Plant Life

7 July 2016

Sexual Reproduction 1.In general terms, explain how the basic plant life cycle with alternation of generations is modified in angiosperms. The basic plant life cycle with alternation of generations is modified in angiosperms by the change of haploid (n) and diploid (2n) generations, which take turns making each other.

2.List four floral parts in order from outside to inside a flower. Sepals Petals Stamen Carpels 3.From a diagram of an idealized flower, correctly label the following structures and describe the function of each structure: a. sepals- Sepals are in charge of protecting the flower’s bud before it blooms. It has the qualities of a leave and is usually in green. b. petals- Several different angiosperms have petals that are attractive and bright in color so that they may attract many pollinators such as bees. c. stamen (filament and anther)- Stamens have filament stalk and a terminal structure called the anther. The anther contains other chambers known as the pollen sacs which provide pollen to the pollinators. d. carpel (style, ovary, ovule, and stigma)- Carpel have a single ovary in the lower side and have a style as their neck figure. The ovary contains ovule waiting for reproduction. The style supports the stigma; sticky substances contained on top of the style that collects and hold pollen for fertilization and reproduction.

Plant Life Essay Example

4.Distinguish between:

a. complete and incomplete flowers- Complete flowers are flowers that contain all four of the floral organs, whereas incomplete flowers are known as flowers that lack one or more of these important organs. b. bisexual and unisexual flowers- Bisexual flowers are flowers that contain both the stamens and carpels.This includes all complete and numerous incomplete flowers as well. However a unisexual flower is missing either stamens, making it a carpellate flower or missing carpels, making it a staminate flower. c. monoecious and dioecious plant species- A monoecious plant has staminate and carpellate flowers at discrete positions on one certain plant. While, the dioecious plant has staminate flowers and carpellate flowers on two different plants.

5.Explain by which generation, structure, and process spores are produced. The diploid plant, called the sporophyte, produces haploid spores by the process of meiosis.

6.Explain by which generation, structure, and process gametes are produced. The spores produced by the diploid plant divide by the process of mitosis. This makes multicellular male and female haploid plants. These plants are ultimately the gametophytes, which later make the gametes known as the male sperm and female egg.

7.Name the structures that represent the male and female gametophytes of flowering plants The gametophytes make the gametes known as the male sperm, or pollen, and female egg, or embryo ovule. 8.Describe the development of an embryo sac and explain the fate of each of its cells. An embryo sac is made from inside the ovules in ovaries. Every pollen grain creates a pollen tube, which develops down into the ovary through the style and releases sperm into the embryo sac, fertilizing the egg.

9.Explain how pollen can be transferred between flowers. Pollination can be transferred between flowers when pollen of other flowers are released from anthers are passed by wind, water, or animals to that flower’s stigma.

10.Distinguish between pollination and fertilization. Pollination is when pollen reaches the style’s stigma, which ultimately leads to fertilization; however, fertilization is when the gametes physically come together.

11.Describe mechanisms that prevent self-pollination Stamen and carpel may mature at different times. Most common is called the self-incompatibility, where a plant may reject the pollen of itself and its close relatives. Based on their S-genes similarities. 12.Outline the process of double fertilization. Explain the adaptive advantage of double fertilization in angiosperms. Double fertilization occurs when two sperms fuse with nuclei in the embryo sac. This has many advantages, such as the fact that double fertilization guarantees that the endosperm will develop only in ovules where the egg has been fertilized. It also avoids angiosperms from wasting nutrients.

13.Explain how fertilization in animals is similar to that in plants. Fertilization in animals is similar to that in plants because its first cellcell change occurs after gamete fusion rises in the cytoplasmic Ca2+ levels as it does in animal gamete fusion. Also, the plants make a block to polyspermy, which is the fertilization of an egg by more than one sperm cell, as do the animal’s cell’s eggs.

14.Describe the fate of the ovule and ovary after double fertilization. Note where major nutrients are stored as the embryo develops. After double fertilization, the ovule matures into a seed, and the ovary matures into a fruit encircling the seed. As the embryo grows the seed stores proteins, oils, and starch.

15.Describe the development and function of the endosperm. Distinguish between liquid endosperm and solid endosperm. After embryo development, endosperm is growth to store nutrients. This happens after double fertilization, when the triploid nucleus of the ovule’s central cell divides. This causes the formation of a milky multinucleate “supercell”. This becomes multicellular after cytokinesis. Finally, when the cell walls are completed, the endosperm becomes solid.

16.Describe the development of a plant embryo from the first mitotic division to the embryonic plant with rudimentary organs. First, the pollen tube yields the style of the carpel and travels into the ovary. In the ovary, it discharges the sperm cells in the embryo sac. After the ovule has the embryo sac and has helper’s such as cells around it to help it grow, layers of defensive tissue from the sporophyte grow, which will in the end make a protective seed coat.

