EVS 207 Midterm Study Guide

Photosynthesis

The process by which plants convert light energy from the sun into chemical energy stored in glucose.

Respiration

The process by which cells break down glucose and other organic molecules to release energy for various cellular activities.

Tertiary Consumer

An organism at the 4th trophic level, such as a fox, that consumes secondary consumers.

Secondary Consumer

An organism at the 3rd trophic level, such as an owl or spider, that consumes primary consumers.

Primary Consumer

An organism at the 2nd trophic level, such as a bug or mouse, that consumes primary producers.

Primary Producer

An organism at the 1st trophic level, usually plants, that creates energy through photosynthesis.

K-strategists

Organisms that demonstrate logistic population growth, reproduce conservatively, and have stable populations, such as birds and larger mammals.

r-strategists

Organisms that grow at maximum rate and demonstrate exponential growth curves, securing a place in the environment; examples include bacteria and insects.

Exponential Growth Curve

A growth pattern where the population growth rate accelerates, represented by a J curve, typical of r-strategists.

Logistic Growth Curve

A growth pattern characterized by acceleration followed by a slowing to a maximum growth point, represented by an S curve, typical of K-strategists.

Demographic Stages of Human Population Growth

Stages 1-5: (1) High birth and death rates; (2) High birth rates, lower death rates; (3) Decreasing birth, low death rates; (4) Stable/low birth and death rates; (5) Low birth rates, potential decrease in population.

Niche

The role an organism plays in its ecosystem, including its feeding, breeding, migration habits, and interactions with the environment.

Habitat

The place where an organism lives, supporting various organisms that must share common resources.

Competitive Exclusion Principle

The principle stating no two organisms can occupy the same niche simultaneously without resulting in harmful competition.

Lethal Dose (LD50)

The dose at which 50% of the test population is sensitive and may be killed.

Soil Particle Sizes

Different sizes include gravel (largest >2mm), sand (0.05-2mm), silt (medium-sized), and clay (smallest).

Water-holding Capacity

The difference between the field capacity and wilting point, largely determined by soil texture and organic matter.

Porosity

A measure of how much water a soil can hold, determined by the open spaces between soil particles.

Permeability

A measure of how easily a fluid (like water) can move through soil.

Demographic factors in human population growth

birth rates, death rates, immigration, emigration

rule 70

doubling time (dt) for a country indicates the predicted year that the current population will double

niche generalists

a species with a broad niche that is easily adaptable to many environmental conditions; more likely to survive by easily relocating, changing food sources, and adapting in other ways

niche specialists

a species with specific needs in order to survive

toxins

poisons produced naturally by an organism

toxicants

type of poison that are made by humans or introduced to the environment by humans