Self - pollination and Cross - pollination

Question 1

where does self pollination occur

Answer 1

whenpollen is transferredbetween flowers of the same plant or the anther and the stigma of thesame flower.

Question 2

what are two ways to prevent sef-pollination

Answer 2

protandryandprotogyny

Question 3

what is protandry

Answer 3

If pollen ripens before the stigma and the pollen is dispersed before the stigma is mature, the flower’s reproductive condition is known asprotandry.

Question 4

what is protogyny

Answer 4

If the stigma matures before the anthers, the flower’s reproductive condition is then known asprotogyny.

Question 5

whenpollen is transferredfrom theflower of one plantto theflower of another plantof thesame species.

Answer 5

where does cross pollination occur

Question 6

why is cross-pollination crucial

Answer 6

itcreatesgenetic diversity

This means that the offspring aregenetically different to the parent.

Question 7

why is genetic diversity important

Answer 7

Genetic diversity ensures that a species has a better chance of surviving unfavourable conditions.

Question 8

what is a pollinating agent

Answer 8

insects like bees, butterflies and wasps flying from flower to flower in order to collect a meal consisting of nectar.

Question 9

what happens to these insects

Answer 9

During the feeding process, pollen sticks to the body of the insects. As the insect moves from flower to flower to feed, the pollen is rubbed off onto the stigmas of other flowers. This process then fertilises the flower.

Question 10

what characteristics do Flowers that insects pollinate often have

Answer 10

• Large, conspicuous,brightly colouredflower petals.
• Sweetscentsto attract insects.
• A food source for pollinators such asnectar.
• Flowers haveUV markingsvisible only to insects.
• The anthers and stigmas are located deep inside the flower so that the insect must brush past them to get to the nectar, thus transferring the pollen.

Question 11

what characteristics do pollen grains inside insect-pollinated flowers often have

Answer 11

• Stickyorspikyto stick (like velcro) to the body of the insect.
• Large quantitiesof pollen are produced because the visiting insect will eat some.

Question 12

what does a bird do as a pollinating agent

Answer 12

birds feed on nectar found inside of flowers, the plants dust the large, sticky pollen grains onto their feathers which they then carry to other plants while feeding.

Question 13

what characteristics flowers that birds pollinate often have

Answer 13

• Largequantities of dilute nectar.
• These flowers aresturdierthan most insect-pollinated flowers.
• Stamensandstigmasprotrude(stick out) beyond the petals.
• Littleorno scentbecause birds have a poor sense of smell.
• Ovules are protectedfrom probing beaks.
• The flowers are borneabovethe leavesso that hovering birds can reach them.

Question 14

what characteristics do pollen grains inside bird-pollinated flowers often have

Answer 14

• Pollen grainsstick together in clumpsso that the bird picks up enough pollen to fertilise many ovules with just one visit.
• Pollen grains havespikesto stick to the pervious (water permeable) feathers of birds.

Question 15

why is wind pollination not that effective

Answer 15

because vast quantities of pollen must be produced foronly someof the pollen to land on areceptive stigma of thecorrect species.

Question 16

what are examples of plants that are pollinated by the wind

Answer 16

Some trees and grasses, restios and sedges are wind-pollinated. Most of our staple crops are wind-pollinated, e.g. maize, oats and rice.

Question 17

what are the characteristics flowers that depend on wind for pollination often have

Answer 17

• The flowersdo nothave a scent or nectar.
• Flowers areextremely smallandgreenorbrownbecause they do not need to attract pollinators.
• The male flowers have prominent anthers.
• The flowers are borne onflexible stalksthat move in the wind.
• Enormous amountsof pollen are produced.
• Stigmas are long and feathery.