lab test answer scheme

BIO3101 SULIT

UNIVERSITI MALAYSIA TERENGGANU
LAB PRACTICAL TEST
(UJIAN AMALI)

SEMESTER II 2018/2019 SESSION
(DEGREE PROGRAMME)

NAME OF COURSE : BIOCHEMISTRY
COURSE CODE : BIO3101
DATE : 14 MAY 2019 (TUESDAY)
PLACE : KOMPLEKS MAKMAL BERPUSAT
TIME : 10:00 – 13:00

ANSWER SCHEME

BIO3101 SULIT

1. a. You are given a set of micropipettes labelled P, Q, R and S. [4M]
(Anda diberikan satu set mikropipet yang berlabel P, Q, R dan S.) [4M]
Identify the micropipettes with the suitable range of volume for each of
the volume fixed below in the table.
(Kenal pasti mikropipet dengan julat isipadu yang sesuai bagi
menyediakan isipadu yang dinyatakan dalam jadual di bawah.)

Micropipettes P Q R S

Volume 0.1-1 0.02- 0.1-1 0.01-
range [1M] 0.2 [1M] 0.1
[1M] [1M]
(in mL)

b. You are given FOUR (4) samples (A, B, C, D) that have been analysed
using different qualitative tests. Based on the colour observed,
determine whether the samples contain either the carbohydrates,
proteins or lipids. [4M]

(Anda diberi EMPAT (4) sampel (A, B, C, D) yang telah dianalisa
menggunakan pelbagai ujian kualitatif. Berdasarkan kepada warna
dilihat, tentukan samada sampel tersebut mengandungi karbohidrat,
protein atau lipid.) [4M]

Sample Contains
(Note: States whether it contains carbohydrates,
I
II proteins or lipids)
III Proteins [1M]
IV
Carbohydrates [1M]

Carbohydrates [1M]

Lipids [1M]

2/7

BIO3101 SULIT

2. A laboratory procedure calls for you to prepare several solutions with known
concentrations. Describe how you would prepare:

(Satu prosedur amali memerlukan anda untuk menyediakan beberapa larutan
dengan kepekatan yang tertentu. Jelaskan bagaimana anda menyediakan:)

a. 100 mL of a 10 mM NaOH solution. [Key: Formula weight of NaOH is 40
g/mol]. Show your calculation. [4M]

(Satu larutan 100 mL NaOH dengan kepekatan 10 mM. [Kekunci: Berat
molekul NaOH is 40 g/mol]. Tunjukkan pengiraan anda.)

To prepare a 1 M NaOH. We need 40 g in 1 L. For 10 mM, we need,
= (10mM) (40 g) / 1000 mL
= 0.4 g in 1L [1M]

Therefore, for a 10 mM NaOH in 100 ml, we need,
= (100mL) (0.4 g) / 1000 mL [1M]
= 0.04 g [1M]

To prepare this solution, weigh a 0.04 g NaOH and dissolved in 100
mL solvent. [1M]

b. If a 25 mL, 2.19 M solution is diluted and the final volume is 72.8 mL, what

is the final concentration of the solution? [3M] [

(Sekiranya satu larutan berisipadu 25 mL dan berkepekatan 2.19 M melalui 4
proses pencairan dengan isipadu akhir 72.8 mL, apakah kepekatan akhir M
]
larutan itu?)

M1V1=M2V2

(2.19M) (25 mL) = M2 (72.8 mL) [1M]

M2= (2.19 M) (25 mL) / 72.8 mL [1M]

= 0.75 M [1M]

c.i) A 20 g fat or oil is dissolved in 50 ml solvent mixture, as stock solution. What
is the concentration of the stock solution? [1M]
(20 g lemak telah dicairkan menggunakan 50 ml pelarut, sebagai larutan
stok. Apakah kepekatan larutan stok tersebut?)

Concentration= amount / volume
Thus, [stock solution] = 20 g / 50 mL

= 0.4 g mL-1 [1M]

3/7

BIO3101 SULIT

ii) After that, 10 mL of the stock solution is used to prepare a sample solution

in solvent mixture. The concentration of the sample solution is 0.1 g mL-1.
(Kemudian, 10 mL daripada larutan stok itu telah digunakan untuk
menyediakan larutan sampel yang dicairkan menngunakan pelarut.
Kepekatan larutan sampel itu adalah 0.1 g mL-1)

What is the final volume of the sample solution? [2M]
(Apakah isipadu akhir larutan sampel itu?)

