OAU BIOLOGY 2007 POST-UTME PLUS ANSWERS

OBAFEMI AWOLOWO UNIVERSITY 2007 POST UTME TEST
BIOLOGY

1. Where is the energy produced in a cell?
(a) nucleus (b) lysosomes(c) mitochondria (d) nucleolus

2. Which of the following organisms does not exist as a single free-living
cell? (a)amoeba (b) euglena (c) clamydomonas (d) volvox

3. Euglena is an autotrophic organism because it
(a) has flagella (b) has plant and animal features
(c) can manufacture its food (d) moves fast

4. In which of the following organisms does a single cell perform all
functions of active movement, nutrition, growth, excretion and photosynthesis?
(a) paramecium (c) euglena (b) amoeba (d) hydra

5. What is the function of contractile vacuole in paramecium?
(a) produces enzymes (b) gets rid of excreta
(c) stores and digests food (d) gets rid of excess water

6. The ability of organism to maintain a constant internal environment is known as
(a) diuresis (b) endosmosis
(c) plasmolysis (d) homeostasis

7. Which of the following is the medium of transportation of nutrients within unicellular organism?
(a) lymph (b) plasma
(c) protoplasm (d) serum

8. In aerobic respiration, oxidative phosphorylation takes place in
(a) cytoplasm (b) lysosome (c) mitochondrion (d) ribosomes

9. Bryophytes are different from flowering plants because they
(a) are simple small plants (b) carry out alternation of generation
(c) posses small (d) posses no vascular tissue

10. In lower plants like mosses, the structure which performs the functions of
roots of higher plants is called
(a) roots hairs (b) rhizoids
(c) hyphae (d) rots

11. Which of the following compoents of an
ecosystem has the greatest biomass?
(a) primary producers
(b) primary consumers
(c) secondary consumers
(d) tertiary consumers

12. The young shoot of a plant is referred to as
(a) radicle(b) plumule (c) bud (d) branch

13. The name of a bacterium which derives its energy form oxidizing nitrites
intonitrates is
(a) Nitrosomonas (b) azotbacter
(c) nitrobacter (d) Escherichia coli

14. Potometer is used to measure
(a) rate of osmosis
(b) rate of diffusion
(c) rate of transpiration
(d) rate of photosynthesis

15. Meiotic cell division ensures that
a. many similar cells are produced
b. chromosome number of cells is halved
c. cells produced are doubled
d. cells produced posses the same chromosome number

16. The stem of young herbaceous plants are kept upright mainly by
(a) osmotic pressure
(b) turgidity
(c) transpiration pull
(d) root pressure

17. Which of the following tissues is not found in the stem and root of
monocotyledons?
(a) xylem (b) cambium (c) pith (d) pericycle

18. Fruit enlargement can be induced by spraying young ovary with
a. gibberellins, ethylene and abssisic acid
b. auxin, abscisic acid and ethylene
c. auxin, cytokinin and gibberellin
d. auxin, kinin and gibberelin

19. A dry indehiscent, winged fruit formed form one carpel is known as
(a) schizocarp (b) caryopsis (c) samara (d) nut

20. A fruit which developes without fertilization is described as (a) simple
b)aggregate (c) multiple (d) parthenocarpic

21. A dwarf plant can be stimulated to grow to normal height by the
application of
(a) thyroxin (b) gibberelin (c) insulin (d) kinin

22. The condition known as cretinism is caused by the deficiency of
(a) vitamin A (b) insulin (c) thyroxin (d) vitamin C

23. The difference between viviparous and oviparous animal is
(a) possession of yolked eggs
(b) laying and brooding of eggs
(c) possession of yolkless egg
(d) laying of unfertilized egg

24. The following are features of the tropical rainforest except
(a) loose and moist soil
(b) short trees growing beneath tall trees
(c) scanty trees with small leaves
(d) presence of many animals

Answers Key

1.C 6.D 11.D 16. C 21. B
2.D 7.C 12.B 17.C 22.C
3.C 8.C 13.C 18. C 23.B
4.C 9.D 14.A 19.C 24.C
5.D 10.B 15.B 20.A

Explanation to Answers

I. The nucleus contains the nucleolus and it is responsible for reproduction
i.e. itcontains the information for genetic make up. Mitochondria is usually referred
toas the power house because they contain enzymes that carry out the oxidation
offood substance and they synthesis ATP (adenosine triphosphate), the energy of
the cell (C ).

