Plant Physiology - What Kinds of Things Do Plants Do? How Do They Live, etc - Lecture Notes

Sep 8, 2026

Plant physiology explains how plants survive and function by coordinating water and nutrient transport, photosynthesis and respiration, growth and reproduction, and defense against herbivores and pathogens. Plant activity is strongly shaped by environmental conditions such as light, temperature, gravity, and nutrient and water availability, as well as disease. It also outlines characteristic plant activities including seed germination, flowering, stomatal opening/closing, tropisms, and different forms of plant movement, linking these behaviors to internal chemistry and gas exchange.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages17

Reading Time43 min

AccessFree to download

Plant Physiology

Core plant functions

Environmental factors affecting plant activities

Plant activities characteristic of many species

Plant chemistry

Photosynthesis

Gas exchange & aerobic respiration

Chemical plant products

Plant Physiology What kinds of things do plants DO? how do they live, etc plants must find water and nutrients and transport them to where they are needed within the plant carry out photosynthesis & respiration grow and reproduce protect themselves from herbivores & pathogens a plant’s ability to do these things is strongly affected by the environment in which it live plants respond to a variety of environmental conditions Some of the most important environmental factors that affect plant activities include: 1. Light (photoperiod) 2. Temperature 3. Gravity 4. Nutrient and Water availability 5. Disease The interactions of these environmental factors with the basic functions of a plant result in a variety of activities characteristic of many plant species 1. Seed germination 2. Growth (stems, roots, leaves, buds, etc) 3. Flowering 4. opening and closing of stomata 5. tropisms (permanent changes in position of plant or parts) 5. plant movements (temporary quicker changes in positions) 6. “sleep” movements Plant Chemistry Photosynthesis probably the most characteristic set of chemical reactions that occur in plants = the manufacture of food, usually sugar, mainly glucose from carbon dioxide and water in the presence of chlorophyll Plants: Plant Physiology , Ziser Lecture Notes, 2005 1 light CO2 + H2O sugar + O 2 chlorophyll (glucose) converts light energy to chemical bond energy this trapped energy can later be used by the organism for synthesis reactions or other energy requiring activities photosynthesis requires carbon dioxide & water CO2 enters through stomata or pores water is absorbed through roots the light sensitive pigment in plants and algae is chlorophyll this chlorophyll is contained with the chloroplasts glucose can serve as a long term energy storage molecule it can also be easily transported throughout plant a. Carbon Dioxide stomata must be open anything that causes the stomata to close could affect photosynthesis b. Water must be continuous supply of water available more difficult in drought areas c. Light amount of light affects rate of photosynthesis d. Salts osmotic stress fertilizer burn prevents absorption esp in hot dry areas, irrigation Plants: Plant Physiology , Ziser Lecture Notes, 2005 2 Gas Exchange & Aerobic Respiration the two main gasses involved in plant metabolism are oxygen gas and carbon dioxide gas gas exchange and transport in plants is usually a process of simple diffusion 􀀡 moving from a higher to a lower concentration plants absorb and release both O2 and CO2 during the processes of photosynthesis and aerobic respiration Photosynthesis: 􀀡plant cells absorb CO2 needed for photosynthesis through the stomata 􀀡 O2 is made during photosynthesis and some of it is released through the stomata Aerobic Respiration: 􀀡plant cells need constant supply of O2 to break down sugars for energy 􀀡CO2 is produced during respiration and excess is released through stomata Aerobic Respiration products of photosynthesis, sugars or starch are broken down as needed for energy to power metabolism 􀀡 Aerobic Respiration requires oxygen to release this energy from the sugars made during photosynthesis photosynthesis makes some oxygen 􀀡 some is released into air through stomata as a waste product 􀀡 some is used by leaf cells for respiration additional oxygen needed by the plant is taken in in several ways: a. stomata Plants: Plant Physiology , Ziser Lecture Notes, 2005 3 herbaceous plants have stomata on leaves and stems to get O2 in b. lenticels woody plants have lenticels to get air to stem cells c. pneumatophores some plants that grow in stagnant water or water logged soil have specialized structure called pneumatophores to get O 2 to root cells Chemical Plant Products Plants produce a large number of chemicals during their normal metabolism: 1. Primary Plan

FAQs

What are primary and secondary plant products?

Primary plant products are required for basic survival and include sugars, amino acids, proteins, nucleic acids, cellulose, lignin, and hormones. Secondary plant products are not critical for basic functions; they include compounds such as alkaloids that may defend the plant, affect germination, regulate growth, or have medicinal and toxic effects.

Sep 8, 2026

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