plant science final

Be able to identify and describe the four major flower parts that make a complete flower.

Primary Flower parts

 • Petals 

• Sepals

• sometimes sepals look like petals

• Provides protection

• Calyx refers to all the sepals in a flower

pistil

• Stigma- where the pollen attaches at the top

• Style- tube part

• Ovary- in the actual flower

 Stamen 

• Anther- top parts

• Filament- tube parts that attach anther to flower

Imperfect flowers

• Staminate (only male) vs. pistillate (only female) flower

• Monoecious (have a staminate and pistillate flower on the same plant) vs. dioecious (whole plant will be only male or female)

What do the terms staminate flower and pistillate flower mean?

• Imperfect flowers

• Staminate (only male) vs. pistillate (only female) flower

Be able to identify the characteristics of flowers pollinated by: bees, wind, moths

Bees- Flower color- blue or yellow

• Flower structure- petals showy with nectar guides visible in UV light

• Nectar- yes

• Odor- sweet

b. Wind- Pine trees, oak trees

• Flower structure- exposed anthers and stigmas, feathery stigmas in some to release pollen

• Flower color- dull

• Nectar- no

• Odor- odorless

c. moths- Flower color- white

• Flower structure- petals used as landing platforms, have long floral tubes to hold nectar, open at night

• Yes

• Heavy musky odor

Out of the six kinds of dormancy discussed in this class, which is the most common type of dormancy in seed germination?

Quisescence- Lack of appropriate conditions to germinate

• Usually lack of water

• When conditions change seed germinates

What does the term double fertilization mean? Do angiosperms or gymnosperms have this type of fertilization?

• In the angiosperms the pollen tube grows through the style into the embryo sac in the ovule and discharges two sperm nuclei (1n each)

• This process in termed double fertilization

• One fertilization produces the embryo (zygote 2n)

• The other fertilizing 2 female nuclei (an each) to make 3n endosperm

• Elapsed time between pollination and fertilization finish

What five negative effects can affect fruit setting in plants?

• Low temperature (flowering too early)

• Lack of pollinators

• Low light intensity

• Lack of adequate soil moisture

• High heat, high night temperatures

Be able to identify characteristics of these fruit types: drupe, pepo, hesperidium

Drupe- Example: plum

• Exocarp and mesocarp fleshy

• Endocarp form stony pit with one seed

b. Pepo- Example: squash

• Exocarp forms a rind

• Mesocarp fleshy

• Seeds distributed through endocarp

c. hesperidium- Example: orange

• Exocarp and mesocarp form rind

• Seeds distributed through endocarp

• Simple fleshy fruit

What do the terms homozygous and heterozygous mean? What would these terms look like if written out? (i.e. PP, Pp)

• Homozygous- PP or pp

• Heterozygous- Pp- Genotype with two different alleles

What do the terms dominant and recessive mean? What would these terms look like if written out?

• Dominant- P- A trait that is always expressed

• Recessive- p

What does the term meiosis mean?

gamete production

• Parts of the chromosome diploids mix and randomly cross over to give different combinations of DNA

•  Meiosis I-

• Reduction division

•  Meiosis II-

• Equational division

What do the terms transcription and translation mean?

•  transcription

• Synthesis or transcribe messenger RNA (mRNA) from a gene

•  Translation

• Synthesize protein by translating mRNA information

•  Happens through free floating ribosomes in the cytoplasm

•  transcription

• 1. Only the genetic information of a gene is copied no the whole DNA

• 2. Transcription begins when RNA polymerase attaches to the promoter

•  Translation

• mutations

• Change in chromosome structure

  • Addition, deletion, inversion

• Change in chromosome number

  • Polyploidy- triploid, tetraploid

  • Aneuploidy

    • Missing chromosomes

    • Extra chromosome

What is the biggest difference between DNA and RNA? Hint: what does thymine get replaced as during transcription?

Rna-uracil

dna-thymine

Be able to identify the four basis of natural selection

 Individuals in a population vary in size because of their traits

 • Only a small percentage of offspring will survive and reproduce 

• Individuals compete for limited resources

 • Individuals best adapted to an environment will survive and reproduce in greatest numbers

What does the term convergent evolution mean?

