What is phototropism in plants?
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| 1 | What is phototropism in plants? |
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Learn how plants detect and respond to environmental stimuli and stressors.
Phototropism is the growth response of a plant toward or away from light, typically caused by the differential distribution of the hormone auxin, which promotes cell elongation on the shaded side. |
| Think of plants 'seeking' light |
| 2 | Which hormone primarily mediates positive phototropism? | Auxin, which accumulates on the shaded side of the plant, promotes cell elongation leading to bending toward the light source. | Remember 'A' for Auxin and 'A' for Attraction to light |
| 3 | How do stomata help plants respond to water stress? | Stomata regulate gas exchange and water loss; during water stress, plants often close stomata to conserve water, reducing transpiration. | Think of stomata as water-saving valves |
| 4 | What is hydrotropism? | Hydrotropism is the growth response of plant roots toward water sources, helping them access moisture in the soil. | Roots 'search' for water |
| 5 | How do plants detect water availability in their environment? | Plants sense soil moisture through changes in turgor pressure and water potential, triggering responses such as root growth toward moist areas. | Water availability influences plant 'turgor' and growth |
| 6 | What is a stress response in plants to drought conditions? | Plants respond to drought by closing stomata, synthesizing abscisic acid (ABA) to signal stress, and developing deeper roots to access water. | ABA is a key drought hormone |
| 7 | Describe how plants respond to excessive light exposure. | Plants can protect themselves from high light intensity by producing protective pigments (e.g., anthocyanins), reducing chlorophyll content, or adjusting leaf orientation to minimize damage. | Think of plants as 'sunglasses' for intense light |
| 8 | What role does the hormone abscisic acid (ABA) play in plant stress responses? | ABA is a key signaling molecule during stress conditions like drought; it promotes stomatal closure and induces stress-related gene expression to conserve water and protect the plant. | ABA = 'Anti-drying' hormone |
| 9 | How do plants adapt to waterlogged conditions? | Plants may develop aerenchyma (air spaces), form adventitious roots, or produce fermentation enzymes to survive low oxygen levels caused by waterlogging. | Think of 'aerenchyma' as internal 'air channels' |
| 10 | What is thigmotropism? | Thigmotropism is the growth response of plants to touch or physical contact, seen in climbing vines that wrap around supports. | Touch guides growth |
| 11 | How does light quality (wavelength) influence plant responses? | Plants detect different light wavelengths through photoreceptors; for example, red and far-red light influence seed germination and shade avoidance responses. | Think of photoreceptors as 'light sensors' |
| 12 | What is the shade avoidance response in plants? | When exposed to low red to far-red light ratios, plants detect shade and respond by elongating stems and leaves to outgrow competitors. | Plants 'seek the sun' when shaded |
| 13 | How do plants respond to cold stress? | Plants can increase production of antifreeze proteins, alter membrane fluidity, and accumulate solutes like sugars to prevent ice formation inside cells. | Think of 'antifreeze' proteins |
| 14 | What is the function of reactive oxygen species (ROS) in plant stress responses? | ROS are produced under stress conditions; at controlled levels, they act as signaling molecules to activate defense mechanisms, but excessive ROS can cause cellular damage. | Balance is key: ROS as 'double-edged sword' |
| 15 | Why do some plants develop thicker leaves or cuticles under stress? | Thicker leaves and cuticles reduce water loss and protect against environmental damage like UV radiation and desiccation. | Physical barriers for survival |
| 16 | What is the role of osmolytes in plant water stress tolerance? | Osmolytes like proline and glycine betaine help maintain cell turgor and protect cellular structures during dehydration. | Osmolytes act as 'cellular protectants' |
| 17 | How do plants detect and respond to light direction? | Plants use photoreceptors to detect light direction, causing differential growth that results in bending toward the light source (phototropism). | Photoreceptors 'sense' where the light is coming from |
| 18 | What adaptive feature helps desert plants conserve water? | Many desert plants have succulent tissues, extensive root systems, reduced leaf surface area, or spines instead of leaves to minimize water loss. | Desert 'survival structures' |
| 19 | How does increased CO₂ concentration affect plant water use efficiency? | Higher CO₂ levels often enhance photosynthesis and allow plants to keep stomata closed longer, reducing water loss and increasing water use efficiency. | CO₂ helps plants 'breathe better' with less water |
| 20 | What is the significance of circadian rhythms in plant responses? | Circadian rhythms regulate daily cycles in processes like opening and closing of stomata, optimizing water use, and anticipating environmental changes. | Internal 'biological clock' for plant timing |
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