Life Sciences Grade 12 IEB 2019 Information Sheet

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAT – INFORMATION SHEET Page i of ii INFORMATION SHEET Five-fold serial dilution A five-fold dilution is done by diluting each successive sample by a factor of 5. Each solution will end up being 1/5th of the concentration of the solution before it. Below is an image showing the process. Snake venom and antivenom Snake venom is the poisonous liquid stored in the modified salivary glands or sacs of venomous snakes. Fangs are sharp, long, hollow teeth that are connected to the sacs. When a snake bites, venom is released and moves along the groove on the fang. The venom starts to work immediately to paralyse or even kill the prey. Not all snakes are venomous. Snake antivenom (also known as antiserum, plural antisera) is a medication made up of antibodies used to treat bites from venomous snakes. Antisera can prevent or reverse the effects of the poisonous venom by neutralising it. Currently, there is an urgent need to ensure the availability of safe, effective and affordable antivenoms, particularly in developing countries. Snake bites kill up to 94 000 people worldwide every year, with the highest number of deaths in South Asia and sub-Saharan Africa. The main obstacle to saving lives is the global scarcity of antivenom. In Africa, the most effective treatment has been a multipurpose antivenom that works against a variety of snakes on the continent. However, the antivenom is costly to produce. [Adapted: <https://www.thoughtco.com/how-snake-venom-works-4161270> and <https://www.who.int/bloodproducts/snake_antivenoms/en/> and https://za.pinterest.com/derekatkinson22/snake-fangs/ and https://news.nationalgeographic.com/2016/05/160503-snake-bite-anti-venom- asia-africa-animals/>] IEB Copyright © 2019 PLEASE TURN OVER

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE: LIFE SCIENCES: PAT – INFORMATION SHEET Page ii of ii Figures A to C show the set-up of the Petri dishes for Part 1 (Investigation) Figure A Figure C IEB Copyright © 2019