Chapter 22 - Cloning and Biotechnology

Question 1

When is micropropagation used?

Answer 1

When a desirable plant:

• does not readily produce seeds
• doesn’t respond well to natural cloning
• is very rare

Question 2

What is the first step of microprogation?

Answer 2

Take a small sample of the plant- the meristem tissue from shoot tips and axial buds is often dissected out in sterile conditions

Question 3

Why is the meristem tissue dissected out in sterile conditions?

Answer 3

To avoid contamination by fungi and bacteria

Question 4

What happens after a sample of meristem tissue is taken in micropropagation?

Answer 4

The sample is sterilised by emmersing it in sterilising agents like bleach

Question 5

What is the tissue sample taken from the plant known as in micropropagation?

Answer 5

The explant

Question 6

What happens after the sample is sterilised in micropropagation?

Answer 6

The explant is placed in a sterile culture medium containing a balance of plant hormones (like auxins and cytokinins)

Question 7

What is the result of the explant being placed in a culture medium containing plant hormones?

Answer 7

The plant hormones stimulate mitosis, causing the cells to proliferate and form a mass/clump of identical cells

Question 8

What is the clump of identical cells formed in micropropagation known as?

Answer 8

A callus

Question 9

What happens after a callus is formed in micropropagation?

Answer 9

The callus is divided up and individual cells or clumps from the callus are transferred to new culture mediums containing a different mixture of hormones and nutrients

Question 10

What is produced from the division of the callus into different culture mediums?

Answer 10

The development of tiny genetically identical plantelets are stimulated

Question 11

What happens after the plantlets are produced in micropropagation?

Answer 11

The plantlets are potted into compost where they grow into small plants, and the young plants are planted out to grow and produce a crop

Question 12

Give 3 arguments for micropropagation

Answer 12

• Allows for rapid production of large numbers of plants with known genetic makeup which will yield good crops
• Produces disease-free plants
• It provides a way of reliably increasing the numbers of rare plants

Question 13

Give 3 arguments for micropropagation

Answer 13

• Produces a monoculture (genetically identical) so they are all susceptible to the same disease
• Relatively expensive process
• If the source material is infected with a virus, all of the clones will also be infected

Question 14

What are monozygotic twins?

Answer 14

When an early embryo splits to form two separate genetically identical embryos

Question 15

What does penicillin mould need to grow well?

Answer 15

High oxygen levels and a rich nutrient medium

Question 16

What are the 3 steps of producing penicillin?

Answer 16

1. The fungus is grown
2. The fungus produces penicillin
3. The penicillin is extracted from the medium and purified

Question 17

How is the pH maintained in the production of penicillin?

Answer 17

The growth medium contains a buffer

Question 18

Why are small bioreactors used in the production of penicillin?

Answer 18

Because it is difficult to maintain high levels of oxygenation in large bioreactors