Pollination and Fertilization in Plants Flashcards
What is Pollination?
Pollination is the process of transfer of pollen grains from the anther to the stigma of a plant
What are pollen grains?
Pollen grains are the powdery substances produced by the anther of the stamen.
State the 3 ways in which pollination occurs.
Autogamy - Same flower
Geitonogamy - Same plant different flowers
Allogamy - Different plant same species
Why do only plants of the same species reproduce when pollination occurs?
Although agents of pollination can transfer pollen grains to plants of different species they pollen grains do not survive unlike the pollen grains of the same species which continue the process of germination. This is because of how nature has designed the process of reproduction.
What is self pollination? When does it occur?
Self pollination is the transfer of pollen grains from the anther to the stigma of the same flower or different flowers of the same plant. It occurs in bisexual as well as unisexual flowers as long as they have the flowers borne on the same plant. It also occurs only when the anther and the stigma mature at the same time.
What are cleistogamous flowers? Give a few examples.
They are the bisexual flowers that do not even open and have their reproductive structure hidden and close to each other in order to facilitate self - pollination. EG - Pansy & Pea
State 2 advantages and disadvantages of Self-pollination.
ADVANTAGES:
1. A surer process in bisexual flowers when the reproductive structures mature at the same time.
1. There is no wastage of pollen grains.
DISADVANTAGES:
1. The seeds are weakened if passed on with the same characteristics for generations.
2. It does not yield new varieties.
What is cross-pollination? How are the flowers in such plants?
Cross pollination is the transfer of pollen grains from the anther to the stigma of different plants of the same species. The flowers of such plants have to be large and colorful to attract pollinating agents like insects.
State 2 advantages and disadvantages of cross pollination.
ADVANTAGES:
1. Offsprings are a healthier
2. New varieties of the seeds are produced
DISADVANTAGES:
1. There is wastage of pollen grains as they are produced in large amounts to ensure maximum chances of pollination.
2. Having large, coloured and scented flowers and producing nectar is uneconomical for the flower.
Nature favors cross pollination. Give 2 reasons.
- Unisexuality - Flowers may either be male or female and be borne on separate plants making only cross-pollination possible.
- Dichogamy - When the anthers and the stigma of a flower mature at different times, only cross pollination can occur.
What is protandry? How is it different from Protogyny?
Protandry is when the anther matures before the stigma of a flower.
Protogyny is when the stigma matures before the anther in a flower.
Describe the flowers of insect pollinated plants.
- Large and brightly coloured flowers
- Emit a scent and produce nectar
- Have sticky or spiny pollen grains carried by insects
- Have a sticky stigma which does not hang out of the flowers.
- The flowers are in clusters to make them conspicous.
What are wind - pollinated flowers called?
Wind pollinated flowers are also called anemophilous flwers
What are the anthers in wind pollinated flowers also called? Why?
The anthers in wind pollinated flowers are also called versatile anthers as they are large and loosely attached to the filaments so that they are transferred easily.
Give an example of a hydrophily and an ornithophily flower?
Hydrophily - Vallisneria
Ornithophily - Canna
