The Scientific Endeavour
Science
– Science is the systemic study of nature to discover facts about them and how they affect living things and the physical environment.
– Scientists gain specific knowledge by using the scientific method.
A) Scientific Method
– The scientific method is a logical and rational orde4r of steps which help scientists reach the conclusions about the world around us.
– The summary of important steps in the scientific method
– After the hypothesis is supported by several investigations, it comes to a theory.
– If the hypothesis is not supported by investigations, a new hypothesis will be established.
– A theory becomes a law of science when it is tested over and over again.
– Some of the desirable attitudes of a person who studies science
– Curiosity
– Creativity
– Genuine Interest
– Integrity
– Patience
– Perseverance
– Willing to accept critics or ideas from other people
Designing a fair experiment
– When designing an experiment, it is important to identify and control the variables
– Variables are factors/conditions which have an effect on the experiment
– It is important to know the cause and effect relationships between the variable you change and the variable you are measuring in the experiment
There are three types of variables
– Independent (what you change)
– Dependent (what you observe measure)
– Controlled (something that is kept constant or the same)
For example
In an experiment, we could like to investigate how the amount of light affects the rate of photosynthesis
Hypothesis of the experiment
Increasing the light intensity will increase the rate of photosynthesis (and its products)
The other factors which can affect the rate of photosynthesis must be kept constant, such as the number of leaves or amount of water (controlled variables)
Example of scientific method
Using the scientific method, let’s plan an investigation to show that the cell wall is needed to keep the cell’s regular shape
1)Observation
Cell walls are only observed in plant cells which have a regular shape.
2) Hypothesis
Cell wall helps to keep the plant cells in its regular shape
3) Experiment
Variables in this experimental design:
– Independent variables: The presence of a cell wall
– Dependent variable: The shape of the cell
– Controlled variable: The type of cell
4) Procedure
Step 1: Prepare 2 identical plant cells
Step 2: Remove the cell wall from one of the plant cells
Step 3: Compare the shape of the plant cells
5) Result
Only the plant cell with the cell wall will have its regular shape
The plant cell without a cell wall will lose its regular shape
6) Analysis and Conclusion
Cell wall helps to ensure that the plant cell has its regular shape
B) Importance of Science
– Technology is an application of scientific knowledge in our world
– Technology improves our everyday life in various fields such as communication, agriculture, medicine transportation and others
– Science has limitations too:
– Science cannot stop or prevent the occurrence of natural disasters such as earthquakes or tsunamis
– Science cannot resolve ethical and moral issues such as abortions or human genetic engineering
– Scientific knowledge may change from time to time. Hence, the explaination for certain observations may noy be relavant in the future
Section A: MCQ
1. Which statements are true
I Advancements in science are always beneficial to help society
II Science is the study of our physical world
III Scientific knowledge is derived from observations
IV We use instruments to help us make accurate measurements
A: I and II only
B: III and IV only
C: II, III and IV only
D: All of the above
2. The following symbols were found on a bottle of reagent
Which of the following does/do not show the safety precaution(s) that should be taken when using the reagent
I Do not leave it near an open flame
II Using a stopper to seal the reagent after use to prevent vapours from escaping into the surrounding
III Use special protective gear during handling
A: I only
B: I and III only
C: II and III only
D: III only
3:
4:
5: Which instrument below can be used to measure the amount of matter in a substance4
A: Burette
B: Spring balance
C: Electronic balance
D: Displacement can
6. Jordan noticed that after several rounds of washing, his T-shirts shrank in size, he then conducted a scientific investigation.
I Jordan measured the size of the t-shirt after the wash and recorded them in a table
II Jordan concluded that the cotton results in a greater shrinkage
III Jordan chose two t-shirts, made up of cotton and polyester respectively, and washed them under the same conditions
IV Jordan predicted that the material of the t-shirts affect whether they would shrink in size after washing
Which of the following correctly corresponds with the key elements of the scientific methods
7. Which row describes the colour of luminous flame and the state of the corresponding air hole of a bunsen burner
8
8. The diagram below shows a girl conduct6ing an experiment
Which of the following statements are safety hazards shown in the diagram
I Not wearing eye protection
II Long hair not tied up
III Looking into a test tube while heating it
IV Not closing the air hole before lighting up the bunsen burner
V Placing ethanol, a flammable substance , near the bunsen burner
A: II an III only
B: I,II and III only
C: I, II, III and V only
D: I, II, III, IV and V only
9. The following shows the steps a scientist performs in answering a question
I The scientist notices that there are fewer soil microorganisms near underground gas tanks
II The scientist suspects that the gasoline leakage has reduced the population of soil microorganisms
III The scientist varies the amount of gas added to a fixed amount of different samples of soil.
IV The scientist counts the number of microorganisms that survived in samples
V From the result, the scientist finds that there is a significant amount of reduction in microorganisms due to the gas
10. The following hazard symbols can be found on na bottle containing a chemikcal in the labatory
What can be concluded from them?
A: The liquid can cause cell damage
B: The liquid can be touched with bare hands
C: The liquid cannot be used near a naked flame
D: The liquid would explode when it is poured out of the container
11. A student tried lighting up a bunsen burner and a strikeback occurred. What could be the cause of the strikeback?
A: The barrel was not cleaned properly
B: Insufficient gas from the gas tap
C: There was a crack in the collar
D: The air-hole was opened
12. A student carried out an experiment and recorded the following statement:
“When the current increases, the filament in the light bulb turns from orange to bright red”, which stage of the scientific method is the student carrying on?
A: Asking a question
B: Constructing a hypothesis
C: There was a crack in the collar
D: The air-hole was opened
13. Which of the following examples is not an application of science
A: Explain the preference for chicken sandwich over tuna sandwich
B: Extraction of vanilla essence from vanilla beans using different solvents
C: Study the effect of river water tempreature on the number of plants and animals
14.
15. Which of the following is a common flammable substance in the labatory
A: Iodine water
B: Chlorine
C: Hydrochloric acid
D: Alcohol
16. A bottle has the following warning label attached on it as shown below
What could be the nature of the substance
A: Radioactive
B: Explosive
C: Corrosive
D: Irritant
17. Which of the following describes the function of the apparatus shown below.
A: For collecting gas during experiments
B: For evaporating the liquid in a solution over a bunsen burner
C: For mixing chemicals to produce a gas when heating is not required
D: For mixing chemicals to produce a gas when heating is required
18. Which of the following differences between a luminous and a non-luminous flame is incorrect
19. Which part of the bunsen burner is responsible for controlling the type of flame produced
A: Barrel
B: Collar
C: Gas tap
D: Rubber tubing
20. Which statement is correct about labortory safety
A: Drinking distilled water in the laboratory