Unit B3 - Using Biology

Overview

Content and How Science Works overview

In Unit B3 students study three topics that give them the opportunity to explore some areas of biology in more depth. The aim is to engender an interest in biology that makes them want to pursue the subject further or simply enjoy finding out more about themselves, other organisms and the applications of biology in the world in which they live.

Practical work throughout the unit will give students opportunities to plan and carry out investigations, to devise their own models and evaluate them, to assess and manage risks, to trial their plans and consider how the quality of their data might be improved. It also enables them to analyse data, to draw conclusions providing evidence to support their conclusions, and evaluate to what degree the conclusion supports the hypothesis.

Throughout the unit, students will have the opportunity to improve and demonstrate mathematical skills, including understanding and using direct proportion and simple ratios, calculating arithmetic means, plotting and drawing graphs (line graphs, bar charts, pie charts, scatter graphs, histograms) selecting appropriate scales for the axes, translating information between graphical and numeric form, extracting and interpreting information from charts, graphs and tables and understanding the idea of probability.

There are several opportunities to investigate the way scientists collect data, such as in the screening of plants for medical properties, and to see how this data is used to produce advances in science, such as in medical treatment. Further research on these advances highlights drawbacks and risks as well as advantages, and these aspects will be studied in relation to the use of dialysis, contraception and fertility treatments. With many treatments decisions need to be made about the social, economic and environmental effects, and some of these will be explored in the context of immunisation programmes.

Students are always fascinated by the complex functions of the human body. Topic 1 enables them to study systems and processes with which they are largely unfamiliar, for example the structure and function of the kidney, and hormonal control of the menstrual cycle. A study of sex-linked disorders and the principles of immunisation add to the variety of this topic.

The way scientific ideas change over time, and the role of the scientific community in validating those changes, will be considered when studying the role of Jenner in the development of immunisation. In Topic 2 students will study different types of behaviour, such as courtship and conditioning. Methods of communication within the animal kingdom are also areas of great interest and the work of ethologists such as Tinbergen and Fossey is covered. Different types of evidence for human evolution are looked at in some depth in the final part of Topic 2.

Unit B3: Using biology

The study of animal and plant behaviour will provide opportunities to see how scientists gather data and use it to construct theories that can be scientifically tested, and then to see how these theories are applied to explain further observations. The continuing development of scientific knowledge, and the fact that science cannot answer all questions, will be explored in the studies of animal behaviour and human migration.

The focus of Topic 3 is on biotechnology and its applications, covering up-to-date issues such as the use of enzyme technology in the manufacture of vegetarian cheese, sweets and biological washing powders. Ethical issues are considered with respect to the genetic modification of crop plants, for example to confer herbicide resistance and insect resistance.

Assessment overview

This unit is externally assessed, through a one hour, 60 mark, tiered written examination, containing six questions.

The examination will contain a mixture of question styles, including objective questions, short answer questions and extended writing questions.

Practical investigations in this unit

Within this unit, students will develop an understanding of the process of scientific investigations, including that investigations:

• use hypotheses which are tested

• require assessment and management of risks

• require the collection, presentation, analysis and interpretation of primary and secondary evidence including the use of appropriate technology

• should include a review of methodology to assess fitness for purpose

• should include a review of hypotheses in the light of outcomes.

The following specification points are practical investigations which that exemplify the scientific process and may appear in the written examination for this unit:

1.28 Investigate the conditions affecting growth of micro-organisms (using resazurin dye)

2.8 Investigate animal behaviour using choice chambers

3.4 Investigate the effect of factors on the growth of yeast, including pH

3.9 Investigate the effect of different factors on yogurt making

3.11 Investigate the use of immobilised lactase to produce lactosefree milk

Unit B3: Using biology

3.12 Investigate the use of enzymes in food production

The following are further suggestions for practical work within this unit:

• Investigate the importance of photoperiodicity in plants

• Investigate the behaviour of animals rearing their young, using video technology

• Investigate different behaviours exhibited by animals

• Investigate how animals use a variety of types of signals to communicate

• Investigate the use of chymosin in the manufacture of vegetarian cheese

• Investigate the use of invertase (sucrase) produced by Saccharomyces cerevisiae (yeast) in the manufacture of sweets

• Investigate the use of enzymes in washing powders

The controlled assessment task (CAT) for the GCSE in Biology will be taken from any of these practical investigations (specification points and further suggested practical work). This task will change every year, so future CATs will be chosen from this list.

Unit B3: Using biology

Detailed unit content

In this specification bold text refers to higher tier only content. Italic text refers to practical investigations, which students are required to demonstrate an understanding of.

