2018_bio_olevel_nov_paper3

Extracted Content: 2018_bio_olevel_nov_paper3

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Centre Number Candidate Numbe,

Candidate Name

EXAMINATIONS COUNCIL

of Education Ordinary Level

ZIMBABWE SCHOOL

General Certificate

BIOLOGY 4025/3

PAPER 3 Practical Test

NOVEMBER 2018 SESSION J hour 30 minutes

Candidates answer on the question paper.
Additional materials:

As listed in Instructions to Supervisors

Electronic calculator Soft clean eraser
\ Pencil (B or HB is recommended) ruler (cm/mm) }

TIME 1 hour 30 minutes

INSTRUCTIONS TO CANDIDATES

Write your name, centre number and candidate number in the spaces at the top of this page.
Answer all questions.

Write your answers in the spaces provided on the question paper.

Use a sharp pencil for your drawings.

Coloured pencils and crayons should not be used.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [] at the end of each question or part question.
FOR EXAMINER’S USE
1
2
TOTAL
Copyright: 73 b: F
AC ASEE BR imbabwe School Examinations Council, N2018.
[Turn over

47

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1

(a)

You are required to investigate propertics of enzymes, You arc
Provided with unboiled potato cubes labelled A and a boiled potato
cube labelled B, hydrogen peroxide solution, boiling tubes labelled,
X,Y and Z.

NB: — Caution hydrogen peroxide is harmful to skin.

Pour hydrogen peroxide solution into boiling tubes X and Y¥ toa
depth of about 2 om.

Carefully drop one potato cube A into boiling tube X and one potato
cube B into boiling tube ¥Y. Observe the boiling tubes.

(i) Record the observations in Table 1.1.
Table 1.1
tube observations
x
Y

[2]

(ii) Suggest the purpose of tube Y.
(1)

Pour hydrogen peroxide into boiling tube Z.
Add the other potato cube A into boiling tube Z.

Test the gas produced using a glowing splint.

4025/3 N2018

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(a)

(iii)

(iv)

(vy)

(vi)

Describe the observations for the test.

er

a (
Identify the gas produced.
eee (1
Draw a conclusion from the investigation.
_ spree [2]
Using a labelled diagram. show how you carried the test

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[3]

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)

@

Gi)

Gi)

(iv)

Design a procedur i i
e to investigate the effe
enzyme activity. 7 © effect of pion

{6]
State any two possible sources of error in the procedure
in (b) (i).
(2]
For one source of error stated in (b) (ii), suggest a possible
solution.
Qi]
State any one method of presenting data from the procedure
in (b) @)-
tH
[Total:20]

For

Use

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re

fa single traitm fring

1 erttance = .
You are to investigate the inherttar ied with five conkatier®

organisms using a model. You are prov
labelicd Py, Pz, A, B and C.

i 25 beads each
P, and P2 contain a mixture of 25 white beads and 25 red
1

Shake containers Py and Pz to mix the beads thoroughly

e same time
Pick a bead from cach of the containers P, and Pz at the sa

randomly.

If you pick both red. place them mto container A. red and white

place in container B and both white place in container C
Record the results in Table 2.1.
NB: two beads picked represent an individual

Repeat picking the beads randomly at the same time until all the beads
in Py and P3 are finished

Table 2.1

beads pair/container tally number

ted, red -A

red, white -B

white, white — C

(a) (i) Complete Table 2.1.

(ii) Suggest how it can be ensured th

random at the picking of beads is

40253 N2018

a)

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16]

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(iit) Stat © what each bead represents. | nm (iv) D i i etermine the ratio of the three genotypes. {i} (vy) Givi i i voprosenn red is dominant, describe the genotypes ented by each of the three containers. A B c 131 (vi) State the type of inheritance demonstrated in this investigation. eo

(vii) The expected ratio, 1:2:1, of offspring genotypes may not be obtained.

Suggest a condition for this ratio to be obtained.

(i)
(b) You are provided with organism T.
Study organism T using a hand lens.
(i) Name organism T.
Ba

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For
[Examiner's
Use

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(ii)

(iii)

Deduc
belongs.

e, with reasons, the kingdo:

m to which organism T

State the roles of such orga!

nisms in the ecosystem.

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(3]

[2]
[Total:20]

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