Unrelated organisms with similar appearances which developed independently

Be able to identify an example of exogenous and endogenous signals in plants

•  Exogenous signals

• Light

  • Quality

  • Quantity

  • Duration

  • Direction

• Mechanical

  • Wind

  • Touch

  • Structures

  • Herbivores

• Soil

  • Nutrients

  • Water

• Atmosphere

  • Temperature

  • Relative humidity

  • Neighboring plants

• Gravity

  • Air pollution

  • pathogens

Endogenous signals

• Hormones

  • Auxin

  • Cytokinins

  • Gibberellins

  • Abscisic acid

  • ethylene

  • Brassinosteroids

• Mechanical

  • Growth induced

  • Tissue compression and tension

• Defense signals

  • Jasmonic acids

  • Salicylic acid

  • Secondary compounds

• maturity/juvenility

Be able to identify the major roles these hormones have on plants. example: auxin is responsible for phototropism, ethylene promotes fruit ripening, etc.

auxin

b. gibberellin

c. abscisic acid

d. Ethylene

•  Auxins

• Located in apical meristem- tip of the plant- triggered by light

• It diffuses down the shoot stimulating growth

• Acid growth hypothesis- auxin signals the plant to make hydrogen ions (H⁺), cell wall expands and elongates the cell, osmosis allows the movement of H⁺ , K⁺ and sugars

• Help plants produce roots

• Promotes cell division and elongation

• Initiates roots on stem cuttings and in tissue culture

• Mediates response to gravity and light

• Stimulates phloem and xylem differentiation

• Promotes growth of flower parts

• Promotes apical dominance

• Delays leaf senescence

• Delays fruit typing and abscission

• High auxin concentrations can stimulate ethylene production

• Gibberellins

• Shoot elongation and fruit size and shape

• Stem elongation by increasing cell division and cell elongation

• Induces seed germination, fruit set and growth

• Bolting in long-day plants

• Breaks bud dormancy

• Abscisic acid

• Causes stomata to close in water stressed plants

• Increases root growth

• Inhibits shoot growth

• Inhibits seed germination

• Ethylene

• Stimulates defense responses in stressed plants

• Induces flowering in some plants

• Stimulates stem thickening, stem elongation, and horizontal bending of stems

• Promotes senescence of leaves, flowers, and fruit

• Stimulates fruit ripening

• High ethylene coincides with high CO2 so it is responsible for cellular respiration

What does blue, red, and far-red light do to plants? What are the receptors for these lights?

Photomorphogenesis

• Blue light

  • Stimulates positive phototropism

  • Phototropins are the receptors

  • Help to determine chloroplast movement

• Red and far-red light

  • Controls seed germination, stem elongation, and flowering

  • Phytochrome is the receptor

  • Far-red light- nighttime

  • Red light- day time

What does the term soil texture mean?

• Soil texture is defined as the percentage of sand, silt, and clay particles in a soil

What are the 3 major components of all organic compounds; makes up 96% of a plant's dry weight? 

• Oxygen, carbon, and hydrogen

What do the terms chlorosis and necrosis mean?

• chlorosis (yellowing), necrosis (dead cells)

What is the most limiting nutrient in plants? What is the second most limiting nutrient?

Most important- nitrogen

Second- phosphorous

third-potassium

What nutrient does mycorrhizal fungi help plants take up?

• Mycorrhizal fungi help plants take up P and can be used as part of a fertility system

• One type of mycorrhizal fungi form a sheath around the root surface, and extensions of the hyphae grow between cells of the root cortex

What do the terms cation and anion mean? What is cation exchange capacity?

• cations

• Positively charges

• NH₄⁺

• Bound to negative particles

• Not easily absorbed by roots

• Not subject to leaching 

•  anions

• Negatively charged

• NO₃^-

• Readily dissolve in water

• Easily absorbed by roots

• Subject to leaching

Cation exchange capacity

•  CEC- an important property of clay and the organic humus fraction of the soil is ability to attract and hold cations

• Clay colloids cary thousands of negative charges throughout the clay particle and as broken edges of the clay’s layers

• A clay colloid acts as a large, highly negative charged particle (anion). Cations are held very loosely by colloids and can be replaced, or “exchanged” with cations in soil water

When discussing osmosis, water will move from high_ water potential to low_ water potential 

What is the most important factor determining where and how many species can live in an environment?

climate

What ‘cell’ is responsible for the humid tropics at the equator and deserts 30N and 30S?

