commercial use of plant hormones (f)

Question 1

What are climacteric fruits?

Answer 1

Fruits that continue to ripen after they’ve been harvested. E.g. bananas, mangoes, tomatoes, avocados etc.

Question 2

How can the effect of ethene on climacteric fruit be seen?

Answer 2

• ethene triggers a series of chemical reactions including a greatly increased respiration rate
• putting a bunch of green bananas in a bag with a single ripe banana will show that they ripen faster due to the ethene from the ripe one stimulating the rapid ripening of the green ones.

Question 3

How is ethene used commercially?

Answer 3

• used in the production of perfectly ripe climacteric fruit
• fruits are harvested when they are fully formed but long before they are ripe, then cooled, stored and transported
• unripe fruit is hard and less easily damaged during transport
• when fruit needed for sale they’re exposed to ethene gas under controlled conditions
• ensures batches ripen at the same rate to be put on shelves together - prevents much wastage of fruit + increases time available for them to be sold

Question 4

How are auxins used to as rooting powders?

Answer 4

• auxin applied to cut shoots stimulates the production of roots = easier to propagate new plants from plant cuttings
• if cutting is placed in soil/compost/water, with the stem dipped into hormone rooting powder, the chances of roots forming and successful propagation increase greatly.

Question 5

How is rooting powder used commercially?

Answer 5

• in horticulture and agriculture, plants are propagated on a large scale by micropropagation - thousands of new plants are grown from a few cells of the original plant
• plant hormones are essential to control the production of the mass of new cells and then the differentiation of the clones into tiny new plants

Question 6

Why are weed killers helpful?

Answer 6

• they interrupt the metabolism of the whole plant and lead it to death
• they kill unwanted weeds that interfere with crop plants, competing for light, space, water, and minerals

Question 7

How are hormones used in weed killers?

Answer 7

• synthetic auxins are very effective weed-killers
• they are absorbed by the bread-leaved plants, affecting their metabolism and makes growth rate unsustainable so they die
• narrow-leaved crop plants are not affected so continue to grow normally, free from competition
• they’re simple and cheap to produce, have a very low toxicity to mammals and are selective