Biology · Oct / Nov 2021 · Paper 62 · Question 1
0610
As printed in the paper
The question as text
A student investigated the effect of temperature on the rate of respiration in yeast cells. When yeast cells respire they produce carbon dioxide gas. In this investigation the gas was collected in a balloon that was attached to a test-tube containing a yeast suspension. Step 1 The student prepared a hot water-bath and a cold water-bath. Step 2 The student measured the temperature of the water in the hot water-bath and in the cold water-bath. Step 3 A yeast suspension was stirred with a glass rod. 25 cm3 of the yeast suspension was put into each of two test-tubes. Step 4 A balloon was stretched over the top of each test-tube. Step 5 One test-tube and balloon was put into the hot water-bath and the other test-tube and balloon was put into the cold water-bath, as shown in Fig. 1.1. yeast suspension test-tube balloon water-bath Fig. 1.1 Step 6 The circumference of each balloon was measured by placing a piece of string around the widest part of the balloon, as shown in Fig. 1.2. A ruler was then used to measure the length of the string that wrapped around each balloon once. 3 string wrapped around the balloon at the widest part balloon top of the test-tube Fig. 1.2 Step 7 The circumference of each balloon was measured at 0 minutes, 5 minutes, 10 minutes and 15 minutes. The student’s results are shown in Fig. 1.3. Cold 0 minutes – 120 mm 5 minutes – 125 mm 10 minutes – 132 mm 15 minutes – 137 mm Hot 0 minutes – 120 mm 5 minutes – 135 mm 10 minutes – 145 mm 15 minutes – 147 mm Fig. 1.3
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Show the answer and mark scheme
1(a)(i)[3]
1
table drawn with a line between headings and data and (at least) 3 columns ;
2
column / row headings with units:
time / minutes
circumference or length / mm
hot and cold ;
3
eight circumferences recorded correctly and times recorded correctly ;
1(a)(ii)[1]
yeast cells respire more (rapidly) at a higher temperature / AW / ora OR
higher volume of gas / carbon dioxide, produced at higher temperature / ora ;
1(a)(iii)[1]
idea of uniform, distribution / concentration (of yeast cells) / AW ;
1(a)(iv)[2]
any two from:
type / age, of yeast ;
concentration of yeast suspension ;
volume of yeast suspension ;
type of balloon ;
time ;
(maintained) temperature(s) of water-bath(s) ;
AVP ;;
1(b)(i)[1]
(gas) syringe
OR
(bung)+(delivery tube) +inverted measuring cylinder over water / AW
OR
downward displacement of water in a graduated container / AW ;
1(b)(ii)[2]
limewater ;
milky / white / cloudy / AW ;
OR
hydrogencarbonate ;
yellow ;
1(c)(i)[2]
two temperatures recorded as: hot 28(°C) AND cold 20(°C) ;
two changes in temperature calculated as hot 12(°C) cold 0(°C) ;
1(c)(ii)[1]
any one from:
1
use thermostatically controlled water-baths ;
2
use a Bunsen burner AND thermometer (method
outlined) / use a Bunsen burner and monitor the temperature ; 3
top up with, hot water / cold water / ice, and monitor /use a thermometer ;
4
insulate the container / AW ;
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