Lab Practical 3 Plants Flashcards
Functions Required for Life
- Reproduction
- Growth
- Homeostasis
- Utilize energy
- Exchange materials with environment
- Internal Transport of molecules
- Structural Support
- Movement
- Senses and Responses
- Defenses
- Adaptations and Evolution
- Cell Differentiation
- Development
The diploid generation of a plant or alga that has a double set of chromosomes
Sporophyte Generation
In the Gymnosperms and flowering plants (Angiosperms), the __________ generation is the most prominent phase, comprising the familiar green plant with its roots, stem, leaves and cones or flowers.
Sporophyte Generation
In the flowering plants, the gametophytes are very reduced in size, and are represented by the pollen and the embryo sac.
Sporophyte
The ___________ produces spores (hence the name), by meiosis
Sporophyte
These meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of homologous chromosomes.
Sporophyte Generation
This phase in the life cycle of a plant is the asexual, spore bearing generation of the plant, featuring diploid cells
Sporophyte Generation
the cells of the plant in this generation or phase have two sets of chromosomes in their cells.
Sporophyte Generation
By the process of meiosis (reduction division), this sporophyte produces haploid spores. Since spores are formed in this generation, the name given to this phase is sporophyte. The haploid spores produced will then form the next gametophyte generation by growing into multicellular, haploid individuals called gametophyte.
Sporophyte Generation
the zygote or fertilized cell is diploid, however, the spores formed by them are haploid. This takes place because of reduction division or meiosis that take place. Meiosis is a process in which the number of chromosomes in each cell is cut down to half and the following cells formed will have half the number of chromosomes of their parent cells.
Sporophyte Generation
This is that phase of the plant in which the gametes, that is the egg and sperm formed are haploid (n), having only one set of chromosomes in them. Thus, gametophyte phase is the sexual, gamete producing stage in the life cycle of the plant.
Gametophyte Generation
Spores are actually the first cells of the gametophyte generation. These spores undergo the process of mitosis, by which identical cells with same number of chromosomes are formed. Male and female gametes with equal ‘n’ number of chromosomes are formed. When these gametes meet, they fuse together, get fertilized and form the zygote, which is diploid (2n).
Gametophyte Generation
This diploid zygote then forms the basis of the next alternating sporophyte generation. It forms the first cell of the diploid sporophyte generation. This zygote then grows into the sporophyte, which then later forms the haploid spores in the sporophyte generation and the cycle continues in the plant’s life cycle.
Gametophyte Generation
Sporophyte Generation vs. Gametophyte Generation
- sporophyte is a diploid phase, whereas gametophyte is a haploid generation.
- Sporophyte stage is asexual, while gametophyte stage is sexual.
- The first cell in a sporophyte generation is the diploid zygote, while the first cell in the gametophyte stage is the haploid spore.
- in the sporophyte phase, haploid spores are formed and in the gametophyte phase, diploid male and female gametes are formed.
in liverworts and mosses, the ________ stage is the larger and familiar form of the plant
Gametophyte
in angiosperms, the ________ phase is the larger and independent phase
Sporophyte
Plant Cell
- ATP, this is a high energy molecule that stores up energy. ATP is produced by the plant cell in the cristae of the mitochondria and chloroplasts and supports the important function of energy transfer within the plant cells.
- Chlorophyll is a molecule that carries on the process of photosynthesis. This is the process of producing sugar and oxygen using light energy, water and carbon dioxide.
- Chloroplast
This is usually the elongated or disc shaped photosynthesis site that contains the chlorophyll. Also a part of the ‘plastids’ group, chloroplasts are similar to mitochondria, but are only found in plants and protista. Chloroplasts have their own DNAs and are protected by the surrounding two lipid-bilayer membranes. - Cell Wall
This is the thin and rigid outer cover that lies above the cell membrane and surrounds the entire plant cell. Made up of cellulose fiber, the cell wall is tough and acts as a filtering mechanism for the plant cell. Its most important function is to maintain internal plant cell pressure and prevent over-expansion when water enters the cell. - Vacuole
These are large fluid-filled, membrane-bound spaces within the plant cell. They help in maintaining the cell shape and most plant cells have just one, single vacuole that represents up to 90 percent of the total plant cell. They contain ions, sugar, secondary metabolites and enzymes.
Function of Stomata in Plants
The most important and major function of stomata is the exchange of gases. In simple terms we can say that the plant takes CO2 from the atmosphere and gives out O2 which is utilized by animals and human beings.
