Some Questions For Through And Study before you study Plant Physiology:
1. Compare and contrast autotrophs and heterotrophs.
Autotroph component consist of the organism that can make its own food by changes of inorganic materials into organic materials and helped by energy such as sunlight (fotoautotroph) and chemicals energy (kemoautotroph). Autorophics act as producers and most of them are plants with chlorophyll. In animals which are heterotrophic, meaning that they must obtain their food (pre-fabricated organic compounds) from the environment. It really contrast with heterotrophy component which has definition is the organism (in this case are plants) that use organic materials supplied by other organism as food. The classified of heterotrophs are animal (include human), fungi, and microbes.
Examples of heterotrophs include mycotrophs (plants that obtain their nutrient source from a fungus like Indian pipes (Monotropa ), decomposers (fungi, bacteria), carnivores, and herbivores. Some parasitic plants (holoparasites like dodder (Cuscuta) and dwarf mistletoe that lack chlorophyll are obligate heterotrophs that can only obtain their nutrients from another plant. Others parasites, like mistletoe ( Phoradendron ) and Indian paintbrush are green and can make their own organic compounds but obtain water and minerals from a host plant (Hershey). But some plants (carnivorous species) feed both autotrophically and heterotrophically.
Following are the similarities between autotrophs and heterotrophs. Have a look at them; (1) Autotrophs, as well as heterotrophs, are living things and both are part of some ecosystem, (2) The autotrophs and heterotrophs, together form various trophic levels in the food pyramid, (3) Both require sunlight and water to live and obtain energy by conversion of chemical molecules. The main difference between autotroph and heterotroph is that autotrophs can synthesize their own food, whereas, heterotrophs cannot. Most autotrophs contain the pigment chlorophyll, that plays a key role in synthesis of food. Chlorophyll is absent in almost all heterotrophs. Autptrophs obtain energy by converting inorganic raw materials into organic compounds, whereas, heterotrophs convert complex organic compounds into simpler ones to obtain energy.
So, this was all about autotroph and heterotroph. The movement of nutrients and energy from autotrophs through the various levels of heterotrophs, makes up a typical food chain. Autotrophs and heterotrophs, together, form an important part of all the ecosystems.
2. Discuss the consequences of being autotrophic. How have plants responded to life as autotroph.
Every living thing requires appropriate environmental conditions for growth and development in their life. In fact, environmental conditions in which living things are always changing. The changes may still be in the area of tolerance of living things, but often the change of environment causes decreased productivity even death in living things. This reinforces that every living thing has limiting factor and tolerance to environment resources. Most of the plants autotrophs spent all his life by settling in one place. They were fixed in place by root growth. To be able to live, plants must respond to various environmental conditions. Response of plants to the environment such as responses by motion, touching, light, chemical, water, and temperature. These various responses from the environment will be used by plants to process the nutrients and mineral salts are dissolved by water from the soil to be used as food with the help of environmental factors outside the body of plants such as sunlight, and temperature environment.
3. How do plant exploit their environment? Consider dendritic form, asexual reproduction, indeterminate growth, heterophylly, foraging and architectural design in your response.
Response of plants to the environment used by plants to live his life as an organism which can only move a limited basis. When the plants are still in seed form that fell above the surface of land, then by the help of water for example, seeds will be planted in the soil and get the appropriate temperature and humidity to grow. Radicle will penetrate the soil and absorb water that is rich in nutrients and mineral salts as food. Cotyledon has grown and penetrated the soil surface, young leaves will make use of air and sunlight to process inorganic materials into organic materials as food. The body plant will continue to grow upwards until it reaches an optimal height to perform photosysnthesis process, and will grow downward through the soil layer to reach a certain part to get enough nutrients for growth and development. Adaptation to the location of the body position of plant leaf and join occurs, when the leaves of plants modified to obtain sufficient sunlight, his body position leads to sunlight, etc.. When the plants reach the adult limit its growth, then these plants will do the flowering process. During the process of pollination to produce new offspring, then the plants take advantage of the environment helps in the process of pollination. With the help of insects, wind, water, or touch, pollination occurs.
The basic shape of the plant body is dendritic - which means "tree-like" or "filamentous". The advantage of this shape is that it provides a large surface-to-volume (s/v) ratio which enables a plant to exploit a large area of the environment. Among other things, this is an advantage for motility.
