Ap Bio Plants
1. ) Roots support photosynthesis and respiration by absorbing minerals and water and by storing organic nutrients. They also anchor the plant. Some roots have mycorrhizae, which increase the surface area and therefore increase the absorption. The endodermis, which is the innermost layer of cells in the root cortex, surrounds the vascular cylinder. It is the passage of minerals from the cortex into the vascular tissue. The stem has a system of nodes where leaves are attached. They have a waxy coating (epidermis) that prevents water loss.
The stem and the roots are the 2 main axes in a vascular plant. Fluids are transported between the roots and the shoots through the stem by the phloem and xylem. Leaves are the main photosynthetic organ of vascular plants. They have a fattened blade, a stalk and a petiole. They have the chloroplast (with chlorophyll) and the gas exchange takes place here. 2. ) Intra-organism communication is possible through the xylem and the phloem. The transpiratinal pull is due to cohesion and adhesion. Evaporative cooling will result. A plant’s defense is due to its skin: the epidermis or periderm.
Another line of defense is a chemical attack that kills pathogens. This is enhanced by the inherited ability to recognize certain pathogens. Plants respond to the environment. Examples are touch, light and gravity. Through photoreceptors they can detect light, its direction, intensity and wavelength. Most responses are triggered due to plant hormones. Tropism is any type of response that results in curvature of of organs toward or away from a stimulus (ex. Light). Plants reproduce by pollination, also called fertilization, which is the transfer of pollen from an anther to a stigma.
A pollen grand produces a pollen tube. Eventually sperm will be discharged near the embryo sac and pollen develops. Products are seeds and fruits. Another way to reproduce is self-fertilization, which unfortunately is difficult for most plants due to self-incompatibility and rejection. 3. ) Plants can now live on land, because they have adoptions like leaves and stems unlike algae. They have vascular tissues for long distance transport like the xylem and phloem. Additionally there is a way for plants to reproduce without requiring water. Another reason is secondary growth with he vascular cambium. The stem or root will grow in diameter and will be thickened, reducing water loss and protecting the surface more fully. The different plant tissues (dermal tissues, vascular tissue and ground tissues) are adoptions as well. 4. ) Water flows from high water potential to low water potential. They have three routes for that: the transmembrane route (out of one cell, across a cell wall and into another cell), the symplastic route (via the continuum of cytosol) and the apoplastic route (via cell walls and extracellular spaces).
Roots are another way for water uptake and transport (example: mycorrhizae and endodermis). This transport is regulated by the compartmental structure of plants. The concept of transpiration is made possible through adhesion and cohesion. 5. ) The plant is required to be able to work at the molecular level, because (as only of many examples) it needs sucrose. Proton pumping and the cotransport of sucrose and H+ are two of the ways for a plant to get its required amounts of sucrose. The plant is also in need of nitrogen for its organic synthesis.
It can acquire that by nitrogen-fixing bacteria that convert atmospheric N2 to nitrogenous minerals. 6. ) An example for an organ is the tuber or bulb. They are sugar sinks that are net consumers and storers of sugar. Chloroplast is another cellular example and it can be found in the leaves of a plant. It is responsible for photosynthesis and contains chlorophyll, which is why plants are green. The plant vacuole is responsible for water (and other nutrients). Through osmosis water is attracted into the vacuole.
This gives the plant a healthy look and provides every part of it with its necessities. The cell wall surrounds cells and is one of the major difference between plants and eukaryotic cells. It allows for cell communication, because signals are allowed to pass the wall, while it also gives the plant its structure. 7. ) There are different types of reproductive systems in a plant. Pollination/ Fertilization is made able through self-fertilization and asexual reproduction with a seed as the product.
Some plants are made perfectly to be able to self fertilize, because the anther with the pollen lies above the stigma. The root is another organ. It anchores the plant and absorbs minerals and water. It also stores organic nutrients. The stem is a system of nodes and it prevents water loss, while the leaves assist in photosynthesis because they contain chloroplast. The vascular system carries out long distance transport with the xylem and phloem in order to give the plant the nutrition it needs and to regulate transpiration etc. 8. )
One type of symbiotic relationships is the symbiotic nitrogen fixation. An example of a plant is the bean. This relationship is between roots and bacteria, while the roots obtain sugar from the plant. The relationship is mutualistic, because the plant gets provided with a built-in source of fixed nitrogen. Mycorrhizae make up the relationship between fungi and roots. There are ectomycorrhizae and endomycorrhizae. The fungus benefits from a steady supply of sugar and the host plant benefits because the fungus increases the surface area for water uptake and mineral absorption.