M1V1=M2V2
Final volume of sample solution is;
(0.4 g mL-1) (10 mL) = (0.1 g mL-1) (V2) [1M]
V2 = (0.4 g mL-1) (10 mL) / (0.1 g mL-1)

= 40 mL [1M]

iii) Calculate the dilution factor (D.F) involved in the dilution process of the stock
solution to sample solution. [2M]
(Hitungkan factor pencairan yang terlibat dalam proses pencairan larutan
stok kepada larutan sampel)

D.F = [sample solution] / [stock solution]
or

volume of stock used / final volume

= 0.1 g mL-1 / 0.4 g mL-1 [1M]
= 1 / 4 dilution [1M]
or

= 10 mL of stock solution / 40 mL (stock + solvent) [1M]
= 1 / 4 dilution [1M]

4/7

BIO3101 SULIT

3. Table 1 lists the absorbance of samples containing different
concentrations of glucose. You also have TWO (2) other samples, I and
II, containing unknown concentration of glucose. [5M]

(Jadual 1 menyenaraikan keserapan sampel mengandungi kepekatan
glukosa yang berbeza. Anda juga mempunyai DUA (2) sampel lain, I
dan II yang mengandungi kepekatan glukosa yang tidak diketahui.)

Table 1 (Jadual 1)

Glucose Absorbance (A510nm)
concentration

(mg/mL)

0.2 0.09

0.4 0.21

0.6 0.33

0.8 0.45

1.0 0.57

a. Plot a graph to show the relationship between the absorbance and
glucose concentrations in the form of a standard curve. Use the
graph paper provided.

(Plotkan graf bagi menunjukkan hubungan antara keserapan dan
kepekatan glukosa dalam bentuk satu lengkung piawai. Guna
kertas graf disediakan.)

5/7

BIO3101 SULIT

b. From the standard curve in (a), determine the concentration of fructose
in samples I and II, with absorbance at 0.23 and 0.38, respectively.
Don’t forget to state the unit as well. [2M]

(Dari lengkung piawai dibina, tentukan kepekatan fruktosa dalam
sampel I dan II yang masing-masing mempunyai nilai serapan pada
0.23 dan 0.38. Jangan lupa untuk menyatakan unitnya.)

Sample I: 0.42 mg/mL or any volume that is correctly identified
in the plot [1M]
Sample II: 0.61 mg/mL or any volume that is correctly identified
in the plot [1M]

c. State ONE (1) importance of a standard curve. (Nyatakan SATU (1)
kepentingan lengkung piawai.) [1M]

To determine the concentration of unknown samples in a
reaction. [1M]

4. Demonstrate how to perform a serial dilution. Prepare THREE (3) working
solutions of bromophenol blue from a stock solution of 1 mg/mL. Use a 4X
dilution factor to prepare a 8 mL solution each. Demonstrate the correct
steps of performing serial dilutions as taught during you lab practicals. [8M]

[Note: You will be observed by the invigilator while performing the dilution.
Marks will be given based on this observation.]

(Tunjukkan cara bagaimana menjalankan pencairan bersiri. Sediakan TIGA
(3) larutan kerja bromofenol biru dari larutan stok berkepekatan 1 mg/mL.
Sila gunakan faktor pencairan 4X untuk menyediakan larutan 8 mL
setiap satu. Tunjukkan langkah-langkah menjalankan pencairan seperti
yang dipelajari semasa praktikal.

[Nota: Anda akan diperhatikan oleh pemeriksa semasa menjalankan
pencairan. Markah akan diberi berdasarkan pemerhatian ini.])

Based on the observation of handling the apparatus and preparing
the right amount for the dilution [8M]

a. What volume of bromophenol blue is needed to prepare each of the
test tubes? [6M]

(Apakah isipadu bromofenol biru diperlukan untuk menyediakan setiap
tabung uji?)

Test tube 1: 2 mL [2M]

Test tube 2: 2 mL [2M]

Test tube 3: 2 mL [2M]

6/7

BIO3101 SULIT
b. What is the final concentration of bromophenol blue in each test
tubes? [6M]

(Apakah kepekatan akhir bromofenol biru dalam setiap tabung uji?)

Test tube 1: 0.25 mg/mL [2M]
Test tube 2: 0.0625 mg/mL [2M]
Test tube 3: 0.0156 g/mL [2M]

- Kertas Soalan Tamat –
End Of Question Paper

7/7