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SC1301~ Biology

Hi This is your brain

                                                  BIOLOGY     PRACTICAL   1  
                                                                The Diversity of Animal Life (mostly)

     This practical has been designed to give you an overview of the range of living organisms in the Animal Kingdom. Charts show the relationships of all 5 kingdoms currently recognised (Monera, Protista, Fungi, Plantae, Animalia)

     Plants and animals (Monera, Fungi and some Protista are often grouped with Plantae, and other Protista with Animalia) are normally studied separately as Botany (Plant Science) and Zoology (Animal Science). There are good reasons for doing this because there are some fundamental differences, for instance: plants are said to be AUTOTROPHS (literally "self nourishing") as they produce food from carbon dioxide, water and minerals by solar power; whereas animals are HETEROTROPHS (literally "different nourishment").  All animal life ultimately depends on plants and they can be grouped into herbivores or plant eaters, carnivores or flesh eaters, omnivores that will eat both plant and animal food, and detritivores that consume dead bits of animals and plants.

     Examples have been selected to give you as diverse a picture as possible and much of the material has been collected locally.
The prac. is a "walk round / self study" class so that you can pace yourself and linger over aspects that you find of particular interest, but you should endeavour to examine all the material in the time available. Some of the exhibits have questions attached. Answer these questions after examining the material. The tutors will be on hand to assist and answer queries.

     You will notice that each example has long words associated with it, often in Latin or Latinised Greek, though seldom in Double Dutch. Every plant or animal is given two names. This system of naming is thus called BINOMIAL (bi=two; nomial=names).
The first of the pair of names is the name of the GENUS (generic name). It is always written with a capital letter. The second of the two is the name of the SPECIES (specific name). It should never be written with a capital letter. (Note that the plural of 'genus' is 'genera', but that the word 'species' is used for both singular and plural).  Conventionally, the binomial is printed in italics, and should be underlined when written by hand or typed.

     Remember that the purpose behind using Latin names is to ensure that the reader or listener is absolutely certain which plant or animal is being referred to. Therefore Latin names can only be abbreviated if their meaning will remain clear in the context in which they are used. The name of a genus can be used on its own in a general sense; you can speak of growing a Lilium  (lily) plant, for instance, and we will know what you mean. It is sometimes permissible to abbreviate the generic name to its initial letter: thus Pinus radiata  can become P. radiata  if it is absolutely clear that you are referring to the genus Pinus,  but this type of abbreviation should never be used when its meaning is not absolutely certain.
  
Every different genus has a different generic name, but the same specific names are often used for many different species. To refer to a plant as P. vulgaris, for instance, without having mentioned the full name of the genus first would be ambiguous because it could mean more than one type of plant. P. vulgaris  has several meanings including Primula vulgaris  (primrose) and Phaseolus vulgaris  (dwarf bean). A plant should never  be referred to by its specific name alone. Allium sativum  is garlic, Lepidium sativum  is cress and Pisum sativum  is pea. To refer to a plant as Allium  tells you it is onion-like (onion is Allium cepa ); to refer to one as sativum  gives you virtually no idea of what it is.

     The basic unit in classifying organisms is the species, but just what constitutes a species is often a matter of some dispute. Several points are agreed upon by taxonomists (classifiers), though no ONE criterion can be used alone. Put simply:
     1) individuals within a species will closely resemble each other and should always be readily recognisable as belonging to that group.
     2) there will be clearly defined differences or gaps between species, rather than just a range of very small variations.
     3) each species will be found in a particular place and will be suited to the environmental conditions there.
     4) the individual should be fully fertile with others of the group, but there should  be some reduction in the level of success when crossed with other species.
     For instance, lions in Africa and in zoos worldwide (Felis leo ) resemble each other closely and can reproduce with each other, but differ from and cannot mate successfully with your common moggy, a different species of cat (Felis domestica); though they can sometimes breed with tigers (Felis tigris ) in captivity. Similarly, cabbages (Brassica oleracea) closely resemble other cabbages and are always recognisable as cabbages.They are related to turnips (Brassica rapa ) though it is easy to tell them apart. They can interbreed, but the resulting plants are less successful than the two species.

