Cell biology：练习题

A stem cell is an undifferentiated cell of an organism. Which statement correctly identifies the differentiation capabilities of stem cells found in adult bone marrow compared to those found in human embryos?

A typical human cell nucleus has a diameter of approximately \( 6 \times 10^{-6} \text{ m} \). A bacterial cell has a diameter of approximately \( 1 \times 10^{-6} \text{ m} \). Based on these orders of magnitude, how many times larger is the nucleus than the bacterial cell?

In therapeutic cloning, an embryo is produced with the same genes as the patient. What is the primary medical advantage of using stem cells derived from this specific process?

What is a defining characteristic of embryonic stem cells that differentiates them from adult bone marrow stem cells in terms of their therapeutic potential?

State the specific role of ribosomes in a cell and identify which type of microscope would be required to see them in detail.

A student uses a microscope to observe a bacterial cell and an animal cell. Describe two structural differences the student would observe between the genetic material of the prokaryotic bacterial cell and the eukaryotic animal cell.

Explain the three stages of the cell cycle that result in the production of two genetically identical daughter cells.

A student uses a microscope to observe a selection of cells. Two of the cells are shown to have specific features: Cell A has a single DNA loop and small rings of DNA called plasmids, while Cell B has its genetic material enclosed within a nucleus.

(a) Name the two broad types of cells represented by Cell A and Cell B. (2)

(b) Identify two sub-cellular structures that would be found in both Cell A and Cell B. (2)

(c) Cell B is an animal cell. Name one additional sub-cellular structure that would be found if Cell B were a plant cell, and state its function. (2)

Stem cells are undifferentiated cells capable of giving rise to more cells of the same type and certain other types of cells through differentiation.

(a) Describe the primary difference between the function of stem cells found in human embryos compared to those found in adult bone marrow.

(b) Therapeutic cloning is a medical process where an embryo is produced with the same genes as the patient. Explain how this process can be used to treat medical conditions and why it is advantageous for the patient’s recovery.

(c) The use of stem cells in medicine is a controversial subject. State one potential clinical risk and one ethical objection that people may have regarding embryonic stem cell research.