Opening and Closing of Stomata
Apart from the transpiration and photosynthesis process, stomata also have another very important function. This function is to save water loss. This is done by the opening and closing of the stomata. Plants cannot make their food at night. This is because they do not get sunlight which in turn does not open the stomata. As soon as sunlight strikes the plant’s leaf, there is a change in turgor pressure. This forces the guard cells to form a crescent shape and open the pores of the stomata. This makes the pores open and the processes of photosynthesis, transpiration and respiration are continued. But once the sun sets, the guard cells lose the turgor pressure and this results in the closing of the stomata. This opening and closing also depends upon the environmental conditions. In adverse condition such as very high temperature, the stomata closes itself to stop water loss. They sometimes also keep moist air closed inside themselves to prevent the plant’s tissues from freezing in excess cold.
Stomata of the Plant
Transpiration
Transpiration is a process of evaporation of water from the surface of the plant. This is done through the stomatal openings. This helps the plant to get cool and also helps in the transfer of minerals and other materials to different parts of the plant. As the plant takes water from the soil, the openings absorb other minerals. But to transfer these minerals to the surface of the plant, the water on the surface of the plant should be evaporated. Once it is evaporated, it will develop pressure which will force the roots to absorb water from the soil and will be transferred to the tips of the plants. The major work of evaporation of water is done by stomata.
Gametangia
Production of Gametes in Multicellular organs called Gametangia.
- The Female gametangia is the Archegonia: Each Archegonium is a pear-shaped organ that produces a nonmotile egg retained within the bulbous part of the organ.
- The Male gametangia is the Antheridia: it produces sperm and releases them into the environment. The sperm can have flagella and swim to eggs through water droplets or a film of water.
- Each egg is ferlized in the Archegonium where the zygote develops into an embryo.
Lily Life Cyle
Fern Life Cyle
Ferns belong to the Division Pterophyta characterized by vascular plants with leaves (fronds) arising from subterranean, creeping rhizomes. In tree ferns, the leaves are produced on a definite woody trunk. The dominant (conspicuous) part of the life cycle is the diploid, leaf-bearing sporophyte. On the underside of the leaves are rows of brown sori. Each sorus is composed of a cluster of sporangia, and is often covered by a thin outer layer called the indusium. Some ferns such as Polypodium and Cyrtomium do not have the indusium. Ferns are classified by the arrangement of the sori and shape of the indusium. The sori and indusium superficially resemble an infestation of scale insects, and some people actually spray their ferns! Spore mother cells within the sporangium undergo meiosis, producing numerous haploid spores. The sporangia split open at maturity, releasing millions of spores that fall to the ground like tiny particles of dust. The splitting open of a sporangium is caused by a thick-walled, outer belt of cells called the annulus. As the cells of the annulus dry out, the annulus contracts and rips open the sporangial wall, thus dispersing the spores.
Each spore germinates and grows into a heart-shaped gametohyte (prothallus) which is smaller than your little finger nail. This haploid gametophyte bears male and female sex organs (antheridia and archegonia). With respect to populations of gametophytes, ferns are typically monoecious with both male and female sex organs on the same gametophytes. Unlike the unisexual gametophytes of a moss, a fern gametophyte is bisexual. Like mosses, ferns have a primitive method of fertilization that involves a multiciliate sperm that swims through water to reach the egg. The gametophytes and sporophytes of ferns are photosynthetic and autotrophic.
Mitosis Review
Meiosis Review
Moss Life Cycle
Mosses belong to the Division Bryophyta characterized by nonvascular plants with embryos that develop within multicellular female sex organs called archegonia. The dominant (conspicuous) part of the life cycle is the haploid, leafy gametophyte. The diploid sporophyte consists of a sporangium-bearing stalk that grows directly out of the gametophyte. Spore mother cells within the sporangium undergo meiosis, producing numerous haploid spores that fall to the ground like tiny particles of dust. Since the sporophyte is without chlorophyll, it is completely dependent on the autotrophic (photosynthetic) gametophyte for its water, minerals and carbohydrate nutrition. Consequently, the sporophyte of the moss is heterotrophic and parasitic on the gametophyte. Most moss gametophytes are dioecious, with separate male and female individuals in the population. The gametophytes are produced by “male” and “female” spores. Mosses have a primitive method of fertilization that involves a motile, biflagellate sperm that swims through water to reach the egg on female plants.