     Similar genera such as Felis  and Acinonyx  (the cheetah), or Brassica and Raphanus  (radish), are grouped within FAMILIES; similar families within ORDERS; orders within CLASSES; classes within PHYLA; and phyla within KINGDOMS. (Note that Bacteria, Fungi and Plants are sometimes grouped in DIVISIONS rather than phyla, though both names can be used interchangeably).
     Your cat or your cabbage could be fully classified as follows:

    Kingdom    Animalia                         Kingdom      Plantae
      Phylum      Chordata                         Division      Anthophyta
        Class          Mammalia                       Class         Dicotyledonae
          Order         Carnivora                       Order        Capparales
            Family        Felidae                           Family       Brassicaceae
              Genus         Felis                               Genus        Brassica
                Species      domestica                       Species     oleracea

     You are NOT expected to memorise all these words, they are there to let you see how various organisms are thought to be related. (If you were asked a question in the exam on classification, some knowledge of the terms used, would, of course be useful). Look for the points of similarity, and the differences.

                                      (i) The Diversity of Animal Life:-

        Look at the charts and specimens of animals on display around the lab. You may like to make sketches (with notes) of any that you are not familiar with, and note their classification. Note their relationships to other organisms.

1. Answer any questions relating to specific charts or specimens. (They will be numbered and marked with an *).

                                                (ii)  Animal Tissues:-

Cells do not function independently of each other, but instead they are organised into groups to perform certain vital functions in the life of the animal. Such a group of cells performing a specific function is called a TISSUE. The physiological or functional differences between various kinds of tissues are often accompanied by differences in physical appearance, since the cells of the tissues are adapted to the tasks they perform. Tissues do not function independently of each other either. Several tissues are organised to work together as a group. Such a group of tissues is called an ORGAN.

You will be examining prepared slides of animal tissues and organs. Look carefully at the types of cells present in each slide, comparing what you can see with the drawings alongside each microscope. Tissues may be divided into 4 main groups:

    A. Epithelial tissue: - cells are generally arranged into sheets which cover the surfaces of the organs or body. Glands are also derived from this tissue. Scrape a small amount of tissue from the lining of your cheek with a toothpick, and suspend the scraping in a drop of water on a microscope slide. Add a drop of toluidine blue stain and put a coverslip on. Notice the shape of the cells.
   
   B. Muscular tissue: - there are three main varieties of muscle, but all are specialised for contraction. Examine the prepared slides of skeletal, smooth and cardiac muscle. Skeletal muscle is sometimes called "striated" or striped muscle. Can you see why?

   C. Nervous tissue: - cells are specialised for the conduction of electrical impulses. Examine the prepared slide of a nerve cell. Note the long extension to the cell called the axon, and the constrictions in the axon called the nodes of Ranvier.

   D. Connective tissue: - consists of several types of cell, usually embedded in a non-cellular substance. It includes blood cells, cartilage, bone, and the cells of "proper" connective tissue. Examine prepared slides of bone tissue and blood. How many types of cell can you find in the blood? How common is each type of cell?

Most organs, of course, consist of more than one type of tissue. For instance, the walls of your digestive tract are lined with epithelial cells, but there are also layers of muscle interlaced with connective tissue, and many small blood vessels and nerves.

2. Examine the prepared slides and the detailed drawings alongside them. Make sure that you can see each tissue type. Think about the function of each tissue.

                      diver.gif (9054 bytes)(iii)   Aquatic Lifedolphin.gif (17449 bytes)


        The source of live material is the Ross River. Two microhabitats were sampled from the river; (a) the mud, and (b) the open water.To sample the mud, carefully scrape a SMALL amount of mud from the mud surface and place it on a clean slide for microscopic examination.
The pond water is best sampled from around the aquatic vegetation using a pasteur pipette and examining on a slide under a coverslip.

3. Carefully examine the mud and pond water samples.
How many different types of organisms can you find? Try and identify them using your lab manual.

4. Answer the following questions.

       (a) You probably found more organisms in the mud sample. Why do you think this is so? (Hint: imagine yourself as one of these organisms - you want to avoid being eaten, you need nutrients, and you need exactly the right conditions to survive).
       (b) Animals need to eat plants, yet you probably saw very few plants in the open water samples. Why was this? (Hint: think about size and what you notice. Where were you instructed to take your sample from?).

