Catalyst Features Key


Numeracy moments contain activities, hints and tips that will develop your scientifi c numeracy skills.


Literacy moments help you to build your scientifi c reading, writing, listening and speaking skills.


Plan, design and carry out Scientifi c Investigations. These investigations can be written up in your Portfolio.


Use your scientifi c knowledge and research skills to investigate the role of Science in Society. You can write your fi ndings up in your Portfolio.


Sometimes a topic in one strand, such as Biological World or Earth and Space, will also feature in another strand. Go links tell you where to go in the book to fi nd out more.


Working as a Scientist


Working as a Scientist tasks appear at the end of every chapter. Each one addresses an aspect of the work scientists do and relates that type of work to something you have learned about in the chapter.


The scientifi c areas addressed in Working as a Scientist tasks include:  Asking questions and making predictions


 Investigation design  Making and recording observations


 Presenting and analysing data


 Communicating science


 Responsible science. 3.5 Biological World Working as a Scientist Making and Recording Observations


Investigating Light and Photosynthesis A student in a diff erent class has designed the investigation shown in Fig. 3.5.1. You have been asked to change it to examine the relationship between light intensity and the rate of photosynthesis. The hypothesis is ʻThe greater the light intensity, the greater the rate of photosynthesis’.


Step 1: Collect the necessary equipment and position the lamp approximately 50 cm away from the Canadian Pondweed. Do not turn on the lamp.


1 Consider the factors that are likely to aff ect the rate of photosynthesis. You must collect data on factors such as:  Distance between the lamp and beaker with Canadian Pondweed.


 Mass of sodium hydrogencarbonate.


 Wattage of bulb.


2 Make a list of at least fi ve other factors that are key to the relationship between light intensity and the rate of photosynthesis. You must collect this data to help you test the hypothesis. Decide what equipment you will need to take and record these measurements.


Water Light


Canadian Pondweed


Lamp  Fig. 3.5.1


Set-up to investigate the relationship between light intensity and rate of photosynthesis


Step 2: Now turn on the lamp. Wait for three minutes and then record the number of bubbles that drift up through the boiling tube over the next 60 seconds.


Step 3: Move the lamp 10 cm closer to the Canadian Pondweed. Wait three minutes and then, once more, record the number of bubbles that drift up through the boiling tube over the next 60 seconds. Repeat three more times until you have reached a distance of 10 cm between the Canadian Pondweed and the lamp.


3 Record your results in a table.


4 Comment on the trend that you have observed and compare with other groups in the class. Does this trend support the original hypothesis?


5 Comment on likely sources of error. How could you change the investigation to improve accuracy? Consider a suitable control for this investigation.


60 x Sodium hydrogencarbonate


Thermometer Oxygen


Oxygen bubbles


Step 1: Collect the necessary equipment and set up the investigation.


Investigating Temperature and Respiration


A student in a diff erent class has designed the investigation shown in Fig. 3.5.2. You have been asked to change this investigation to examine the relationship between temperature and the rate of respiration. The hypothesis is ʻThe higher the temperature, the faster the rate of respiration’.


Plastic tubing Clip


Capillary tube


The Energy of Life 3.5 Digital Resources Key


As you work through the textbook, you will see the following icons. Each icon tells you where there is a digital resource related to what you are learning. These resources are available online at educateplus.ie.


This icon


indicates that there is an


animated version of the illustration available to watch.


This icon indicates there is an interactive version of the investigation that you can complete. The videos embedded in the investigation can also be viewed separately.


This icon appears at the end of each chapter to remind you that you can complete an online quiz to test what you have learned in the chapter.


Seeds


Wire gauze


Soda lime Water bath


1 How will you collect all of the data needed to test your hypothesis? You can use the following incomplete data collection sheet to help you get started, but there are some important factors that are not included. What other data should you collect? Consider both controls and variables to make this a fair test.


 Fig. 3.5.2


Set-up to investigate the relationship between temperature and the rate of respiration


Controls Mass of seeds


Mass of soda lime Time


10 20 30 40 50


Step 2: You may start your investigation when you are satisfi ed that your method is appropriate and you have considered all key factors. Record your data. When you have fi nished collecting your data, consider the following questions:


2 Does this investigation need a control? If yes, what would be a suitable control? 3 Present the data that you have collected and recorded using a suitable chart or graph.


4 Comment on the trend that you have observed. Does this trend support the original hypothesis?


5 Comment on likely sources of error. How could you change the investigation to improve accuracy?


61 Variables


Temperature (°C) Rate of respiration (cm) 0


Water and food dye

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