1.4: Aims

• acquire an understanding of scientific ideas, how they develop, the factors which may affect their development and their power and limitations...
• interpret and evaluate scientific data from a variety of sources

B2.3: What are antibiotics, and why can they become less effective? How are new drugs developed and tested?

1. recall that we can kill bacteria and fungi, but not viruses, using chemicals called antibiotics;
2. recall that over a period of time bacteria and fungi may become resistant to antibiotics;
3. understand that random changes (mutations) in the genes of these microorganisms sometimes lead to varieties which are less affected by the antibiotic;
4. understand that to reduce antibiotic resistance we should only use antibiotics when necessary and always complete the course

TiS: We have no disagreement with this section.

B3: Life on Earth

• Theories for the origin of life on Earth often feature in the media and popular culture. Candidates consider different explanations for life on Earth, and its subsequent evolution. These contexts illustrate how explanations arise and become accepted, and the role of the scientific community in this process. Natural selection is introduced as the mechanism for evolution...
  

Evolution of multicellular organisms has led to complex body communication systems, both nervous and hormonal. Through the context of human evolution candidates consider implications of data for given theories.

Living organisms are dependent on their environment and each other for survival. Biodiversity is recognised as an important natural resource, which is increasingly threatened by human activity. Candidates consider causes of extinction, and whether extinctions should be a global concern.

Issues for citizens	Questions that science may help to answer
Where did life on Earth come from?	How did life on Earth begin and evolve?
Is evolution ‘just a theory’?	How have scientists developed explanations of evolution?
How do some species survive?	How did humans evolve? How are our nervous systems organized?
Why do some species become extinct, and does it matter?	What is the importance of biodiversity?

Science Explanations	Ideas about Science
SE4b,c   The interdependence of living things.	IaS 3   Developing explanations.
SE7e   Maintenance of life.	IaS 4.3 - 4.4   The scientific community.
SE9   The theory of evolution by natural selection.

ICT Opportunities

• This module offers opportunities for illustrating the use of ICT in science, for example:
• recording and displaying the results of DNA analysis;
• monitoring and recording human and animal behaviour.

Use of ICT in teaching and learning can include:

• video clips to illustrate varied ecosystems; 
• internet to research endangered plant or animal;
• presentation to show how understanding of evolution develops as new evidence is discovered.

(page 18)

B3.1 How did life on Earth begin and evolve?

1. recall that the many different species of living things on Earth (and many species that are now extinct) evolved from very simple living things;

2. recall that life on Earth began about 3500 million years ago;

3. understand that evidence for evolution is provided by fossils and from the analysis of similarities and differences in DNA of organisms;

4. recall that the first living things developed from molecules that could copy themselves;

5. understand that these molecules were produced by the conditions on Earth at that time, or may have come from elsewhere;

6. recall that evolution happens due to natural selection;

7. understand the process of natural selection in terms of variation, competition, increased chance of survival and reproduction, and increased number of individuals displaying certain characteristics in later generations;

8. understand that variation is caused by both environment and genes, but only genetic variation can be passed on;

9. explain the difference between natural selection and selective breeding;

10. interpret data on changes in a species in terms of natural selection;

11. recall that changes can occur in genes (mutations);

12. understand that mutated genes in sex cells can be passed on to offspring and may occasionally produce new characteristics;

13. understand that the combined effect of mutations, environmental changes and natural selection can produce new species;

14. understand that if the conditions on Earth had, at any stage, been different from what they actually were, evolution by natural selection could have produced different results.

(page 19)

B3.2 How have scientists developed explanations of evolution?

1. When provided with information about alternative views on the origination of life on Earth, or the evolutionary process:

• can identify statements which are data and statements which are (all or part of) an explanation;
• can recognise data or observations that are accounted for by, or conflict with, an explanation;
• can identify imagination and creativity in the development of an explanation;
• can justify accepting or rejecting a proposed explanation on the grounds that it:    a) accounts for observations; b) and/or provides an explanation that links things previously thought to be unrelated;
• can identify a scientific question for which there is not yet an agreed answer and suggest a reason why;
• can suggest plausible reasons why scientists involved in a scientific event or issue disagree(d);
• can suggest reasons for scientists’ reluctance to give up an accepted explanation when new data appear to conflict with it.

(page 20)

B3.3 How did humans evolve? How are our nervous systems organised?

1. recall that the evolution of multicellular organisms has led to nervous and hormonal communication systems…

...continued...

9. recall that the evolution of a larger brain gave some early humans a better chance of survival;

10. understand human evolution in terms of a common ancestor, divergence of hominid species, extinction of all but one of these species.

11. When provided with additional information about human evolution:

• can draw valid conclusions about the implications of given data for a given theory, for example:
  

- recognises that an observation that agrees with a prediction (derived from an explanation) increases confidence in the explanation but does not prove it is correct;

-recognises that an observation that disagrees with a prediction (derived from an explanation) indicates that either the observation or the prediction is wrong, and that this may decrease our confidence in the explanation.

(Page 21)

B7 – Further Biology

B7.3 Heterotrophic nutrition

...

5. ...understand that the evolution of a parasite is thought to be closely linked to that of its host;

6. recall the symptoms of sickle-cell anaemia, caused by a faulty recessive allele;

7. understand that carriers of the sickle-cell allele have some protection from malaria;

8. understand how natural selection has resulted in an increased frequency of the sickle-cell allele in certain populations.

(page 41)

Appendix G: Science Explanations...

SE 9 The theory of evolution by natural selection

a The first living things developed from molecules that could copy themselves. These molecules were produced in the conditions on Earth at that time. Most biologists believe that the many different species of living things that now exist, and the many more species which once existed but have died out (become extinct) all evolved from the same, very simple living things that first appeared on Earth about 3,500 million years ago.

b Evolution happened, and continues to happen, mainly because of a process called natural selection. Individuals of the same species are not identical; their characteristics vary. If the environment changes, or if vital resources become scarce, individuals with certain characteristics may have a better chance of surviving long enough to reproduce. This means that there will be more individuals with these characteristics in the next generation and, if the environment stays the same, even more in the generation after that. This process is called natural selection because it produces changes like the ones deliberately produced by farmers or pet-owners when they select the animals or plants with the characteristics that they prefer for breeding the next generation. Natural selection, however, does not involve people making deliberate selections.

c The genes that control the way an organism develops can be changed by certain chemicals, by ionising radiation and by copying errors when chromosomes are copied. This is called mutation. Mutations can cause body cells to reproduce in an uncontrolled way (cancer). Mutated genes in sex cells may be passed on to offspring and produce new characteristics. Mutations usually have such a harmful effect that the fertilised eggs do not develop. Some mutations, though, have no effect on an individual or may even improve the chance of surviving and reproducing. When this happens, the mutated gene is passed on and becomes more common.

d Over a very long period of time (and many generations) new species have evolved. The combined effects of mutations, environmental changes and natural selection can produce new species. The 3 500 million years since life on Earth first evolved are believed by most biologists to have been long enough for all the living things that exist (or that have existed) to have evolved in this way. A large change in the environment may cause a whole species to become extinct.

e Evolution has happened in the way that it has because of random mutation, random breeding and natural selection. If the conditions on Earth had, at any stage, been different from what they actually were, evolution by natural selection would have produced different results.

(Page 93)