Very important questions on biology for your next examination

33. (a) What is meant by ‘tropisms’ (or tropic movements)? Explain with an example.

(b) What are the different types of tropisms? Define each type of tropism. Write the name of stimulus in each case.

(c) How do tropisms differ from nasties (or nastic movements)?

34. (a) Define phototropism. Give one example of phototropism.

(b)How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.

(c)What is meant by positive phototropism and negative phototropism? Give one example of each type,

35. (a) Define geotropism. Give one example of geotropism.

(b)What is meant by ‘positive geotropism’ and ‘negative geotropism? Give one example of each type. Draw a labelled diagram to illustrate your answer indicating the plant part which shows positive geotropic and the plant part which shows negative geotropism.

(c) Name one plant part which exhibits positive thigmotropism.

36. (a) How does control and coordination take place in plants ? How does it differ from that in animals?

(b)Name five stimuli which act on plants. Name the type of tropism produced by each one of these stimuli.

(c) Define hydrotropism. Give one example of hydrotropism. State whether this example is of positive hydrotropism or negative hydrotropism. Illustrate your answer with the help of labelled diagram.

37. (a) What is meant by positive tropism and negative tropism? Explain with examples.

(b)Define thigmotropism. Give one example of thigmotropism.

(c) What is the difference between thigmotropism and thigmonasty? Name one plant which exhibits thigmotropism and one plant which exhibits thigmonasty. What behaviour (or responses) of these plants make you think that they exhibit thigmotropism and thigmonasty respectively?