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International Baccalaureate: Biology
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- Marked by Teachers essays 11
- Peer Reviewed essays 1
Gram-positive organisms normally do not have the outer membrane, whereas Gram-negative organisms do. Gram-positive bacteria include many well -known genera like Streptococcus and Bacillus. Most pathogenic bacteria in humans are Gram-positive organisms and these are used to manufacture antibiotics. Bacillus subtilis, also known as the hay bacillus or grass bacillus is a Gram- positive bacterium, which is mostly found in soil. Bacillus subtilis is not a human pathogen and it can contaminate food but rarely causes food poisoning. Bacillus subtilis spores can survive the extreme heat during cooking and Bacillus subtilis is responsible for causing a sticky, stringy consistency in spoiled bread dough.
- Word count: 748
The Effect of Temperature on Enzymatic Activity. Aim To investigate enzyme activity of yeast on glucose at different temperatures3 star(s)
� � 5 cm3 syringes x5 � � 10 cm3 of 10% yeast solution � � 15cm3 of 2% glucose solution � � 1 thermometer � � 2 hotplates � � Stopwatch � � Ice cubes x 6 � � 400mL water � � Observations chart & pen Method 1. 1. Place 6 ice cubes and 80 mL of water into Beaker A 2. 2. Measure and record the temperature (should be around 10�C) 3. 3. Fill 3cm3 of glucose solution into the syringe and then in the same syringe insert 2 cm3 of the yeast solution 4.
- Word count: 862