17.From a diagram, identify the following structures of a seed and state a function for each:a. seed coat- a. The seed coat involves protective layers that cover the seed. b. proembryo- It is a multicellular organism before it arises from the seed. c. suspensor- The bottom cell progresses into a multicellular structurecalled the suspensor. d. hypocotyls- The hypocotyl is underneath the place of attachment. e. radicle- The mature embryo consists of an embryonic root known as the radicle, an embryonic shoot, and one or two cotyledons. f. epicotyl- The epicotyl part of the stem above the cotyledon. g. plumule- The embryonic shoot, recognized as the plumule, has two parts called the epicotyl and the hypocotyl. h. endosperm- The endosperm stores food, usually many starches. i. cotyledons- The cotyledonis is the seed leaf that stores food in starch and protein. j. shoot apex- The embryonic shoot is known as the plumule as well. 18.Explain how a monocot and dicot seed differ.

The main difference between the two is that monocots have one cotyledon, whereas dicots have two.

19.Explain how fruit forms and ripens. As the seeds are coming from the ovules, the ovary of the flower is developing into a fruit. It is so that it will protects the enclosed seeds and help it travel to get fertilized later on. The fruit mostly ripens at the same time as when the seeds finish their development.

20.Distinguish among simple, aggregate, and multiple fruit. Give an example of each type of fruit. Fruit that is made from carpel or several fused carpels and is called a simple fruit, like a pea pod. When a flower has more than one carpel, each forming a small fruit, it is called an aggregate fruit, like a raspberry. When a group of flowers tightly cluster together, they make multiple fruit, like a pineapple.

21.Explain how selective breeding by humans has changed fruits. Selective breeding by humans has changed fruits so that they could not endure or reproduce in the wild, such as the maize, which is unable to live on in the wild.

22.Explain how seed dormancy can be advantageous to a plant. Describe some conditions for breaking dormancy. Dormancy can be advantages for plants that want to germinate at an advantaged timing. Natural fires and seeds that are in the surface can break dormancy.

23.Describe the process of germination in a garden bean. In garden beans and other dicots, a hook forms in the hypocotyl, and growth shoves it aboveground. Asexual Reproduction 24.Describe the natural mechanisms of vegetative reproduction in plants, including fragmentation and apomixis. Asexual reproduction is helping the indeterminate growth of some plants. Separate remains of some plants can mature into whole offspring Fragmentation is when a parent plant separates into parts that reconstruct into whole plants. Also there is apomixism which happens in dandelions, occurs without going through fertilization.

25.Explain the advantages and disadvantages of reproducing sexually and asexually. Reproducing sexual can help with diversity, while it may also produce some negative characteristics in a plant, such as a sickness. Also, sexual reproduction may fail, when the seeds cannot combine, or the pollen does not reach the ovule. Reproduction asexual is easier and there is a certainty that you will reproduce, however, this may put the offspring in a disadvantage due to limited diverse traits of survival.

26.Explain various methods that horticulturalists use to propagate plants from cuttings. Propagation can be repeated asexually from plant fragments called cutting, using hoots or stems of a flower.

27.Explain how the technique of plant tissue culture can be used to clone and genetically engineer plants. Specialized storage stems can be cut into several pieces and develop into clones the same way a potato bud will regenerate a whole plant, emerging from the node to produce a small root, later to mature into a plant.

28.Describe the process of protoplast fusion and its potential agricultural impact. Protoplast is when a plant cell has had its cell walls removed enzymatically by cellulases and pectinases. When this is combined with the tissue method, then new plants can be created and invented.

Plant Biotechnology 29.Compare traditional plant-breeding techniques and genetic engineering, noting similarities and differences. Both alter the new offspring so that it will contain certain traits, however, traditional plant breeding using no alternation in the way the plant is produced, rather just chooses the pollen they prefer, whereas genetic engineering alter that method, by altering the pollen itself to produce new plants. Also, it is not limited to the same species of that plant.

30.Describe two transgenic crops. Cotton- Is altered to have different varieties, and different textures and levels of comfort. Maize- cannot survive in the wild without the help of a caretaking human. 31.Describe some of the biological arguments for and against genetically modified crops. It can produce a weed that is very difficult to control and get rid of. Can affect other organisms that approach the new plant invention that not involved in the genetic engineering in a negative way. They may lack some essential nutrients, though may not be created for human consumption.

Chapter 39 Control Systems in Plants

Signal Transduction and Plant Responses 1.Compare the growth of a plant in darkness (etiolation) to the characteristics of greening (de-etiolation). The morphological adaptations known as etiolation, is in the seeds that have been germinated in the dark and make sense for plants sprouting underground. They do not need a thick stem as well as well as need a root system because their shoot is supported by the surrounding soil, unlike the greening plants.

