Plants Flashcards
Sonoran Desert (Location)
An ecosystem located in Southwest USA and Northwest Mexico
When is the growing season in the Sonoran Desert and why?
It has a real issue of running out of water in the summer (only 1.5 inches of rain) so the only good growing season for plants is during winter
What are annual plants?
A plant that completes it life cycle in one year then die (shorter-lived, faster growing)
What are perennial plants?
A plant that regrows in a specific season, grow back every year (slower growing, longer life)
How is climate changing?
Temperature increases, rainfall is more episodic and the amount of rain decreases (althought it can be more intense), more flooding and droughts
Why is water important for plants?
For structural purposes; on a cell level, it causes osmosis and turgor pressure
What part of the plant absorbs water?
Roots
What part of the plan has the sugar or sunlight?
Leaf
What percentage of plants make up the Earth’s biomass?
80%
What molecule makes up most of a plant’s biomass?
Cellulose
Where does the carbon in cellulose in a plant come from?
From the air (CO2)
Photosynthesis
6CO2 + 6H2O (l) + sunlight –> glucose + 6O2 (g)
Equilibrium Concentration
Movement from high to low concentration in order to create balance
Passive Transport
ATP is not needed, potential energy in the form of a gradient is transformed to kinetic energy
Diffusion
Net movement of molecules from areas of high concentration to low concentration
Osmolarity
Movement of solvent (water) across a semipermeable membrane from high to low concentration (created equilibrium of solute and solvent)
Osmosis
Diffusion of water, water concentration and solute concentration are opposites
Dilute: high H20, low solute
Concentrate: low H20, high solute
Turgid Cell
water enters through osmosis, vacuole swells and pushed against cell wall
Flaccid Cell
water is lost, vacuole shrinks, cell loses shape
How does water enter from the roots (bottom) and leave from the stomata (top)?
Due to the transport system in plants
What are a plant’s vascular tissue?
Xylem and Phloem
Xylem
Only moves water in one direction from the roots to the leaves (water up)
Phloem
Carries nutrients, sugar, hormones, etc. around through osmosis (glucose down)
Turgor Pressure
Created when water flows into the vacuole of a plant cell and then pushes outward on the cell wall, allows the plant to stand straight and grow
How does the xylem move water?
passive transport, capillary action
Stomata
gaps in the leaf/ that open and close for gas exchange using guard cells
Why is biodiversity important in the Somoran Desert?
All organisms want to maximize fitness
Gas Exchange
stomata will open when guard cells are turgid with an abundance of water and closed when water is scarce and the guard cells are flaccid, the exchange of O2 and CO2 that causes water loss
What would happen if the stomata never opened?
no photosynthesis, O2 toxicity and no growth/death of plant
How will a plant wilt faster?
drier air (humidity), high temperatures, windy, surface area (more exposure and more stomata)
Transpiration
evaporation of water from plants
What does the total amount of water transpired depend on?
Depends on the amount of time stomata are open and the rate of water loss
How can winter annuals survive without a lot of water?
1) when it does rain, the plant can grow quickly and hope they don’t dry out (quick growth)
2) limit water waster and conserve, have a slow life cycle
Risks of Fast Growth
Could die without reproduction
Risks of Slow Growth
Could be out competed by faster growing plants
Relative Growth Rate (RGR)
biomass gained over time
Water Use Efficiency (WUE)
carbon gained (growth) over water loss
Why can you not be high in RGR and WUE?
high RGR means a lot of leaves for photosynthesis but with more stomata on the leaves and more surface area, there is more water loss
What are the issues with the amount of winter precipitation and plants?
the amount of precipitation is not consistent which means there is more of a chance of smaller rain events (which is better for slower growers) meaning that there are different plants growing different years
Why do we keep losing energy as heat?
Due to the second law of thermodynamics, as a natural byproduct of biological processes (only ~10% is conserved)
How do we replenish lost energy?
Photosynthesis
Respiration
equation
O2 + glucose –> H2O + CO2 + ATP
Potential Energy
Energy held by an object due to its relative position to other objects, stored in a gradient which is where kinetic energy comes from
Resting Energy
energy possessed by an object relative to its position, higher from the ground = more energy (same for the relative energy of electrons and their distance from the nuclei), the reason photosynthesis works and electrons can be “excited” by photons
Carbon-based Life
CO2 (inorganic carbon) —> glucose (easier energy to access) –> cellulose —> organisms
Carbohydrates
combination of carbon and oxygen, sugars or starches (-ose)
Carbon
always need 4 covalent bonds (either C, O, H), can have partial charge due to electronegativity but no overall charge
Carbon Bonds
Carbon-Oxygen (lowest potential energy), Carbon-Carbon (electrons are equidistant), Carbon-Hydrogen (most potential energy)
To be reduced?
gain of potential energy (more of it), gain of electrons
Oxidized
loss of potential energy (less of it), loss of electrons
Redox Reactions
Transfer of electrons within a chemical reaction
A is oxidized by B = B is the oxidizing agent
B is reduced by A = A is the reducing agent
Oxidation and Reduction In Photosynthesis
CO2 is reduced, H2O is oxidized, and energy is added (CO2 has less energy than glucose in its bonds)
Leaves
Palisade (mesophyll) cells on upper surface on the leaf where a majority of photosynthesis takes place
Leaf Structures
cell wall, cell membrane (phospholipid bilayer), vacuole, nucleus, nuclear envelope, chloroplast, mitochondria
Endosymbiosis
mutualism, a relationship where one organism lives inside the other (example: mitochondria and chloroplast)
Chlorophyll Structures
stroma (space), thylakoid, semipermeable membrane, lumen, granum (stacks of thylakoid)
Photosystems and Chlorophyll A
embedded proteins in thylakoid, has light absorbing pigment (chlorophyll a), the pigment absorbs red, blue, and violet light but reflects green wavelength
Light-Dependent Reaction
converts light to chemical energy in the thylakoid membrane
Calvin Cycle
uses chemical energy to reduce Carbon in CO2 into sugar energy from ATP and NADPH (short-term energy) and glucose (long term energy) in the stroma
How many molecules does Calvin Cycle need?
