Bacteria Experiment

Purpose:

• The reason that we did this experiment is to find out if boys or girls have more bacteria, if old or young have more bacteria, if pencil or eraser have more bacteria, and if wall or door knob have more bacteria.

Hypothesis:

• I think boys are likely to have more bacteria than girls because they play more sports and do more outdoor activities than girls. And most of the boys doesn’t really care about cleaning.
• I think young people would have more bacteria that old people because they play a lot more. For example when kids are playing in the playground, they touch many things such as slider, swing, etc.
• I think pencil would have more bacteria than eraser because people touch and use pencil more than they use erase.
• I think door knob would have more bacteria than the wall because we touch door knob almost everyday therefore it’s more likely to get more bacteria than the wall.

Equipments Lists:

• Autoclave (uses high temperature and pressure to sterilize; to kill bacteria)
• 3 small petri dishes (glass)
• nutrient agar
  • 0.5 grams of sodium chlorine (salt)
  • 0.5 grams of yeast extract
  • 1.5 grams of agar (stuff that make jelly)
  • 1 grams of tryptone (amino acid)
• distilled water (H20 and nothing else)
• fume hood (machine that suck up air)
• thermometer (go up 150 degree Celsius)
• incubator
• microwave
• 200mL beakers
• stirring rods
• goggles
• lab coats
• gloves
• balance scale
• maker
• cotton buds

Procedure :

1. Wear gloves, lab coats (buttoned up), goggles
2. Turn on the weighing machine
3. Weigh 0.5 grams of salt
4. Add the salt into a beaker
5. Weigh 0.5 grams of yeast
6. Add the yeast into the same beaker
7. Weigh 1 gram of tryptone
8. Add the tryptone into the same beaker
9. Weigh 1.5 grams of agar
10. Add the agar into the same beaker
11. Then add 100 ml of distilled water
12. Use the glass stirring rods to stir
13. Then, bring it to the microwave (80-90 degrees Celsius)
14. After its about 80-90 degrees Celsius, keep on stirring the beaker with the stirring rod
15. While stirring, put the beaker into the fume hood (sucks the air)
16. Stick the thermometer in it when its in the fume hood.
17. Wait until it drops to 60 degrees Celsius in the fume hood.
18. Remove the thermometer.
19. Remove the lid from the plate while both are facing down and shake the water off them.
20. Lift the lid from the plate but only just enough to pour in nutrients agar.
21. Pour in the nutrients agar until about a little less than half of the petri dish is filled.
22. Gently push the petri dish far back into the fume hood.
23. Leave the lid open just a little for the steam to come out.
24. Repeat steps 18-22 until all the dishes are done, these steps are all done in the fume hood.
25. Close the glass panel of the fume hood.
26. Wait until the nutrients agar to settle for about two days.
27. Close the lid of the petri-dish and take it out from the incubator.
28. Use a marker to divide the bottom of the plate into four sections.
29. Write girls, boys, old, and young on the section.
30. Do the same thing with the second petri-dish. Use marker to divide the bottom of the plate into four section.
31. Write pencil, eraser, wall, and door knob on different section.
32. Get 3 boys and 3 girls, then let each of them touch different sides of the section. ( section that labeled boys and section that labeled girls)
33. Get 3 young people and 3 old people, then let each of them touch different sides of the section (section that labeled young and section that labeled old)
34. Use cotton buds to swab 3 pencils and gently roll the cotton buds on the section labeled pencil.
35. Use cotton buds to swab 3 erasers and gently roll the cotton buds on the section labeled eraser.
36. Use cotton buds to swab the doorknob and gently roll the cotton buds on the section labeled doorknob.
37. Use cotton buds to swab the wall and gently roll the cotton buds on the area labeled wall.
38. For the step 32-27, make sure you didn’t broke the surface of nutrients agar while you are rolling on the bacteria on it.
39. Put the agar plates back into the incubator, make sure they are upside down so the steam will not fall back onto the bacteria.
40. After two days, take them out and count the number of colonies and types of bacteria in each section and record the results.

 

Result:

Object	Boys	Girls	Old	Young	Pencil	Eraser	Door knob	Wall
Colonies	19	23	24	26	15	7	13	9
Types	4	6	4	6	3	2	3	5

 

Analysis:

• We could have better results on finding the types and colonies of bacteria if we use microscope to look at the petri-dishes to find the bacteria.
• We also did some mistakes in doing the experiment. First was the mistakes in the nutrient agar, it didn’t work as what we expect. Therefore, we could only use 2 petri-dishes instead of 3 petri-dishes. To avoid this mistake, we should have make sure in the measuring things and put everything in the correct amount.
• The other mistake that we did is when we let people touched the nutrient agar to find out who got more bacteria. Because the petri-dishes are quite small, so when people touched it, the bacterias were too close to each other. Especially for the old and young section, some of the bacteria got mixed and we couldn’t find out whose bacteria is it.

