OAU BIOLOGY 2009 POST-UTME PLUS ANSWERS AND EXPLANATIONS

OBAFEMI AWOLOWO UNIVERSITY 2009 POST UME TEST

BIOLOGY

1. One of these is not found in the urine
(a) water
(b) sodium chloride
(c) nitrogenous compounds
(d)calcium chloride
(e) nitrogenous salts.

2. An organism with a pair of in distinguishable genes is a
(a) heterozygote (b) hybrid
(c) allelomorph (d) homozygote
(e) diploid

3. The fruit formed from a single flower having several free carpels in called
(a) multiple fruit (b) Simple fruit
(c) aggregate fruit (d) dehinscent fruit
e) indehiscent fruit.

4. The function of ossicles (maleus, incus and stapes) in the mammalian ear to
a) transmit vibrations
b) regulate pressure
c) support of the inner ear
d) maintain balance during motion
e) secrete oil

5. “Joined skeleton” is absent in the
a) cockroach b) spider
c) millipede d) snail
e) house fly

6. Mucor and spirogyra can be put in a because group they
a. Are unicellular
b. Have spores that are dispersed by wind
c. Can live independent lives
d. Reproduce sexually
e. Have bodies made up of thallus and filaments alternatively.

7. The organ through which nourishment and oxygen diffuse into an embryo is
called
a) Amnion b) chorion
c) umbilical cord d) oviduct
e) placenta

8. A tapeworm fasten itself to the intestine of its host with
a) Neck & sucker
b) hooks & suckers
c) rostellum & suckers
d) proglottis & neck
e) rostellum hooks & suckers

9. Which of these is false about the piliferous layer of a root? It
a) Has a thin cuticle
b) Is the outermost layer of the corex
c) May bear root hairs
(d) Breaks down with age
(f) Is replaced by cork in old roots.

10. Anaerobic respiration in yeast produces
a) CO2 & ethanol
b) CO2 &H2O
c) CO2&O2
d) CO2 & glucose
e) Ethanol & H2O

11. Which one of these set of factors is completely abiotic? (a) Turbidity,
tide
salinity, plankton (b) pressure, pH, soil insect (c) Water, soil, bacteria,
salinity (d) pH, bamboos, wind, rainfall (e) Light, altitude, wind, humidity

12. In which of these are flagella and cilia found?
(a) Flatworms (b) Protozoa
(c) Coelenterates (d) Annelids
(e) Nematodes

13. The three important organs that are situated close to the stomach are (a)
Liver,kidney & gall bladder (b) pancreas, liver & kidney (c) Gall bladder, pancreas
& spleen (d) liver, kidney & spleen (e) kidney, gall bladder, liver

14. The plantain reproduces asexually by (a) Spores (b)Buds (c) Fragments (d)
Suckers (e) Flowers

15. The major function of swim-bladder in fish is (a) Breathing (b) Swimming
(c)
Diving (d) Repelling enemy (e) Buoyancy

16. The part of the central nervous system concerned with answering an
examination
question is the (a) Spinal Cord (b) Cerebellum (c) Oryx (d) cerebrum (e) Medulla oblongata

17. Wind pollinated flowers usually have
(a) long styles
(b) sticky stigmas
(c) small and short stigmas
(d) rough pollen grains
(e) small styles and pollen.

18. The ridicule of a bean seedling grows most rapidly in the region
(a) of the root tip (b) below the top soil
(c) just around the root tip
(d) just below the root tip
(e) just above the root tip.

19. A key similarity between nervous and hormonal system is that both
a) Involve chemical transmission
b) Have widespread effects
c) Shed chemicals into the blood stream
a. Evoke rapid response
b. Eliminate response

20. The bone of the neck on which the skull rests is
(a) Odontoid (b) Axis (c) Occipital
(d) Atlas (e) patella

21. A child blood group genotype different form those of both parents and with
a mother of genotype 00, can only have a father of genotype
(a) A (b) B (c) OO (d) AB (e) AA

22. A true climax community a) changes from year to year b) persists until the
environment changes
c) Is the first stage in plant succession
d) Consists of tallest trees and small animals e) Is in a state of
perturbation.

23. In a predator food chain involving secondary and tertiary consumers, the
organisms become progressively
(a) smaller
(b) equal in number
(c) large and fewer along the food chain
(d) parasitized along the food chain as consumers get bigger
(e) sparse in distribution.

