropods (including all insects, spiders and crustaceans) probably outnumber all other animals on earth, yet most of them are very small and easily overlooked. Invertebrates are found in every conceivable type of habitat, but they are most plentiful in the oceans, which is where animal life first arose. This week we will look at how living organisms are classified, some of the characteristics used in taxonomy and how different groups are related according to their evolution.

We often hear how many species are becoming extinct each year – less often we hear about the new species that have been discovered. In 2007, over 18,000 new species were described. This year a naturally decaffeinated coffee plant, a tiny seahorse and bacteria that thrive in hair spray have been discovered. Article from Scientific American, “Top 10 new Species“,  here.

I will be away at the school cross country on Tuesday, 26th May, so you are asked to complete Activity 8.1 in your practical manuals – “A key to sorting snakes”, about using a dichotomous key to extract information and identify various species. Please leave me a comment on this post to let me know how you went and waht you learnt.

A simple introduction to Classification from KidsBiology.com

Excellent site for Classification of Animals including characterisitics of each of the Phyla, images and links.

Go to ARKive for a growing collection of information, images and videos about all our magnificent organisms on earth. There is a collection of education resources, which includes downloads for different age groups. We will be looking at the ARKive Classification Resource in class on Wednesday, 27th May.

A more in-depth introductionabout the Linnaen Binomial System of Nomenclature and Principles of Taxonomy. 

Identify eight marine creatures from Chesapeake Bay, near Baltimore, USA using a dichotomous key.

Table of the Five kingdoms.

Excellent Glossary of terms.

Flashcards for Introduction and taxonomy.

Excellent interactive “Essential Study Guide” from McGraw Hill

Internal and External Fertilization

Horseshoe crabs spawning

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Amongst animals that reproduce sexually, there are those that use external fertilization (usually marine and aquatic organisms, such as corals, frogs, fish and the ancient horseshoe crabs shown above) and those that practise internal fertilization (mammals, birds, reptiles and some insects).

Six page handout including student worksheet on internal vs external fertilization.

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

 

Our Amazing Filters – Kidneys!

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Our kidneys are part of our excretory system, to remove nitrogenous wastes from our body. The nephron is the functioning unit that removes urea from the blood and allows water, nutrientsand salts to be re-absorbed to the body.

Great interactive animation showing structure and function of the kidneys.

The nephron – structure and function.

The Kidney Quiz from Zerobio.

The science of tea-bags!

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I learnt something new yesterday – Mr Foreman and I were talking about why some people prefer leaf tea to tea bags. Apparently tea bags have salt in them! Remembering some basic biological principles from the beginning of term 1, what could be a reason that manufacturers add small amounts of salt to tea bags? Leave a comment with your thoughts in the comments section above.

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.