Download 1 NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY

NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
Faculty of Science and technology
Department of Biology
EXAMINATION IN: BI 1004 - PHYSIOLOGY
DATE: Thursday 7. June 2007
ENGLISH
Time: 09:00–15:00
Permitted aids: Approved calculateor
Studiepoeng: 15
number of pages: 2
Contact during the exam: Richard Strimbeck 73551284 (Bot.) and Claus Bech 73596292 (Zoo.)
Grades to be announced Thursday 28. June 2007
Question 1, 2, 3 and 4 counts 15% each, and question 5 counts 40%.
The answers to the botanical and the zoological parts must be written on separate sheets and placed
in separate jackets marked 'botanical part' and 'zoological part' respectively.
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Zoophysiology part:
Question 1.
a) Describe (shortly) the general outline of the gas exchange system in insects. In some insects the
CO2 output is cyclic. Explain this phenomenon. What is the purpose?
b) What is Q10? An insect has an oxygen uptake of 10 μl g-1 min-1 at an ambient temperature of
13°C. At 18°C the oxygen uptake has increased to 15 μl g-1 min-1. Calculate Q10.
Question 2.
a) Describe (using a figure) the O2-dissocation curve (ODC) of the blood. Explain how the ODC
change with changes of i) temperature, ii) CO2 concentration and iii) pH of the blood. What is
the physiological significance of these effects?
b) Explain (shortly) the difference in the blood’s ODC between large and small mammals. What is
the physiological significance of this size-effect in ODC?
Question 3.
Explain how the ice nucleators and antifreeze proteins contribute to the cold hardiness of insects.
Question 4.
a) Explain the mechanisms for transmission of electrical signals at synapses.
b) Explain (shortly) postsynaptic potentials and neural integration.
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Plant physiology part:
Question 5.
(The numbers in the parentheses are points. 180 points total in the plant physiology part of the
exam.)
1. In a laboratory experiment, potato plants are grown in nutrient solutions rather than soil. The
growth solution contains a mixture of nutrient salts with a total osmotic concentration of 0.04
M. The plants are kept at 27°C. After several weeks of growth the plants are 30 cm tall. In
samples of phloem sap from the base and top of the stem taken during the night, the average
solute concentration is 0.4 M in the sap from the base and 0.7 M in the sap from the top.
a. Calculate the night time total water potential and all relevant water potential components in
the following locations: phloem cell at the bottom of the stem, phloem cell at the top of the
stem, xylem cell at the bottom of the stem, and xylem cell at the top of the stem. Show your
calculations and units of measurement, and explain the assumptions that you make in order
to proceed. Ignore water potential components less than 0.01 MPa. R=8.3 x 10-6 MPa m3
mol-1 K-1. (30)
b. Measurements from the same plants show that the phloem sap is flowing down the stem,
from leaves to the potato tuber (and within the phloem from higher to lower solute
concentration). Use the calculated water potentials and the current theory of phloem sap
flow to explain how the sap can flow against the concentration gradient. Use a diagram to
support your answer. (30)
2. Define and describe CAM photosynthesis and explain its advantages in specific environment.
(30)
3. How do coleoptiles sense and respond to light? Discuss the role of pigments, hormones, and cell
growth in your answer. (30)
4. The hypersensitive response is an important part of the inducible defense against pathogens in
plants. Explain what happens in plants during the hypersensitive response. (30)
5. Why can’t plants absorb and use atmospheric nitrogen? How does atmospheric nitrogen become
available to plants? Discuss the challenges in using genetic engineering to make maize plants
that can use atmospheric nitrogen. (30)
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