Animal Behaviour and Plant Responses.

1. Animal Behaviour and Plant Responses. Year 13 Biology

2. Overview • Orientation • Tropisms • Nastic responses • Plant hormones • Taxes and Kineses • Migration and Dispersal • Homing

3. Overview • Timing • Environmental Cycles • Biological clocks • Biological rhythms

4. Revision • The environment • The environment includes all the factors, both living (biotic) and non-living (abiotic), that affect the lives of organisms. • Abiotic – The physical factors in an environment (non-living) • Biotic – The living factors in an environment.

5. Revision • Main Abiotic factors • Light (photo-) • Gravity (geo- or gravi-) • Temperature (thermo-) • Water (hydro-) • Chemicals (chemo-) • Touch (thigmo-) • Current (rheo-)

6. Revision • Abiotic Factors • are the physical parts of the environment to which organisms respond. For most organisms, the physical factors must be kept within quite a narrow optimum range that fits the tolerance for that species. • If the factor is extreme in either direction the organism suffers from physiological stress, and if the factor becomes too extreme it leads to death. (recall the zones of tolerance)

7. Niche • Niche - You could say that the habitat is an organism’s address, and that the ecological niche is its profession. The ecological niche is a description of; • the opportunities provided by the habitat; and • The adaptations of the organism that enable it to take advantage of those opportunities.

8. Adaptations • Most organisms are a combination of many adaptations that allow them to fit into their environment easily. Adaptations are grouped into three types; • Structural • Behavioural • Physiological

9. Detecting a stimulus • A stimulus is a change in the environment (external or internal) that causes a response in an organism. • A receptor is any cell or group of cells that can detect this change • A effector is a cell or group of cells that can respond to the change.

10. Detecting a stimulus Environmental stimulus Receptor detects Coordinating system Communicating system Effector responds Other information

11. Orientation responses of plants • Plants respond to light, gravity, water, chemicals and touch. They do this by a growth curve towards or away from a stimulus. • If the growth is towards the stimulus we say it is positive; if it is away from the stimulus we say it is negative. • The prefixes you learnt before tell us the type of stimulus e.g. photo = light.

12. Tropisms • A tropism is a GROWTH response towards or away from an environmental stimulus coming from one direction. • For example • If the shoot of a plant grows towards the light, we say it is positively phototropic • If the root of a seedling grows down, then we say it is positively geotropic

13. Nastic Responses • The response of plants to diffuse stimuli that do not come from any particular direction, such as the temperature, humidity and light that surround a plant, are called nastic responses. • For example • the opening and closing of flowers in response to different light intensities.

14. Nastic Responses • Nastic movements are classified according to the nature of the stimulus • For example • Photonasty is the response to alterations in the light intensity • Thermonasty is the response to changes in the temperature

15. Plant structure

16. Plant structure

17. Plant structure

18. Plant Hormones • Plants use hormones to regulate their growth and development. • Plant hormones (or phytohormones) are organic compounds produced in one part of the plant and transported to another part, where they produce a growth response.

19. Plant Hormones • There are 5 groups of plant hormones; • Auxins (indolacetic acid or IAA) • Cytokinins • Gibberellins • Ethene • Abscisic acid (ABA) • Together they control growth and development on the plant at various stages.

20. Auxin – indolacetic acid IAA • The effect of auxin on roots and shoots • The effect of auxin is different on the shoot, lateral buds (side buds found in the axis of the leaves where the leaf joins the stem), and the root. • It all depends on the concentration of the auxin

21. The effect of auxin on plant growth

22. Auxin Concentrations • Low auxin concentrations stimulate root growth, and high concentrations inhibit root growth. • Low auxin concentrations stimulate growth of lateral buds; high concentrations inhibit this. • Low auxin concentrations do not stimulate the growth of shoots, but high concentrations do.

23. Apical dominance • Apical dominance • If you take a bean shoot and leave it to grow, the intact tip keeps the lateral buds from growing. • If, however you remove the apical bud (the bud at the tip of the main growing shoot) the two lateral buds start to grow within hours. • If you were to place a plug onto the apical bud that contained auxin you would find that the growth of the lateral buds is inhibited.

24. Apical dominance

25. Other effects of auxin • Cell elongation • Encourages root development • Involved in the abscission (dropping of leaves and fruit). It appears to delay this. • Stimulates growth of the cambium when a tree stem is under stress • Suppression of root elongation • Initiations of flowering in some plants

26. Cytokinins • Produced mainly in the roots • Functions • Promote cell division • Slow down the process of aging (senescence) in plants. • If applied to leaves it can prevent the yellowing of mature leaves in autumn and their dropping (abscission)

27. Gibberellins • Originates from a fungus Gibberellafugikuroi . This caused a disease that made plants grow so tall they toppled over and rotted. Gibberellins have now been isolated from this fungus.