Conclusion:

• In conclusion, as we can see from the results, girls seem to have more colonies and types of bacteria than boys. And also young people have more colonies and types of bacteria than old people as well. We also could see that pencils have more colonies and types of bacteria than erasers too. For door knob and wall, we can see that door knob has more bacteria colonies than the wall. But the wall has more types of bacteria than the door knob.
• We also know that girls have healthier skin than boys since girls have more bacteria colonies than boys. But however, girls have more types of bacteria, and this means that girls’s skin is dirtier than boy’s. And this is the same thing with young people and old people. Young people have healthier skin but is dirtier than old people.
• We also found that the common type of bacteria which occur in every section of the nutrients agar is the smooth white one.

 

Evolution: Dolphin Human Bird

 

JavaScript Data Types

1. What is a String Data Type in JavaScript?

– A string is a variable which stores a series of characters like “John Doe”.

– A string can be any text inside quotes. You can use single or double quotes.

– You can use quotes inside a string, as long as they don’t match the quotes surrounding the string.

2. Give 3 examples of data considered as String.

– ar msg=’Result’;

– var num1=’3′;

– var app=’Whatsapp’;

3. What is an Integer Data Type?

– A data type which represents some finite subset of the mathematical integers.

4. Give 3 examples of data considered as Integer.

– var num1=13;

– var num2=33;

– var num3=23;

5. What is a Floating-point value?

– Floating-point numbers are like real numbers in mathematics, for example, 3.14159, -0.000001. Java has two kinds of floating-point numbers: float and double

7. Give 3 examples of data considered as Floating-point numbers.

– var num1=300.234;

– var nem2=5.5;

– var num3=888.12;

8. What are the two values considered as Boolean Data Type?

-true/false

9. What are the Composite Data Types?

–a composite data type is any data types which can be constructed in a program using its programming language’s primitive data types and other composite types.

10. What are the Special Data types in JavaScript?

-null and undefined

sources:

http://msdn.microsoft.com/en-us/library/wts33hb3.aspx

http://en.wikipedia.org/wiki/Composite_data_type

http://oreilly.com/javascript/excerpts/learning-javascript/javascript-datatypes-variables.html

credit:

http://nicolelee397.wordpress.com

Intro to JavaScript

1.What is JavaScript?

– JavaScript is the world’s most popular programming language. It is the language for HTML and the web, for servers, PCs, laptops, tablets, smart phones, and more.

2. What company started JavaScript?

– Netscape

3. Explain briefly the main difference of Java and JavaScript.

– Java is an OOP programming language while Java Script is an OOP scripting language.

– Java creates applications that run in a virtual machine or browser while JavaScript code is run on a browser only.

– Java code needs to be compiled while JavaScript code are all in text.

4. What are the things can we do to a webpage using JavaScript?

– Loading new page content or submitting data to the server via AJAX without reloading the page

– Animation of page elements, fading them in and out, resizing them, moving them

– Interactive content, for example game

– Transmitting information about the user’s reading habits and browsing activities to various websites.

5. Where do we write JavaScript codes? On which programs/applications?

– there are 2 ways to write your JavaScript code. The first is by embedding the code in your HTML document. we do this by using the opening and closing script tags, defining the script type & typing our code. The second method is to write our code in an external file. This benefit of this method is that we can run the same code on multiple pages if necessary.

6. How can we see the result of our JavaScript code?

– you can take any script that yo have written or any script that you have obtained from a script library and convert it from being coded into the page into an externally referenced JavaScript file.

7. What is the HTML tag to start a JavaScript code?

– <script>

document.write(“Hello World!”)

</script>

8. What is a variable? How is it different to a value?

– a variable’s purpose is to store information so that it can be used later, it is a name identifier that represents some data that you set.

– in variable, you can make changed but value is constant, its palace is in Readonly memory means you can’t means you can’t make changes to it.

9. What are the data types in JavaScript?

– primary data type: String, Number, Boolean

– composite data type: Object, Array

– special data type: null, undefined

10. How do we write comments in JavaScript?

– The following example uses single line comments to explain the code:

// Write to a heading:
document.getElementById(“myH1″).innerHTML=”Welcome to my Homepage”;
// Write to a paragraph:
document.getElementById(“myP”).innerHTML=”This is my first paragraph.”;

Sources:

http://www.w3schools.com/js/js_intro.asp

http://www.java.com/en/download/faq/java_javascript.xml

http://en.wikipedia.org/wiki/JavaScript

http://www.w3schools.com/tags/tag_script.asp

http://msdn.microsoft.com/en-us/library/ie/7wkd9z69%28v=vs.94%29.aspx