1. Which part of the cell contains chromosomes, and what are they made of ?
Answer
Chromosomes are located in the nucleus and are composed of DNA.
2. The figure below shows an animal cell with some of its structures magnified to show more detail. Name parts A–C.
Answer
3. Plants contain meristem tissue. What is their function ?
Answer
It can differentiate into any type of plant cell, throughout the life of the plant.
4. The figure below shows a chromosome before and after one of the stages of the cell cycle. What process has caused the change in the appearance of the chromosome ?
Answer
DNA replication, which forms two copies of each chromosome.
5. A cell from an onion has eight chromosomes. The cell divides by mitosis. Give the number of chromosomes in one of the new cells.
Answer
The new cells have also eight chromosomes.
6. What is a "stem cell" ?
Answer
An undifferentiated cell that can give rise to many more cells of the same type, and can differentiate to produce other cell types.
7. What is one benefit of using genetically identical cells from therapeutic cloning for treatment ?
Answer
The cells are not rejected by the patient's body.
8. Describe some reasons why people may be against the use of stem cells.
Answer
It carries potential risks, such as the transmission of viral infections. Additionally, some people have ethical or religious objections—for instance, they believe that using human embryos involves destroying a potential life.
9. A patient with leukaemia can be treated using stem cells derived from human embryos. What are the advantages and disadvantages of using these stem cells ?
Answer
Using stem cells from human embryos offers advantages such as utilizing already-created embryos rather than discarding them, the ability of embryonic cells to differentiate into any human cell, and the fact that their use does not cause pain to the patient.
Using stem cells from human embryos has several disadvantages: the technique is relatively new and may involve side effects or long-term issues, there is a risk of viral infection or uncontrolled cell division, the embryo—considered by some as a potential human life—is destroyed in the process, and it cannot provide consent.