Plants have indeterminate growth. Process by which a plant continues to grow and get larger throughout its life cycle. The advantage of this is that it allows the plant, especially roots, to grow into new areas. In contrast, determinate growth is where an organism or part reaches a certain size and then stops growing. This is characteristic of animals and some plant parts ( eg , leaves, fruits).
Plants have a well developed ability to reproduce asexually. This can be viewed as a quick and energetically inexpensive way to expand the influence of the parent into a new location. One testable prediction from this hypothesis is that plants under nutrient stress should increase their rate of asexual reproduction (see foraging data below).
Plants (may) exhibit heterophylly refers to leaves with different shapes. For example, the aerial leaves of aquatic plants are entire but the submerged leaves are dissected. Sun leaves tend to be smaller and thicker than shade leaves. The leaves of the vine Monstera are more or less heart-shaped and pressed to the trunk as the vine climbs into the tropical forest canopy. Once in the canopy, the leaves take on the mature form with slits and holes.
Plants can forage. The growth patterns of plants, especially vines and plants with stolons (runners), are similar to the foraging tactics of animals. As an example, rhizomes of Hydrocotyle veer from patches of grass to avoid competition. A brief overview of the anatomy of a clonal plant like Glechoma hederacea (ground ivy): parent plant, stolon (internode), ramet (individual of a clone).
4. Compare and contrast animals and plants interm of body design (i.e. architectural vs. mechanical design).
Plants have an architectural design. The plant body is constructed like a building - modular (Silverton & Gordon). It is built of a limited number of units, each of which is relatively independent of the others and that are united into a single structure. Thus, just like a building is made of rooms, the leaves, stems and roots of a plant are analogous to a rooms in the building. Each room is somewhat independent, yet they all function together to make an integrated whole. We could remove a leaf or fruit, with little harm to the overall integrity of the structure. This is critical for plants to be able to add or remove parts (leaves, stems, flowers, fruits) as necessary. One conclusion is that because of their indeterminate growth and architectural design, plants are not limited by size. This gives plants the ability to colonize and exploit new areas for resources.
In contrast, an animal has a mechanical design. Animals are built more like a machine, made of numerous, different parts that function together. The parts are highly integrated. Parts cannot be added or removed without reducing the efficiency of the operation of the whole. Animals are limited by size.
5. Discuss some of mechanism by which plants sense changes in environment. Why are these important?
The plants must be able to respond to changes in their environment. They respond to their environment in a variety of ways, such as:
a. Plants typically respond by various growth movements to unpredictable, usually short-term environmental fluctuations, like changes in temperature or light. For example, some flowers like crocus are temperature sensitive and open when it is warm and close when it is cooler. The flowers of an alpine species ( Gentiana algida) close up before a thunderstorm. The flowers actually respond to the decreased temperature associated with the storm front and close to avoid pollen being washed out of the flower by the rain.
b. Plant form responds to the environment. Light is one of the most important environmental cues for plant development. This phenomenon is called photomorphogenesis and one classic example is etiolation (discussed above). Another example: increased levels of carbon dioxide in the air has lead to a decrease in the number of stomata on leaf surfaces and have similarly been shown to increase the toothiness of dandelions. The leaves of plants in the rainforest usually have an elongated tip (drip tip) to help funnel water off the leaf surface to minimize the growth of fungi and other leaf epiphytes that might cause disease or block sunlight. Leaf margins are also a response to the environment.
c. Plants usually respond to predictable, often longer-term environmental changes, like seasonal changes, by growth and developmental changes because of the constraints of their architectural design . Since these changes take time, a plant must "know" or "predict" when the environment will change and prepare for the change. ndeterminate growth is important here since it provides plants with the ability to change developmentally through the life cycle. Some examples of this phenomenon include: preparing for winter (by forming buds in summer) and photoperiodism (timing flowering so the appropriate pollinator is available and that the seeds have enough time to develop before winter); circadian rhythms (various types in response to day/night), and nyctinasty (sleep movements).
