Download 5.1 Activity and temperature – Further questions and answers Q1. Bk

5.1 Activity and temperature – Further questions and answers
Q1.
Bk Ch5 S5.1 FQ1
Study the following graph of enzyme activity.
a
b
c
Describe what happens to enzyme activity as the temperature increases from 10°C to 40°C.
What is the optimum temperature for the enzyme?
What happens to the enzyme above 40°C?
A1.
Bk Ch5 S5.1 FA1
a
b
c
Enzyme activity increases as temperature increases.
About 40C
Above 40C the enzyme has been denatured.
Q2.
Bk Ch5 S5.1 FQ2
Some chemical substances inhibit enzyme activity. This may be temporary and reversible, or
permanent and irreversible. Research examples of each type of inhibition. Suggest two ways by which
an enzyme could be irreversibly inhibited from working.
A2.
Bk Ch5 S5.1 FA2
Irreversible inhibition of enzymes occurs for several reasons, for example when a chemical substance
binds permanently to the active site of an enzyme. Sulfanilamide is an antibiotic that inhibits enzyme
activity in bacteria. The antibiotic is used to combat infection by permanently binding to the active site
of certain enzymes in the bacteria. The sulfanilamide is able to bind to the active site of the enzyme
because its molecular structure is similar to the normal substrate used by the enzyme. As a result of the
inactivity of the enzyme the bacteria die. Heating enzymes beyond the temperature for optimal activity
can denature enzymes; this also leads to irreversible inhibition of enzyme activity.
Q3.
Bk Ch5 S5.1 FQ3
a
b
Ectothermic organisms are sometimes referred to as ‘cold-blooded’. Why is this term incorrect?
Describe the relationship between the body temperature of an ectotherm and its environment.
A3.
Bk Ch5 S5.1 FA3
a
The body temperature of an ectotherm varies widely; sometimes cool and other times relatively
warm, depending on the environmental conditions at the time, therefore it is incorrect to say an
ectotherm is cold-blooded.
5.1 Activity and temperature FQA
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b
Because the body temperature of an ectotherm is dependent on the ambient temperature its body
temperature will vary with the ambient temperature. For example, an increase in ambient
temperature will lead to an increase in the body temperature.
Q4.
Bk Ch5 S5.1 FQ4
a
b
Outline the benefits to an organism in raising its body temperature above that of its environment.
What kinds of organisms are able to do this?
A4.
Bk Ch5 S5.1 FA4
a
b
Organisms that are able to maintain a body temperature above that of their environment have the
advantage of being able to inhabit a wide range of habitats including very cold environments such
as those found in the Arctic and Antarctic circles. These animals can be active in spite of the cold
conditions, finding food and reproducing.
Birds and mammals are able to maintain a body temperature above that of their environment, for
example penguins, polar bears.
Q5.
Bk Ch5 S5.1 FQ5
a
b
Find out how sweating in humans works to cool the body.
Most mammals do not have sweat glands distributed over most of their skin surface.
i Explain why not.
ii What alternative mechanism is used for cooling in these mammals? Describe how the
mechanism works to cool the body.
A5.
Bk Ch5 S5.1 FA5
a
b
When humans sweat, droplets of water exuded from sweat glands appear on the skin surface. As
air currents pass over the skin the water droplets are evaporated and the skin is cooled. (The
process of evaporation requires heat energy; when evaporation occurs at the skin surface heat
energy is removed from the body.)
i Most mammals do not have sweat glands distributed over the skin surface because mammals
generally have a covering of fur. Sweat glands would not be able to function effectively.
ii Panting is an alternative to sweating in other mammals. For example, panting in dogs results
in cooling of the body when warm air is exhaled and evaporation of moisture occurs from
the moist surfaces of the mouth. Kangaroos cool themselves by licking their forepaws—the
saliva is evaporated, a process that takes heat from the body.
Q6.
Bk Ch5 S5.1 FQ6
Draw a concept map to summarise the way in which body temperature is regulated in mammals.
Include each of the following:
hypothalamus detector optimum temperature external environment feedback mechanism
internal environment
A6.
Bk Ch5 S5.1 FA6
5.1 Activity and temperature FQA
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Example concept map:
Q7.
Bk Ch5 S5.1 FQ7
Tulips are plants adapted to very cold climates. They are not native to Australia. Find out how nurseries
artificially control their plant stocks to produce flowers that are not adapted to our harsh climate.
A7.
Bk Ch5 S5.1 FA7
Nurseries in Australia simulate the conditions needed by plants such as tulips in order to induce
flowering. In their native environments the bulbs of tulips are exposed to very cold conditions in the
ground over the winter and this is necessary for flowering to occur. This requirement for exposure to
cold conditions to induce flowering is called vernalisation. Nurseries simulate such conditions by
placing bulbs in the refrigerator for a period of weeks before planting out.
5.1 Activity and temperature FQA
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