Semester 2 Final Review Part 2

Carbohydrates, Photosynthesis & Respiration and Ecology

DECOMPOSERS Cause decay and release essential

nutrients back into the environment to be recycled.1. Scavengers2. Detritivores3. Saprotrophs

• Obtain their energy from organic wastes and dead bodies that are produced at all trophic levels

• Ex vultures.

1. Scavenger:

Scavergers can also include: Secondary (2nd Order) CONSUMERS (Omnivores)-

Omnivore Eats herbivores

as well as being a scavengerEx. Bear,

racoon

2. Detritivore: Consume

detritus (dead organic matter) Ex. Worms

3. Saprotrophs Feed exclusively on

dead or decaying organic material.

Saprophyte: Release digestive

enzymes to break down organic material in their surrounding environment and survive by taking up the simpler soluble substances produced (spit and suck) Ex. Fungi, bacteria

FOOD WEB

FOOD WEB shows the interactions between a wide variety

of organisms in the environment creating a complicated, interconnected path of

energy flow. are used to study effects of the changing or

introduction of a variable in an environment

Ecological Pyramids:

graphs which illustrate the trophic levels in a community.

Does all the energy this caterpillar eats get passed to the bird who eats him?

Plant material eaten by caterpillar

100 kilocalories (kcal)

Feces50 kcal

Growth

15 kcal

Cellular respiration

35 kcal

Most ecological pyramids are large at the base and narrow at

the top. This is because every time that an organism is eaten by the next trophic level, some of the energy is lost as heat.

More Energy

Less Energy

Pyramid of Biomass:• Illustrates the amount of biomass in each trophic

level – Biomass weight is determined after dehydration

• Shows the amount of matter lost between trophic levels.

• Measured in Kg, grams or pounds

Pyramid of Energy:• Shows the energy available at each trophic

level.– The size of the blocks represents the proportion of

productivity– Measured in Joules or Calories

Pyramid of Numbers:• Illustration of the number of organisms at

each level

POPULATIONS

Definition:All the members of a species that live in one place at one time.

PROPERTIES of Populations

Population SIZE The number of individuals in a population

Population DENSITY Number of individuals per unit of area

DISPERSION SPATIAL distribution of individuals within the population

Uniform Random Clumped

Population Growth RATE

Definition The amount by which a population’s size

changes over time.

Population Growth RATE

Depends on: Birth Death Emigration: movement of individuals OUT OF a

population Immigration: movement of individuals INTO a

population

+-

-

+

EXPONENTIAL Model of Population Growth

Population increases rapidly with no limit What will a graph look like? Rare in nature. Why?

“J” shaped curve

Limit on the amount of resources (food / space)

Population Growth

Limited by Carrying Capacity

Definition: The number of individualsthe environment can support over a long period of time

LOGISTIC Model of Population Growth

Accounts for influence of limiting factors (like food, space)

What will the graph look like?

Stretched out “S”When population is small, birth rate is higher

than death rate

As population reaches carrying capacity,

death rate increases

When at carrying capacity, birth rate is equal to

death rate

Population Size REGULATION

1. Density Independent Factors: reduce population regardless of population sizeExamples: Weather Fires Floods

Population Size REGULATION

2. Density Dependent Factors: triggered by increasing population densityExamples Food shortages Space limitations Waste accumulation

Example of Exponential Growth Phase (J-Shaped Curve)

Ex. Human Population Human population increased

relatively slowly until about 1650. It then doubled in the next two

centuries It doubled again in the next 80

years.

Our population is now about 6.9 billion. This increases by 80 million/year This in an increase of 214,000/day. It takes 3 years for the world population to add

the population equivalent of another US.

Ecological Principles VocabularyBiome Predation Decomposer

Parasitism ScavengerBiodiversity Mutualism Detritivore Commensalism Saprotroph

Population Pyramid of Energy Food Chain Pyramid of Biomass Food Web Pyramid of Numbers Autotroph Population Producer Immigration

Trophic Levle Heterotroph EmigrationEcology Consumer LogisticBiosphere -primary, etc… ExponentialHabitat Herbivore Carrying CapacityBiotic/Abiotic Omnivore Density Dependent Limiting Factor

Community Carnivore Density Independent Limiting Factor

Dispersion Patterns