Query: And some plants – like algae which use carbon for photosynthesis – may even benefit.

Relevant passages:
Carbon dioxide <=SEP=> Carbon dioxide ( chemical formula ) is a colorless gas with a density about 60 % higher than that of air ( 1.225 g/L ) that is odorless at normally encountered concentrations . Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms . It occurs naturally in Earth 's atmosphere as a trace gas at a concentration of about 0.04 percent ( 400 ppm ) by volume . Natural sources include volcanoes , hot springs and geysers , and it is freed from carbonate rocks by dissolution in water and acids . Because carbon dioxide is soluble in water , it occurs naturally in groundwater , rivers and lakes , ice caps , glaciers and seawater . It is present in deposits of petroleum and natural gas .   As the source of available carbon in the carbon cycle , atmospheric carbon dioxide is the primary carbon source for life on Earth and its concentration in Earth 's pre-industrial atmosphere since late in the Precambrian has been regulated by photosynthetic organisms and geological phenomena . Plants , algae and cyanobacteria use light energy to photosynthesize carbohydrate from carbon dioxide and water , with oxygen produced as a waste product .   Carbon dioxide is produced by all aerobic organisms when they metabolize carbohydrates and lipids to produce energy by respiration . It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals , including humans . Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars in bread , beer and winemaking . It is produced by combustion of wood and other organic materials and fossil fuels such as coal , peat , petroleum and natural gas .   It is a versatile industrial material , used , for example , as an inert gas in welding and fire extinguishers , as a pressurizing gas in air guns and oil recovery , as a chemical feedstock and in liquid form as a solvent in decaffeination of coffee and supercritical drying . It is added to drinking water and carbonated beverages including beer and sparkling wine to add effervescence . The frozen solid form of , known as `` dry ice '' is used as a refrigerant and as an abrasive in dry-ice blasting .   Carbon dioxide is the most significant long-lived greenhouse gas in Earth 's atmosphere . Since the Industrial Revolution anthropogenic emissions - primarily from use of fossil fuels and deforestation - have rapidly increased its concentration in the atmosphere , leading to global warming . Carbon dioxide also causes ocean acidification because it dissolves in water to form carbonic acid .

Cyanobacteria <=SEP=> Cyanobacteria -LSB- saɪˌænoʊbækˈtɪəriə -RSB- , also known as Cyanophyta , is a phylum of bacteria that obtain their energy through photosynthesis , and are the only photosynthetic prokaryotes able to produce oxygen . The name `` cyanobacteria '' comes from the color of the bacteria ( κυανός ( kyanós ) = blue ) . Cyanobacteria used to be incorrectly called blue-green algae , but being prokaryotes , the term `` algae '' in modern usage refers to eukaryotes .   Like other prokaryotes , cyanobacteria have no membrane-sheathed organelles . Photosynthesis is performed in distinctive folds in the outer membrane of the cell ( unlike green plants which use chloroplasts for this purpose ) . Biologists commonly agree that chloroplasts found in eukaryotes have their ancestry in cyanobacteria , via a process called endosymbiosis .   By producing oxygen as a byproduct of photosynthesis , cyanobacteria are thought to have converted the early oxygen-poor , reducing atmosphere , into an oxidizing one , causing the `` rusting of the Earth '' and the Great Oxygenation Event , that dramatically changed the composition of life forms and led to the near-extinction of anaerobic organisms .   Cyanobacteria are thought to eventually have evolved into plastids found in eukaryotic plants , which later differentiated into specialized organelles like the etioplast , leucoplast and the chloroplast .

Plant <=SEP=> Plants are mainly multicellular , predominantly photosynthetic eukaryotes of the kingdom Plantae .   The term is today generally limited to the green plants , which form an unranked clade Viridiplantae ( Latin for `` green plants '' ) . This includes the flowering plants , conifers and other gymnosperms , ferns , clubmosses , hornworts , liverworts , mosses and the green algae , and excludes the red and brown algae . Historically , plants formed one of two kingdoms covering all living things that were not animals , and both algae and fungi were treated as plants ; however all current definitions of `` plant '' exclude the fungi and some algae , as well as the prokaryotes ( the archaea and bacteria ) .   Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts , derived from endosymbiosis with cyanobacteria . Their chloroplasts contain chlorophylls a and b , which gives them their green color . Some plants are parasitic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize . Plants are characterized by sexual reproduction and alternation of generations , although asexual reproduction is also common .   There are about 300 -- 315 thousand species of plants , of which the great majority , some 260 -- 290 thousand , are seed plants ( see the table below ) . Green plants provide most of the world 's molecular oxygen and are the basis of most of Earth 's ecologies , especially on land . Plants that produce grains , fruits and vegetables form humankind 's basic foodstuffs , and have been domesticated for millennia . Plants play many roles in culture . They are used as ornaments and , until recently and in great variety , they have served as the source of most medicines and drugs . The scientific study of plants is known as botany , a branch of biology .