2. Some organisms are made of many similar cells which are joined or massed
together and they can not be differentiated form each other. Example of such
organisms which exist as colonies are VOLVOX (D).

3. The word antho means “Self’. Anthotrophic is the mode of nutrition for
organisms that manufacture their own food and euglena has chloroplast which
makes it possible for euglena to manufacture its own food (C).

4 Euglena is the only organism in the option that has chioroplast for
photosynthesis
(C).

5 Contractive vacuole in paramecium is for osmoregulation i.e to get rid of
excesswater (d)

6. Homeostasis is defined as the maintenance of a steady state in living
organismsby control of the internal environment (D).

7. The living material of the cell consists of the nucleus and cytoplasm
calledprotoplasm.Unicellular organism exchange materials through the protoplasm (C).

8. Phosphorylation of hexose sugar is a necessary first step in the oxidative
breakdown of sugar in respiration and the process of expending energy takes
place in the mitochondria (C).

9. Bryophytes are complex, multicellular green plant that lack vascular tissue
(D).

10. Rhizoids are the false roots in mosses (D). rhizoids grow into the soil
from the base of the stem.

11. Biomass takes into aecount both the size of the individual organism and
their numbers. The number of the species decreases and size increases as we move
upward in the tropic level. The tertiary consumer has the greatest size (D).

12. Plumule is the young shoot in a plant (B) while radical is the young root.

13. Nitrosomonas convert ammonia to nithtes while nitrobacter convert the
nitrite to nitrates (C).

14. The rate of transpiration is monitored using potometer (A).

15. During meiosis, the chromosome number in gamates becomes half (haiploid)
of the original mother cell (diploid) (B)

16. Transpiration pull involve the force which maintain the transpiration
streams,these forces are strong. Root pressure is responsible for the conduction of
waterthrough the root. Turgid parenchyma makes the cell. Strong and rigid, so they
give mechanical support (B)

17. In the internal structure of the root, is a wide and clearly marked pith
surrounded by ring of conducting tissue while there is no pith in the internal structure
of the stem (C).

18. Auxins promotes cell elongation and stimulate cell division likewise
Gibbrellin also promote cell division, hormone abscisic acid can make stomata close and
falling off of fruits and leaf withering. Ethylene dramatically increase the
respiration rate which leads to the ripening of fruit, cytokinins is found
where rapid cell division is occurring (C).

19, Samara is a simple tree fruit in which the pericarp is extended to form
one or more wing like structures. It develops from a superior ovary made-up of more
than one carpel (C).

20. Occasionally, fruit formation occurs in the absence of fertilization known
as parthenocarpy, can be induced by treating unpollinated flowers with IAA (D).

21. Hormone Gibberellins stimulate cell division (B).

22. Thyroxine is responsible for controlling the basal metabolic rate and its
thereforeparticularly important in growth. Under secretion of it during development
(hypothyroidism) causes arrested physical & mental development, a condition
called cretinism (C).

23. Oviparity is when the fertilized egg can be enclosed within a protective
covering before it leaves the females body as in many invertebrates. Viviparity is when
the embryo is protected and nourished within the uterus, with the placental of
mammals (B).

24. The tropical rainforest vegetables is dominated by tall trees with their
widespread canopies. The plant community falls into five layers and can be identified
with three top layer of trees. The soil is most and loose rich in humus. Scanty
trees with small leaves in a feature of savannah vegetation (C).

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