Biology 5090 · O Level · Coordination and response in plants
Coordination and response in plants — practice question
As a seed begins to germinate, the radicle appears first and starts to develop into the root. A student chose to study how the radicle grows during germination.
The student used a seed that had already been germinating for several days. Eight evenly spaced lines were drawn on the radicle, as shown in Fig. 3.1.
The seed was then kept in suitable conditions in the dark, with the radicle directed vertically downwards. Two days later, the radicle had grown as shown in Fig. 3.1.
(a(i))[2]
Describe the visible differences that occurred during the two days after the radicle was marked.
(a(ii))[1]
Suggest why the student placed the seed with the radicle pointing vertically downwards instead of horizontally.
(a(iii))[2]
State two environmental conditions, other than light, that the student could control to ensure maximum growth of the radicle.
(b(i))[4]
In the space below, produce a large drawing of cell $A$ exactly as shown in the photomicrograph in Fig. 3.2.
(b(ii))[3]
Lines $B$ and $C$ show the length of cell $A$. Draw a straight line on the photomicrograph to join $B$ and $C$. Measure the line and record its length.
Calculate the actual length of the cell and record it to the nearest two decimal places.
Worked solution & mark scheme
This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Length of the radicle increased” …