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WorksheetsGrade 9 Biology: Paper 1
Total questions: 40
Worksheet time: 1hrs 20mins
Which statement about biological molecules is correct?
DNA is made up of nucleic acids.
Glycogen is made from glycerol molecules.
Oils are made from amino acids and glucose.
Proteins are made from fatty acids.
The elements _______ are found in all of organic compounds.
carbon and nitrogen
carbon and oxygen
carbon and iron
carbon and hyrogen
Which element is found in proteins but not carbohydrates?
carbon
hydrogen
nitrogen
oxygen
The diagram shows part of a protein molecule.
What does X represent?
amino acid
fatty acid
glycerol
sugar
Which of the following can proteins do?
store genetic information
store energy (long-term)
store energy (short-term)
build skin, hair, nails, muscles
What is the main protein in hair called?
keratin
albumin
histone
collagen
What do you call the biological molecules that are responsible for the transmission of genetic information and heredity?
Carbohydrates
Lipids
Proteins
Nucleic Acids
Which row shows the elements and basic units that are used in the construction of large food molecules?
A
B
C
D
The diagram represents a starch molecule.
What do the small circles represent?
amino acids
nucleic acids
glucose
glycerol
What is the difference between fat and oil?
At room temperature, fat is solid while oil is liquid.
At room temperature, fat is liquid while oil is solid.
Fat is a type of carbohydrate while oil is a type of fat.
Fat is a type of protein while oil is a type of fat.
DCPIP can be used to test for vitamin C in food. Lemon juice contains vitamin C.
When lemon juice is tested what are the results?
starts blue, finishes colorless
starts colorless, finishes blue
stays blue
stays colorless
The test tubes show the results of a food test. The negative result is on the left while the positive result is on the right.
What solution was used for the test?
biuret solution
DCPIP solution
Benedict's solution
iodine solution
When a food substance is tested with iodine solution, which color shows the presence of starch?
blue-black
brown
orange
purple
Which nutrient produces a purple color when mixed with biuret solution?
fat
protein
glucose
starch
Enzymes are biological catalysts. What is meant by this?
Enzymes speed up chemical reaction in living things.
Enzymes slow down chemical reactions in living things.
Enzymes are substrates that turn into products.
Enzymes are products that turn into substrates.
The diagram represents enzyme action.
What are parts W, X and Y in this chemical reaction?
W is the enzyme, X is the product, Y is the substrate
X is the enzyme, W is the product, Y is the substrate
X is the enzyme, Y is the product, W is the substrate
Y is the enzyme, W is the product, X is the substrate
The diagram represents the shape of an enzyme molecule.
With which substrate would this enzyme most easily form an enzyme-substrate complex?
Lactase is a human enzyme that catalyses the breakdown of lactose in milk.
At which temperature does lactase work fastest?
0°C
18°C
37°C
100°C
The diagrams show molecules involved in the action of a a catabolic enzyme such as maltase.
Which is the substrate?
Which explains how enzymes can be recycled?
Enzymes are not used up in a chemical reaction.
Enzymes increases during a chemical reaction.
Enzymes change to a different type after a chemical reaction.
Enzymes reuse substrates in a chemical reaction.
What is left at the end of an enzyme-controlled reaction?
enzymes and products
enzymes and substrates
enzymes only
products only
The graph shows the effect of pH on a particular enzyme-controlled reaction.
When is the enzyme not active?
at pH 1 and pH 13
at pH 3 and pH 11
at pH 5 and pH 9
at pH 7
Many enzymes do not work at temperatures above 60 °C.
Which statement explains this?
Product molecules are not made because the active site has changed shape.
Product molecules change shape so they do not fit the active site.
Substrate molecules are moving too fast.
Substrate molecules are moving too slowly.
Two samples of a human enzyme were used in an experiment. Before they were used
● sample X was heated to 80 °C and then cooled to 37 °C,
● sample Y was cooled to 0 °C and then heated to 37 °C.
How will this affect their activity?
Sample X and sample Y are no longer active
Sample X and sample Y will be equally active.
Sample X will be more active than sample Y.
Sample Y will be more active than sample X.
The graph shows the activity of three digestive enzymes at differing pH levels.
Which statement is correct?
Enzymes X and Y are both active at pH 7.
Enzymes X and Z are both active at pH 4.
Enzymes Y and Z are both active at pH 4.
Enzymes Y and Z are both active at pH 8.
The diagram shows the effect of an enzyme working in the human digestive system.
What would reduce the rate of production of amino acids?
removing the amino acids as they are formed
increasing the amount of protein
raising the temperature to 37.1 °C
raising the pH to 7.5
Enzymes __________________ the activation energy of a chemical reaction.
decrease
increase
absorb
release
Many enzymes do not work at temperatures above 60 °C.
Which statement explains this?
Product molecules are not made because the active site has changed shape.
Product molecules change shape so they do not fit the active site.
Substrate molecules are moving too fast.
Substrate molecules are moving too slowly.
The diagram shows the effect of an enzyme working in the digestive system.
What would reduce the rate of production of amino acids?
removing the amino acids as they are formed
increasing the amount of protein
raising the temperature to 37.1 °C
raising the pH to 7.5
An experiment was carried out to investigate the effect of pH on enzyme action. The graph shows the results.
What are the labels for the x-axis and the y-axis?
x-axis is pH, y-axis is rate of reaction
x-axis is pH, y-axis is time
x-axis is rate of reaction, y-axis is pH
x-axis is time, y-axis is pH
Which statement about enzyme-controlled reactions is correct?
During the reaction, a substrate changes into a product.
The enzyme is slowly broken down during the reaction.
The higher the pH the faster the reaction.
The product is gradually used up during the reaction.
Enzymes function best at their optimum temperature.
Which statement describes the effect on an enzyme of increasing the temperature to the enzyme’s optimum temperature?
There are more frequent successful collisions.
The kinetic energy of the enzymes decreases.
The enzymes begin to lose their complementary shape.
The rate at which enzyme-substrate complexes form is reduced.
Increasing temperature above the optimum for the enzyme results in loss of enzyme activity.
How is this explained?
less frequent collisions between the enzyme and the substrate
reduced kinetic energy of the enzyme molecule
substrate molecules move faster and effective collisions are less likely
the shape of the active site is changed and the substrate will no longer fit into it
An enzyme is denatured when it loses its 3D shape. True or false?
true
false
What is true of all enzymes?
A
B
C
D
Why does enzyme activity decline at temperatures higher than the optimum value?
denaturation
increased pH
decreased kinetic motion
active sites become full
The two graphs shows the effects of temperature and pH on an enzyme.
Which part shows the enzyme at its optimum temperature and pH?
optimum temperature at Q, optimum pH at R
optimum temperature at Q, optimum pH at S
optimum temperature at P, optimum pH at R
optimum temperature at P, optimum pH at S