6. Identify some of the physical and biological threats to plants. How do plants protect themselves from these dangers?
The plants have some way to protect their self from physical and biological dangers threatens the well being of plants such as:
a. Physical dangers
In physical dangers such wind, water (flood), drought, cold (winter) that a plant faces. In general, plants cope with these (at least the predictable ones like winter and drought during summer) by dormancy, senescence, and even death. The evergreen and deciduous lifestyle are in part a response to adverse conditions. Evergreens are much better able to tolerate cold, dry conditions. They also do better in poor soil because they don't loose as many leaves.
b. Biological dangers
The plants solved their biological dangers by evolved their specific body structure from predators or herbivores and competitors or other plants such as Anatomical weapons (thorns, hairs, thick cuticle). Some plants are even "smart" enough to stop producing defenses when they are out of range of a herbivore. For example, the upper parts of Acacia trees above giraffe height produce few thorns. Similarly, holly leaves have few prickles above herbivore ( eg , deer) height;
c. Chemical weapons that could produce toxic, unpalatable chemicals. These can be inducible (produced in response to attack) or constitutive (always present) (Karban & Myers. 1989. Ann Rev Systemat. Ecol 20:331); Allelopathy is chemical warfare between plants. Phytoalexins are chemicals produced by plants to resist microbial infection.
d. Mimicry-"tricking" predators. For example, lithops in S. African deserts look like pebbles - are stone mimics. NZ mistletoe leaves look just like the host tree leaves to avoid being eaten which is important because they contain even higher amounts of nitrogen. Alseuosmia is a non-toxic New Zealand plant that looks very similar to Wintera pseudocolorata (a toxic species). When young, NZ lancewood looks very unappetizing - much like a woody umbrella that is folded up. However, when it gets about 15 feet tall, above predator ( eg , moa) height, it branches out and has a more "traditional" appearance.
e. Armed Forces in some plants, like wild tobacco, when attacked by herbivores release volatile chemicals that summon predatory insects to the damaged plants. These insects in turn, kill the herbivores.
7. How do plants find a "mate" and disperse offspring?
A non-motile organism cannot seek a mate (for gamete transfer) or easily disperse offspring. Plants solve the gamete transfer problem by relying on various pollination vectors. Fruits/seed dispersal mechanisms help disperse offspring. As example, the fragrance of a particular orchid changes after pollination. Prior to pollination the orchid released a fragrance that was an "aphrodisiac" for the male but once the flower was pollinated it produced a fragrance to repel him. And, when a few fruits of Hamelia patens , a neo-tropical tree, are removed it stimulates the rest of the fruit to ripen - it essentially tells them that a dispersal agent is in the area.
8. Discuss some of the problems unique to the plant way of life. In general how have plants responded to each of these problems?
Plants are unique of organism. They could stay a live with autotroph. They just need the inorganic materials from the land and processed it to be foods for their body and just helped by the sunlight, CO2 and external environment to stay live. They didn’t need other organism to do it. But some distrubed factors come from the other organism and abiotic component of environment. Plants act as non-motile organism is unable to move to a more favorable location to carry out its vital functions. Thus, plants have at least three major problems to contend with:
a. Environmental Positioning/Location - or, Getting Started in the Right Spot. When a plant is stuck once the seed germinates. For most plants getting started in the right place is a matter of luck. Thus, it is no surprise that plants exhibit a Type III survivorship curve (produce lots of offspring, few survive, no parental care of offspring. However, there are a few "tricks" that plants use to help increase the odds that seeds will germinate in a favorable environment such as
o Light - some seeds, like certain varieties of lettuce, require light for germination. This is a mechanism to insure that they germinate on the soil surface. It's no surprise that a garden develops a healthy crop of weeds after the soil is turned - it brings light-sensitive seeds to the surface. Light sensitive seeds are usually small and without much stored food. Thus, it is important that they begin to photosynthesize soon after germination.
o Ethylene - some seeds require ethylene to germinate. This naturally occurring plant hormone is produced by plants and soil microbes. Once the ethylene concentration reaches a critical level it induces the seeds to germinate. This happens if the seed is buried. These seeds are usually larger than light sensitive ones. One advantage of being buried is that the seeds will be more likely to be in a moist, humid environment. e.g., witchweed (Striga)
o Specialized Dispersal Mechanisms - some plants have specialized mechanisms for dispersal that will increase the odds of the seed getting into the proper place. For example, mistletoes have sticky seeds that often stick to the beak of a hungry bird. The bird will try to rub it off on a branch where the seed will adhere and germinate.
b. Axis orientation. Once a seed germinates in a favorable environment it must determine which way is up/down to insure that the roots grow down and shoots up. Thus, gravitropism is a very important physiological response characteristic of all plants.
c. Fine Tuning. Even non-motile organisms need to "fine-tune" their position in the environment. Thus plants have a variety of mechanisms that enable them to optimize their position in the environment including Phototropism, Skototropism, Thigmomorphogenesis, Solar tracking, Leaf mosaics, Etiolation, and Habitat selection.