Topic 1

Control systems

1.1 Demonstrate an understanding that cell metabolism leads to the build-up of waste products in the blood, including carbon dioxide and urea

1.2 Recall that urea is produced from the breakdown of excess amino acids in the liver and is removed by the kidneys

1.3 Describe the structure of the urinary system, including:

- renal artery and vein

- kidneys

- ureters

- bladder

- urethra

1.4 Describe possible treatments for kidney failure, including kidney dialysis and organ donation

1.5 Describe the structure of a nephron, including:

- glomerulus and Bowman’s capsule

- convoluted tubules

- loop of Henlé

- collecting duct

1.6 Explain how the structure of the nephron is related to its function in filtering the blood and forming urine (osmoregulation), including:

- filtration in the glomerulus and Bowman’s capsule

- selective reabsorption of glucose

- reabsorption of water (osmoregulation)

- removal of excess water in urine

1.7 Demonstrate an understanding of the role of ADH (produced by the pituitary gland) in regulating the water content of the blood

1.8 Demonstrate an understanding of how ADH production is controlled by a negative feedback mechanism

1.9 Recall that the menstrual cycle is controlled by the hormones oestrogen and progesterone

1.10 Describe the stages of the menstrual cycle including menstruation, uterus lining thickening and ovulation

1.11 Explain why the uterus lining is maintained if fertilisation occurs

Unit B3: Using biology

1.12 Demonstrate an understanding of how oestrogen, progesterone, FSH and LH control the menstrual cycle, including:

- FSH stimulates maturation of follicles, which stimulates oestrogen production

- oestrogen is responsible for repair of the uterus wall

- high levels of oestrogen stimulate a surge in LH, which triggers ovulation

- corpus luteum secretes progesterone, which maintains the lining of the uterus

- progesterone inhibits FSH and LH production

- during pregnancy, progesterone levels remain high

- menstruation is triggered by a drop in oestrogen and progesterone levels

- low progesterone levels allow an increase in FSH levels

1.13 Demonstrate an understanding of how the menstrual cycle is controlled by a negative feedback mechanism

1.14 Explain how the structure of an egg is adapted to its function:

- cytoplasm to provide nutrients

- haploid nucleus containing one set of the genetic material

- immediately after fertilisation the cell membrane around the egg changes to block entry of other sperm

1.15 Explain how the structure of a sperm cell is adapted to its function, including:

- acrosome containing enzymes

- haploid nucleus containing one set of the genetic material

- middle section containing mitochondria

- tail for motility

1.16 Demonstrate an understanding of the advantages and disadvantages of infertility treatments, including:

- donation of eggs

- in vitro fertilisation (IVF)

- use of surrogate mothers

- use of hormones

1.17 Recall that the sex of a person is controlled by one pair of chromosomes, XX in a female and XY in a male

1.18 Explain how the sex of offspring is determined at fertilisation, using a genetic diagram

Unit B3: Using biology

1.19 Explain (using probabilities, ratios and percentages) how sexlinked genetic disorders are inherited, including:

- haemophilia

- colour blindness

1.20 Describe Edward Jenner’s contribution to the development of vaccines

1.21 Explain the process of immunisation, including:

- harmless pathogen or antigenic material introduced

- the antigens trigger an immune response which causes the production of antibodies

- the antigens also trigger production of memory lymphocytes

1.22 Demonstrate an understanding of the advantages and risks associated with immunisation

1.23 Describe the role of memory lymphocytes in secondary responses to antigen; interpret data showing variation in blood antibody levels in response to first and subsequent infections

1.24 Describe the production of monoclonal antibodies, including:

- use of B lymphocytes which produce desired antibodies but do not divide

- production of hybridoma cells

- hybridoma cells produce antibodies and they divide

1.25 Demonstrate an understanding of the use of monoclonal antibodies, including:

- in pregnancy testing

- in diagnosis including locating the position of blood clots and cancer cells and in treatment of diseases including cancer

- the advantages of using monoclonal antibodies to target specific cells compared to drug and radiotherapy treatments

1.26 Describe how the exponential growth of a population of bacteria can lead to rapid development of an infection

1.27 Demonstrate an understanding of Louis Pasteur’s contribution to the development of aseptic techniques

1.28 Investigate the conditions affecting growth of micro-organisms (using resazurin dye)

1.29 Demonstrate an understanding that plants defend themselves against attack from pests and pathogens by producing chemicals, some of which can be used to treat human diseases, disorders or relieve symptoms

1.30 Demonstrate an understanding of the impact that attack by pests and pathogens on plants has on human food supply

Unit B3: Using biology

1.31 Explain the importance of photoperiodicity in plants, including

- plant germination

- growth

- reproduction

1.32 Demonstrate an understanding of circadian rhythms in living organisms

Topic 2

Behaviour

2.1 Describe that sexual reproduction requires the finding and selection of a suitable mate, and can involve courtship behaviours that advertise an individual’s quality

