Plant Nutrition & Nutrient Acquisition

Chapter 37: Plant Nutrition

• Plants can engage in limited carnivory by exploiting other organisms for nutrients, as suggested by a study where Arabidopsis and tomato plants took up and digested bacteria and yeast.
• Microorganisms may provide only a tiny fraction of a plant's nitrogen needs, though this may vary among plant species.

Concept 37.1: Soil as a Complex Ecosystem

• Soil contains particles of various sizes from rock breakdown, affecting water, oxygen, and mineral availability.
• Soil composition includes inorganic and organic components, forming a complex ecosystem with bacteria, fungi, protists, animals, and plant roots.
• Agricultural practices can deplete soil mineral content, tax water reserves, and promote erosion; soil conservation aims to minimize this damage.

Concept 37.2: Plant Roots and Essential Elements

• Macronutrients, required in large amounts, include carbon, oxygen, hydrogen, and nitrogen, serving as major ingredients of organic compounds.
• Micronutrients, required in small amounts, typically function as enzyme cofactors.
• Mobile nutrient deficiencies affect older organs more, while less mobile nutrient deficiencies affect younger ones.
• Macronutrient deficiencies, especially of nitrogen, phosphorus, and potassium, are most common.
• Genetic engineers are tailoring plants to match the soil.

Concept 37.3: Plant Nutrition and Organism Relationships

• Rhizobacteria in the rhizosphere, microorganism-enriched ecosystems associated with roots, obtain energy from plant secretions.
• Some rhizobacteria produce antibiotics, others enhance nutrient availability for plants; most are free-living, but some live inside plants.
• Plants acquire most nitrogen from bacterial decomposition of humus and fixation of gaseous nitrogen.
• Nitrogen-fixing bacteria convert atmospheric N₂ to nitrogenous minerals usable by plants.
• Mutualism between plants and nitrogen-fixing Rhizobium bacteria in legume root nodules involves bacteria obtaining sugar from the plant and supplying fixed nitrogen.
• Legume crops are rotated to restore soil nitrogen.
• Mycorrhizae, mutualistic associations of fungi and roots, involve fungal hyphae absorbing and supplying water and minerals to the plant.

Chapter 39: Plant Responses

Concept 39.1: Signal Transduction Pathways

• Signal transduction pathways link signal reception to response, involving reception, transduction, and response stages within cells.
• Signal transduction pathways enhance enzyme activity through post-translational modification of preexisting proteins or transcriptional regulation.

Concept 39.2: Plant Hormones

• Hormones control plant growth, development, and responses to stimuli by affecting cell division, elongation, and differentiation.
• Auxin stimulates cell elongation, regulates branching and organ bending.
• Cytokinins stimulate cell division, promote later bud growth, and slow organ death.
• Gibberellins promote stem elongation and help seeds break dormancy.
• Abscisic acid promotes stomatal closure in response to drought and seed dormancy.
• Ethylene mediates fruit ripening and the triple response.
• Brassinosteroids induce cell elongation and division, similar to animal sex hormones chemically.
• Jasmonates mediate defenses against insect herbivores and regulate a range of physiological processes.
• Strigolactones regulate apical dominance, seed germination, and mycorrhizal associations.

Concept 39.3: Light Responses

• Blue-light photoreceptors regulate hypocotyl elongation, stomatal opening, and phototropism.
• Phytochromes act like molecular "on-off" switches that regulate seed germination and shade avoidance.
• Phytochrome conversion provides flowering time information.
• Photoperiodism regulates flowering time.
• Short-day plants require a longer night.
• Long-day plants need a shorter night to flower.
• Daily rhythms are controlled by internal circadian clocks.
• Circadian rhythms are approximately 24 hours but entrained to dawn and dusk effects on phytochrome form.

Concept 39.4: Stimulus Responses

• Gravitropism is bending in response to gravity.
• Roots positive gravitropism, stems negative.
• Statoliths enable roots to detect gravity.
• Thigmotropism is a growth response to touch.
• Rapid leaf movements utilize electrical impulses.
• Plants sensitive to environmental stresses like drought and salinity.
• Drought responses include closing stomata.
• Flooding forms air tubes that improves oxygen.

Concept 39.5: Pathogen/Herbivore Responses

• Hypersensitive response seals off infection
• Generalized defense response in distant organs
• Systemic acquired resistance.

Chapter 40: Animal Form and Function

Concept 40.1: Animal Form and Function

• Physical evolution constraints body size
• Each cell needs aquous environment
• Animal body based on hierarchy tissue/organs
• Endocrine and nervous system communicating

Concept 40.2: Feedback Control

• Regulator controls internal variable
• Conformer changes with stimuli
• Homeostasis maintains steady state

Concept 40.3: Thermoregulation

• Endo gets heat by metabolism whereas ecto gets from outside
• Endo needs more energy expenditure
• Body temp varies like poikilotherms or constantly for homeotherms
• Heat gain/loss occurs

Concept 40.4: Energy Requirements

• Energy from food for chemical energy
• Animal metabolic rate
• Metabolic rate inversely related
• Animals allocate energy
• Torpor conserves energy.

Chapter 41: Animal nutrition

Concept 41.1: Diet supplies chemicals:

• Hervibores eat plants etc
• Animals use food for energy
• Must get amino acids and fatty acids that cannot synthesize
• Vitamins organic and minerals are inorganic

Concept 41.2: processing Ingestion

• Digestion is necessary to avoid self digestion
• Extracellular happens outside cells

Concept 41.3: Mammalian digestive system

• Food passes through mouth

Concept 41.4:

• Bodies correlate with diet adaptions
• Teeth for dentition

Concept 41.5

• Nutrition regulated at different levels
• Glucose availability
• Vertebrates store stored energy

Explore plant nutrition, focusing on nutrient uptake methods and the rhizosphere's role. Delve into symbiotic relationships and the significance of studies broadening our understanding of plant nutrition. Discover the implications of plants uptaking bacteria and yeast, and the advantages of small pore size in cell walls for phagocytosis.