                                                 (iv)  Classification

       The figures on the sheet you have been given represent 26 imaginary animals called CAMINALCULES after their creator Joseph H. Camin of the University of Kansas.
Cut them out individually and group them together based on their similarities and differences.
Compare your arrangement with your neighbours. Do you think there is just one way of arranging them?  What other information might you need to know about these "animals" to classify them properly?

5. Construct a dichotomous key for these 26 organisms using the methods set out below.

Because these are "unknown" animals, we cannot be sure of the use to which they put their body parts, but we shall ignore this problem. The caminalcules all have a body, usually more or less round but sometimes long; a head which may have eyes, a crest, tentacles, or nose; front limbs that are either feet with toes, pads, nails or claws, or else are tentacles, or may even be absent. Hind limbs may be absent, finlike, or leglike, and may number one or two. As well, there are a wide variety of markings on the body. Have a look at the labelled examples below and use the same terms in your key.


Remember, almost any way they are set out that correctly identifies each caminalcule is "right", but some ways are better than others. Think of examples you know in real life. Coat colour in dogs may be a fairly obvious feature, but how good is it in separating out the breeds? It might be better to use a less variable feature like length of snout or legs.

Constructing a Dichotomous Key:
Study the key set out below. It is a dichotomous key which means a key "separating into two parts", and describes the kind of choices you make in using the key. Among the 9 animals used in this key, it is easy to separate them into two groups based on easily distinguished features - an animal either HAS hair, or it does NOT. Taking the group with hair first, they either have claws, or do not - dividing them further. Clawed animals have short or long ears, and so on. The group without hair can also be further divided, on the basis of whether they have wings or not, then feathers, or legs, or scales. At each step we reduce the number of animals left until there is only one.
The key can be set out as below:

1. animal has hair--------------------------------------------2  (go to choice 2)
animal does not have hair------------------------------------5  (go to choice 5)

2. animal has claws------------------------------------------3
animal does not have claws----------------------------------4

3. animal has short ears------------------------------------- CAT
animal has long ears----------------------------------------- RABBIT

4. animal has horns on its head------------------------------ COW
animal has no horns on its head------------------------------ HORSE

5. animal has wings------------------------------------------ 6
animal does not have wings---------------------------------- 7

6. animal has feathers---------------------------------------- BIRD
animal does not have feathers-------------------------------- BUTTERFLY

7. animal has four legs--------------------------------------- TURTLE
animal has no legs------------------------------------------- 8

8. animal has scales on its body------------------------------ SNAKE
animal has no scales on its body------------------------------ EARTHWORM


A key is obviously a convenience in making identifications. Keys can be made to carry identifications all the way down to the species level. You must not, however, assume that the simplified key used above will indicate the correct identification of ANY animal. A key will give you a correct identification ONLY if it is used with the group of organisms for which it was constructed. If, for example, you attempted to identify a snail using the above key, the key will identify it as an earthworm!!

Note that giving three choices is not a valid step in constructing a dichotomous key. At each step there must only be TWO choices.

To be handed in:

(a) The answers to the questions around the lab marked with *.

(b) The answers to the questions on the pond water.

(c) Neatly set out the dichotomous key you have constructed, sticking each caminalcule in its correct place. Select your favourite creature and give it a descriptive name - either a common name, or if you think you are sufficiently familiar with Latin and Greek terms, a scientific name; or both.


                                                       BIOLOGY   PRACTICAL  2
                                                     Plant Cells, Tissues and Organs (mostly)

 

Cells do not function independently of each other, but instead they are organised into groups to perform certain vital functions in the life of the organism. Such a group of cells performing a specific function is called a TISSUE. The physiological or functional differences between various kinds of tissues are often accompanied by differences in physical appearance, since the cells of the tissues are adapted to the tasks they perform. Tissues do not function independently of each other either. Several tissues are organised to work together as a group. Such a group of tissues is called an ORGAN.

You will be examining prepared slides of plant tissues and organs, looking at the different cells present and their arrangement. Examine each type of cell, particularly looking at its shape, how thick its walls are, any visible structures in it, where in the plant they occur, and perhaps even why they occur there!

