|
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.
 (iii) Aquatic Life
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.
|
|
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.
|
|
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.
PLEASE READ THE SAFETY PAGE |
BIOLOGY PRACTICAL 1 
BIOLOGY PRACTICAL 2
BIOLOGY PRACTICAL 3