Polyploidy and GMOs (2)

Question 1

What is polyploidy?

Answer 1

Polyploidy is a condition of having more than the basic two copies of chromosomes. It is especially common among ferns and flowering plants.

Question 2

How does polyploidy occur?

Answer 2

It may occur through hybridization between two species, resulting in new species (speciation) which makes it very important in the evolution of new species of plants, eg bread wheat (6n) which is one of the most important food sources today, arose from two separate events of hybridization.

Question 3

Many other cultivated plants are polyploidy, e.g- bananas are ___, potatoes are ____, some strawberries are ____.

Answer 3

triploid
tetraploid
octoploid

Question 4

Through biotechnology, many species of polyploidy plants will have: (5)

Answer 4

• larger flowers, e.g. marigold, snapdragon
• larger fruits, e.g., watermelons
• larger storage organs, e.g. potatoes seedless fruits, e.g. banana, grapes
• resistance to disease, e.g. tobacco
• resistant to mosaic virus infection.

Question 5

It has been calculated that, if we continue with current agricultural practices, Africa, south of the Sahara, will have a grain shortage of 88.7 million tons by the year 2025. What can be done? Using GM crops will: (2)

Answer 5

• give increased yield which will help to solve the world’s hunger and malnutrition problems.
• help protect and preserve the environment by reducing reliance on chemical pesticides and herbicides.

Question 6

Overall, therefore, genetic engineering has enabled new traits in important agricultural crops to improve their: (4)

Answer 6

• resistance to pests and herbicides e.g. introduction of Bt bacteria into cotton, maize and potato plants. (Bt bacteria produce a protein that kills certain insects.)
• Nutrient value, e.g. golden rice. (Genes from carotene-producing are introduced into rice which can form vitamin A when the rice is eaten.)
• taste and quality, e.g. new species of tomatoes
• resistance to weather extremes.

Question 7

GM crops are now grown in over ___ countries on six continents.

Answer 7

40

Question 8

A group of scientists from the Department of Molecular and Cell Biology at the University of Cape Town, Kenyatta University in Kenya and the CSIR in Pretoria are all working on developing drought tolerance in a number of important African crops. Genes from an ____ ‘resurrection plant ‘are being used. These plants are able to survive on only 5% of their water content - they appear to be dead. When water returns, however, they can resurrect within 72 hours and appear very much alive again. The idea is to introduce ___ from these plants into maize so that this vital crop can become resistant to ____

Answer 8

indigenous
genes
drought

Question 9

Because of the potentially huge benefits to be gained from the use of GMOs, there is great pressure to continue producing them. There are many concerns, however, about ethical and environmental issues regarding the use of GMOs. The major concerns centre on: (3)

Answer 9

• potential danger to the environment
• possible health risks to humans
• economics

Question 10

Disadvantages of Genetically modified crops: (7)

Answer 10

• costly to produce as they involve modern biotechnology which requires highly skilled people and sophisticated and expensive equipment.
• may include a pesticide-resistance gene that unintentionally harms wildlife and disrupts food webs, e.g. the Monarch butterfly being affected by GM crops.
• are a threat to the biodiversity of wild species. GM crops with new traits could be grown on such a large scale that they destroy the habitats of wild species.
• could be more vulnerable to climate change, pests and diseases if grown as a monoculture.
• can interbreed with wild plants and spread to future generations in an unpredictable uncontrollable way, e.g. a gene for resistance to adverse conditions might be transferred from a crop plant into a weed species.
• if ingested by animals (especially humans), may disrupt normal gene function, causing diseases such as cancer.
• may be harmful to some, e.g. new proteins causing allergies in humans.

Question 11

What are some of the economic objections to GMOs?

Answer 11

Economically, one of the objections to GMOs is that they put power, money and control of our food supply in the hands of a few big companies. The problem is that only these large companies have the resources to afford the expense, legal exposure and regulatory system involved in bringing GMOs to the market.

Question 12

Further studies are needed to assess the potential ____ of GM foods even though the technology promises many benefits. Until further studies can show that GM foods and crops do not pose serious threats to human health or the world’s ____, the debate over their release will continue.

Answer 12

risks

ecosystems

Question 13

How safe is food derived from GM crops?

Answer 13

Each application for a commercial release of a crop is assessed by the Genetic Resource Center of the Department of Agriculture. Foodstuffs that are currently made of genetically modified (mainly maize, soybean and rape) have been judged safe to eat, and the methods used to test them approved.

Question 14

However, the lack of evidence of negative effects does not mean that new genetically ____ food crops are without risk. The possibility of long-term effects from genetically modified plants cannot be excluded and must be examined on a case-by-case basis. New techniques are being developed to address concerns such as the possibility of the unintended transfer of _____-_____ genes.

Answer 14

modified

antibiotic-resistance

Question 15

How is the release of GMOs controlled?

Answer 15

In South Africa, there is a Genetically Modified Organisms Act administered by the Department of Agriculture. They have the responsibility of considering each application for a field trial or commercial release on a case-by-case basis. Contravention of the Act can result in a fine or imprisonment of up to four years

Question 16

In September 2003 the biosafety protocol, a subsidiary agreement to the UN Convention on Biological Diversity, came into force. What does it ential? (4)

Answer 16

• It is designed to regulate the international trade by monitoring the handling and use of any genetically engineered organism that may have adverse effects on the conservation and sustainable use of biological diversity, taking into account risks to human health.
• The protocol requires that countries are informed and agree in advance to imports of GE crops. This is called the Advance Informed Agreement (AIA). Before countries are allowed to export any genetically engineered organisms be introduced into the destined environment, they must first obtain the importing country’s consent, e.g. Zimbabwe recently refused GM wheat / maize.
• The biosafety protocol is achievement. For the first time under international law, there is a requirement that countries take precautionary measures to prevent GMOS from causing harm to biodiversity and human health.
• One hundred countries have signed the agreement. The US, Argentina and Canada governments have not ratified the protocol, despite the fact that these countries some 90% of GM crops in the world.

Question 17

What are environmental watchdogs?

Answer 17

Environmental watchdogs such as Biowatch and SafeAge (South African Freeze Alliance on Genetic Engineering) are NGOS, established in the late 1990s to publicize, monitor and research issues of genetic modification, and to promote biological diversity. Their role is very important in making the government and the public aware of potential problems related to GMOs.

Question 18

The creation of GMOs, however, creates extreme reactions and a ____ approach should be encouraged. Consumers should weigh up the pros and cons of GMOs and not be kept in the dark by those in power and by large corporations which may not have the general public’s interests as their primary goal.

Answer 18

balanced

Question 19

Genetic engineering may offer opportunities for increased production, productivity, product quality and adaptive fitness, but they will certainly create challenges for the ___ and ____ capacity of developing countries to avoid causing unintended harm to human health and the environment as a result of enthusiasm for this powerful technology.

Answer 19

research

regulatory