Collab worksheet bio – Flashcards
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Tomato plants grown in shade show increased susceptibility to herbivory by insects compared to plants grown in light. If this effect is mediated by phytochrome, then which of the following is/are true? The increased susceptibility to herbivory of shade grown tomato plants will be reversed by exposure to far-red light. The increased susceptibility to herbivory of shade grown tomato plants will be reversed by exposure to red light. Phytochrome-deficient mutants will be less sensitive to herbivores
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Both a and c are true
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If a plant flowers in a controlled changer with a daily cycle of 10 hours of light and 14 hours of darkness, is it a short day plant?
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Yes because they require less amount of daytime than nighttime.
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Spraying plants daily with compound X causes dwarfism, compared with untreated control plants. Is this evidence sufficient to conclude that compound X is a plant hormone?
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No, plants must synthesize compound X at physiologically active concentrations.
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To test whether increased carbon dioxide increases plant growth, a traditional experiment is to have a biologist breathe on one group of plants and not breathe on a control group of plants. Plants that have been breathed upon often accumulate greater biomass. What is wrong with concluding that this extra growth is a result from the increase in carbon dioxide
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More CO2, limits ethylene production -> more growth due to being indirectly more CO2. CO2 inhibits synthesis of new ethylene which means there is less inhibition of stem elongation. (not just CO2)
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Discuss how heliotropism differs from phototropism
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Heliotropism: growth toward sun light; phototropism: any reactions toward a source of light. Heliotropism is the daily movement of plant parts in response to direction of light. Phototropism is the growth of a shoot toward light or away from it. i.e. heliotropism refers to plant locomotion in response to where the light is, phototropism is the growth of that plant toward/away from light.
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Why do houseplants placed by a window grow towards the window (explain in terms of tropisms and hormones)? How can you prevent this bending?
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Phototropism and auxin. Remove coleoptile tip or separating by the impermeable membrane. Or you could rotate the plant daily.
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The roots of strangler figs exhibit positive gravitropism. Which way do the roots grow: towards the ground or towards the sky?
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towards the ground
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After a vacation to Antarctica,you decide to do an experiment. Inspired by the Antarctic pearlwort (Colobanthus quitensis), one of the two flowering plant species in Antarctica, you wondered whether a seed of a plant that was native to Washington could break dormancy in Antarctica. What type of plant hormone would you use?
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strigolactones
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Prior to genetic engineering, tomatoes were picked green and stored for long periods of time. Before being shipped to the grocery store, the tomatoes were exposed to the hormone (BLANK) to promote their ripening.
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Ethylene
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Gregor Mendel found that some of his pea plants were short (dwarfs) and others were tall. If he had wanted to reverse the dwarfism in the plants, what could he have done?
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Gibberellins
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When clipped willow branches are placed in "root hormone" they produce new roots. "Root hormone" is a synthetic version of the natural plant hormone
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Iba (The natural auxin indolebutyric acid.)
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A sprouting corn seedling, growing in the dark, was rotated 90 degrees to the right ( see image to the right and note the shoots and roots). Predict how the seedling will respond in 24 hours
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just sideways
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You notice that the flowers of a previously unidentified plant close when people are talking, yet are open when the lab is quiet. You suspect that this plant may have the ability to hear! Based on what you know about plant sensory systems, which of the following hypotheses could explain this phenomenon?
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Hairs on epidermal cells bend in response to sound, triggering an action potential in epidermal cells. Action potential: the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.
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True or False? Thigmomorphogenesis allows roots to navigate around rocks in order to seek water.
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FALSE (Triple response that enables the shoot to avoid the response.) Thigmomorphogenesis is the response by plants to mechanical sensation (touch) by altering their growth patterns. In the wild, these patterns can be evinced by wind, raindrops, and rubbing by passing animals. Triple Response: When there is mechanical stress on the stem of a plant (e.g. pushing against a rock. above as it is sprouting) Ethylene is produced. Ethylene instigates seedling to perform growth maneuver called Triple Response. Triple response allows stem to go around an object above.
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True or False? Abscisic Acid plays a key role in leaf abscission?
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TRUE
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What is the specific term that refers to seasonal changes in the relative lengths of night and day? Circadian rhythm Chemotaxis Phototaxis Photoperiod "the period of daylight/night in every 24 hours, especially in relation to its effects on plants and animals" Photrophism
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either circadian or photoperiod
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You are growing cucumbers in your kitchen window. Although you lack pollinators (the yellow flowers typically attract bees and other insects that you don't want inside), you spray a synthetic auxin on your plants and voila, you get fruit (cucumbers)! However, upon closer examination you find that these fruits do not form _____.
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mature seeds
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Instead of a wood or metal fence, you plant a hedgerow between your and your neighbor's yards. To maximize privacy, you want the shrubs in your hedgerow to be very bushy. What is the best way to achieve this? _____. Are scientists certain of the mechanism by which this occurs?
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Clip the apical buds; no
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You plant some seeds in winter. Why don't they germinate immediately?
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The seeds contain too much abscisic acid to germinate.
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The hormones involved in controlling plant growth in response to age or environmental conditions include auxin, gibberellins, cytokinins, ABA, and ethylene. Which of the following statements best summarizes how these plant growth regulators work?
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It is common for a single hormone to affect many different target tissues, and in most cases individual hormones interact with other hormones to effect a response.
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Auxins are responsible for which of the following tropisms: Phototropism, Gravitropism, Thigmotropism?
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Phototropism, Gravitropism
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Pea tendrils will often wrap around a wire support (or other plants). What is this response called?
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Thigmotropism: directional growth in response to touch
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Shoots that grow vertically toward the sun can be characterized as _____.
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Positively phototropic and negatively gravitropic
