Plants Pt2 Flashcards
(30 cards)
What are stomata? and what are they made of (two cells that do what)
tiny pores found in the plant epidermis (mouth) that performs gas exchange = close and open relating to hydration of plant
Made of Guard Cells = the two cells on either side of the stomata opening. Their chloroplasts create glucose from photosynthesis, causing water to enter through the cell and gausing the guard cell to swell (through controlling carbs)
What do stomata do during the day vs night?
Photosynthesis during the day = stomata open, glucose formed
Respiration during night = stomata closed, glucose used to form ATP, carbon dioxide, and water
Explain Xylem through transpiration:
XYLEM - moves the water and minerals from roots to leaves (transpiration)
Transpiration - water evaporates through stomata causing negative pressure to form “transpiration pull.” Water diffuses. Able to move upwards as each water molecule is linked to each other (passive transport)
Increases with: high temperature and wind, and low humidity
Explain Phloem through translocation:
moves sugars (amino acids) from leaves (source) to other needy places (sinks). Translocation
Translocation - companion cells offer support and energy. Sieve tubes allow flow of nutrients. The source sugars are moved to the sink. Requires ACTIVE TRANSPORT
Explain the 3 steps of root uptaking minerals through cation exchange:
Roots release CO2 from respiration and acidifying the soil (H+) ions
H+ displaces mineral cations on the soil particles
Roots absorb the released mineral cations through root hairs
What is a parasitic plant?
A plant that gets at least some if not all its nutrients from another plant
Parasitic plants (e.g. mycoheterotrophic (use fungus), haustorial (directly from plants) Holoparasites (don’t use photosynthesis), and hemiparasites (photosynthesize) - use other plants to get the nutrients they need. Many different types!
Waht are carnivorous plants? Whcih nutrient do they typically recieve from what?
Carnivorous plants - through trapping and eating animals or insects, but still are able to photosynthesis. Often live in nitrogen-poor soils (get nitrogen from digestion of insects and whatnot)
Impacts of nutrient deficiencies (nitrogen, phosphorus, and potassium)
Nitrogen = chlorosis, yellowing of the leaves
Phosphorus = purpling on the underside of leaves
Potassium = scorching on edges and ends of leaves.
Explain the symbiotic relatinoships between legumes and nitrogen-fixing bacteria
Nitrogen is very hard to obtain for plants as it’s in the atmosphere as N2 with very strong triple bonds. Nitrogen fixing bacteria are able to fix the atmospheric nitrogen into ammonia with hydrogen.
What is the pathway from atmospheric N2 to nitrogen the plant can absorb
atmospheric N2 –> Soil nitrogen-fixing bacteria → NH3 (ammonia) + H+ cation → NH4+ (ammonium) → NO2- (nitrite) → NO3- (nitrate) through nitrifying bacteria
What is the rhizobium and what are the steps to encorporate the nitrogen-fixing bacteria inside the plant?
Rhizobium - mutualistic symbiotic, nitrogen fixing, foot nodules containing rhizobacteria.
- Root signals from plant attract rhizobium bacteria
- Infection thread allows bacteria to infect plant root cortex to stimulate cell division
- Nodule formation differentiates into Nitrogen-fixing bacteria
Waht is mycorrhizae?
Mycorrhizae - mutualistic extensive fungal network (free-living bacteria)
How does mycorrhizae support plant growth?
The fungus is able to receive sugars while the plant receives nutrients through either ectomycorrhiza (hyphae go around cells) or endomycorrhiza (arbuscular) - (penetrate into cells)
Enhances nutrient and water uptake, improves soil structure, and increases plant resilience to stress. Mycorrhizae acts as an extension of the plant root systems, increasing surface area, and thus absorption. Phosphorus is able to be accessed through mycorrhizae , which helps the plant grow.
What are the different definitions for mycorrhiza, hyphae, and mycelium?
Mycorrhiza - symbiotic association between roots of plants and fungi
Hyphae - group of long, thread-like structure that makes up the mycelium of fungi
Mycelium - network of hyphae
waht does the casparian strip do?
Casparian strip helps block out unnecessary and toxic material, and prevents leakage of solution out of the root by forcing solutions to go through a living cell membrane into the xylem.
what is tropism? what are some exaples?
Tropism - directional movements towards (positive) or away (negative) from an environmental cue
Gravitropism, phototropism, chemotropism, hydrotropism, thigmotropism, etc.
give a brief overview of the discovery of auxin and what it does:
- Darwin (1880) - explored phototropism phenotype - found bending only on top bit of plant shoot (“Darwin’s Influence” = where the plant tips or parts are covered and growth is observed)
- Boysen-Jensen - cut tip, put agar or mica, and replaced the tip (only agar allowed signals through, showing signals are water soluble.
- Fris Went (1926) - agar auxin block, growth straight vs curved and named “auxin”
What are the steps of stimulus to response in plants?
- Stimulus - something in the environment changed
- Receptor - in the plasma membrane (involving receptor and hormone or environmental stimulus)
- Tranduction - inside the cytoplasm (involving relay proteins and second messengers
- Response - activation of cellular responses inside the cytoplasm
Explain the whole process of phototropin to auxin production of plant cell walls
Example: “Phototropin senses blue light (from the wavelengths around 320-500) and causes a conformational change by activating kinase. This moves the phototropin from the inactive form to the active form to help bend the plant through the transduction pathway (the phosphorylation of proteins). The transduction pathway continues to the steps of activating transcription in the plant cell nucleus, then translation to produce proteins or genes that help to increase auxin production to then loosen microfibril in the plant cell wall.”
What si a hormone? How does it stimulate cellular responses?
Hormones - mobile signalling molecules, produced in low concentrations by one part of an organism’s body and transported to other parts, where it binds to a specific receptor and triggers responses in target cells and tissues, and are internal regulators of plant growth.
What is a phytohormone vs phototreceptor vs phototropin vs phytochrome?
Phytohormone - plant hormone (e.g. auxin)
Photoreceptor - receptor molecules used to detect light by absorbing a photon of light
Phototropins - photoreceptors that sense blue light wavelengths (320-500)
Phytochromes - photoreceptors that sense red light wavelengths (600-750)
What is photomorphogenesis?
plant developmental responses to light signals (e.g. seed germination, stem elongation, leaf expansion, and shade avoidance) that is motivated by phytochromes sensing red and far-red light.
explain the phytochrome red light activation:
Phytochromes activated by red light change over to Pfr (far-red), which produces less auxin ⇒ Low inhibition of phytochrome (inactive form) produces high amounts of auxin. High inhibition of phytochrome (active form) decreases the amount of auxin produced.
high FR ==>
Low Red: Far-red ratio
