DP Chemistry: B.6 Biochemistry & the environment

B.6 Biochemistry & the environment

Written specifically for students to provide help and support for the IB Diploma chemistry programme this page provides full coverage of the syllabus content of Option B - sub topic B.6. It encourages you to think critically and provides many questions with full worked answers so that you can monitor and improve your knowledge and understanding.

Learning outcomes

After studying this topic you should be able to:

Understand:

  • Chemicals found in an organism that are not normally present there are known as xenobiotics.
  • Bacteria or other living organisms can consume or break down biodegradable or compostable plastics.
  • Host–guest chemistry involves the creation of synthetic host molecules that selectively bind to specific guest species, such as toxic materials in the environment, and so mimic some of the actions performed by enzymes in cells.
  • Enzymes have been developed to help in the breakdown of oil spills and other industrial wastes.
  • Enzymes found in biological detergents can improve the energy efficiency by enabling effective cleaning at lower temperatures.
  • The increase in concentration of a substance in a food chain is known as biomagnification.
  • Green chemistry, also called sustainable chemistry, is an approach to chemical research and engineering that seeks to minimize the production and release to the environment of hazardous substances.

Apply your knowledge to:

  • Discuss the increasing problem of xenobiotics such as antibiotics in sewage treatment plants.
  • Describe the role of starch in biodegradable plastics.
  • Apply host–guest chemistry to the removal of a specific pollutant in the environment.
  • Describe an example of biomagnification, including the chemical source of the substance. Examples could include heavy metals or pesticides.
  • Discuss the challenges and criteria in assessing the “greenness” of a substance used in biochemical research, including the atom economy.

Relationships & vocabulary

Nature of science

Scientists have the responsibility to consider ways in which the products of their research and findings have a negative impact on the environment, and to find ways to counter this. For example, the use of enzymes in biological detergents and to break up oil spills, and green chemistry in general.

International-mindedness

The term 'green chemistry', which was first coined in 1991, and the acceptance of its philosophy has led to developments in education and legislation in many different countries.

Most countries have banned the use of the pesticide DDT due to its toxic effects and biomagnification. It does, however, continue to be used in countries where malaria remains a major public health challenge.

Vocabulary

xenobioticbiodegradablebiomagnificationdioxin
PCB (polychlorinated biphenyl)PCDD (polychlorinated dibenzodioxin)DDT (dichlorophenyltrichlorethane)

Learning slides

You can use this slide gallery for learning or for reviewing concepts and information. It covers all the key points in the syllabus for this sub-topic.

  

Something to think about

Photograph taken in the Vietnam War museum in Ho Chi Minh City

It is generally well known that dioxins, which were made infamous by the spraying of Agent Orange during the Vietnam War, are highly toxic. They can be formed when persistent organic pollutants (POPs) are combusted at insufficiently high temperatures and the rules surrounding industrial waste incinerators are now very stringent.

Perhaps less well-known, but equally toxic, are the rather similar PCBs. There are 209 possible configurations for polychlorinated biphenyls with the general formula C12H(10-x)Clx, of which about 130 have been used commercially. Although they are now banned they were used extensively as a coolant fluid in transformers and capacitors. This is because they reduced the chances of electrical fires occurring due to their high thermal stability and their high electrical resistance. However, although they are no longer used, they persist in the environment and are fat-soluble so also undergo biomagnification. This is a particular problem with fish farming. Farmed salmon contain up to five times as much PCBs as wild salmon. This is thought to be due to the fact that they are fed on ground-up fish, which are already high in PCBs. Because of these high levels of PCBs the Environmental Protection Agency in the USA recommends that people should not eat more than one helping of farmed salmon per month.

Test your understanding of this topic

(Note that your teacher may have restricted your access to some or all of these questions and worked answers if they are going to use them as a class test or set them as an assignment.)

For ten 'quiz' questions (for quick testing of knowledge and understanding with the answers explained) see MC test: Biochemistry & the environment.

For short-answer questions see Biochemistry & the environment questions together with the worked answers on a separate page Biochemistry & the environment answers.

More resources

1. Rachel Carson first brought biomagnification into the spotlight in her book 'Silent Spring', first published in 1960 - particularly the problems with using the pesticide, DDT. This is an interesting historic account of her work.

  Pesticides, DDT and Silent Spring

2. A rather fast-talking video on how oil spills can be cleaned up.

  Cleaning up oils spills

3. How biodegradable is biodegradable plastic?

  Biodegradable plastic

All materials on this website are for the exclusive use of teachers and students at subscribing schools for the period of their subscription. Any unauthorised copying or posting of materials on other websites is an infringement of our copyright and could result in your account being blocked and legal action being taken against you.