It needs 18 ATP, 6 CO2, 12 NADPH
Photosystem 2
light focuses on chlorophyll, photons excite out electron, gets taken to ETC resulting in chlorophyll+, breaks water down to replace the electron, the oxygen leaves through the stomata and ions stay in lumen, electron goes with chlorophyll
Electron Transport Chain
shuttle electrons from one photosystem to another, electron is excited and moves through proteins releasing energy, using the released energy to move H+ from stroma to lumen (out to in, against concentration), arrives in photosystem 1 in its normal form
Photosystem 1
chlorophyll+ gets electron from the ETC, light re-excites the electron, chlorophyll donates its electron to create NADPH from NADP+ (reduced), and the replacement electron arrives from ETC like a cycle
Active Transport
from low to high concentration, uses ATP to against concentration gradient
ATP-synthase
done by enzyme, uses established H+ gradient (high to low concentration = passive transport) which built into the thylakoid membrane, converts ADP to ATP (low to high energy) and converts the potential energy gradient to kinetic energy to chemical energy
Fixation
1 RuBP (5-C sugar) + CO2 –(Rubisco enzyme)–> 2 PGA (3-C sugar)
Reduction
2 PGA –> 2 G3P (3-C sugar), ATP becomes ADP and NADPH becomes NADP+
Regeneration
2 G3P –> RuBP, ATP becomes ADP
Why are the winter annual communities in the Sonoran Desert so diverse?
Because of gas exchange and photorespiration
Gas Exchange Issue
winter precipitation is unpredictable, so different species survives each year; due to climate change small rain events are more likely which is better for slow growth plants, but the intensity of the rain changes so the winning strategy relies solely on whatever allows for higher fitness (more offsprings/seeds)
Photorespiration Issue
Rubisco binds to oxygen gas and not CO2 which produces excess CO2, uses up ATP, does not make sugar, more likely in hot temperatures and when stomata are closed (minimal available CO2)
C3 Photosynthesis
most common photosynthetic process that happens in 90% of plants, CO2 –> Calvin Cycle
C4 Photosynthesis
takes CO2 turns it into malate sugar which is moved to bundle sheath cells, converted back to CO2 for Calvin Cycle, has seperate C-fixation and O2 so the rubisco never comes in contact with oxygen
CAM Photosynthesis
Only open the stomata during the night, stores malate during the day, converts it into CO2 (takes energy) and surrounds Rubisco by CO2 so the processes of Calvin Cycle and C-fixation are seperate
Cons of C4 and CAM Photosynthesis
C4 will use excess energy and is for plants with excess water and CAM is good for plants in hot and dry areas with slow growth only
Competition
species compete for limited resources, negative impact for both of them (-,-)
Niche
environmental conditions and resources necessary for survival and reproduction (can include climate envelop)
When is competition the strongest?
between species that use resources similarly
Niche Partitioning
With certain conditions species can use the same set of resources, weaker species with give up overlapping resource “niche space” but if there is anything remaining, they get it
Spatal Niche Partitioning
similar resources used by multiple species, but in a slightly different physical area like when different birds occupy different layers of a tree
Temporal Niche Partitioning
the same resources are used by multiple species, but they are taken at different times (for example, day vs night, or seasons)
Functional Niche Partitioning
Any other way that the similar resource pool can be divided as a catch-all
How does the Sonoran Desert coexist?
Through temporal niche partitioning
Niche Space
All the resources and conditions of an ecosystem
Options for Niche Space
1) there’s a better competitor across the whole niche space and the other species are excluded
2) there is no best competitor so the all give up a little niche space and coexist
Specialist
narrow niche = specialized requirements (more of them in biodiverse spaces)
Generalist
wide niche = can utilize different resources
Fundamental
The niche that is potentially occupied by a species in the absence of competition
Realized
The niche that is occupied by a species in the presence of competition
Intraspecific vs Interspecific Competition
Intraspecific competition is competition within a singular species but interspecific competition is between 2 different species
Can fundamental and realized niche be the same?
Yes, it can be the same if the species is either the best competitor or if there is no competition
K-Selected
low offspring production, high parental involvement, long lifespan, slow period of maturity, long gestation period
R-Selected
- reproduce quickly
- produce many offsprings
- low parental involvement
- high offspring mortality
- small lifespans
- short gestational periods
Survivorship Curves
k-selected curve: most live to the max age
r-selected: most die young, those that make it to a certain life span usually achieve max age
neither r nor k: these organisms do not experience age related morality (linear)
How fast can a population grow?
exponential growth = no limitations on resources, not sustainable or realistic
logistic growth = limited resources limit populations over time
Is there a better strategy between reproductive strategies?
There is not, it is a spectrum and there are tradeoffs to each option
Per Capita Growth Rate
the average # of offspring an individual has over a given time period (year
Population Growth Rate
the # of indiv. added (or lost) to a population in a given time period (year)
