plant bio exam3

Auxin

Plant hormone that promotes growth through cell elongation

Phototropism

Growth of a plant toward light

Gravitropism

Growth of a plant in response to gravity

Auxin distribution

Moves to the shaded side of the plant shoot

Auxin function

Causes cells on shaded side to elongate, bending plant toward light

Auxin location

Found at the tip of plant shoots

Ethylene

Gas plant hormone that controls fruit ripening

Ethylene signaling

Released during plant wounding to signal nearby plants

Ethylene property

Only plant hormone that is a gas

Gibberellins

Hormones that promote rapid growth and seed germination

Gibberellins function

suppressing growth suppressors

Gibberellins excess

Causes excessive growth with no fruit production (“foolish seedling disease”)

Abscisic Acid (ABA)

Plant hormone that slows growth and responds to stress

ABA function

Closes stomata during drought

ABA role

Induces seed dormancy and prevents germination

ABA trigger

Activated by environmental stress like drought or temperature

Rhizosphere

Soil region surrounding plant roots

Rhizobium

Bacteria that live in roots and help plants

Rhizobium function

Fix nitrogen into usable forms for plants

Nitrogen fixation

Conversion of nitrogen gas into usable ammonia

Nitrogenase

Enzyme used by microbes to fix nitrogen

Siderophores

Molecules that capture iron for plant use

Metal detoxification

Microbes absorb toxic metals to protect plants

Plant hormone production (microbes)

Bacteria can produce auxin to enhance root growth

Bacteria (plant benefits)

Improve nutrients, protect against toxins, and produce hormones

Ice nucleation bacteria

Cause plants to freeze more easily

Disease triangle

Pathogen, host, and environment required for disease. refers to the shape of the sporangia during a phytophthora infestans infection

Pathogen

Disease causing organism

Host

Plant susceptible to disease

Environment

Conditions that allow disease to occur

Phytophthora infestans

Pathogen causing Irish Potato Famine

Monoculture

Growing genetically identical crops

Monoculture risk

Increases disease susceptibility

R genes

Plant resistance genes that detect pathogens, but they do not engulf the pathogen

R gene specificity

Each recognizes a specific pathogen

Plant immunity

Requires pathogen detection before defense

Programmed cell death

Killing infected cells to stop pathogen spread

Hypersensitive response

Localized cell death to stop infection

Virus

Nonliving pathogen that requires host cells

Virus replication

Hijacks host machinery

Virus type (plants)

Biotrophic (needs living tissue)

Necrotroph

Pathogen that feeds on dead tissue

Hyphae

Single-celled fungal filaments

Hyphae transport

Move nutrients in multiple directions

Mycelium

Network of hyphae forming main fungal body

Fruiting body

Visible mushroom structure

Fungi nutrition

Secrete enzymes outside cells to digest material

Arbuscules

Fungal structures inside roots for nutrient exchange

Fungi plant symbiosis

Fungi provide nutrients to plants

Non photosynthetic plants

Some plants obtain nutrients parasitically or via fungi

Lichens

very slow-growing but very hardy and can grow on bones, rubber, and in the presence of toxins

Lichens property

Extremely slow growing and hardy

Pollen

Produced in anthers for plant reproduction

Pollen transport

Spread by wind or animals

Pollen tube

Grows to deliver sperm to ovule

Exine

Outer layer of pollen

Sporopollenin

Tough biopolymer strengthening exine

Aperture

Opening in pollen for sperm release

Pollination

Transfer of pollen to stigma

Volatile compounds

Chemicals that evaporate and spread scent

Petal color

Attracts pollinators

UV markings

Invisible signals that attract insects

Crinkled petal cells

Create iridescent effect

Cone shaped cells

helps insects grip flowers

Mimicry (flowers)

Imitate organisms to attract pollinators

Nectar

Sugar reward for pollinators

Secondary metabolites

Chemicals used for defense or attraction

Primary metabolites

Essential compounds for growth (e.g., sugars)

Alkaloids

Compounds affecting nervous systems, often toxic

Alkaloid examples

Caffeine, nicotine, cocaine

Trichomes

Hair like structures that deliver toxins

Cyanide (plants)

Toxic compound found in seeds

Cyanide location

Almonds, apple seeds, pits

Cyanide effect

Kills herbivores and can harm livestock

Glucosinolates

Defensive compounds in Brassica plants released upon damage, makes them taste bitter

Glucosinolate trigger

Released when plant tissue is damaged

Evolutionary arms race

Adaptation between plants and herbivores

Tannins

Compounds that reduce digestibility via astringency, potent and found in large quantities

Astringency

Drying sensation caused by tannins binding proteins

Terpenes

Volatile compounds producing plant scents

Terpene release

Triggered by wounding or crushing

Plant signaling (defense)

Ethylene and jasmonate signal defenses

Jasmonate

Hormone signaling herbivore attack

Wood composition

Made of cellulose and lignin

Cellulose

Provides tensile strength in plants

Lignin

Provides rigidity and waterproofing

Suberin

Waterproof compound in cork

Cork

Outer protective tissue containing suberin

Cambium

Stem cells that produce wood

Vascular cambium

Produces wood (lignin

Cork cambium

Produces bark (suberin

Tree rings

Formed by cambium growth over time

Boreal forest

Largest terrestrial biome

Deforestation

Removal of forests for agriculture or industry

Climate change (forests)

Causes drought, pests, and fires

Pine beetles

Pests that increased due to warmer winters

Warmer winters

Allow pests to survive and spread

Drought

Dries forests and increases fire risk

Wildfires

More common due to dry conditions and climate change

Isoprene

5-carbon diene building block of plant compounds and rubber.