2.Describe the signal pathways associated with de-etiolation. The signal pathways associated with de-etiolation are the three major pathways known as reception, which is the detection of the receptors, transduction, which is the processing, and response, which reacts to the receptors..

3.Describe the role of second messengers in the process of de-etiolation. Second messengers are small, internally created chemicals that transmit and amplify the signal from the receptor to proteins that cause the specific response.

4.Describe the two main mechanisms by which a signaling pathway can activate an enzyme. The two main mechanisms by which a signaling pathway can activate an enzyme are cyclic GMP (cGMP) and Ca2+.

5.Explain, using several examples, what researchers have learned about the activity of plant hormones by study of mutant plants. They have learned that Auxin is also involved in the branching of roots, because a Arabidopsis mutant that releases a great number of proliferation of lateral roots has an auxin concentration a lot higher than normal. We have also seen that auxin stimulates a constant growth response of producing additional cytoplasm and wall material required by elongation.

Plant Responses to Hormones 6.For the following scientists, describe their hypothesis, experiments, and conclusions about the mechanism of phototropism. a. Charles and Francis Darwin- Charles Darwin and his son Francis in 1880, found that the phototropic stimulus is sensed at the tip of the plant.They used grass seedlings for some of their experiments ans saw that the tips focused on the tip of the plant to move. b. Peter Boysen-Jensen- found what part of the coleoptile senses light. In 1913 he made an experiment where the phototropic response happened only when light would reach the tip of coleoptile, hence making it obvious that the tip senses light. c. Frits Went- In 1926, Frits Went removed the chemical messenger for phototropism, which is now known as the auxin.

7.List six classes of plant hormones, describe their major functions, and note where they are produced in the plant. Auxin helps in the stimulation of cell elongation, Root growth, differentiation and branching. It is produced in embryo and young leaves; Cytokinins helps stimulate cell division and stimulates germination and is produced in the roots. Gibberellins is in charge of stimulating cell elongation and cell division and is produced in apical buds. Abscisic acid slows growth and maintains seed dormancy. It is produced in the terminal buds. Ethylene promotes fruit ripening and stimulates development of the abscission layer. It is produced in ripening fruits and nodes. Brassinosteroids helps with cell elongation and separation in stem segments and seedlings at concentrations as less as 10−12 M.

8.Explain how a hormone may cause its effect on plant growth and development. A hormone may cause its effect on plant growth and development by stimulating the division, elongation and differentiation of the plant in order to promote its health. 9.Describe a possible mechanism for the polar transport of auxin. A possible mechanism for the polar transport of auxin is polar transport to the shot apex.

10.According to the acid growth hypothesis, explain how auxin can initiate cell elongation. Auxin can initiate cell elongation by exciting proton pumpand causing the growth of the cytoplasm and wall. 11.Explain why 2,4-D is widely used as a weed killer.

2,4-dichlorophenoxyacetic acid is the auxin which can be easily deactivated by monocot plants such as maize.

12.Explain how the ratio of cytokinin to auxin affects cell division and cell differentiation. When there are more amounts of cytokine the buds develop, while more auxin develops the roots. 13.Describe the evidence that suggests that factors other than auxin from the terminal bud may control apical dominance. It was said that auxin and cytokinin act antagonistically in regulating axillary bud growth, however, we see that independently, auxin levels would inhibit axillary bud growth, while cytokinins would stimulate growth.

14.Describe how stem elongation and fruit growth depend on a synergism between auxin and gibberellins. In many plants, both auxin and gibberellins must be present for fruit to set because they protect the fruit, such as grown grapes, to enhance circulation and reject infections.

15.Explain the probable mechanism by which gibberellins trigger seed germination.  The probable mechanism by which gibberellins trigger seed germination is facilitating the penetration of expansins, so that gibberellins act to promote elongation.

16.Describe the functions of brassinosteroids in plants. Brassinosteroids helps with cell elongation and separation in stem segments and seedlings at concentrations as less as 10−12 M.

17.Describe how abscisic acid (ABA) helps prepare a plant for winter. Abscisic acid (ABA) helps prepare a plant for winter because it slows the growth process and helps rid of leaves before the harsh temperature of the winter season.

18.Describe the effects of ABA on seed dormancy and drought stress. ABA will have an effect on seed dormancy and drought stress because it determines the final physiological outcome. 19.Describe the role of ethylene in the triple response to mechanical stress, apoptosis, leaf abscission, and fruit ripening. Plants produce ethylene in response to stresses such as drought, flooding, mechanical pressure, injury, and infection. Its triple response allows a seedling to circumvent an obstacle as it matures through soil.

Plant Responses to Light

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