Some lichens superficially resemble mosses from a distance, particularly fruticose (branched) lichens growing on the branches and trunks of trees. Lichens are essentially fungi containing symbiotic algal cells. The photosynthetic algae provide carbohydrate nutrition for the fungus, while the fungus provides a protective place for the algal cells to thrive in an otherwise hostile environment. Because the relationship or “marriage” is beneficial to both partners, this particular example of symbiosis is classified as mutualism.
Pine Life Cyle
Flowering Plant Structure
In the above illustration of a bisexual flower, the “female” pistil is composed of the stigma, style and ovary. A simple pistil is composed of one carpel, while a compound pistil is composed of several carpels fused together. Carpels are actually modified leaves which can be readily observed when certain fruits dry and split open. For example the fruit or seed capsule of cotton is composed of five carpels, while yucca capsules contain three carpels. Some botanists prefer to use the term gynoecium instead of pistil. This term also applies to flowers with multiple pistils, each composed of separate and distinct carpels. The “male” stamen is composed of a pollen-bearing anther and a filament (stalk). Some flowers, such as species of eucalyptus and cactus, have literally hundreds of stamens. Unisexual flowers are either staminate (with one or more stamens) or pistillate (with one or more pistils). The variation in size, color, number and arrangement of floral parts in blossoms of different plant families is absolutely staggering.
Flowering Plant Life Cyle
Flowering plants (angiosperms) belong to the vascular plant division Anthophyta. Like ferns, the diploid sporophyte consists of a herbaceous or woody plant with roots, stems and leaves. Unlike ferns, flowering plants produce reproductive organs called flowers and seed-bearing fruits. The term angiosperm is derived from angio (vessel) and sperm (seed), referring to the seed-bearing vessels (containers) called fruits. Flowers may be unisexual or bisexual, depending on whether they contain only one type of sex organ (the male stamen or female pistil), or whether they contain both stamens and pistil in the same flower. Species with separate male and female flowers on the same plant are termed monoecious, including oaks (Quercus), alder (Alnus) and walnut (Juglans). Species with separate male and female flowers on separate individuals are termed dioecious, including willows (Salix), cottonwoods (Populus), date palms (Phoenix), some figs (Ficus) and marijuana (Cannabis).
Sporangium
A sporangium is an enclosure in which spores are formed.[2] It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores.
Strobilus
A strobilus (plural strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but many botanists restrict the use of the term cone to the woody seed strobili of conifers. Strobili are characterized by a central axis (anatomically a stem) surrounded by spirally arranged or decussate structures that may be modified leaves or modified stems.
Apical Meristems
The apical meristem, or growing tip, is a completely undifferentiated meristematic tissue found in the buds and growing tips of roots in plants. Its main function is to begin growth of new cells in young seedlings at the tips of roots and shoots (forming buds, among other things). Specifically, an active apical meristem lays down a growing root or shoot behind itself, pushing itself forward. Apical meristems are very small, compared to the cylinder-shaped lateral meristems
Apical meristems are composed of several layers. The number of layers varies according to plant type. In general the outermost layer is called the tunica while the innermost layers are the corpus. In monocots, the tunica determine the physical characteristics of the leaf edge and margin. In dicots, layer two of the corpus determine the characteristics of the edge of the leaf. The corpus and tunica play a critical part of the plant physical appearance as all plant cells are formed from the meristems. Apical meristems are found in two locations: the root and the stem.
Organisation of an apical meristem (growing tip)
1 - Central zone
2 - Peripheral zone
3 - Medullary (i.e. central) meristem
4 - Medullary tissue
Phylogenetic Terms
character – Heritable trait possessed by an organism; characters are usually described in terms of their states, for example: “hair present” vs. “hair absent,” where “hair” is the character, and “present” and “absent” are its states.
- derived – Describes a character state that is present in one or more subclades, but not all, of a clade under consideration. A derived character state is inferred to be a modified version of the primitive condition of that character, and to have arisen later in the evolution of the clade. For example, “presence of hair” is a primitive character state for all mammals, whereas the “hairlessness” of whales is a derived state for one subclade within the Mammalia.
- ancestor – Any organism, population, or species from which some other organism, population, or species is descended by reproduction.
