CORE PRACTICAL 7 Flashcards
What is core practical 7? (1)
dissect an insect to show the structure of the gas exchange system.
what ethical issues stand with this practical? (1)
-its expected that any handling is done with the uttermost care and respect.
what is the first step of this practical? (1)
hold the insect with the forceps and examine it carefully using a hand lens.
what is the second step of this practical? (2)
secure the insect to the bottom of the dissecting dish using plain straight pins with a row of visible spiracles pointing upwards. do the same to the wings so that the side of the abdomen is not covered.
what is the third step of this practical? (1)
hold the insect firmly with the forceps and cut through the exoskeleton around one spiracle.
what is the fourth step of this practical? (1)
use the forceps to take hold of the spiracle and the small piece of exoskeleton and pull gently to remove it from the abdomen.
what is the fifth step of this practical? (2)
mount the spiracle and the tissue on a microscope slide with a drop of water and add the cover slip. avoid any trapped air bubbles.
what is the sixth step of this practical? (1)
examine the slide carefully under medium power of the microscope and looks for trachea rings or chitin to add to previous observations.
what is the seventh step of this practical? (1)
select a suitable part of your slide and draw a simple illustration of what you see.
what is the eighth step of this practical? (3)
turn the insect over on its back and relocate the pins. you may need to cut off the wings to do this. insert the scisssors one side of the abdomen, keep the scissors pointed upwards to avoid cutting into the tissue beneath. cut the exoskeleton in a line down one side towards the head. repeat this on the other side so you can remove a whole strip of the exoskeleton under the abdomen.
what is the nineth step of this practical? (1)
you will see white fat surrounding the gut, do not disturb this but use a magnifying glass to identify the tracheal system .