28. Gibberellins • Functions • Increases the internode length • Promotes the germination of a wide variety of seeds that would otherwise be hard to germinate • Causes flowering on biennials that normally need a period of chilling (vernalisation)

29. Gibberellins • Which plant received gibberellin treatment?

30. Ethene • The saying that ‘one rotten apple will spoil the barrel’ is actually true – a ripening apple gives off a gas called ethylene that ripens adjacent fruit, even a fruit of a different type! • Functions • Accumulates in mature fruit to induce ripening • Promotes leaf fall

31. Abscisic Acid (ABA) • Generally abscisic acid functions as an inhibiting hormone acting against auxin, gibberellins and cytokinins all of which tend to promote growth • Functions • growth inhibitor made in the leaf chloroplasts in response to water stress. Acts on guard cells causing stomatal closure • Induces leaf fall (only in a few selected species) • Promotes seed dormancy

32. Biological orientation responses in animals • In this case the term orientations means a behaviour by which the animals positions itself in a certain way in relation to its surroundings. • These include taxes and kinesis, homing and migration.

33. Taxis • This is the movement of the whole animal, towards or away from a stimulus which is coming from one side only. • As with tropisms, movement towards a stimulus is positive and away from a stimulus is negative. • The stimulus is also denoted by the same prefixes.

34. Taxis • Examples • Flatworms moving towards a pieces of raw meat are showing positivechemotaxis • Moths flying to a light are positivelyphototactic • Trout will line themselves up in an upstream direction, so they are positivelyrheotactic

35. Taxis • Taxes often involve moving the head (which carries the sensory receptors) from side to side. • If there are two sensory organs then the animal can move directly towards or away from the stimulus as it can constantly check the position of the stimulus. • If there is only one sensory organ, the animal must move around to get information about the stimulus. E.g. a maggot must move its head from side to side to keep in position. It performs a zigzag ‘direct’ line.

36. Taxis • Task • Identify the environmentalcue involved and the adaptivevalue of the behaviour • Chemotaxis • Thermotaxis • Phototaxis • Thigmotaxis • Gravitaxis • Hydrotaxis

37. Kinesis • This is a non-directional response to a stimulus. • It is the change in activity rate in response to a change in the intensity of the stimulus. • Example • If woodlice are placed in a wet/dry choice chamber, the animals in the dry side increases their random movements and rate of turning compared with those on the wet side.

38. Kinesis • Orthokinesis – the speed of the movement is related to the intensity of the stimulation • Klinokinesis – the amount of randomturning is related to the intensity of the stimulation. • See diagrams for summary.

39. Pheromones • A pheromone is a chemical produced by an animal and released into the external environment where it has an effect on the physiology or behaviour of members of the same species. • Task • Outline the many ways animals use pheromones.

40. Migration • Refers to regular, annual or seasonal mass movements made by animals from their breeding area to another area.

41. Advantages of Migration • Animals remain in a favourable temperature • They grow larger • They leave more offspring • They have a constant supply of food • It may lead to the colonisation of a new area • Reduces predation/parasitism disease • Greater genetic mixing • Better breeding conditions

42. Disadvantages of Migration • They may get lost or caught in a storm • They may get eaten by a predator • The may use up too much energy in the migration, leading to exhaustion • They may starve • It is a huge investment in energy

43. Trigger to migration • The behavioural trigger that sets off migratory behaviour varies. • Some trigger include • Maturation – some animals migrate as the sex organs mature and there is a need or desire to reproduce • Environmentalcues – such as drop in temperature, shortening of the length of the day e.g. migratory birds (migratory restlessness) • Genetic Drive – The trigger may be inbuilt (innate) e.g star patterns for navigation are learned, but how to learn then is innate • Endogenous circadian rhythm – internal biological clock.

44. Methods of Migration • Piloting – An animal moves from one landmark that it is familiar with to another landmark, until it reaches its destination • Generally used over short distances and uses visual cues.

45. Methods of Migration • Compass Orientation – an animal can detect a compass direction, and travels in a straight-line path until it reaches its destination. This can be accomplished using the magnetic field lines of the earth, chemical cues and sound.

46. Methods of Migration • Navigation – is the process by which an animal uses various cues to determine its position in reference to a particular goal.

47. Methods of Navigation • Visual • Solar • Magnetic fields • Stellar (stars) • Chemical • Sonar (sound)

48. Homing • This is the ability of an individual to return to the home site after it has been away to look for food, sometimes over considerable distances.

49. Timing Responses • Timing • Environmental Cycles • Biological clocks • Biological rhythms

50. Environmental Cycles • The astronomical cycles • The motions of the Earth, moon and sun result in complex and interdependent cycles. • These create environmental changes that range from short term to long term.