Algae <=SEP=> Algae ( -LSB- ˈældʒi , _ ˈælɡi -RSB- singular alga -LSB- ˈælɡə -RSB- ) is an informal term for a large , diverse group of photosynthetic organisms which are not necessarily closely related , and is thus polyphyletic . Included organisms range from unicellular genera , such as Chlorella and the diatoms , to multicellular forms , such as the giant kelp , a large brown alga which may grow up to 50 m in length . Most are aquatic and autotrophic and lack many of the distinct cell and tissue types , such as stomata , xylem , and phloem , which are found in land plants . The largest and most complex marine algae are called seaweeds , while the most complex freshwater forms are the Charophyta , a division of green algae which includes , for example , Spirogyra and the stoneworts .   No definition of algae is generally accepted . One definition is that algae `` have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells '' . Some authors exclude all prokaryotes thus do not consider cyanobacteria ( blue-green algae ) as algae .   Algae constitute a polyphyletic group since they do not include a common ancestor , and although their plastids seem to have a single origin , from cyanobacteria , they were acquired in different ways . Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria . Diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga .   Algae exhibit a wide range of reproductive strategies , from simple asexual cell division to complex forms of sexual reproduction .   Algae lack the various structures that characterize land plants , such as the phyllids ( leaf-like structures ) of bryophytes , rhizoids in nonvascular plants , and the roots , leaves , and other organs found in tracheophytes ( vascular plants ) . Most are phototrophic , although some are mixotrophic , deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy , myzotrophy , or phagotrophy . Some unicellular species of green algae , many golden algae , euglenids , dinoflagellates , and other algae have become heterotrophs ( also called colorless or apochlorotic algae ) , sometimes parasitic , relying entirely on external energy sources and have limited or no photosynthetic apparatus . Some other heterotrophic organisms , such as the apicomplexans , are also derived from cells whose ancestors possessed plastids , but are not traditionally considered as algae . Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a by-product of photosynthesis , unlike other photosynthetic bacteria such as purple and green sulfur bacteria . Fossilized filamentous algae from the Vindhya basin have been dated back to 1.6 to 1.7 billion years ago .

Botany <=SEP=> Botany , also called plant science ( s ) , plant biology or phytology , is the science of plant life and a branch of biology . A botanist or plant scientist is a scientist who specialises in this field . The term `` botany '' comes from the Ancient Greek word βοτάνη ( botanē ) meaning `` pasture '' , `` grass '' , or `` fodder '' ; βοτάνη is in turn derived from βόσκειν ( boskein ) , `` to feed '' or `` to graze '' . Traditionally , botany has also included the study of fungi and algae by mycologists and phycologists respectively , with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress . Nowadays , botanists ( in the strict sense ) study approximately 410,000 species of land plants of which some 391,000 species are vascular plants ( including ca 369,000 species of flowering plants ) , and ca 20,000 are bryophytes .   Botany originated in prehistory as herbalism with the efforts of early humans to identify -- and later cultivate -- edible , medicinal and poisonous plants , making it one of the oldest branches of science . Medieval physic gardens , often attached to monasteries , contained plants of medical importance . They were forerunners of the first botanical gardens attached to universities , founded from the 1540s onwards . One of the earliest was the Padua botanical garden . These gardens facilitated the academic study of plants . Efforts to catalogue and describe their collections were the beginnings of plant taxonomy , and led in 1753 to the binomial system of Carl Linnaeus that remains in use to this day .   In the 19th and 20th centuries , new techniques were developed for the study of plants , including methods of optical microscopy and live cell imaging , electron microscopy , analysis of chromosome number , plant chemistry and the structure and function of enzymes and other proteins . In the last two decades of the 20th century , botanists exploited the techniques of molecular genetic analysis , including genomics and proteomics and DNA sequences to classify plants more accurately .   Modern botany is a broad , multidisciplinary subject with inputs from most other areas of science and technology . Research topics include the study of plant structure , growth and differentiation , reproduction , biochemistry and primary metabolism , chemical products , development , diseases , evolutionary relationships , systematics , and plant taxonomy . Dominant themes in 21st century plant science are molecular genetics and epigenetics , which are the mechanisms and control of gene expression during differentiation of plant cells and tissues . Botanical research has diverse applications in providing staple foods , materials such as timber , oil , rubber , fibre and drugs , in modern horticulture , agriculture and forestry , plant propagation , breeding and genetic modification , in the synthesis of chemicals and raw materials for construction and energy production , in environmental management , and the maintenance of biodiversity .