Practicals

Question 1

What are the 4 groups of arthropods?

Answer 1

the crustaceans, chelicerates, insects and myriapods

Question 2

Outline some examples of species from these 4 groups of arthropods?

Answer 2

squid and periwinkle (molluscs), crayfish (crustaceans), spiders (chelicerates), cockroaches (insects), and millipedes (myriapods).

Question 3

What are the 4 main features that Molluscs are characterised by?

Answer 3

1. The muscular ‘foot’ primarily used for movement.
2. A rasping tongue-like structure called a radula, used for feeding.
3. A shell, primarily for protection.
4. The mantle, which secretes the shell and is part of the dorsal body wall.

Question 4

What are some examples of Gastropoda and Cephalopoda?

Answer 4

Gastropoda - e.g. snails and slugs.

Cephalopoda - e.g. squid, octopus, cuttlefish.

Question 5

What terms refer generally to the position on an animal?

Answer 5

Dorsal - Back of an animal

Ventral - Underside of an animal

Anterior - Towards the front or head end.

Posterior- Towards the rear or tail end

Question 6

What key terms can be used for chelicerates?

Answer 6

Prosoma - Equivalent to the head and thorax fused together

Opisthosoma - Equivalent to the abdomen

Chelicerae - Poison fangs

Question 7

What key terms can be used for crustaceans?

Answer 7

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

Question 8

Outline some Arthropods characteristic features?

Answer 8

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).

Question 9

What are the insecta?

Answer 9

a very large, diverse and important class of invertebrates.

Question 10

Examples of orders within the class Insecta.

Answer 10

Orthoptera
Diptera
Blattodea
Hymenoptera
Coleoptera

Question 11

What are the main points in applying a scale bar?

Answer 11

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.

Question 12

How do you ensure that the size of specimens is accurate and can be referred to later?

Answer 12

A scale bar

Question 13

Which of the following species are NOT found within the Mollusc phylum?

Loligo sp.

Astacus sp.

Mytilus edulis

Littorina littoralis

Answer 13

Astacus sp.

Question 14

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?

Answer 14

Annelida

Question 15

Compound microscopes are different from dissecting microscopes because…

Answer 15

Compound microscopes have lenses with much greater magnifications

Compound microscopes have a shorter depth of focus

Question 16

Which of the following morphological characteristics are found in the Molluscs?

Answer 16

Locomotion using a muscular “foot”
Mantle
Radula
Shell secretion

Question 17

Of the following animal common-names, select the ones which are members of the phylum Mollusca.

Answer 17

Cuttlefish
Slug
Squid
Cuttlefish
Oyster
Limpet (true limpets, that is)

Question 18

What are ‘wet mounts’?

Answer 18

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.

Question 19

What are the reasons for adding a coverslip to a microscope slide?

Answer 19

Keeps the sample wet - 
Prevents the sample from dripping off the slide -
Creates a flat surface - 
Improves transmission of light - 
Protect the microscope- .

Question 20

What are the benefits of keeping the sample wet?

Answer 20

Most biological samples need moisture to maintain their shape and structure. Drying out will prevent you from seeing the sample in its natural state.

Question 21

Benefits of preventing the sample from dripping off the slide

Answer 21

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.

Question 22

Benefits of creating a flat surface:

Answer 22

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.

Question 23

Benefits of Improving the transmission of light

Answer 23

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 .

Question 24

Benefits of protecting the microscope-

Answer 24

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.

Question 25

Which of the following is a cellular characteristic of fungi that distinguishes them from plants, animals and micro-organisms?

Answer 25

Cell walls contain chitin.

Question 26

Why should lactophenol cotton blue be handled with care?

Answer 26

The stain is toxic

Question 27

What is the purpose of the diaphragm in a compound microscope?

Answer 27

Adjust the light intensity on the image.

Question 28

A student has drawn a specimen viewed using a microscope and measured its size. They now want to add a scale bar to the drawing.

Calculate the scale bar length (in mm) using these numbers.

Scale of the drawing = Drawing length / Specimen length = 66 mm / 0.11 mm = 600

Label value = 100 µm

Scale bar length = ? mm

Answer 28

Scale of the drawing = Drawing length / Specimen length = 66 mm / 0.11 mm = 600

Scale bar label value = 100 µm = 0.1 mm

Scale bar length = 0.1 mm x 600 = 60 mm

Question 29

What equipment may you need to prepare these slides?

Answer 29

Glass slides and coverslips - handle with care as they can break easily.

Sterile mounted needles - blunt and sharp pins are available.

Lactophenol blue stain - Toxic. On contact with skin, wash off immediately with water. Avoid inhalation of fumes.

Question 30

During the investigation of Sordaria humana, a Pyrenomycete, How will you examine the contents of a perithecium?

Answer 30

by dissecting it.

involves using two sharp mounted needles.

Question 31

How is the dissecting achieved?

Answer 31

Observing the perithecia using a dissecting microscope, the tip of the mounted needle is used to gently remove samples.
The tip of the needle is gently dipped into a drop of water on a microscope slide to suspend the sample.
While viewing with the dissecting microscope, gently hold the perithicium using the tip of one mounted needle and using a second needle puncture the structure to release the contents. Finally move the empty perithicium away from the specimen and add a coverslip.
This is a fiddly procedure and may take a few tries.
Be aware that prodding too hard or using a blunt needle can damage the internal detail.

Question 32

Which of these fungal classes are NOT examined in this practical?

Answer 32

Zygomycetes

Question 33

What structure makes up the majority of the vegetative growth in fungi?

Answer 33

Hyphae make up the main soma of multicellular fungi, growing filamentously through a medium - often a decaying substrate. Mushrooms are a specialised sexual structure, and ascospores are the groups of (normally) 8 spores produced by the ascus.

Question 34

When drawing specimens, which of the following should be included?

Answer 34

Species name

Title

Question 35

What should not be included in biological drawings?

Answer 35

Coloured lines and shading should not be included in biological drawings. Information about colour and texture should be included in notes and annotations.

Question 36

When viewing transparent samples under a microscope, which of the following can make the image more defined?

Answer 36

Stain the sample.

Adjust the condenser iris diaphragm to create the contrast by allowing the right amount of light through.

Question 37

Yeast are single-celled fungi. Which of the following are features of single-celled fungi?

Answer 37

Asexual reproduction through fission