Bio test #2 Grade 10

Question 1

chemical equation of experiment

Answer 1

2h2o2 -> 2h20 + 02

Question 2

What is the enzyme used in this reaction

Answer 2

catalase

Question 3

Ingredients

Answer 3

potato puree
hydrogen peroxide
alkalines (naoh)
acids (hcl)

Question 4

what are enzymes

Answer 4

biological catalysts that speed up the rate of chemical reactions without being changed or consumed

Question 5

how do enzymes work

Answer 5

• active site is specific to only one type of reaction
• can catalyze infinite amount of reactions

Question 6

what is pH

Answer 6

per hydrogen
measures the acidity or alkalinity of the substance

Question 7

ionization

Answer 7

occurs when pure water separates into h+ and oh- ions

occurs because chemical bonds are not infinitely strong

Question 8

what are acids

Answer 8

any substance that when added to an aqueous solution causes an excess of h+ ions

Question 9

what is an alkaline

Answer 9

any substance that when added to an aqueous solution causes an excess of oh- ions

Question 10

why does the active site get denatured when acids are added to the solution

Answer 10

because the hcl ionizes into h+ and cl-, which causes an excess of h+. The excess h+ bond with the negatively charged amino acids (in the hydrogen bonds) which break the bonds

Question 11

why does the active site get denatured when akalis are added to the solution

Answer 11

because the NaOh ionizes into na+ and oh-, which causes an excess of oh-. The excess oh- bond with the positively charged amino acids (in the hydrogen bonds) which break the bonds

Question 12

what are the products and reactants

Answer 12

hydrogen peroxide -> oxygen + water

Question 13

research question

Answer 13

what is the effect of changing pH on the rate of reaction catalyzed by catalase

Question 14

Hypothesis

Answer 14

At acidic pH (4.0 - 6.0), the rate of reaction will be slow and will increase as the pH gets closer to neutral. This is because the excess h+ will break the hydrogen bonds that give the enzyme it’s unique shape. At neutral pH (7.0), the rate of reaction will be at its highest since the h+ and oh- ions will be in balance. At alkaline pH (8.0 - 11.0), the rate of reaction will slow down once again due to the excess oh- denaturing the active site. Overall, the more acidic or alkaline the solution is, the slower the rate of reaction will be.

Question 15

Independent variable

Answer 15

pH

Question 16

dependent variable

Answer 16

rate of reaction (oxygen gas produced in 30s)

Question 17

fixed variables

Answer 17

• temp h202
• temp potato puree
• volume h202
• volume potato puree
• time of each reaction
• concentration of hydrogen peroxide solution
• amount of light
• collection method

Question 18

defects of experiment

Answer 18

• oxygen gas lost as a result of the collection method
• discrepancies between how each group collected their data

Question 19

solutions to problems

Answer 19

• adding a hole with a secure lid to the ‘lid’ of the beaker to lose less oxygen gas
• having one person collect all data to ensure it is done in a consistent manner

Question 20

how to graph

Answer 20

• ph on x
• rate of reaction on y
• curve of best fit starting at first and ending at last point
• title and axis titles
• use ruler

Question 21

why do we do multiple trials

Answer 21

because there is variability in life
when there are mutliple trials, we calculate the mean

Question 22

mean

Answer 22

add up all elements then divide by the amount

• useful as it accounts for variability and gets us closer to the true value

Question 23

purpose of a graph

Answer 23

visual representation - allows us to draw conclusions we wouldn’t be able to otherwise

Question 24

measurement uncertainty

Answer 24

degree to which we can measure precisely
- after the measurement, add +/- ___
- in the ___ we put to what place the form of measurement goes to
- ex. thermometer only goes to ones place, so it would be 17C +/- 1C
ruler goes to one tenths place so it would be 50.9cm +/- 0.1cm

Question 25

How to graph

Answer 25

find mean of points, then graph that number with its corresponding pH

Question 26

needed elements

Answer 26

- water - hcl solution - naoh solution - water - potato puree - graduated buret - clamps - bowl - graduated cylinder - stand - pipet - stopwatch - ruler - thermometer - marker - blender - test tubes - beakers

Question 27

evaluation (2)

Answer 27

As you are conducting the experiment, try to think of problems or defects in the method that might be preventing you from fully answering the research question. What improvements to the method can you suggest to solve these problems/defects?

Question 28

conclusion (6)

Answer 28

A re-statement of your Research question. A re-statement of your Hypothesis. A verbal description/summary of your experimental results. Did your results support your hypothesis? Or not? A scientific explanation of the reasons for the outcome of the experiment. A statement regarding how reliable you think your results are, given the measurement uncertainties and other potential difficulties in interpreting.