Life Sciences Practical

QUESTION 2

2.1 Bob decided to see how light intensity affects flower buds opening in a particular species of plant known as Watsonias that is found in the Mediterranean-climate regions. He built four outside enclosures for the Watsonias.

- The first one was covered with one layer of green shade cloth.
- The second one was covered with two layers.
- The third one with three layers.
- The fourth one with four layers.

Watsonias flower in spring to early summer so Bob did his experiment in October with flowers that he bought from the nursery.

- In each enclosure, Bob put five identical pots of Watsonias.
- Each pot had a single Watsonia plant which was 20 cm high and had no open flowers.
- Each enclosure was placed on his lawn in full sun.
- At the end of each week, he counted the total number of flowers open in each enclosure and recorded his results.

His results are shown in the table below.

\begin{tabular}{|c|c|c|c|c|}
\hline \multicolumn{5}{|c|}{\begin{tabular}{l}
Number of flower buds opening on Watsonia plants in four different \\
enclosures over four weeks in October
\end{tabular}} \\
\hline Enclosure No. & Week 1 & Week 2 & Week 3 & Week 4 \\
\hline 1 ( [tex]$25 \%$[/tex] shade) & 4 & 7 & 17 & 29 \\
\hline 2 (50\% shade) & 2 & 5 & 9 & 15 \\
\hline 3 (75\% shade) & 0 & 3 & 4 & 7 \\
\hline 4 (100\% shade) & 0 & 0 & 0 & 3 \\
\hline
\end{tabular}

2.1.1 State the:

a. Dependent variable:
(1)

b. Independent variable:
(1)

2.1.2 Bob's experiment demonstrates several good practices in ensuring validity and reliability.

a. Name two good practices ensuring the validity of the experiment:
[tex]$\qquad$[/tex]
[tex]$\qquad$[/tex]

b. Name two good practices ensuring the reliability of the experiment:
[tex]$\qquad$[/tex]
[tex]$\qquad$[/tex]