2.2 Describe how animals have different mating strategies, including:

- a mate for life

- several mates over a lifetime

- a mate for a breeding season

- several mates over one breeding season

2.3 Describe that some animals, in particular birds and mammals, have developed special behaviours for rearing their young

2.4 Demonstrate an understanding of why parental care can be a successful evolutionary strategy, including:

- increased chance of survival of offspring

- increased chance of parental genes being passed on by the offspring

2.5 Explain how, within the animal kingdom, parental care may involve risks to the parents

2.6 Describe the different behaviours exhibited by animals, including:

- innate behaviour

- imprinting

- habituation

- classical conditioning

- operant conditioning

2.7 Explain how humans can make use of conditioning when training captive animals for specific purposes, including:

- sniffer dogs

- police horses

- dolphins

2.8 Investigate animal behaviour using choice chambers

2.9 Describe how some animal behaviour requires communication

Unit B3: Using biology

2.10 Explain how animals use a variety of types of signals to communicate, including:

- sound signals

- chemical signals (pheromones)

- visual signals (gestures, body language, facial expression)

2.11 Describe how plants can communicate using chemicals, including:

- with animals (particularly insects)

- with other plants

2.12 Demonstrate an understanding of the work of ethologists, including:

- Tinbergen, innate behaviour in gulls

- Lorenz, imprinting in geese

- Fossey, social behaviour in gorillas

- Goodall, social behaviour in chimpanzees

2.13 Demonstrate an understanding of how plants and animals have co-evolved, including:

- flower structure and insect behaviour in pollination

- plant defence and animal metabolism

2.14 Describe the evidence for human evolution, based on fossils, including:

- Ardi from 4.4 million years ago

- Lucy from 3.2 million years ago

- Leakey’s discovery of fossils from 1.6 million years ago

2.15 Describe the evidence for human evolution based on stone tools, including:

- the development of stone tools over time

- how these can be dated from their environment

2.16 Describe why mitochondrial DNA provides evidence for the African Eve theory for non-Africans, including:

- its inheritance down the female line

- its high mutation rate

2.17 Demonstrate an understanding of why mitochondrial DNA is more useful than nuclear DNA for tracking human migration and evolution, including:

- mitochondrial DNA is less likely to have degraded over time

- mitochondrial DNA is more abundant

2.18 Demonstrate an understanding of the impact of climate change on human behaviour, including:

- the effect of the Ice Age

- human migration

Unit B3: Using biology

Topic 3

Biotechnology

3.1 Describe biotechnology as the alteration of natural biomolecules using science and engineering to provide goods and services

3.2 Describe a fermenter as a vessel used to cultivate microorganisms for the production of biomolecules on a large scale

3.3 Explain the need to supply suitable conditions in fermenters, and the effect they have on growth rates, including:

- aseptic precautions

- nutrients

- optimum temperature

- pH

- oxygenation

- agitation

3.5 Explain the advantages of using micro-organisms for food production, including:

- rapid population growth

- ease of manipulation

- production independent of climate

- use of waste products from other industrial processes

3.6 Describe how mycoprotein is manufactured, including the role of the fungus Fusarium sp.

3.7 Explain the advantages of using mycoprotein as a food source

3.8 Describe how bacteria are used in the production of yogurt from milk by the conversion of lactose to lactic acid

3.9 Investigate the effect of different factors on yogurt making

3.10 Describe the use of enzyme technology including:

- chymosin, produced by genetically modified micro-organisms, used in the manufacture of vegetarian cheese

- invertase (sucrase) produced by Saccharomyces cerevisiae (yeast), used in the manufacture of sweets

- enzymes used in washing powders

3.11 Investigate the use of immobilised lactase to produce lactosefree milk

3.12 Investigate the use of enzymes in food production

Unit B3: Using biology

3.13 Explain recombinant DNA technology using insulin as an example, including:

- restriction enzymes

- ligase

- sticky ends

3.14 Demonstrate an understanding of the impact of human population growth on global food security

3.15 Explain how Agrobacterium tumefaciens is used as a vector in creating transgenic plants

3.16 Demonstrate an understanding of the advantages and disadvantages of introducing genes for insect resistance from Bacillus thuringiensis into crop plants

3.17 Demonstrate an understanding of the costs and benefits of genetic modification of crop plants in the context of developed and developing countries, including the introduction of flavonoids in the purple tomato

3.18 Explain how increased food production for humans includes:

- conventional plant breeding programmes

- pest management strategies

- genetic modification

3.19 Demonstrate an understanding of the advantages and disadvantages of replacing fossil fuels with biofuels, including the facts that biofuels are renewable and that their production uses carbon dioxide but that growing the crops to make them requires land and may affect the availability of land for growing food