Download Plant Root Structure and Function and more Exams Marketing Business-to-business (B2B) in PDF only on Docsity!
IB 103 EXAM 2 with complete solutions
What are the two main functions of roots - ANSWER- absorption and anchorage Monocots - ANSWER- short-lived. Grasses. mass of roots Eudicots - ANSWER- singular priamary root How do plants massively increase the absorptive surface area of their roots? - ANSWER- root hairs (projections of the epidermal cell) can be on lateral roots why is the root-to-shoot ratio important - ANSWER- Leaves and roots. supply and demand, need enough roots for P in ATP. Need leaves for sugar In gynosperms and eudicots, the primary root is called? - ANSWER- Taproot After you transplant a shrub which of the followung is the most effective step you should take to increase the chances that the shrub will survive? - ANSWER- cut back the shoot Cortex - ANSWER- Amylopast cells found in this. Storage and absorption Epidermis - ANSWER- Protection of vascular tissue and absorption Stele - ANSWER- transport, protection, and lateral roots
Endodermis - ANSWER- Innermost layer of cells in the cortex and outermost layer of cells in steele; contains casparian strip which doesn't allow water or nutrients to pass Pericycle - ANSWER- Provide tissue from which lateral roots will emerge. lateral roots orginate from ring of cells inside endodermis phloem - ANSWER- transcellular root-regulated movement across cell using transporter How do we get from apoplast to symplast - ANSWER- active transplast Why do stomata open/close - ANSWER- due to turgor pressure How have roots been modified over evolutionary time? - ANSWER- modified for storage. mangroves modified roots allow aeration. Also modified for anchorage What plastid types can be found in roots? - ANSWER- amalylast and chromoplast Differences between monocot and dicot roots in regards to xylem and phloem - ANSWER- Monocots have root xylem and phloem arranged in ring. Dicot roots have their xylem in the center of the root and the phloem on the outside. Differenes between monocot and dicot roots - ANSWER- Monocots are fibourous mass of roots, dicots have a taproot system. Dicot roots also have secondary growth whereas monocot does not Three ways water and nutrients can pass through a cell - ANSWER- apoplatically, symplastically, and by transmembrane Apoplastic transport - ANSWER- Moves through apoplast (water filled cell walls and intercellular spaces) Symplastic transport - ANSWER- Moves through symplast (continum of cytosol linked by plasmdesmata)
What force moves water through a plant? - ANSWER- Cohesion Tension Theory Water evaporates from stomates by transpiration. Then, the water pressure of the intercellular space drops below cell water pressure. So, the water moves from cells to intercellular airspace. This results in a decrease in cellular water pressure relative to xylem water pressure and water moves from xylem to cell How is water drawn into a plant? - ANSWER- Negative water pressure of roots helps draw water in Root order - ANSWER- epidermis -> cortex ->endodermis ->pericycle -> phloem -> xylem Because roots have endodermal layers, they are able to: - ANSWER- control intake of minerals If water is to move from the soil through a plant out into the air via transpiration, the water potential must be LOWEST in the: a. air. b. soil. c. xylem of the stem. d. xylem of the leaf. e. endodermis. - ANSWER- a. air Starch is stored in the roots of plants in the - ANSWER- cortex The Casparian strip forms a waterproof seal around the cells of the - ANSWER- endodermis cell The function of the Casparian strip is to: - ANSWER- force water and solutes to traverse the endodermis only via the symplast. Water can enter the cortex region of a root without going through any cell membranes. It does so by traveling through - ANSWER- the cell wall
