Question

Name several mechanisms of seed or/and fruit dispersal. Contrast the germination of a bean seed and that of corn grain.

Answer 1

Seed dispersal is a method of asexual reproduction in plants. The plants produce their offspring (identical to it) by spreading or dispersing its seeds in the surrounding atmosphere where it settles down in the soil and germinates to produce a new plant. Germination is the process of formation of a seedling from a seed of angiosperms or gynoecium plants.

Complete answer:
The plants disperse its seeds or the fruits containing seeds inside it, with the help of the following mechanisms:
-Biotic mechanism- Birds, insects, butterflies, honey bees sit on the plant or fruit to eat it. At the same time, the seeds fall on the ground or stick to the body parts of birds or honeybees (pollen grains), from where it is transferred to the soil for germination.
-Abiotic mechanism - vectors like water, wind, gravity, and ballistic vectors help the seeds to reach distant places and grow in favorable conditions. Eg. Geranium spp.
-Autochory- The autochthonous plants disperse its seed without the help of any vector. Eg. Runners (grass), banyan tree.
-Mechanical dispersal- Dehiscent fruits burst with a force which results in the spread of seeds in the fruit in all directions. Eg. Poppy.
The germination process of bean seeds and that of corn grains is different:
Bean seed is a dicot seed, while a corn grain is a monocot.
Dicots have two cotyledons while monocots have single cotyledons
The dicot seeds are oily seeds whereas monocot seeds are starchy.
The dicot seeds need at least 50% moisture to germinate, that of monocot can germinate when moisture level reaches 30%.
Dicot seeds give rise to radicles from which the root and shoot system evolves. In monocots first, the roots covered in coleorhiza (sheath) grow and then the leaves are covered by coleoptiles.

Note: Germination of seeds requires favorable environmental conditions. Both the dicots and monocot plants need similar conditions to grow. They should have properly developed embryos, endosperm, cotyledons, testa, etc.Until the newly grown plant prepares food by photosynthesis, the cotyledons and the endosperm provide nutrients to the germinating seed.