Thursday, January 6, 2011
Task 2 - Plantae
Non-flowering plants do not have flowers or fruits, like mosses and ferns, which reproduce from spores. They are green and can make their own food.
Non-flowering plants do not produce seeds and usually reproduce from spores. Spores are found in spore bags located on the underside of mature leaves or at the end of stalks.
Spores are tiny and can only be examined under a microscope. They are generally dispersed by wind as they are light. Like seeds, spores will germinate and grow into young plants when the conditions are favourable.
Other than reproducing by spores, plants can reproduce by plant parts too, such as:
Such buds have buds and leaves or leaf scars. It’s leaves are not green, and they can be scaly or fleshly. Some common examples are potato, ginger, and onion.
Suckers are shoots that grows from a small bud. These buds are found at the base of the stem of the parent plant. Some common examples are banana plants, palm, pineapple and heliconia.
The plant’s leaves are think and fleshy. Buds are found on the edge of a mature leaf. When the leaf falls to the ground, these buds grow and develop into new plants. Some common examples are bryophyllum, the african violet and the begonia violet.
Done By: Ethan Soh
AND a Science Revision Guide Book (Science psle revision guide. (2007). Singapore: Marshall Cavendish Education.)
Flowering plants are also known as Angiosperms or Magnoliophyta, and are the most diverse group of land plants. Angiosperms are seed-producing plants like gymnosperms(plants that reproduce by seeds such as acorns, cones and pines). They have many key derived characteristics, which are:
The flowers, which are the reproductive organs of flowering plants, are the most remarkable feature distinguishing them from the other seed plants. Flowers aid angiosperms by enabling a wider range of adaptability and broadening the ecological niches open to them. This has allowed flowering plants to largely dominate terrestrial ecosystems.
-Stamens with two pairs of pollen sacs
Stamens are much lighter than the corresponding organs of gymnosperms and have contributed to the diversification of angiosperms through time with adaptations to specialized pollination syndromes, such as particular pollinators. Stamens have also become modified through time to prevent self-fertilization, which has permitted further diversification, allowing angiosperms eventually to fill more niches.
Endosperm formation generally begins after fertilization and before the first division of the zygote. Endosperm is a highly nutritive tissue that can provide food for the developing embryo and sometimes for the seedling when it first appears.
Despite their diversity, angiosperms are clearly united by a suite of synapomorphies(i.e., shared, dervied features) including
Ovules that are enclosed within a carpel, that is, a structure that is made up of an ovary, which encloses the ovules and the stigma, a structure where pollen germination takes place,
Double fertilization, which leads to the formation of an endosperm(a nutritive tissue within the seed that feeds the developing plant embryo),
Stamen with two pairs of pollen sacs,
Features of the gametophyte structure and development and
Phloem tissue composed of sieve tubes and companion cells.
Done By: Celine Chee
They have tiny needle like leaves which help reduces water loss in their habitat, the desert.
The cactus also have a thick stem to store water.
Did you know that most people who goes on desert expeditions, cut cactus to drink the water in it. Cactuses are stored with quite a huge amount of water in them.
Lichens,Mosses,Algae and liverworts.
Of all the plants, lichens are best adapted to survive in the harsh polar climate.
The peculiarity of lichens is that they are not one homogeneous organism but a symbiosis of two different partners, a fungus and an alga. The fungus part supplies the plant with water and nutritious salt, meanwhile the alga part organic substance, like carbohydrate produce. With this ideal "job-sharing", lichens can survive the hardest conditions.
The grow in swamp areas thus the soil in usually denser, making water harder to flow through to reach the roots.
Thus the roots stick out of the soil to get more water and air.
They have the ability to live in saltwater by strainging freshwater from the saltwater through their roots
Done By: Clarabelle Ang