iGCSE Biology Section 1 lesson 1

1. iGCSE Biology Section 1 lesson 1

2. Content Section 1 The nature and variety of living organisms • Characteristics of living organisms • Variety of living organisms

3. Content Lesson 1 a) Character-istics of living organisms • Characteristics of living • organisms 1.1 Understand that living organisms share the following characteristics: – they require nutrition – they respire – they excrete their waste – they respond to their surroundings – they move – they control their internal conditions – they reproduce – they grow and develop. BONUS: Classification of living organisms

4. How many species?

6. About 1.4 million species have been described.

7. It has been estimated that there may be as many as 8.7 million species!

8. The vast majority have therefore not been identified.

10. Suppose you landed on another planet in our galaxy.

11. What signs of life would you look for?

12. What are the characteristics of living organisms?

13. MRS GREN

14. Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition

15. Movement Most single-celled creatures, and larger animals, move about as a whole. Fungi and plants make movements with parts of their bodies. Movement does not necessarily involve locomotion (movement of an organism from place to place)

16. Respiration Glucose + oxygen  Carbon dioxide + water C6H12O6 + 6O2 6CO2 + 6H2O All living organisms break down food to obtain energy. Most organisms need oxygen for this (aerobic respiration) whereas others are able to respire without oxygen (anaerobic respiration). Taking in oxygen and removing carbon dioxide is the process of breathing.

17. Sensitivity All living organisms respond to their environment. Sensitivity is the ability of living organisms to respond to stimuli. A stimulus is a change in the external or internal environment of an organism. Plants, for example, respond to gravity. This is known as geotropism.

18. Sensitivity Living organisms are also aware of their internal environment and are able to respond to changes and restore the body to its normal state. This regulation of the internal environment is known as homeostasis.

19. Growth Bacteria and single-celled creatures increase in size. Many-celled organisms increase the number of cells in their bodies, become more complicated and change their shape as well as increasing in size.

20. Reproduction Off spring are produced by the process of reproduction. Single-celled organisms and bacteria may simply keep dividing into two (eg. binary fission). Many-celled plants and animals may reproduce sexually or asexually.

21. Excretion Excretion involves the removal of waste products from the body, such as carbon dioxide ( a product of respiration). Living organisms expel these substances from their bodies in various ways.

22. Nutrition Nutrition is the process of obtaining food. There are two main methods of obtaining food – aututrophic nutrition (green plants) and heterotrophic nutrition (organisms use ready-made organic compounds as their food source).

23. MRS GREN

24. Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition

25. CLASSIFICATION – a method of scientific taxonomy used to group and categorize organisms into groups such as a genus or species.

26. CLASSIFICATION – a method of scientific taxonomy used to group and categorize organisms into groups such as a genus or species. These groups are known as taxa.

27. The modern system of putting different organisms into certain groups was developed by the Swedish botanist and zoologist Carl Linnaeus in the eighteenth century. He gave each species a Latin name, consisting of the genus and the species. This is known as binomial nomenclature.

28. For example, the scientific name for the rabbit is Oryctolagus cuniculus. It is known by this name all over the world by the scientific community. Similarly, the binomial name for human beings is Homo sapiens. Homo is the genus, and sapiens is the species.

29. Classification Kingdom The largest group of organisms recognised by biologists. But how many?

30. Classification Kingdom The largest group of organisms recognised by biologists. But how many? For many years most biologists favoured the use of two kingdoms, Plants and Animals.

31. Classification Kingdom The largest group of organisms recognised by biologists. But how many? For many years most biologists favoured the use of two kingdoms, Plants and Animals. Modern classification tends to favour the adoption of 5 kingdoms – Prokaryotes (Monera), Protoctista, Fungi, Plants and Animals

32. Classification Kingdom

33. Classification Kingdom Viruses are not considered to be living, so are not included in this classification scheme.

34. Classification Eg. Lion

35. Classification Kingdom Animalia

36. Classification Kingdom Animalia Phylum Vertebrates

37. Classification Kingdom Animalia Phylum Vertebrates Class Mammals

38. Classification Kingdom Animalia Phylum Vertebrates Class Mammals Order Carnivores

39. Classification Kingdom Animalia Phylum Vertebrates Class Mammals Order Carnivores Family Felidae (cats)

40. Classification Kingdom Animalia Phylum Vertebrates Class Mammals Order Carnivores Family Felidae (cats) Genus Panthera

41. Classification Kingdom Animalia Phylum Vertebrates Class Mammals Order Carnivores Family Felidae (cats) Genus Panthera Species leo

42. Classification Panthera leo

43. End of Section 1 Lesson 1 • In this lesson we have covered: • Species diversity • Characteristics of living organisms • Classification