Which is responsible for guttation? - ANSWER- Ψw difference between soil and root What is the transported sucrose from photosynthesis used for? - ANSWER- short term chemical energy and biosynthesis-breaks down and releases energy required for enzymatic reactions What kind of energy does sucrose represent? - ANSWER- long term chemical energy What is the purpose of respiration? - ANSWER- provides energy to the cells it needs to function. convert the energy of carbon-carbon bonds to phosphate bond energy of ATP. Water forced out of xylem - ANSWER- guttation When does respiration happen? - ANSWER- Respiration happens all the time What is the connection between photosythesis and respiration? - ANSWER- photosynthesis produces the glucose that is used in respiration to make ATP Where does respirtation happen in plants? - ANSWER- In all cells How do plants get glucose from sucrose? - ANSWER- Inside the cells, sucrose is converted back into glucose and fructose by hydrolysis How is energy extracted from the C-C bonds of glucose? - ANSWER- Glycolysis- is a series of reactions that and extract energy from glucose by splitting it into two three-carbon molecules called pyruvates. How many parts of glycolysis are there? - ANSWER- 2- energy spent and energy gained Energy spent portion of glycolysis - ANSWER- Glucose is phosphorylated, cleaved to 2 triose phosphates, costs 2 ATP called preperation
What is the major requirement for aerobic respiration? - ANSWER- oxygen Where in the cell does aerobic respiration take place? - ANSWER- mitochandria What are the major steps in aerobic respiration? - ANSWER- Glycolysis, TCA cycle, electron transport chain Products of aerobic respiration - ANSWER- 36 ATP, H2O, CO Is glucose breakdown complete or incomplete in aerobic respiration? - ANSWER- complete Where does the TCA cycle occur in aerobic respiration? - ANSWER- matrix Where does ATP production and the electron transport chain happen in aerobic respiration? - ANSWER- cristae How is energy harvested from Acetyl CoA? - ANSWER- Extraction of high energy electrons. NADH and FADH2 are shuttled to electron transport chain because they are electron donors Outputs of transtition pathway and TCA cycle - ANSWER- CO2 NADH. The products of TCA cycle include 3 NADH, 1 FADH2, and 1 GTP Where do electrons come from in the mitochandrial electron transport? - ANSWER- NADH and FADH From where and to where are H+ protons pumped during mitochandrial electron transport? - ANSWER- matrix to inner membrane space What is the final electron acceptor in the mitochandrial electron transport? - ANSWER- oxygen because H2O is produced How and where is ATP made in the mitochandria? - ANSWER- Oxidative phosphoication/inner membrane
How efficent is aerobic respiration in converting the energy in glucose to ATP? - ANSWER- 40% What is the movement of protons across membrane into inner membrane space gradient across membrane is called - ANSWER- electrochemical gradient During aerobic respiration, excess hydrogen ions (H+) accumulate in the intermembrane space compared to their concentration in the matrix of the mitochondrion. What is the significance of this hydrogen ion gradient? - ANSWER- As the hydrogen ions pass through ATP synthase in the inner membrane, ADP is converted to ATP. Acetyl CoA formation - ANSWER- occurs in mitochondria, occurs with the liberation of 1 CO2 molecule per acetyl CoA formed, is associated with the production of NADH, is a required step prior to the citric acid cycle The first input into Krebs Cycle is: - ANSWER- Acetyl CoA Kreb's cycle is an important source of - ANSWER- NADH and carbon bioskeletons The Transition Reaction represents the transition between: - ANSWER- Glycolysis and the Krebs Cycle. When we go on a diet, the weight we lose is actually CO2 given off during which stages of respiration? - ANSWER- the transition reaction and the Krebs cycle Which of the following could be considered the key products of the Krebs Cycle?
- ANSWER- Substrates for biosynthesis and NADH Is heat a product of aerobic respiration? - ANSWER- yes what is a meristem? - ANSWER- a region of plant tissue, found chiefly at the growing tips of roots and shoots in the cambium, consisting of actively dividing cells forming new tissue.