9. Think about the statement "Plants are smarter than you think!"
This statement let me agree that the plants are smarter than we think in some cases specially in face their life. According to Webster's dictionaries define intelligence as "the ability to cope with a new situation" (Agnes 2002) or "the ability to learn or understand or to deal with new or trying situations" (Woolf 1973). We could think that the intelegence means has ability to make a sound or talk, move to other place or move freely, and eat some foot directly. The intelegence of plants could be seen when they face and take the advantage of surrounding environment to stay a live. And it likes animals include human, even they could protect their self from the predators.
For example, the non-motile condition of plants as the adjusting themselves to sources of inorganic foods contained in the soil. They modified their part of body (in this case is root) to penetrte and reached the layer of soil to absorb the nutrient from there. Their models of leaves are modificated to catch the sunlight and CO2 in photosythesis process maximally. Their stem also modificated as long as they need to get the good position in photosynthesis and distribution of food. And even the plants have some unique responses to the environment that make them could survive to stay a live. They can adapted their self to the changes environment with their own self.
10. Identify the characteristics of the plant kingdom.
Plants appeared on land about 425 million years ago and the evolutionary history of the plant kingdom reflects increasing adaptation to the terrestrial environment. Here the general characteristics of plants:
a. Multicellular eukaryotes that are photosynthetic autotrophs.
b. Contain chloroplasts with the photosynthetic pigments chlorophyll a, and b and carotenoids.
c. Cell walls containing cellulose.
d. Food reserve is starch that is stored in plastids.
e. Aerial parts are coated with a waxy cuticle that helps prevent desiccation.
f. Gas exchange cannot occur across the waxy cuticle so specialized openings on the under surface of the leaf, called stomata, allow gas exchange.
g. Reproductive adaptations necessary as plants moved from and aquatic to terrestrial environment.
h. Plants produce gametes within gametangia, organs with protective jackets of non reproductive cells that prevent the gametes from drying out. The ovum is fertilized within the female organ.
i. Embryos must be protected against desiccation. The zygote develops into an embryo that is retained for awhile within the female gametangia's jacket.
j. All plant life cycles have “Alternation of Generation”. Gametophyte generation produces and alternates with a diploid sporophyte generation. The sporophyte in turn produces the haploid gametophyte. The life cycles are heteromorphic; sporophytes and gametophytes differ in morphology. The sporophyte is larger more conspicuous and more dominate in all except the Bryophytes and their relatives.
11. Autotrophs are typically non-motile and heterotrophs are typically motile. Why did evolution favor this situation?
One of the main reasons for motility is to obtain food. Since the nutrients required by plants are "omnipotent" there was never an evolutionary pressure for "motility." Check out corals, sea fans, and hydra. These are all non-motile animals that occur in aquatic environments which enables them to "feed like a plant"-food is essentially brought to them via water currents. Thus, they never had any pressure for motility and they have very similar lifestyles/forms as plants. In addition, note that motility is really not possible for terrestrial plants. Once plants evolved roots it precluded movement. These evolutionary "choices" are closely connected. The typically of non-motile plants and motile animals are favor of evolution it cause the plant which need inorganic materials just could absorb by roots make them lucky as non-motile, so do with the animals which are need organic material might be take from plants or other animals make them lucky with motile condition so they could catch their prey by their self.
12. Explain why leaves are broad and flat.
The photosynthesis in plants takes place on the surface of the leaves. Since photosynthesis is the main energy-generating process in the plant, the leaves are broad and flat in order to increase the surface area of the leaf. In having so, it helps the plants expose the maximum number of cells to the sunlight and thereby making food more efficiently. Leaves are perfect solar collectors. These organs are broad and flat to allow for efficient light harvest. The leaves are broad to maximize surface area for light harvest and they are thin since light cannot penetrate too deeply into the leaf (the amount of light decreases exponentially with distance).
