7th Básico
Senior School
IGCSE Biology
7° Básico Biology Test (1st semester, 30% Nota 4)
UNIT: The Scientific Method
NAME:
CLASS:
TEACHER:
DATE:
DURATION:
-
TOTAL MARKS [21]
40 mins
Use blue/ black ink to answer the questions.
Use pencil when drawing tables or graphs.
One mark will be deducted for not following these
instructions.
This test consists of 5 pages.
NOTA:
1
7th Básico
Senior School
IGCSE Biology
Yeast is a living organism which consists of only one cell (i.e. it is a unicellular
organism). It gets the energy that it needs for respiration from glucose. Carbon
dioxide gas is released as a waste product from the chemical reaction of
respiration.
Daniel wanted to investigate the effect of temperature on the respiration of yeast
cells.
His hypothesis is: “If the yeast cells are grown at lower temperatures, then
they will release more carbon dioxide from respiration”.
Daniel grew yeast cells in the same type and size of glass containers, but at
different temperatures. He made sure that they all received the same volume of
glucose solution as food. He took measurements every two hours over an 8-hour
period to record how much CO2 gas was produced.
2
7th Básico
Senior School
IGCSE Biology
(a.) Help organize Daniel’s results into a table to show the average volume of CO2 gas
produced by the yeast cells at each temperature. [4]
(b.) What is the independent variable in this experiment?
__________________________________________________________________ [1]
(c.) What is the dependent variable in this experiment?
___________________________________________________________________ [1]
(d.) State three variables which Daniel should standardize in order to make sure that
there is only one factor affecting the respiration rate of the yeast.
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
___________________________________________________________________ [3]
3
7th Básico
Senior School
IGCSE Biology
(e.) On the grid below, draw a line graph to show Daniel’s results. [6]
Title: ___________________________________________________________________
__________________________________________________________________
4
7th Básico
Senior School
IGCSE Biology
(f.) Use your graph (by drawing the corresponding dashed lines) to answer the
following questions.
(i.)
What temperature coincides with a volume of 24cm3 of gas produced?
____________________________________________ [2]
(ii.)
At 20°C, what was the average volume of CO2 gas produced?
____________________________________________ [2]
(g.) Daniel’s hypothesis was shown to be incorrect. Write a new, more accurate
hypothesis for this experiment (using an “if…then…” statement). [2]
______________________________________________________________________
______________________________________________________________________
*** END OF TEST ***
5
7th Básico
Senior School
IGCSE Biology
PAUTA
(a.)
-
Temperature (°C)
Average volume of CO2
gas produced (cm3)
10
2
16
7
24
15
32
27
38
34
45
1
Vertical and horizontal lines drawn with a ruler to create closed cells;
Heading for each column, with units;
Correct values in T°C, in ascending order;
MARKS DEDUCTED IF…
Corresponding values in CO2 gas column;
- Units are included in the table
- Cells are not closed
(b.)
-
What is the independent variable in this experiment?
Temperature
(c.) What is the dependent variable in this experiment?
-
Volume of CO2 gas produced
(d.) Three standardized variables
-
Same type/ species of yeast
Same amount of yeast in each container
Same type/ size of glass container
Same volume of glucose provided as food
Same time duration of experiment
Same device/ equipment used to collect CO2 gas
ANYTHING SUITABLE DIRECTLY RELATED TO THIS SPECIFIC EXPERIMENT!
6
7th Básico
Senior School
IGCSE Biology
(e.)
-
Appropriate title;
X-axis label with units;
Y-axis label with units;
Appropriate scale (graph uses at least ¾ of the grid)
Correct plotting of points;
Plots joined point-to-point, with a ruler;
MARKS DEDUCTED IF…
-
Graph is extrapolated/ extended
(f.) (i.) What temperature coincides with a volume of 24cm3 of gas produced?
-
30°C (one mark for correct value with units; one mark for correctly showing dashed line on
the graph).
(f.) (ii.) At 20°C, what was the average volume of CO2 gas produced?
- 11cm3 (one mark for correct value with units; one mark for correctly showing dashed line
on the graph).
(g.) - If the yeast cells are grown at higher temperatures (up until 38°C), then they will release
more carbon dioxide from respiration.
If the yeast cells are grown at lower temperatures, then they will release less carbon
dioxide from respiration.
(one mark for a hypothesis which makes sense; one mark for using an “if… then…”
statement to phrase their answer).
7