Horticulture Exam 1

Annual Plant

Completes its life cycle in one season and dies

Biennial Plant

Completes its life cycle in 2 seasons and dies

Perennial Plant

Lives for more than 2 years, in cold climates seasonally dies back to its below-ground structures

Woody Plant

Produces wood as a structural tissue, has hard stems

Herbaceous Plant

Never forms wood

Shrub

Woody plant smaller than a tree

Invasive Species

An introduced organism that overwhelms and harms it new environment

Native Species

Indigenous to a given region/ecosystem

Aggressive Species

Not invasive but grows rapidly

Hardy

Tolerant to hrash conditions, like freezing temperatures, drought, or disease

Deciduous

Tree or shrub that sheds its leaves annually

Evergreen

Retains green leaves throughout the year

Angiosperm

Flower and fruit bearing plant

Gymnosperm/Conifer

Cone bearing plant

Cotyledon

First leaves on germinating seedling, will fall off as “true” leaves form

Monocot

• One cotyledon at shoot

• Parallel veins

• Ex. grasses, orchids, bananas

Eudicot

• Two cotyledons at shoot

• Branching veins like most broad-leafed tree

Which step of photosynthesis is also referred to as the Calvin Cycle? Would you describe the Calvin Cycle as efficient – why or why not?

The dark reaction of photosynthesis that occurs in the stroma is also referred to as the Calvin Cycle. The Calvin Cycle is inefficient because the key enzyme RuBisCO often mistakenly binds oxygen instead of CO₂, causing photorespiration that wastes energy and can reduce photosynthetic efficiency. Additionally, RuBisCO is a slow enzyme, requiring plants to produce massive amounts of it to compensate.

Calvin Cycle

1) CO₂ combines with (RuBP) to form unstable 6 carbon molecule

2) Immediately breaks down 2 molecules of gycerate-3-phosphate, 3 carbons per molecule

3) Ribulose biphosphate regenerated and glucose and fructose produced

Meristematic Tissue

Group of undifferentiated cells that can keep dividing to form new cells

Roots

• Anchor and support plant

• Absorb minerals, water, and oxygen along their entire length

• Grow and branch continuously

  • Root hairs help increase surface area

Mycorrhizae

• Symbiotic soil fungus

• Hyphae extend into the soil, helping the plant mine for minerals

  • Fine enough to reach into mesopores

• Attracted to sugary mucilage on roots

• Ecto- —> grow around plant roots

• Endo- —> grow into plant roots

Nitrogen Fixing Bacteria

• Invade legume roots

  • Live inside root nodule

• Convert nitrogen gas from atmosphere into nitrogenous salts

• Surrounding soil is higher in available nitrogen

  • Plants use as fertilizer

• Extract sugar from plant in exchange

Macronutrients

• H₂O

• CO₂

• O₂

• N

• P

• K

• Mg

• Ca

• S

Micronutrients

• Fe

• Mn

• Cu

• Zn

• B

• Cl

• Mo

• Ni

Electric Conductivity (EC)

• Measure of the total dissolved salts in a solution

• Low EC —> poor nutrition (chemical fertilizers are salts)

• High EC —> nutrient toxicity

Soil Formation

• Weathering of rocks through physical and chemical degradation over millions of years

• 5 factors

  • Parent material

  • Relief or topography

  • Organisms (including humans)

  • Climate

  • Time

Nutrient toxicity

• Overuse of nutrients can be toxic

• Symptoms

  • Chlorosis and necrosis at leaf tip

    • Plant shunts excess nutrients to farthest extremity, pushing it away from vascular system

How did photosynthetic organisms alter Earth’s atmosphere

• Increased atmospheric O₂ levels converted to O₃ (ozone layer)

  • Protects life on Earth from UV radiation

  • Allowed for aerobic respiration

    • Emergence of eukaryotes

Why did plants colonize land?

Land provides light, CO₂, O₂, and minerals at higher concentrations