Practicals Flashcards
What are the 4 groups of arthropods?
the crustaceans, chelicerates, insects and myriapods
Outline some examples of species from these 4 groups of arthropods?
squid and periwinkle (molluscs), crayfish (crustaceans), spiders (chelicerates), cockroaches (insects), and millipedes (myriapods).
What are the 4 main features that Molluscs are characterised by?
- The muscular ‘foot’ primarily used for movement.
- A rasping tongue-like structure called a radula, used for feeding.
- A shell, primarily for protection.
- The mantle, which secretes the shell and is part of the dorsal body wall.
What are some examples of Gastropoda and Cephalopoda?
Gastropoda - e.g. snails and slugs.
Cephalopoda - e.g. squid, octopus, cuttlefish.
What terms refer generally to the position on an animal?
Dorsal - Back of an animal
Ventral - Underside of an animal
Anterior - Towards the front or head end.
Posterior- Towards the rear or tail end
What key terms can be used for chelicerates?
Prosoma - Equivalent to the head and thorax fused together
Opisthosoma - Equivalent to the abdomen
Chelicerae - Poison fangs
What key terms can be used for crustaceans?
Cephalothorax - Equivalent to the head and thorax
Antennules - These are the 1st pair of antennae
Biramous - Describing the limbs which have two sections: exopodites and endopodites
Outline some Arthropods characteristic features?
Ocellus - Simple eyes with light sensitive cells (plural ocelli)
Coxa - The first segment of the insect leg, attached to the thorax (plural coxae).
Labium, maxillae, mandibles, sensory palps - These make up the insect mouthparts.
Spiracles - Holes along the insect body; part of the respiratory system.
Cerci - Pair of sensory appendages located at the posterior of the insect body (singular cercus).
What are the insecta?
a very large, diverse and important class of invertebrates.
Examples of orders within the class Insecta.
Orthoptera Diptera Blattodea Hymenoptera Coleoptera
What are the main points in applying a scale bar?
Measure the specimen length and drawing length precisely - Use a ruler, calipers, or an eyepiece graticule for microscope specimens.
Calculate the scale value - this tells you the size difference between specimen and drawing, e.g. scale value of 2 means the drawing is twice as big.
Choose a sensible value for the scale bar label - This is what you will write next to the scale bar and must be relevant to the original specimen size.
Multiply the scale bar label by the scale value to give the scale bar length - Finally draw a line of this length and write the label value next to it.
How do you ensure that the size of specimens is accurate and can be referred to later?
A scale bar
Which of the following species are NOT found within the Mollusc phylum?
Loligo sp.
Astacus sp.
Mytilus edulis
Littorina littoralis
Astacus sp.
Molluscs are members of the Lophotrochozoa (which does not have a strict taxonomic rank, but is sometimes referred to as a “superphylum”). Which of these phyla are also contained within Lophotrochozoa?
Annelida
Compound microscopes are different from dissecting microscopes because…
Compound microscopes have lenses with much greater magnifications
Compound microscopes have a shorter depth of focus
Which of the following morphological characteristics are found in the Molluscs?
Locomotion using a muscular “foot”
Mantle
Radula
Shell secretion
Of the following animal common-names, select the ones which are members of the phylum Mollusca.
Cuttlefish Slug Squid Cuttlefish Oyster Limpet (true limpets, that is)
What are ‘wet mounts’?
Because the sample needs water or another liquid between the slide and coverslip. Making temporary mounts of samples on microscope slides usually involves placing a coverslip onto the slide.
What are the reasons for adding a coverslip to a microscope slide?
Keeps the sample wet - Prevents the sample from dripping off the slide - Creates a flat surface - Improves transmission of light - Protect the microscope- .
What are the benefits of keeping the sample wet?
Most biological samples need moisture to maintain their shape and structure. Drying out will prevent you from seeing the sample in its natural state.
Benefits of preventing the sample from dripping off the slide
For wet mounts, the sample can sometimes drip off the slide, potentially contaminating other materials or surfaces. The forces holding the coverslip to the slide also prevent the liquid from easily running off.
Benefits of creating a flat surface:
Some samples may have an uneven surface when viewed without a coverslip. This can be a problem when viewing at high magnification because the depth of field (the depth of the image which can be viewed in sharp focus at the same time) is very small. By flattening uneven surfaces, more of the sample can be viewed in focus within the small depth of field.
Benefits of Improving the transmission of light
The coverslip helps to make the distance light travel through the specimen shorter and more even across the whole sample, creating a more consistent image when viewed through .
Benefits of protecting the microscope-
A coverslip can help protect the objective lens from getting wet and becoming contaminated, however, if a microscope is used correctly the coverslip should not come into contact with the lens.
