Bio II; Exam III (part one; Lecture 13 to Lecture 17)

El Niño/ La Nina and large volcanic eruptions

can dampen or enhance the overall trend of temperature anomalies

greenhouse effect

warming that results when solar radiation is trapped by the atmosphere

Eunice Foote

first person to scientifically test CO2 as greenhouse gas, warned of warming; John Tyndall provided experimental proof for her hypothesis

Svante Arrhenius

calculated that humans were adding CO2 to the atmosphere, and suggested that this would warm the planet

Radiative Forcing

The change in the earth's energy balance caused by a given variable such as change in greenhouse gas

The Keeling Curve shows

Atmospheric carbon dioxide has been increasing since 1960

Ice core data have revealed what?

since ice cores trap samples of air, scientists can analyze them, showing that atmospheric CO2 started increasing after 1800
(it didn't vary much between 1000 and 1800)

CO2 Levels and pH

CO2 conc in oceans is rising, causing the pH to fall and make the water more acidic (ocean acidification)

Why are greenhouse gas levels increasing

-disruptions in the carbon cycle (human caused)
-burning of fossil fuels
-deforestation

two big tipping points

1. melting of the Greenland and Antartic ice caps
2. thawing of the arctic permafrost

sea levels will rise due to

1. thermal expansion
2. melting of ice on land
3. once the melting starts it will be hard to stop and may accelerate

Tipping cascades

tipping points are likely to be interrelated

rapid habitat change leads to

extinction

what can be done about climate change?

1. adaptation
2. mitigation

adaptation

learning how to survive and prosper in a warming world

mitigation

limiting the extent of warming by limiting greenhouse gas emissions

changes/causes for population growth of our current era

medicine:
-sewers
-filtered water
agriculture:
-cheap fertilizer
-bigger food supply

Human populations can exist at two equilibrium densities. Which are:

1. High Birth and High death (back then)
2. low birth and low death (now)

demographic transition

Movement from a high birth rate, high death rate to a low birth rate, low death rate.

demographic transition stages

1. equilibrium
2. pop growth
3. growth slows
4. equilibrium again

needed total fertility rate needed for zero pop growth

2.1 (differs in different places)

where food resources go

60% - livestock
36% - humans
4% - wild animals

biomagnification

The increase in chemical concentration in animal tissues as the chemical moves up the food chain

paul muller

discovered insecticide that killed mosquitoes, and malaria went down.

Rachel Carson

wrote silent spring, which led to the endangered species act

non vascular plant characteristics

-small
-water permeable
-no organs for water uptake
-no true roots
-desiccation tolerant
-high sa to vol ratio

vascular plant characteristics

-larger
-specialized cells to transport nutrients internally
-true roots

the stem: purpose

-connects roots and leaves
-primary transport between roots and leaves
-provides support
-transports sugar, water, and minerals

stem petiole

stalk that connects leaf to stem

collenchyma cells

alive at maturity, provide support, found below epidermis
ex; celery strings

meristematic tissues

-allow plants to grow
-found in meristems
-a lot of cell division

atypical meristems

tips of branches and roots, allow for length increase

lateral meristems

found within branches, increases girth

intercalary meristems

-found in monocots
-evolutionary adaptation to heavy grazing
-typically grasses
-can increase length after top is cut off

primary plant organs

flowers, roots, stems, leaves
-dermal, vascular, and ground tissues found in all organs

sclerenchyma cells

-dead at maturity
-cell walls structured with ligin
-very strong structural support
-used for linen and rope

permanent tissue

plant tissue composed of cells that are no longer actively dividing

dermal tissue

tissue of the plant that makes up the waxy outer layer of the plant

vascular tissue

Plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body.

ground tissue

tissue system that makes up the majority of a plant
-stores water and sugars
-anchors vascular tissue
-site for photosynthesis

stem epidermis (dermal)

prevents water loss
provides barrier between inside and outside of plant

stomata (dermal)

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

guard cells (dermal)

control the opening and closing of stomata

trichomes (dermal)

Tiny, spikelike projections on some leaves for protection

dermal tissues

-epidermis
-trichomes
-stomata
-guard cells

xylem (vascular)

-carries water within the plant
-dead when mature
-works without energy in a similar way to a straw
transports UP

tracheids (vascular)