                   (i) Plant Tissues - Transverse Section of an herbaceous dicot
Examine the tissues in this cross-section of a dicot stem. Compare the outline and position of each tissue with the diagram provided.

a. Simple Tissues - composed of only one cell type.

Epidermis - note the thin layer (the cuticle) on its outer surface. Epidermal cells protect the underlying tissues.

Parenchyma - the most common and least specialised of all tissues; occurring throughout the plant. The cells are typically large, isodiametric and possess only a thin wall, and a living protoplast containing a large vacuole. Intercellular spaces occur between the cells. Parenchyma cells are the "packing" between organs in the plant body. They also act as storage containers for substances like starch.

Chlorenchyma - parenchyma tissue in which the cells contain chloroplasts. These cells photosynthesise to produce food for the plant.

Collenchyma - situated in the outer part of a stem to provide flexible support in the young plant. The cells are brick- shaped and are thickened in the corners.

Sclerenchyma - supportive tissue. A hard substance called LIGNIN is laid down inside the cell wall, often killing the cell. The most common type of sclerenchyma cells are FIBRES. Fibres are most often found as caps of tissue on the outside of vascular bundles.

b.  Complex Tissues -  composed of more than one cell type, these tissues are found in the vascular bundles.

             Xylem - the water-conducting tissues of the plant. They have thickened walls made of lignin. The most common cell in xylem tissue in flowering plants is the VESSEL. These are short cells with perforations in the end walls, and arranged so as to form a continuous cylinder. Other cells that occur in xylem are TRACHEIDS, FIBRES, and PARENCHYMA.

             Phloem - these tissues conduct soluble carbohydrates (made by the photosynthetic, food-producing, regions of the plant) to the non- photosynthetic parts of the plant. The main cell type is the SIEVE TUBE. Associated with these are COMPANION CELLS. Other types are fibres and parenchyma.

                 (ii) Monocots and Dicots

       The corn (Zea mays ) stem is a typical monocot stem and contains a number of vascular bundles or strands, (containing the xylem and phloem tissue) that in cross-section appear scattered throughout the ground tissue (parenchyma).

       Compare this arrangement of vascular bundles with the arrangement in the dicot stem you examined in part (i).  There are several other differences between dicots and monocots, e.g. flower parts, the number of seed leaves, wood.
        Examine the display on the side bench  and make brief notes on these other differences between monocots and dicots.

       1. Examine carefully the "unknown" plants on the side bench. State whether they are Monocots or Dicots. Give reasons for your choice.

                        (iii)  Cutting Plant Sections

       The plant material you have been looking at so far has been prepared by special machines called MICROTOMES that cut very thin sections. Hand-cut
sections however, are usually satisfactory for general observations. Full instructions are given in the appendix at the end of this practical. The technique will be demonstrated by your tutor.

       2. Cut a thin section of a plant stem and stain it AS DIRECTED by the tutor. Compare the cells and tissues you can see with the prepared slides you examined in parts (i) and (ii). Your best section should be mounted in a drop of glycerine with a
coverslip. Label the slide with your name.

                    (iv) Cell Division and Reproduction

Every normal cell contains within its nucleus a full set of genes characteristic of the organism of which that cell is a part. Genes control:

      1) the types of molecules which are manufactured by cells;
      2) the ways in which these molecules are arranged to form new cells; and
      3) the ways in which the cells are arranged to give an organism its shape.

     The genes are carried on somewhat worm-shaped chromosomes which form
the bulk of the cells nucleus. Most of the time the chromosomes cannot beseen inside a nucleus, but they become clearly visible when it starts todivide.
Plant and animal  cells exist in two basic conditions: DIPLOID and HAPLOID. Haploid cells contain a single set of chromosomes and genes; the number of chromosomes in a single set of such cells  is referred to as 'n'. Diploid cells contain two complete sets of chromosomes and genes and the number of chromosomes is therefore said to be '2n'.

     The cells which are directly involved in sexual reproduction (the sperm and egg cells - known as GAMETES) are haploid (n). All cells which are not gametes are referred to as SOMATIC (body) cells and are typically diploid (2n).