24. Which one of these is an adaptation to a
xerophyte environment?
a) fleshy tissue with reduced leaves
b) extensive surface roots and broad leaves
c) thick barks and broad leaves
d) rough leaves and shallow root system
e) stunted growth and surface roots.

25. When it is cold, the blood vessels of the skin
a) dilate to increase blood flow to the skin
b) constrict to reduce the amount of blood flowing to the skin
c) dilate to reduce the amount of blood flowing to the skin
d) constrict to increase the amount of blood flowing to the skin

ANSWERS KEY

1. D 6.B 11.C 16.D 21.D
2. D 7.E 12.B 17.C 22.B
3. C 8.B 13.C 18.A 23.C
4. A 9.A 14.D 19.D 24.A
5.D 10.A 15.E 20.D 25.B

EXPLANATIONS TO THE QUESTIONS

1. Calcium chloride is not found in urine. Urine contains sodium chloride,
urea,water in addition to other compounds (D).

2. An individual is said to be homozygous if it has two similar genes for the
same character i.e. it has two identical alleles at the same position on a pair of
chromosomes e.g. TT is for tallness (D).

3. Aggregate fruits are produced form a single flower with an apocarpous
pistil i.e.several free carpels and hence a collection of simple fruit e.g cola-fruit and
rose fruit (C)

4. Three tiny bones called ossicles, fit against one another to form a chain
of bones stretching from the inside of the eardrum across the middle ear. Sound
vibration travel down the outer ear and vibrate the eardrum. This causes vibration of
fluid in the inner ear, so that the sensors cells in the cochlea receive the
stimulus (A)

5. Snail do not have joined skeleton, its soft
body muscle is enclosed or housed in a shell(D)

6. They can for spores which can be blown
by wind (B)

7. The embryo develops an organ called the placenta. The placenta is firmly
attached
to the wall of the uterus and through it nourishment and Oxygen are obtained
by the embryo from the mother and waste products are removed (E)

8. On top of the scolex is a projection called the rostellum, which has hooks
and four evenly spaced sucker on the outside. The tapeworm fasten itself to the
intestine using hooks & sucker (B)

9. The outermost layer of the cortex is called piliferous layer. Unlike the
epidermis
of the stem, the piliferous layer has no cuticle (A).

10. Anaerobic respiration is the breaking down of complex molecules in the
absence of Oxygen to give carbondioxide and Ethanol (A)

11. Abiotic factors in ecology study are those that do not involve living
things e.g temperature, Rainfall, Relatives humidity, light, pressure soil acidity,
topograph are commonly called Edaphic factors (C)

12 Flagella and cilia are locomotive organs i.e. for movement, paramecium use
cilia while eugelena use flagella, it is common to protozoa (B).

13 Gall bladder, pancreas & spleen are available in the stomach

14. Sucker is the root part of plantain & it is also used for vegetative
propagation (D)

15. Swim bladder is used for buoyancy in fish (E)

16. The cerebrum controls all voluntary action like learning intelligence,
thinking,
imagination and memory which are aspect of intelligent behavior (D)

17 Small and short stigmas are feature of wind- pollinated flowers (C).

18 Apical meristems are responsible for the increase in length of roots and
stem, re
found at the tip of stem and root (A).

19 Nervous and hormonal system are both reflex action, it is rapid and
automatic response to stimulus without the involvement of the brain (D).

20 The skull rest on the atlas bone of the cervical vertebra (D).

21 Since mother blood group —0 (JOJ0) the child can only have a father with
blood group AB, to have a blood group different from both parents i.e. either blood
group A or B (D).

22 A climax community do not change form time to time, it persists until the
environment change (D).

23 As we move upward in the food chain, the size of the organism increased and
become fewer in number (C).

24 Xerophyte are plant adapted with desert habitat. They have flashy tissue
and reduced leaves to reduce transpiration and (water lose) and extensive roots
for water. Hydrophytes are aquatic plants with broad leaves, to tap enough
sunlight, for photosynthesis i.e. increase in rate of water loss and short roots since
water is in abundance (A).

25 In cold, the blood vessel in the skin will get smaller (or constrict) so
that very little blood will reach the skin surface, this reduces heat loss by radiation (B)

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