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MAB701S - MARINE BIOLOGY 3A - 2ND OPP - JULY 2023 |
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n Am I BI A u n IVER s I TY
OF SCIEnCE AnDTECHnOLOGY
FACULTY OF HEALTH, NATURAL RESOURCESAND APPLIED SCIENCES
SCHOOL OF NATURAL AND APPLIED SCIENCES
DEPARTMENT OF BIOLOGY, CHEMISTRY AND PHYSICS
QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE CODE: MAB701S
SESSION: JULY 2023
DURATION: 3 HOURS
LEVEL: 7
COURSE NAME: MARINE BIOLOGY 3A
PAPER: THEORY
MARKS: 100
SUPPLEMENTARY/ SECOND OPPORTUNITY EXAMINATION PAPER
EXAMINER (S): Dr. Edosa Omoregie
MODERATOR:
Dr. Johannes litembu
INSTRUCTIONS
1. Answer all questions in Sections A, Band C
2. Write clearly and neatly.
3. Number your answers correctly.
PERMISSIBLE MATERIALS
Calculator
THIS QUESTION PAPER CONSISTS OF 4 PAGES
(Including this front page)
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SECTION A
Answer all questions
Total marks [15]
1. The diagrams below show ventral and dorsal views of a marine invertebrate collected from
the intertidal zone of the Namibian coast.
i. Name the parts labelled as A, B, C and D.
(2)
ii. What is the common name of this invertebrate?
(2)
iii. What Phylum does this invertebrate belong to?
(2)
iv. Briefly describe the structural characteristics of this marine benthos.
(4)
2. Which of the following statements regarding marine productivity resulting from upwelling
is true?
(1)
a. Water that rises to the surface from the bottom of the sea because of upwelling is
typically colder and is rich in microalgae.
b. Water that rises to the surface from the bottom of the sea because of upwelling is
typically colder and is rich in nutrients.
c. Water that rises to the surface from the bottom of the sea because of upwelling is
typically warmer and is poor in microalgae.
d. Water that rises to the surface from the bottom of the sea because of upwelling is
typically colder and is poor in nutrients.
e. Water that rises to the surface from the bottom of the sea because of upwelling is
typically warmer and is rich in nutrients.
3. The solubility of oxygen in seawater is affected non-linearly by temperature. Is this
statement true or false?
(1)
a. True
b. False
5. Which of the following options best describes morphological structure of the horse
mackerel caudal fin?
(1)
a. Heterocercal
b. Truncated
c. Lunate
d. Rounded
e. Forked
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6. Crustaceans are distinguished from other arthropods by their possession of a pair of
________
(two-parted limbs).
(1)
SECTION B
Answer all questions
Total marks [40]
7. List and explain the 2 primary sources of dissolved oxygen in seawater.
(6)
8. Why are nutrient cycles in the marine environment referred to as biogeochemical
cycles?
(4)
9. Briefly explain the main sources of nitrogen in the marine environment.
(6)
10. What is denitrification? Why is this process a chemical reduction process?
(4)
11. How would the ratio of Carbon to Nitrogen (C:N} affect the rate of decomposition of
dissolved organic matter in the aquatic environment?
(4)
12. Name any two marine dinoflagellates that produce the phytotoxin, saxitoxin.
(2)
13. Briefly describe the features of marine foraminiferians. How do they differ structurally
from the radiolarians?
(6)
14. What are Phycocolloids? Name any two Phycocolloids and their economic importance. (4)
15. What is the main function of the choanocytes in marine sponges?
(2)
SECTIONC
Answer all questions
Total marks [45]
16 (a). With reference to the time of the day and photosynthetic activities, briefly explain
the relationship between pH levels and alkalinity levels within the aquatic
environment.
(11)
(b). Outline the four most common factors affecting dissolved oxygen solubility in the
aquatic environment.
(4)
17. (a). Briefly describe the generalized structure of the marine Echinoderm.
(5)
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(b). With reference to body characteristics, movement, and respiratory and digestive
systems, describe the structure of marine nematodes.
(10)
18. (a). Discussthe counter-current gas exchange mechanism in marine fish.
(7)
(b). Using schematic diagrams, explain the differences between the opercular and buccal
suction pumps during respiration in fish.
(8)
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