Biology 9700 · AS & A Level · Structure of nucleic acids and replication of DNA
Structure of nucleic acids and replication of DNA — practice question
In interphase of the cell cycle, individual chromosomes are not visible inside the nucleus. At this stage, the genetic material is called chromatin.
(a)[1]
Chromatin is altered during mitosis so that chromosomes can be seen. State what happens to chromatin that allows individual chromosomes to be visible during mitosis.
(b)[4]
Fig. 5.1 is a transmission electron micrograph of two human chromosomes at metaphase of mitosis. Describe the structure of chromosomes at metaphase, using the two chromosomes shown in Fig. 5.1 as an example.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Chromosomes condense/supercoil, so they become shorter and thicker.” …