     With a few exceptions, the number of chromosomes per cell is the same in every somatic cell of every organism of the same species. Thus every somatic cell of every normal man, woman and child of every race contains 46 chromosomes. But the number of chromosomes per cell varies from one species to another, e.g. Pisum sativum  (pea) plants have 14 chromosomes per somatic cell, whereas Phaseolus vulgaris  (bean) plants have 22, and Drosophila melanogaster  (fruit-fly) has only 4 chromosomes.

     Plants and animals grow mainly as a result of cell division. Dividing somatic cells go through a sequence known as MITOSIS. Immediately after a mitotic division, a cell doubles its volume by making new cytoplasm, a new cell wall (if a plant), and new nuclear material. During division, the nucleus splits into two identical nuclei, each of which contains exactly the same number of chromosomes and the same genes as the parent cell.

In mitosis, each chromosome duplicates itself. The duplicates separate as the nucleus divides, so that the daughter nuclei are identical in chromosomal constitution.

      During the formation of gametes the number of chromosomes per cell is halved in such a way that each gamete has one complete set of chromosomes. The process which ensures that this precise halving occurs is called MEIOSIS.
The first stage of meiosis involves the division of the nucleus in such a way that each of the two nuclei produced has a complete set of chromosomes but with only half the original number (remember that diploid cells contain two sets of chromosomes). Each nucleus is thus haploid. The nuclear division which results in the halving of the chromosome number is often termed REDUCTION DIVISION.

     This reduction division is immediately followed by a second nuclear division in which each of the haploid nuclei divides again to produce a total  of four haploid nuclei. These four nuclei are then separated by the formation of new cell membranes and/or walls.

In meiosis, each chromosome duplicates itself, and then pairs off with another chromosome in each cell. Genetic material is exchanged. The pairs separate, and then the duplicates separate, to form four slightly different daughter nuclei in sex cells or gametes.

     Sexual reproduction is the formation of new plants or animals as a result of the fusion of two gametes. The process of fusion of the nuclei of two gametes is termed FERTILISATION. The two fused gametes form a ZYGOTE which grows into a new organism in which each somatic cell has as many chromosomes as those of the two gametes combined. Each gamete is haploid (n); the fusion of gametes (n + n) results in a diploid (2n) zygote.

     The life cycle of most animals is very simple. Diploid organisms produce haploid gametes which fuse to form diploid organisms which produce haploid gametes and so on .......... The life cycles of plants are commonly more complex and varied than this.

     Examine the prepared slides showing cell division (mitosis).   Can you see cells with the chromosomes forming worm-like structures?

     See if you can find cells where the chromosomes are spread out across the centre of the cell, and ones where they are being drawn apart. Use your diagrams to identify these stages.

3. Select a region of the onion root under high power. Count each cell in the field of view and note which stage of mitosis it is in. Repeat this count with another completely different field of view. Now write your total results (from both counts) up on the board.

If cells divide once every 24 hours, then the number in any particular stage will tell us approximately how long that stage lasts. e.g. If you counted 200 cells and 20 of them were in Metaphase (10%), then you could say that Metaphase lasted about 10% of the total mitotic cycle, or 2.4 hours.

4. Using the class results only, calculate how long each stage of mitosis lasts, if the whole process lasts 24 hours.

To be handed in:
a. Your identifications of the unknown plants as dicots or monocots.
b. Your labelled slide of a plant section.
c. Your calculations of the length of each stage of mitosis.
d. Your answers to the following questions:
(i) Why were you asked to use the class results rather than your individual results for the mitosis calculations.
(ii) What is the essential difference between mitosis and meiosis? Be brief.

                                                   BIOLOGY PRACTICAL 3
                                                                  Ant Music


In any area studied, some species of plant and animal will be present and other species absent. The individuals of a species present in a given area are known as a population. A population can be defined as a group of organisms of the same species occupying a particular space at a particular time. Ecologists are often interested in knowing in what manner the individuals of a population are spread out through the landscape. The way in which they are spread out can tell us a lot about the environmental conditions and other plants or animals that may affect the behaviour or survival of individuals.