What do transcription factors do? - ANSWER- Transcription factors bind to promoters, once they bind they recruit polymerase, and then the gene is expressed What do KNOX1 transcription factors do? - ANSWER- KNOX 1 genes maintain the meristem in an indeterminate state Hows does KNOX 1 work? - ANSWER- Binds to transcription factors and encodes them What are the differences between meristem and leaf primordial cells? - ANSWER- KNOX1 is expressed in the meristem and the cells are indeterminate. KNOX1 is not expressed in the leaf primordial cells and are therefore determinate Where do new leaves form? - ANSWER- On the shoulder of the apical dome SAM v RAM - ANSWER- SAM- located on the surface and produces tissues and organs (leaves) RAM- buried inside, only produces tissues Procambium - ANSWER- Where leaf primordia form Protoderm - ANSWER- Outer layer, what becomes epidermis Apex - ANSWER- zone of root where there is active cell division Ground meristem becomes - ANSWER- cortex What do plants start off as and what do they become? - ANSWER- Plants start off as a single cell, a zygote, and through cell division becomes an embryo What does the first cell division of the zygote establish? - ANSWER- Apical-basal polarity. What do the apical cell and basa cell form? - ANSWER- The apical cell forms the embryo and the basal cell forms the suspensor
What would happen to an embryo lacking a properly developed suspensor? - ANSWER- It would suffer from a lack of nutrition At what stage of cell division are the basil cells determined to form a suspensor?
- ANSWER- 8 cell stage What happens to the endosperm when the seed matures? - ANSWER- It is degraded Cotyledons - ANSWER- Serve as the endosperm for dicot plants, starch is stored here Differences between dicot and monocot seeds - ANSWER- Endosperm still present in monocot. When monocots germinate, coleoptile comes out A seedling emerging from a seed in which the ______ did not develop as precousily as it normally does might suffer from ______ - ANSWER- radicle, wilting What is seed maturation? - ANSWER- Build up of food reserves in either the endosperm or cotyledon Why do seeds need oxygen to germinate succesfully? - ANSWER- They need oxygen to degrade starch in aerobic respiration What do seeds need to germinate? - ANSWER- All seeds need water, oxygen, and temperature to prevent germination from unoptimal growing conditions What is startification and scarification? - ANSWER- Seeds needs be cold before it can germinate and seed needs to be knicked before it can germinate If plants need additional environmental stimulus to germiante, what are they refered to as? If they don't need extra stimulus? - ANSWER- dormat, quiscent
Why don't plants green up right away - ANSWER- photosystems are expensive to build Etioplast (chloroplast precursor) - ANSWER- contains what will become the thylakoid membrane How is light signal percieved? What type of light is percived? - ANSWER- phytochrome, red and far red How does this pigment work? Describe and contrast inactive and active forms - ANSWER- Pr (inactive) and Pfr (active) when Pr absorbs red, it becomes active Where does Pfr move to? - ANSWER- Pfr moves from cytosol to nucleus Photomorphogenesis - ANSWER- leaf expansison, chloroplast development, stem elongation Why is phytochrome found in roots? - ANSWER- Roots need to sense light so they can grow away from it What are tropisms? - ANSWER- Directional movement responses that occur in response to directional stimulus Gravatropism - ANSWER- Roots- postive response, shoots- negative How do plants sense gravity? - ANSWER- Statolith inside statocyte, it is denser than cytoplasm so it falls against gravity Gravitropism in shoots - ANSWER- in shoots auxin is more accumulated on the lower side of the stem, causing it to elongate How can auxin have opposite effect in roots and shoots? - ANSWER- The cells in the roots are more sensitive to auxin than in the shoots Hydrotropism - ANSWER- roots growing toward water
Thigmotropism - ANSWER- turning or bending of plant in response to touch stimulus What are the ways plants respond to light? - ANSWER- Photoreceptor of 400- nm How does auxin make cells expand? - ANSWER- Unequal pressure on one wall. Membrane energized, ions and sugars pumped in, decreased water pressure draws water in. Cell wall acidified, build up of H+ protons in apoplastic space becomes acidic, as H+ pumped out, other ions pumped in also lowering water pressure which in turn draws water in. Cell walls break once becomes acidified How woudl you test which wavelength of light a photoreceptor is activated at? - ANSWER- Comparing the action spectrum for a response with the absorption spectrum for a pigment helps physiologists determine which pigment abssorbs light that makes repsonse Etiolation - ANSWER- caused by little or no light and results in elongated stem and little to no chlroplast Germination of small seeds is frequently under phytochrome control and occurs when there is: - ANSWER- high levels of Pfr Phytochrome functions in plant development as which of the following? - ANSWER- light receptor and signal transducer Phytochrome is a plant pigment that changes chemical forms when exposed to red light. Which if the following processes are thought to be under the control of the phytochrome system? a. germination of light-dependent seeds and etiolation b. germination of small seeds c. all of these responses d. phototropism e. etiolation - ANSWER-. germination of light-dependent seeds and etiolation
