Chapter 2: Cell Division

Question 1

Cell Division

Answer 1

• Chromosomes are found in pairs
• Body cells divide in a series of stages called the cell cycle
• During the cycle the genetic material is doubled. It then divides into two identical nuclei in a process called mitosis.
• Before a cell can divide it needs to grow, replicate the DNA to form two copies of each chromosome and increase the number of sub-cellular structures. In mitosis one set of chromosomes is pulled to each end of the cell by microtubules and the nucleus divides. Finally, the cytoplasm and cell membranes divide to form two identical cells
• Mitotic cell division is important in the growth, and development of multicellular organisms.

Question 2

Growth and Differentiation

Answer 2

• In plant cells, mitosis takes place throughout life in the meristems found in the shoot and root tips
• Many types of plant cells retain the ability to differentiate throughout life
• Most types of animal cells differentiate at an early stage of development

Question 3

Stem Cells

Answer 3

• Embryonic stem cells (from embryos) and adult stem cells (from adult bone marrow) can be cloned and made to differentiate into many different types of cell
• Treatment with stem cells may be able to help conditions such as paralysis and diabetes.
• Stem cells from plant meristems are used to produce new plant clones quickly and economically for research, horticulture, and agriculture.

Question 4

Stem Cell Dilemma

Answer 4

• Treatment with stem cells, from embryos or adult cell cloning, may be able to help with conditions such as diabetes
• In therapeutic cloning, an embryo is produced with the same genes as the patient, so the stem cells are not rejected and may be used for medical treatment.
• The use of stem cells has some potential risks and some people have ethical or religious objections.