Hadley cells

Of the eight major terrestrial biomes, be sure to identify the major characteristics of these biomes:

arctic tundra

•Large areas of land north of 65° latitude in North America and Eurasia

•Very little area in Southern hemisphere

•Growing season- up to three months

•Permafrost —layer of permanently frozen ground

•Rainfall is low, <25 cm per year

•Summer 3 to 12°C; winter -34°C

•<2,000 species of plants

•No trees grow in the tundra

•Mostly low growing shrubs: willows, birch, blueberry, Labrador tea

•Other plants: sedges, mosses, small perennial flowering plants

•Lichens

•Majority of biomass is underground

•Low primary productivity and low resilience

b. temperate grasslands- grasslands- drier climate unable to support tree growth

•Between deserts and temperate forest

•Dominate the interior of North America (prairie) and Eurasia (steppe)

•Pronounced seasons

•Rainfall about 85 cm

•Soil rich in organic matter

•Grasses: bluestem, buffalograss, other drought adapted grasses

•Some herbaceous plants

•A few trees along streams

•More than 90% have been converted to crop lands for wheat, corn, and other grains

c. chaparral- Broadleaf (thorny) shrubs able to withstand long summer droughts

d. deserts and xeric shrublands- •Primarily around 30°N and 30°S latitude

•In Australia, Africa, South and Central America, and Southern Asia

•The Sahara desert- the largest desert

•Broad range of temperatures from a few degrees below freezing to 30°C

•Typically dry with little rain except North American deserts (26 cm)

•Soil is low in organic matter but high in mineral content

Most plants are low growing, with small leaves, and spines for protection

• Some have thick, fleshy leaves with a thick cuticle to prevent water loss and to store water

Typical plants in north america

• Mesquite tree, joshua tree, creosote bush, sage brush

• Succulent perennials such as cacti and agave

e. tropical and subtropical moist broadleaf forest- aka rainforests

•In the tropic and subtropic areas

•Very high rainfall ranging from 200 to 400 cm

•Temperature year round between 25 to 30°C

•Warm and moist year around

•Largest number of plants and animals

•Three layers of vegetation

•Weathered, mineral-poor soil

•High rate of decomposition

•Up to 300 tree species in one hectare

•Most trees are evergreen and have broad leaves

•Multiple layers of larger and smaller trees, shrubs, vines including lianas, epiphytes growing on the branches and stems of other plants

Industrial expansion and human population growth threaten the rain forests

Be able to identify examples of mutualism, commensalism, and predation/parasitism

• mutualism

• Both organisms benefit

•  examples:

• Rhizobium bacteria fixing nitrogen for host plants

• Mycorrhizal associations between fungi and plants

• Insect pollinators for flowers

• Myrmecophytes such as bull’s-horn acacia and ants

•  commensalism

• One organism benefits and the other is neither harmed nor benefitted

•  examples

• Epiphytes

• Nurse trees for germinating cacti

• Seed dispersal by animals

•  competition

• Organisms compete for limited resources

  • Light

  • Water

  • nutrients

•  Predation or parasitism

• One organism is negatively affected and the other gains

Be able to identify the five ways a population's size can be affected

•  Population size affected by

• Environmental resources

• With or without competition

•  carrying capacity

• Reproductive pattern

•  rate of death

What does the term carrying capacity mean?

The maximum number of organisms that an ecosystem can support

Be able to identify the differences between r-selected populations and k-selected populations 

•  r-selected populations- in an unstable environment which has a greater carrying capacity conditions

• Fast maturation

• Reproduction at an early age

• Large numbers of offspring

• Low survival rate

• Short lifespans

• Poorly adapted to competition

•  K-selected populations- in a stable environment which has reached its carrying capacity

• Longer time to mature

• Longer time to reproduce

• Fewer offspring

• Greater survival rate

• Long lifespans

• Adapted to competition

What are the five major benefits wetlands can provide to ecological and biological functions?

 Prevent shoreline erosion

 • Provide areas to store water during floods

 • Act as natural water filter

 • Are part of the global water cycle

 • Are important carbon sinks

Where are autotrophs located in a food chain?

the bottom

What do the terms primary succession and secondary succession mean?

Primary succession- When an area without existing soil previously not occupied by vegetation is colonized for the first time 

Secondary succession- When vegetation is getting re-established after existing vegetation is cleared by humans or natural disasters

 Eudicot- two cotyledons in the seed for food storage