What is 24 D and how is it used? - ANSWER- It is a synthetic auxin, used to kill plants because it causes uncontrolable cell elongation that the plants metabolism cannot keep up with Annual growth rings - ANSWER- Shows the cells that were added each year. These annual rings show the amount of wood produced during one growing season. ... They form the summerwood (latewood) which appears as a darker ring on the tree cross section. What is the difference between heartwood and sap wood? - ANSWER- Sapwood is the living outermost layer and heartwood is the dead inner wood Where does primary xylem orginate from? - ANSWER- procambium What are advantages and disadvantages of sexual reproduction? - ANSWER- Genetic variation, energy input in finding partner What are advantages/disadvantages of asexual reproduction? - ANSWER- Reproduce faster; lower genetic variation (more suseptable to extinction) Apomixis - ANSWER- Apomixis is an asexual mode of seed formation that produces clonal progency with a maternal genotype. It primarily influences reproductive events in the ovule of the flower Grafting - ANSWER- a horticultural technique whereby tissues of plants are joined so as to continue their growth together. In a tree trunk, cell division regularly occurs in the/a: a. phloem fibers. b. heartwood cells. c. phloem companion cells. d. thin layer of cambial cells. e. pith cells. - ANSWER- d. thin layer of cambial cells. Where does wood orginate from? - ANSWER- Vascular cambium
Where does bark orginate from? - ANSWER- Cork cambium Mitotic cell divisions in the vascular cambium result in - ANSWER- increased stem diameter What are the dark inner layers and light outer layers in a tree called? - ANSWER- heartwood; sapwood What does meosis do? - ANSWER- Meosis reduces a chromosomes number by half, while also creating new allele combinations distrubuted across daugther cells through segregartion and recombination What are the major steps of meosis? - ANSWER- Prophase- recombination of genes, metaphase I and II chromosomes seperate, 4 gamates produced What are the outcomes of meosis I and II? - ANSWER- 4 daugther gamates, all haploid (1n) What are differences and similarities in mitosis and meoisis? - ANSWER- The end result of both are daughter cells produced from a parent cell. ... Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis homologous chromosomes separate leading to daughter cells that are not genetically identical. In mitosis the result is an exact clone with the same number of chromosomes as parent cell When did meosis most likely arise? - ANSWER- The 'invention' of meosis dates back to before the last common ancestor of extant eukaroytes What is recombination and why is it important? - ANSWER- Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is important for genetic variation What is a chromatid? - ANSWER- A chromatid are the halves of the chromosome held together by centromiere
Why do plants produce flowers? - ANSWER- To attract pollinators, protect reproductive organs, and promote genetic variation What is the difference between a complete flower and an incomplete flower? - ANSWER- A complete flower has all 4 whorls, an incomplete flower is missing a whorl What is the difference between a perfect and imperfect flower? - ANSWER- perfect flower has both the stamen and carpel, imperfect has only one What is a reason that flowers have carpel and stamen on different flowers? - ANSWER- protects against self-fertilization Whorl 1 - ANSWER- sepal Whorl 2 - ANSWER- petal Whorl 3 - ANSWER- stamen Whorl 4 - ANSWER- carpel How and where is pollen formed? - ANSWER- Pollen is formed in the anthers Where is the ovule located? - ANSWER- Ovule is located at the base of the carpel Where does meosis occur in a plant? - ANSWER- In the spore mother cells of anthers and ovules A vernalization requirement permits plants to: - ANSWER- flower after the danger of frost is reduced. Which flower part has as its primary function the protection of the developing flower bud? - ANSWER- sepal
principle of segregation - ANSWER- During meiosis, chromosome pairs separate into different gametes such that each of the two alleles for a given trait appears in a different gamete. principle of independent assortment - ANSWER- the principle stating that the inheritance of alleles residing on one pair of chromosomes does not affect the inheritance of alleles on a different pair of chromosomes