Derived homologies (synapomorphies=shared, derived characters) are new to a clade of interest (first seen in ancestor of clade). Ancestral homologies (symplesiomorphies=shared, ancestral characters) arose before the common ancestor of the clade.
parsimony – Refers to a rule used to choose among possible cladograms, which states that the cladogram implying the least number of changes in character states is the best.
outgroup – In a cladistic analysis, any taxon used to help resolve the polarity of characters, and which is hypothesized to be less closely related to each of the taxa under consideration than any are to each other.
node – Nodes on the trees (where branches meet) represent the common (shared) ancestor of all taxa beyond the node
Monocots vs. Eudicot organs
Closer look at differences in Vascular Bundles
Rubisco
Ribulose-1,5-bisphosphate carboxylase oxygenase, commonly known by the abbreviation RuBisCO, is an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants to energy-rich molecules such as glucose. In chemical terms, it catalyzes the carboxylation of ribulose-1,5-bisphosphate (also known as RuBP). It is probably the most abundant protein on Earth.
It can be used to produce larger molecules such as glucose.
It is recycled through a sequence of reactions called photorespiration, which involves enzymes and cytochromes located in the mitochondria and peroxisomes. In this process, two molecules of phosphoglycolate are converted to one molecule of carbon dioxide and one molecule of 3-phosphoglycerate, which can reenter the Calvin cycle.
Cell division in the apical meristems and subsequent elongation and maturation of the new cells produces primary growth.
Primary Root Growth:
is concentrated near the tip and results in the root growing in length. The root tip contains 4 zones of development: The root cap, which protects the area behind it and softens the soil ahead of it by producing a polysaccharide. The apical meristem, is an area of rapidly dividing cells. It will replace the cells of the root cap as they wear away and push cells above them that will develop into the main tissues of the plant. The zone of elongation, is an area where the cells elongate 10 times their original length. This elongation helps push the root into the soil. The zone of maturation, is the area farthest from the root tip. Here the new cells will specialize and carry out the functions of the epidermal, ground, and vascular tissue. The primary tissues in a dicot root are arranges in a central x pattern for the xylem with the phloem located in each of the angles of the xylem. In a monocot the vascular tissues are alternated in a circle.
Primary Stem Growth:
begins at the tip of the terminal bud in the area called the apical meristem. The cell divisions are responsible for the stem’s growth in length. The primary vascular tissue in monocots takes on a scattered arrangement. In a dicot, it takes a circular pattern.
The other type of growth, secondary growth, is the increase in girth of stems and roots.
Secondary Growth:
Increases the girth of a stem it is caused by the vascular and cork cambium.
Vascular Cambium:
meristematic parenchyma produces xylem on the inside and phloem on its outer side. The secondary xylem accumulates and forms the wood. The secondary phloem does not accumulate and is sloughed off with the bark.
Cork Cambium:
forms in the outer cortex. Produces cork and epidermal tissues.
Wood has 2 zones: Heartwood- the older (inner) layers of xylem blocked with resins. It is non -functional in water transport. Sap wood- outer xylem, vascular cambium, phloem and cork cambium. Conducts water and food.
Rooted versus Unrooted Trees
- Trees may be rooted or unrooted.
- Rooted trees reflect the most basal ancestor of the tree in question.
- There are competing techniques for rooting a tree; one of the most common methods is through the use of an “outgroup”
Unrooted trees do not imply a known ancestral root.
Parsimony Methods
- Parsimony analysis is the second primary way to estimate phylogenetic trees from aligned sequences.
- Parsimony may be used to estimate “species” or “gene” phylogenies.
- In the parsimony approach, the goal is to identify that phylogeny that requires the fewest necessary changes to explain the differences among the observed sequences.
In the example below, note that the gene sequences for species I and II have a “T” at the tenth position, while those for species III and IV have a “C”.
Nitrogen Cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification.
The processes of the nitrogen cycle
- Nitrogen fixation
Atmospheric nitrogen must be processed, or “fixed” (see page on nitrogen fixation), to be used by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is then further converted by the bacteria to make their own organic compounds.
- Assimilation
Plants take nitrogen from the soil, by absorption through their roots in the form of either nitrate ions or ammonium ions. All nitrogen obtained by animals can be traced back to the eating of plants at some stage of the food chain.
- Ammonification
When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into ammonium, a process called ammonification or mineralization.
- Denitrification
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. This process is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions.[5] They use the nitrate as an electron acceptor in the place of oxygen during respiration.