-thick cell walls
-dead tissue
-narrower chambers adjacent to vessels
-connected to others via small pits

xylem disruption

-collapse (too much neg pressure)
-air bubbles (liquid below bubble is lost)
-freezing conditions (water expands, bubbles trapped, physical blockage)

phloem (vascular)

transports carbs and nutrients, alive
transports DOWN

sieve tube cells

Living cells without nuclei that conduct phloem in plants
arranged end to end

companion cells

the active cells found next to sieve tube elements that supply the phloem vessels with all of their metabolic needs

root purpose

-absorb H2O and nutrients
-provide stability
-store excess sugars

root cap

area of rapid cell and division damaged by soil

root hairs

extensions of the root epidermis to maximize surface area

ancestral plants

-Relied on water to move sperm to fertilize eggs
-Water buffered gametes from temperature changes
-Water prevented gamete desiccation

land plants

evolved the ability to transport gametes and offspring via:
-air
-animals
-water

alternation of generation

life cycle that has two alternating phases—a haploid (N) phase and diploid (2N) phase
-diploid gen produces haploid gen
-haploid gen combines and creates diploid again

monecious

sperm and egg on the same plant

gymnosperms

A plant that produces seeds that are exposed rather than seeds enclosed in fruits
ex: connifers, colder climates

monecious male vs female gametes

females are larger and protected by hard plating, take more energy to produce
males are smaller and softer, they take less energy to make so are less of an energetic loss

sporangia

located on the tip of the mature sporophyte, where meiosis occurs, producing haploid spores

male gametophytes on connifers

-produce a ridiculous amount of pollen
-wind carries the pollen very far
-the pollen causes nasal congestion in surrounding animals

ovum

egg!

gymnosperm seed

seed coat: diploid
female gamete: haploid
embryo: diploid
-can be dormant and then germinated up to 100 years later

characteristics/ protection of different mature seeds

-hair-like fibers catch wind
-spikes attach to animals
-wings help move them through the air
-fruit helps seeds travel through animal feces

flowers

capture visual attention of pollinators

self-compatible plants

fertilize themselves, minimal genetic shuffling

self-incompatible plants

cannot fertilize themselves and neither can close relatives
increases genetic diversity

angiosperm female gemete

contain 8 haploid nuclei in 7 cells

endosperm

food-rich tissue that nourishes a seedling as it grows

double-fertilization

A fertilization process that requires two sperm to fuse with two other cells (angiosperms)

apomixis

The ability of some plant species to reproduce asexually through seeds without fertilization by a male gamete.

vegetative reproduction

a form of asexual reproduction in which offspring grow from a part of an existing parent plant

epidermis

-first layer of defense
-thicker than most cell walls
-waxy cuticle
-pathogens can't enter easily unless the skin is broken by herbivores

virulent infection

able to cause severe disease and may be life-threatening
-circumvent plant immune system

avirulent infection

cause minor infections that the plant can eventually clear
-pathogens can enter but are then stopped

basal resitance

first line of defense; triggered by MAMPS;
-causes cell to thicken
-produces toxic phytochemicals
-NOT specific
-typically faster and works first

specific resistance

responds to a SPECIFIC pathogen; controlled by R genes ;
-triggers a strong antimicrobial response against an individual virus, bacteria, fungus, etc

responses to plant infection

-physical
-chemical
-hypersensitive (unique to plants)

physical response

plug the xylem to kill off infected parts of the plant, preventing the infection from spreading to the rest of the plant
-can accidentally plug too much and kill itself

chemical response

produce antibacterial and antimicrobial chemicals

systemic acquired resistance (SAR)

A defensive response in infected plants that helps protect healthy tissue from pathogenic invasion.

plant pathogens

-fungi
-bacteria
-viruses
-protists
-parasitic plants

biotrophic pathogens

A plant pathogen that obtains resources from living cells.
-keeps the host alive and feeds off the living tissue

necrotrophic pathogens

A plant pathogen that kills cells before drawing resources from them.
-want to work rapidly

parasitic plants

absorb water, sugars, and minerals from their living host plant

defense against herbivores

-mechanical
-chemical
-symbiont defense
-rapid regrowth

mechanical plant defense

developing structures like thorns that make it harder for animals to eat them

rapid regrowth (monocots)

grasses have evolved to grow from the base, so when the top is eaten off they can grow in length

modulated defenses

regulated by turning certain genes on and off
-ex: chem defenses

resource allocation for defense

plants trade off different uses for their energy
-growth can be inhibited by defense, vice versa
-decide where to put resources based on environmental factors

Defense and diversity

pathogens and herbivores can increase plant diversity
-plants grow poorly under adults of the same species

bryophytes

A moss, liverwort, or hornwort; a nonvascular plant that inhabits the land but lacks many of the terrestrial adaptations of vascular plants.

lycophytes, ferns, and horsetails

disperse by spores and rely on swimming sperm for fertilization

The Anthropocene

the modern geological era during which humans have dramatically affected the environment

Climate

The average weather conditions in an area over a long period of time

Is the Earth warming up?

YES!
historical and proxy data show a global pattern of increasing temps

Results of Climate Change

-plants are decreasing in population
-glaciers and decreasing in size
-The Arctic is heating rapidly
-The ice cap is in danger of disappearing
-atmospheric ratio changed

Future Climate Shift

-fewer super cold days
-more hot temp records (2-3 times more hot records than cold)

CO2

has risen by 36% since measurements began in 1958