Populations of different species within an area may interact and influence the way other species spread out. This interaction, or ASSOCIATION, may be positive, where each species benefits in some way from the presence of the other; or negative, where each species is harmed by the other species.

Australia has a varied ant fauna found in all sorts of habitats from rainforests to Eucalyptus woodland, from human habitations to grassland and desert. There are several species of ant which nest and forage for food in the trees on the James Cook University campus. Two species of tree-nesting ant are particularly common on campus, they are Oecophylla smaragdina  (the green ant) and Crematogaster sp. (a small black ant). Other species of ants you will see today are found on trees, though most are also found on the ground.


Part A:- Getting to Know your Ants.

1. Each group has a container with small vials numbered 1 - 10. These vials contain 10 ant species found on campus. Examine each species of ant, and look for points of similarity and difference. Note especially things like size, colour and shape. You will probably need to take the ants out of the vials and look at them under binocular microscopes. Handle the ants carefully as they can be quite fragile after they have been in alcohol for a while. Use the forceps or small brushes provided. Fill out the table below with your observations.


Ant No. Name of Ant         Size(mm)        Colour         Body Shape     Other

1)  Crematogaster                                                          
2)  Iridomyrmex A                                                        
3)  Iridomyrmex purpurea                                                   
4)  Tetraponera                                                            
5)  Oecophylla smaragdina                                                  
6)  Opisthopsis A                                                          
7)  Opisthopsis B                                                          
8)  Polyrachis                                                             
9)  Camponotus                                                             
10) Calomyrmex                                                             
    
2. Now we will use these observations to construct a simple key that we can take outside and identify ants on trees.

Part B:- Finding Your Ants

3. You will proceed outside in pairs to look for ants. Your tutor will tell you how to go about finding your ants. You will be examining the trunks of 20 trees. So that the same tree is not examined twice, you will mark each tree with chalk after you have
examined it. You do not have to count how many ants you see, but if you see an ant, identify it using your key, and write the name of the ant down alongside the number of the tree. You may see anything from one to as many as six ant species on any  one tree. If you do not see ANY ants on a tree, go on to another. Make sure that you examine 20 different trees WITH ants. Enter your results in the following table.

Tree No.                            Ant species seen in this tree          
1
2
3
4
5
6   
7                                                                          
8
9
10
[continue to 20]


Part C: - Counting Your Ants

Now we will use the information we have gathered to tell us something about ants, and where they like to be found.

4. Using your own results, total up how many trees had one ant species, how many had two ant species, how many had three, and so on. Write the number in the table below, and on the board. Your tutor will construct a table on the blackboard for you. (enter in here the number of trees YOU counted that had only 1 ant species
on it).
Number of ant species found on each tree

                       1                 2                3                4               5               6          

Your results          

Class results


5. Now count up how many times each species of ant was seen on your 20 trees. Enter your results in the table below, and write your results up on the blackboard also.

Ant Species                                  Your Results                        Class Results        
1) Crematogaster                                                           
                         .
2) Iridomyrmex A                                                           
                        
3) Iridomyrmex purpurea                                                    
                    
4) Tetraponera                                                             
                              
5) Oecophylla smaragdina                                                   
                    
6) Opisthopsis A                                                           
                          
7) Opisthopsis B                                                           
                          
8) Polyrachis                                                              
                            
9) Camponotus                                                              
                           
10) Calomyrmex                                                             
                        

6. Choose the three commonest species of ant. Your tutor will advise you on this. We will now re-examine our information looking at just two species at a time.
For instance, if we were looking at Crematogaster  and Tetraponera , we would look at each of the 20 trees we looked at and decide whether
a) both of these species were present,
b) only Crematogaster  was present,
c) only Tetraponera  was present, or
d) neither of these species was present.
Fill out the table below, and write your results on the board.

                               Pairs of Species             Your Results               Class Total
A.

present present
present absent
absent present
absent absent

B.

present present
present absent
absent present
absent absent

C.

present present
present absent
absent present
absent absent

When these class results are written into ASSOCIATION SQUARES, we can see
very quickly whether there is a positive or negative association between pairs of species.
7. Copy the class results for each pair of species into the three Association Squares below, as shown by your tutor. Your tutor will also discuss with you how to interpret your results.


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