Page 4 - 新思维科学活动用书9 样章

How to use this book
How to use this book
This workbook provides questions for
you to practise what you have learnt
in class. There is a topic to match each
topic in your Learner’s Book. Each
topic contains the following sections:
Focus: these questions help you to
master the basics
4 In this exercise, you will provide explanations using your scientific knowledge.
Practice: these questions help you to
become more confident in using what
you have learnt
14
Challenge: these questions will make
you think very hard
16
1 Photosynthesis and
the carbon cycle
1.1 Photosynthesis
Exercise 1.1A How light level affects photosynthesis
Focus
In this exercise, you will decide which variables to keep the same in an experiment. You will put
results into a table and make a conclusion.
1 Photosynthesis and the carbon cycle
Arun does an experiment to investigate whether plants photosynthesise faster when they have more
light.
6 Explain how Sofia’s results support her conclusion.
The diagram shows the apparatus he uses.
7 How can Sofia improve her experiment? Apparatus C
Apparatus A
Apparatus B
Arun puts Apparatus A next to a window.
Tick (✓) the correct answer.
He puts Apparatus B in a shady corner of the same room.
Use three sets of dishes for each quantity of fertiliser.
He puts Apparatus C in a dark cupboard.
Use a different kind of water plant in each dish.
Put each dish in a different temperature.
Exercise 1.2B Testing a variegated leaf for starch
Practice
Zara found a plant that had leaves with some green areas and some white areas. Leaves like this are
called variegated leaves.
white
green
She decided to test one of the leaves for starch using iodine solution. She made this prediction:
The green parts of the leaf will contain starch, but the white parts will not.
1 Photosynthesis and the carbon cycle
Exercise 1.2C Floating discs experiment
Challenge
In this task, you will interpret the results of an experiment. You will think about variables, write a
conclusion and use your scientific knowledge to explain a set of results.
Sofia and Zara do an experiment to investigate photosynthesis.
They cut ten little discs out of a leaf. Each disc is exactly the same size and is cut from the same leaf.
They put one disc into water in a small beaker and shine light onto it.
Little bubbles appear on the underside of the leaf disc.
After a while, the bubbles of gas make the leaf disc float to the surface of the water.
Sofia and Zara record the time taken for the leaf disc to float to the surface, then repeat their
experiment with four more leaf discs.
leaf disc
bubbles
1 Name the gas that the leaf disc produced when it photosynthesised.
2 Explain why the bubbles of gas formed on the underside of the leaf, not on the top.
3
3 In what way does the time taken for the leaf disc to rise and float depend on the bubbles of gas?
Explain your answer.