B1.2- Cell division

Question 1

What are genes?

Answer 1

Sections of DNA that contain the code for a particular protein.

Question 2

In what arrangement are chromosomes found normally?

Answer 2

Pairs.

Question 3

How many chromosomes does a human have?

Answer 3

23 pairs OR 46 in total.

Question 4

What has to happen within the cell before it can divide? (2 steps)

Answer 4

1. Cell organelles (e.g. mitochondria and ribosomes) have to replicate, 2. DNA has to be replicated (copied).

Question 5

How many chromosomes will be present in a cell after DNA replication?

Answer 5

92 OR 46 pairs.

Question 6

To where do the chromosomes moves to during mitosis?

Answer 6

To opposite ends of the cell.

Question 7

What occurs during cytokinesis?

Answer 7

The cytoplasm and cell membranes divide.

Question 8

Mitosis is critical for….

Answer 8

…growth, replacement and development of an organism.

Question 9

What is a stem cell?

Answer 9

An undifferentiated cell capable of giving rise to many more cells of the same type.

Question 10

Describe the function of stem cells in embryos.

Answer 10

To develop into multiple cell types aiding in the development of the embryo into a mature organism.

Question 11

Describe the function of stem cells in adult animals.

Answer 11

To be the source of cells used in growth and repair of the mature animal.

Question 12

Describe the function of stem cells in plant meristems.

Answer 12

To allow a plant to keep growing throughout its life (animals stop growing when mature) by specialising into any type of cell.

Question 13

What is a potential use of stem cells in medicine?

Answer 13

To treat conditions where cells have been damaged e.g. diabetes, paralysis.

Question 14

What is the principle of therapeutic cloning?

Answer 14

An embryo is produced with the same genes as the patient.

Question 15

Give an advantage of therapeutic cloning.

Answer 15

No rejection of the new cells by the patient (as they are the patitent’s own cells).

Question 16

Give two potential problems with therapeutic cloning.

Answer 16

1. Risk of viral infection, 2. Religious/ethical objections around the use of embryos.

Question 17

How are plant stem cells used in horticulture (commercial plant growing)?

Answer 17

To create plant cuttings (clones of the original plant).

Question 18

Give two advantages of the use of clones in horticulture.

Answer 18

1. Rare species can be cloned to prevent extinction, 2. Crops with special adaptations (e.g. disease resistance) can be identically produced in large numbers.