Grade 11 Science Related Reading/Chemistry
Chemistry
ChemistryGr10
11F
Name:____________________
Class:____________________
Date:____________________
Chlorinated
hydrocarbons
Biochemical
Reactions
and their uses
Task 1 – Pre-Reading Activity
Using your prior knowledge about reactions and write if the following statements are
True or False.
1. A substance that forms as a result of a chemical reaction is called a reactant.
_______________
2. Only some chemical reactions need energy to get started. ________________
3. A chemical reaction that releases heat is an endothermic reaction.
________________
4. Biochemical reactions take place inside cells. ________________
5. The energy needed to start a reaction is called Activation energy. _______________
6. Enzymes are Biocatalysts. _____________________
7. Enzymes speed up reactions by increasing the activation energy. _____________
8. Increasing the temperature speeds up reactions. ________________
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Task 2 – Reading Activity
Biochemical reactions are chemical reactions that take
place inside the cells of living things. The two most
important biochemical reactions are respiration and
photosynthesis.
The sum of all the biochemical reactions in an organism is
called metabolism. It includes both exothermic and
endothermic reactions.
Exothermic reactions in an organism are called catabolic
reactions. These reactions break down molecules into
smaller units and release energy. An example of a
catabolic reaction is the breakdown of glucose , which releases energy that cells need to
carry out life processes. Endothermic reactions in organisms are called anabolic reactions.
These reactions build up bigger molecules from smaller ones. An example of an anabolic
reaction is the joining of amino acids to form a protein.
Most biochemical reactions in organisms need help in order to take place. Why is this the
case? For one thing, temperatures are usually too low inside living things for biochemical
reactions to occur quickly enough to maintain life. The concentrations of reactants may
also be too low for them to come together and react. Where do the biochemical reactions
get the help they need to proceed. The help comes from enzymes.
An enzyme is a protein that speeds up a biochemical reaction. An enzyme works by
reducing the amount of activation energy needed to start the reaction. Less activation
energy is needed when the correct enzyme is present . Enzymes are involved in most
biochemical reactions and they do their job very well. A typical biochemical reaction can
take several days to occur without an enzyme. With the proper enzyme the same reaction
could occur in a split second. Without enzymes to speed up biochemical reactions , most
organisms could not survive. The activities of enzymes depend on temperature , ionic
conditions and pH .
The South American Bombardier beetle has an unusual way of
defending itself against predators. It sprays a hot corrosive
liquid from a gland on the tip of its abdomen.
The gland has two separate chambers one contains a mixture
of hydroquinone and hydrogen peroxide and the other
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contains two enzymes , catalase and peroxidase. When the beetle is threatened it mixes
the contents of the two chambers. The enzymes catalyze the decomposition of
hydroquinone and hydrogen peroxide in a rapid exothermic reaction.
The oxygen produced from the decomposition reaction builds up pressure which propels
the hot spray towards the attacker.
Key Vocabulary
Biochemical
exothermic
endothermic
catabolic
anabolic
temperature
concentration
reactant
enzyme
Activation energy
A. Choose the correct answer:
1. Activities of enzyme depend on
a. pH
b. temperature
c. ionic conditions
d. all of the above
2. An enzyme is classified as
a. lipid
b. carbohydrate
c. protein
d. nucleic acid
3. Reactions that take place inside cells are called
a. Cellular reactions
b. Enzyme reactions
c. Biochemical reactions
d. Metabolic reactions
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4. Another name for a “bio catalyst ” is
a. reactant
b. enzyme
c. activator
d. metabolism
5. The joining of amino acids to form a protein is a(n)
a. Anabolic reaction
b. Catabolic reaction
c. Amino acid reaction
d. Polypeptide reaction
B. Compare Endothermic and Exothermic reactions with atleast one example.
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C. Match the terms with the right definitions by writing the numeral in the middle :
Terms
Definitions
1. Activation energy
Represents a chemical reaction
2. Anabolic reaction
A protein that speeds up a biochemical reaction
3. Biochemical
reaction
A substance that forms as a result of a chemical
reaction
4. Catabolic reaction
Substance that starts a chemical reaction
5. Chemical equation
Sum of all the biochemical reactions in an organism
6. Chemical reaction
A process that changes some chemical substances into
others
7. Enzyme
Endothermic reactions in organisms
8. Endothermic
Exothermic reactions in organisms
9. Exothermic
Chemical reactions taking place inside the cells of
living things
10.
Metabolism
Chemical reaction that releases energy
11.
Product
Chemical reaction that absorbs energy
12.
Reactant
The energy needed to start a chemical reaction
D. The chemical reaction that takes place in the abdomen of the Bombardier beetle is as
shown:
C6H4(OH)2(aq) + H2O2(aq) --> C6H4O2(aq) + H2O(l)
Balance this chemical equation and represent it properly to show whether the
reaction is endothermic or exothermic.
__________________________________________________________________
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Task 3 – Post Reading Activity
Use the given writing frame to write about the Bombardier Beetle and explain how it uses
a chemical reaction for self defense
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