1. Describe the broad evolution of plants in the plant kingdom (in terms of phyl
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1. Describe the broad evolution of plants in the plant kingdom (in terms of phylogeny, reproduction, alternation of generations, leaf modifications, and vascularity) 2. Compare and contrast sporogenesis and gametogenesis in anther and ovary (of angiosperms) You must use, but are not limited to, the following terms: anther, eggs, embryo sac, generative cell, microsporocytes, megasporocyte, microspores, pollen sacs, pollen grain, 2 nucleate, 4 nucleate, 8 nucleate, polar nuclei, sperm, synergids, tetrads, tube cel, 3. Compare and contrast megagametogenesis and embryo development in Pinus and angiosperms. You must use, but are not limited to, the following terms functional megaspore, archegonia, eggs, free nuclear, suspensor, basal cell, developing embryo, megagametophyte, fertilization 4. Describe 5 different types of pollination associations/co-evolution. You must describe the type of flower and what specifically aids in moving pollen to stigma 5. Describe 5 methods of fruit/seed dispersal in angiosperms. You must describe the type of fruit, or seed, and the type of mechanism involved 6. Describe and illustrate all of the following life cycles mosses, ferns, gymnosperms, and angiosperms. (I will definitely choose one of these in a separate section of the test - for gymnosperms and angiosperms I would be able to recognize and label the sections)Explanation / Answer
5) 1- Animal dispersal:
Animals disperse seeds in several ways. First, some plants, like the burr at left, have barbs or other structures that get tangled in animal fur or feathers, and are then carried to new sites. Other plants produce their seeds inside fleshy fruits that then get eaten be an animal. The fruit is digested by the animal, but the seeds pass through the digestive tract, and are dropped in other locations. Some animals bury seeds, like squirrels with acorns, to save for later, but may not return to get the seed. It can grow into a new plant.
2)- Wind dispersal
The kind of seeds which are often wind dispersed are smaller seeds that have wings or other hair-like or feather-like structures. Plants that produce wind blown seeds, like the dandelion , often produce lots of seeds to ensure that some of the seeds are blown to areas where the seeds can germinate.
3- Floating in water
Many aquatic plants and plants that live near water have seeds that can float, and are carried by water. Plants living along streams and rivers have seeds that float downstream, and therefore become germinate at new sites. The size of the seed is not a factor in determining whether or not a seed can float. Some very large seeds, like coconuts, can float. Some small seeds also float.
4) Dispersal of Seeds by Gravity
Large, round, heavy fruits just drop straight off the tree onto the ground when they are ripe.If they have a tough outer shell, they may roll some distance from the parent plant. The higher up the tree they are, and the larger they are, the further they can roll.
If they have a soft skin, they may break open when they hit the ground and the individual seeds may be scattered.
On lower-growing plants, many fruits and seeds are also heavy enough to fall to the ground without any other help.
When they reach the ground, some seeds are taken further from the parent plant by animals or water.
5- Dispersal of Seeds by Force
Some plants provide their fruits (seedpods) with a mechanism that ejects the seeds from the pod by force.
There are several methods plants use to fling their seeds out of the seedpod. All of them rely on the effect of evaporation of water in the seedpod, so this method of seed dispersal usually takes place in the sun. It is one of the favourite methods used by members of the Papilionaceae (formerly Leguminosae). If you walk over heathland near Gorse bushes on a hot sunny day, you can hear the explosions of the seedpods as they burst open and send their seeds out. Lupins, too, have a similar system. The side of the seedpod facing the sun dries out more quickly than the side in the shade, causing the pod to buckle and pop open. The seedpods then curl up like animal horns, sending the seeds flying.
Geraniums also use the heat of the sun to shoot their seeds from the pods. The seeds are in a ring at the base of the style, each one with its own cover which is attached to the tip of the style by a thin woody strip. When the seeds are ripe, the seed covers split apart, and the strip rips up the style but is stopped suddenly because the strip remains attached to the style. The seeds are catapulted out at high speed.
Oxalis seeds are covered by an elastic coating. When this dries out, it splits suddenly, shooting the individual seeds out of the pod.
Euphorbia is another plant whose seedpods crack open with a loud explosion. When the three joints in the seedpod dry out, they split open suddenly, and the seeds are shot out. Ceanothus berries also operate this system when the fleshy outer covering has dried out.
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