Designing experiments

A student is designing an experiment to investigate whether heavier female rats produce more offspring than lighter female rats. In the experiment, what are the independent and dependent variables?

• independent variable: age of the female rats

  dependent variable: weight of the female rats

• independent variable: number of offspring

  dependent variable: weight of the female rats

• independent variable: weight of the female rats

  dependent variable: number of offspring

• independent variable: weight of the female rats

  dependent variable: age of the female rats

Tags

NGSS.HS-LS4-2

Carol wanted to know which colour of light was most effective in promoting plant growth. She divided 15 seedlings of the same height into three groups and shone a different colour of light on each group of seedlings. After 3 days, she measured the increase in height of the seedlings.

Which of the following is the hypothesis in Carol’s investigation?

• Red light is most effective in promoting plant growth.

• Blue light is least effective in promoting plant growth.

• Green light is most effective in promoting plant growth.

• No hypothesis is needed in her investigation.

What are the independent and dependent variables in Carol’s investigation?

• Independent variable: number of seedlings in each group

  Dependent variable: colour of light

• Independent variable: height of seedlings

  Dependent variable: colour of light

• Independent variable: colour of light

  Dependent variable: height of seedlings

• Independent variable: air temperature

  Dependent variable: height of seedlings

Why did Carol use 5 seedlings instead of a single seedling in each group?

• To ensure that her investigation is a fair test.

• To increase the confidence that the results are not by chance.

• To show that any difference in the results is due to the colour of light.

The set-ups are left at room temperature for two days. To investigate whether light is necessary for seed germination, which of the set-ups should be compared?

• (1) and (3) only

• (1) and (4) only

• (2) and (3) only

• (2) and (4) only

Tags

NGSS.MS-LS1-5

NGSS.MS-LS1-6

The set-up is used to investigate whether sodium chloride solution can preserve peas.

Which of the following set-up should be included as the control in this investigation?

• 
• 
• 
• 

Which of the following statements about the control set-up of an experiment is/are correct?

(1) It is identical to the experimental set-up except that the factor under investigation is absent.

(2) It is to ensure the result of the experiment is due to the factor under investigation.

(3) Not all the investigations require a control set-up.

• (1) only

• (1) and (2) only

• (2) and (3) only

• (1), (2) and (3)