13. Compare animals and plants in terms of nutrients (type, concentration, location).
Here the comparison of animals and plants in term of nutrients:
| Comparison of Plant & Animal Nutrition | ||
| Nutrient | Plant | Animal |
| form of uptake | inorganic (CO 2 , water, ions) | organic (proteins, carbohydrates, fats) |
| concentration | dilute (ie, CO 2 = 0.03%) | concentrated |
| location | Just around the growth place | Could looking for to another place |
Conclusion : plants must be adapted for harvesting dilute nutrients that occur everywhere, whereas animals are adapted for searching out and trapping widely dispersed, concentrated packets of food.
14. Explain why plants are not limited by size.
The plant body is constructed like a building - modular (Silverton & Gordon). It is built of a limited number of units, each of which is relatively independent of the others and that are united into a single structure. Thus, just like a building is made of rooms, the leaves, stems and roots of a plant are analogous to a rooms in the building. Each room is somewhat independent, yet they all function together to make an integrated whole. This is critical for plants to be able to add or remove parts (leaves, stems, flowers, fruits) as necessary. One conclusion is that because of their indeterminate growth and architectural design, plants are not limited by size . This gives plants the ability to colonize and exploit new areas for resources.
As a consequence, plants are not a static shape - plants constantly change shape by adding/loosing parts - by accumulating modular units. Thus, growth in plants occurs by the addition of new "units" not enlargement.
15. Identify the specialized structures (and their function) that plants use for autotrophism.
Plants required specialized structures adapted for the autotrophic mode of nutrition. Specialization occurs at all levels of biological organization (eg, organ, tissue, cell, organelle). The plant body structure adapted to its function as an autotroph plant such :
a. In photosynthesis process
In order for photosynthesis to function properly and efficiently, it was necessary to separate it from other reactions that occur in the cell. Thus, the evolution of a specialized organelle for this process - the chloroplasts. Even within the chloroplast specialization was required. There are three major areas in a chloroplast - the stroma, inner membrane, and inter-membrane space. Each of these three regions is important for the functioning of photosynthesis. Electron transfer reactions require the highly ordered environment provided by the inner membrane. The Calvin cycle (light-independent reactions) are aqueous biochemical reactions which occur in the stroma and the inter-membrane space is needed to generate the pH gradient across the membrane that is important for photophosphorylation (ATP production).
b. In efficient light harversting of photosynthesis
Leaves are perfect solar collectors. These organs are broad and flat to allow for efficient light harvest. The leaves are broad to maximize surface area for light harvest and they are thin since light cannot penetrate too deeply into the leaf (the amount of light decreases exponentially with distance). As an aside, although the majority of light is absorbed near the leaf surface, in some situations plant tissues act like fiber optic cables that can funnel some light deeply into the plant body (Briggs et al ). The window plant in the Namib desert funnels light through translucent cell into the photosynthetic tissue that is buried in the soil (Attenborough). Even within the thin leaf, most chloroplasts are found in the upper layer of cells, the palisade layer, which is the tissue layer just beneath the upper epidermis. This makes "sense" since these cells will be receiving the greatest amount of light of any region in the leaf. Thus, this is an example of specialization at the tissue level.
c. Photosynthesis requires an apparatus for gas exchange.
Leaves double as a means to exchange photosynthetic gases (take up carbon dioxide and get rid of oxygen) with the environment. Leaves have pores in the surface (stomata) that regulate the entry/exit of gases and prevent the loss of excessive water. The spongy layer of the leaf acts like a "lung" increasing the internal surface area and provides for more rapid diffusion within the leaf. Since diffusion rates are inversely related to distance, diffusion can account for gas movements into/out of a leaf. As a consequence, no cell if more than 2 or 3 cells from the air. An added advantage of having large leaves for light harvest is that they provide lots of surface area for absorption of carbon dioxide.
d. Photosynthesis requires a water supply.
With the exception of the algae and aquatic plants, plants obtain their water through the roots from soil. Essentially the roots "mine" the soil for water. Thus, photosynthesis and the transition to a terrestrial environment necessitated the evolution of a root system to obtain water (specialization at the organ level). And, it required the evolution of specialized transport tissue (xylem) to move the water from the roots to the leaves.
e. Photosynthesis requires a mechanism to transport end products throughout the plant.
Once carbohydrate is produced during photosynthesis there must be a mechanism to transport it to other locations throughout the plant. The evolution of vascular tissue, specifically phloem, permitted movement of photosynthate from leaves to roots, fruits and other tissues where required.
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JUDUL SUBJEK : PP 01 (CLASS : ICP) ;
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