Bio questions?

Question

1) what is one disadvantage of insect pollination?

2) advanatges of cross pollination?

3) why the great variability seen in the structure of pollen grains?

Answer 1

1. Insects eat the very item the plant wants delivered - pollen.

They tend to be generalist feeders and eat other parts of the plant, including the sexual organs.

They could be considered to be 'unreliable pollinators' as the pollinator might not go anywhere near the female organs of the same species of plant.

2.Cross pollination occurs between flowers of the same or closely related species. Cross pollination happens in different ways using pollinators, which are insects or mammals that are used to transfer pollen to other plants. Cross pollination is also called syngamy. (World Book)

The advantages of cross pollination is that the beneficial genes are transmitted faster to their offspring. Their offspring will the spread that beneficial gene to their offspring. Cross pollination introduces the plant to different genes which causes the plant to be able to deal with weather changes easier. Also, with cross pollination the plant is more likely to not be extinct because if one plant dies because of the weather or predators the new genes make it possible that the plant can still survive.

3. Pollen grains vary in structure bc different plants are genereally pollinated in a different way.  Obviously, dandelions rely on wind pollination, thus, those grains differ greatly from say, a tiger lilly, which generally relies on insects or birds.

Answer 2

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Answer 3

1.  If a plant relies on insects for pollination, then if the insect population declines, the plant's reproductive ability also declines.  Another problem is that insects often visit different types of plants (you've seen bees visiting lots of different types of flowers), so the insect will be carrying pollen from different species.

2.  The biggest advantage of cross-pollination is genetic diversity.  Fusion of gametes from different individuals creates a larger pool of alleles available for offspring.  This results in potentially new adaptations, but also creates diverse offspring so they are less likely to compete so heavily with each other.

3.  Pollen grains have such different structures because of the answer to #1.  If insects carry around lots of different species' pollen, then having different structures allows the stigma to differentiate between pollen of its own species from that of others.