Biology 9700 · AS & A Level · Structure of nucleic acids and replication of DNA

Structure of nucleic acids and replication of DNA — practice question

Fig. 1.1 shows a photomicrograph of an onion, Allium cepa, root tip, with cells visible in interphase and at different stages of mitosis.

(a)[3]

Name the mitotic stages seen in cells A, B and C.

(b)[1]

Suggest a reason why the cells labelled D are smaller than most of the other cells in Fig. 1.1.

(c)[2]

Interphase is often called a ‘resting stage’. Explain why the phrase ‘resting stage’ does not describe cells in interphase accurately.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A is identified as anaphase” …