16.4 Tropisms in plants

Question 1

define tropism

Answer 1

growth response to a stimulus

Question 2

explain phototropism

Answer 2

• light

- ensures plant receives as much light as possible

Question 3

explain geotropism

Answer 3

• gravity
• shoots = negative = grow up
• roots = positive = grow down

Question 4

explain hydrotropism

Answer 4

• moisture

- root tips grow towards damper soil

Question 5

explain thigmotropism

Answer 5

• touch

- climbing plants detect a support and curl around it

Question 6

explain chemotropism

Answer 6

• chemicals

- pollen tubes grow down flowers stigma towards ovules due to chemicals

Question 7

what are nostic movements

Answer 7

• non-directional responses
• similar to thigmotropism
• leaflets fold in rapidly (caused by rapid uptake of water at the base of each leaflet and adjacent cells lose water+collapse)
• not a tropism
• caused by bioelectrical signals