Ecology & Plant Matter

What is ecology?

The study of relationships among organisms and between them and their environment

What are the levels of ecology?

Individual, Population, Community, Ecosystem

What is a population?

Groups of interacting individuals from a species within a given space and time

What is a community?

Populations of different species that interact with each other within a given space and time

What is an ecosystem?

All of the organisms and the abiotic environment they interact with in a given space and time

What kind of environments do ecosystems have?

Abiotic and Biotic

What are biotic factors?

Members of the community

What makes up the abiotic factors of an ecosystem?

Physical and chemical aspects of the environment

What are examples of physical conditions and resources?

Temperature, light availability, wind

What are examples of chemical conditions and resources?

Nitrogen, phosphorus, water

How can ecosystems be defined at different scales?

Examples include within a human’s intestines, within a national park, and the whole planet

How are ecosystems linked?

Things that are happening in one ecosystem impact into others

What is the primary energy source for life?

Sunlight (or chemical energy source)

What are the components of an ecosystem?

Sunlight, atmosphere, soil, producers, consumers, decomposers

What is energy flow?

From/to environment, across trophic levels

What is water potential?

The difference in potential energy between that of pure water under ambient pressure and the actual potential energy of water in a given part of a system

What is water potential also known as?

Can think about it as the propensity of water to move

What is the concept of water potential?

The measure of the tendency of water to move from higher to lower potential

How does water tend to move based on energy?

Water moves towards places where it has lower energy (think of dumping water on a hill)

What is solute/osmotic potential?

Water potential due to differences in solute concentrations (water moving in and out of the cell)

How do cells change their water potential?

Cells can change concentration of solutes

What happens when a cell changes by increasing in solute concentration?

Leads to the net movement of water molecules into cell

What is the beginning of water movement in plants?

Water is taken up from soil

What is the first step of water movement in plants?

The water enters the roots through root hairs

What is the second step of water movement in plants?

The water moves up through xylem in the stem(s)

What is the third step of water movement in plants?

Water enters veins in the leaves

What is the last step of water movement in plants?

Water evaporates through the stomata

What systems do the vascular plant structure involve?

Shoot and Root system

What is generally the primary site of photosynthesis?

Leaves

How does a plant actually move water against gravity?

The cohesion-tension mechanism

What is the first step of the cohesion-tension mechanism?

Evaporation

What is evaporation?

Due to low water potential/concentration in the air relative to the leaf, molecules of water are vaporized

What is the second step of the cohesion-tension mechanism?

Cohesion

What is cohesion?

Water molecules hydrogen bond with one another, causes the molecules to stick to each other and xylem walls

What is the third step of the cohesion-evaporation mechanism?

Tension

What is tension?

Cohesion of water molecules links them together all the way down to the roots, as one molecule evaporates it pulls up the molecule next to it, creating tension

What is embolism?

The blockage of xylem vessels by air bubbles, which breaks the water column and disrupts water transport from roots to leaves

What environments can you see higher incidences of embolism?

Hot & windy, Very dry soil, Freezing conditions, and plant damage

Why would hot & windy environments increase higher incidence of embolism?

Conditions that increase water loss from leaves

Why would very dry soil increase higher incidence of embolism?

Conditions that decrease uptake from soil

Why would freezing environments increase higher incidence of embolism?

Conditions that release air into water column (Cold water holds more air, the air releases when turns into ice)

What are environmental stressors for plants?

Wind, aridity, temperature extremes, heterogeneity of resources, and salinity

What would plants want to avoid/tolerate an environmental stressor like wind?

It can directly damage plant tissues & increase transpirational loss of water

What would plants want to avoid/tolerate an environmental stressor like aridity (net loss of water)?

It can increase transpirational loss of water

What would plants want to avoid/tolerate an environmental stressor like temperature extremes?

It can disrupt cellular function & can affect loss of water, rate of embolism

What would plants want to avoid/tolerate an environmental stressor like heterogeneity of resources?

Resources are not distributed evenly across the environment

What would plants want to avoid/tolerate an environmental stressor like salinity?

Can make it hard to absorb water

Why might plants have buttress roots?

Very windy site, or sites with shallow soils to help with anchoring

Why might plants have fibrous roots?

Might help plant thoroughly explore soil for nutrients, water (Differential growth rates improve efficiency)

Why might plants have fibrous roots?

Can access deep water, store food

What might be the reason of the surface area of leaves in dark, humid areas?

Large relative to mass to maximize light capture

What might be the reason of the surface area of leaves in dry, exposed areas?

Might be smaller, thicker to minimize overheating, water loss

What is drought deciduousness?

Leaves might be dropped (lose ALL surface area), in places with periodic drought

What are trichomes?

Hairs on surface of leaf

What are waxy cuticles?

Wax covering found on epidermis of plants

What are salt excretion?

Some plants can take up, excrete salt

What do trichomes do?

Can change color of leaf to increase albedo & Maintain boundary layer

What do waxy cuticles do?

Can be thicker on leaves in dry areas, reduces water loss

What do salt excretion do?

Changes albedo

What type of water has a potential of zero?

Pure water

What are the water potential of life and plants?

Negative values

How is water potential applied to a scale?

The more negative you get the lower you are

Why do plant cells care about water?

Their rigidity/structure

What are one of the primary functions of roots?

To absorb water and nutrients for the soil

What happens when increasing surface area?

Increasing surface area = increasing the rate of absorption (more places where it can be absorbed)

What can increasing the level of solutes inside of plants do?

More likely that water will move in (i.e. plants that can live in very salty areas)

When you hold up a mirror why is there a little puff of air when breathing out in front of it?

The air is drier so that is why water is always leaving us

What happens to the water that a plant takes in from the roots?

90% of the water that is taken up in the roots of plants goes out into the air

Where do we need water and split it to get oxygen?

In light reactions

What are the properties of water?

It’s sticky, cohesion and adhesion

What happens to water from inside the plant?

It evaporates

What drives water movement between the plant and the air due to differences in water potential?

There is a difference in water potential, there is a difference how water in the air vs inside the plant (molecules in the leaves tend to vaporize)

Molecules are linked to a chain (holding on to each other by hydrogen bonds), water leaving the plant and going into the atmosphere = as it leaves, it pulls, etc.. (the water molecule chain goes all the way down from the soil), creates tension on this chain of water molecules since water is sticky and tends not to fall back down because it adheres to if not it will fall (evaporation pulling on the continuous large chain)

How does a C3 plant differ putting a bag over it on the day and night?

Day:

Night

What happens to plants that do not get enough water?

It dries out and dies, water potential is going down in the soil

How does embolism occur in plants?

Creates a negative pressure, making air in the xylem, the water column breaks and snaps back (plant requires a continuous chain of water molecules that are cohesive/adhering to each other - introducing an air bubble will snap back the chain so no more movement in the xylem)

What happens when its too hot in plants?

Too hot means we are breaking things down or shut down photosynthesis since losing too much water so cant grow as fast and damage photosynthetic mechanism

What is aridity?

Less water coming in than is coming out

What is abiotic?

Non-living components

What is biotic?

Living components