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UNIT 2 NOTES ECOLOGY
ECOLOGY-the study of living things and their environment.
Biomass-the dry weight of a single organism or group.
Plants in the Ecosystem
-plants are the producers (autotroph)
-turn solar energy into chemical energy (glucose)
-pigments (light absorbing compound) absorb light energy
-Main pigment used in photosynthesis is chlorophyll.
-Chlorophyll appears green because it reflects green light.
Seeds- important to plant reproduction
Two types of plants have seeds:
Gynmosperms-naked seeds (no fruit), most are conifers.
Angiosperms-flowering plants, have fruit to protect seeds
Two Types of seeds:
Monocot-one cotyledon ( Ex. Corn)
Dicot-two cotyledon ( Ex. Lima bean)
SEEDS
Draw a monocot:
Draw dicot.
Mature ovules become seeds. Each seed contains an embryo which may become a new plant
under the right conditions.
Seeds Parts:
Epicotyl- tip of the embryo which may become a leaves.
Hypocotyl-become the stem.
Radical-becomes the root.
Endosperm-nourishment for a dicot embryo.
Cotyledon-nourishment for a monocot embryo.
Seed Coat- protects the embryo, controls germination by restricting water and oxygen.
Hilium-scar where seed was attached to the ovary.
* Seeds are dispersed when they are dormant. A seed that is capable of germinating is viable.
Seeds need moisture, oxygen, light, and a certain temperature to germinate.
Energy in Ecosystems
Trophic Levels-feeding levels within an ecosystem
1st Trophic level
-all autotrophs are the producers.
-Examples: plants, algae, and some bacteria
2nd Trophic Level
-Animals that eat plants
-Primary consumers or herbivores
-Examples: Cow, elephant, duck
3rd Trophic Level
-Animals that eat primary consumers
-Secondary consumers or carnivores/omnivores
-Examples: hawk, lion
Scavengers-organisms that feed on animals that died recently.
Example: hyenas
Decomposers-break down dead, decaying matter
Examples: fungi, bacteria
The amount of energy available to higher trophic levels is less the further you get from the original
source (sun) because:
-90% of the energy is lost as heat or used by the organism.
-10% becomes part of the organism’s body and is available to the next level.
-You rarely see more that 4 or 5 trophic levels because there is not enough energy to support
higher levels.
The number of total organisms become less at the higher trophic levels. The number of
total organisms becomes more at the lower trophic levels.
Example: Suppose 10,000 units of energy are available to the levels of grasses. What is
the total # of energy units lost by the time energy reaches the coyotes? 9990 unit 10%
law
Food Chains-show a specific sequence in which organisms obtain energy in an ecosystem.
-Arrows point in the direction of energy flow. As matter and energy move through the food chain
the amount of available energy decreases.
Food Webs- interrelated food chains because consumers eat more than one food type and more
that one consumer may feed on the same plant or animal.
Diagrams of food chains, food webs, food pyramids, and trophic levels are all ways to
demonstrate energy relationships.
CYCLES in Ecosystems
Nutrients-chemicals/compounds that organisms must have to grow.
Nutrients cycle through the ecosystem.
1.) Water cycle
Involves evaporation, transpiration-water vapor leaves plants through the stomata,
condensation, and precipitation.
 Humans affect that water cycle by deforestation.
2.) Carbon Cycle
-Recycling of carbon through two main biological processes: Photosynthesis and
Respiration
-Humans have added the process of combustion to the cycle by the
burning of fossil fuels (formed over millions of years from organic
compound (carbon) left from decaying organisms)
-Increased combustion may be contributing to global warming.
3.) Nitrogen Cycle
-Atmosphere is 78% NITROGEN
- all organisms need nitrogen to make protein and nucleic acids.
-Most organisms can not use atmospheric nitrogen.
How do plants get nitrogen?
-Decomposed organisms (plants, animals, fungi, bacteria)
-man-made fertilizers
-some plants( alfalfa, clover, legumes(beans) have bacteria in their root nodules that can convert
nitrogen into a usable form.
This is a symbiotic relationship called Mutualism because both the plant and the bacteria
benefit from living together.
How do animals get nitrogen?
-from eating plants and other organisms that contain nitrogen compounds.
How does the atmosphere get nitrogen?
-bacteria and fungi in the soil convert nitrogen compounds into nitrogen gas.
-lightning
*Humans affect the nitrogen cycle by adding too much fertilizer to the soil.
LEAF STRUCTURE
Angiosperms-plants that have seeds that are enclosed in a protective covering. Produce fruit that
protects the seed after it had been fertilized. Have Flowers.
Two Types of Angiosperms
-Monocot-has one cotyledon (seed leaf), parallel veins, and parts in multiples of 3.
-Dicot-has two cotyledon, netted veins, and parts in multiples of 4 or 5.
Leaf Structure
-Waxy layer on top of cells called the cuticle that protects the plants and keeps it from drying out.
-Dermal Tissue- single layer of cells surrounding the entire leaf called the epidermis.
STOMATA(stoma)- located in the epidermis, controls water loss and gas exchange.
-Each stoma has a guard cell on each side that controls the opening and closing of
the stoma.
-Guard cells are the only cells in the epidermis with cholorplasts.
-Ground Tissue-Mesophyll-between the upper and lower epidermis which includes palisade cells
and spongy cells.
-Two Main Types of Cells:
-palisade parenchyma-where most photosynthesis occurs, directly under the
upper epidermis, at right angles to epidermis, in columns.
-Spongy parenchyma-beneath the palisade, some photosynthesis occurs here, air
spaces surround the cells and allow for circulation of water and gas.
Vascular Tissue-Veins
-contains tissue that transport nutrients.
-Xylem- transport water and minerals.
-Pholem-transport food
-Also called vascular bundles
-Cells that bundle together are called the bundle sheath.
Name:______________________________
Unit 2 Review Ecology
What is an independent variable?
What is a dependent variable?
Name the six levels of organization in ecology. Define each one.
What are biotic and abiotic factors? Give an example of each one.
What is a habitat?
What is a niche? Should different species occupy the same niche? Why or why not?
What is a biome?
Name and describe two terrestrial biomes.
Name and describe two aquatic biomes.
What is the purpose of the arrows in a food chain?
Which is a more accurate description of energy in a ecosystem? Why?
What are decomposers?
What are producers? What trophic level would you find them on?
What are secondary consumers? What trophic level would you find them on?
What are primary consumers? What trophic level would you find them on?
What is the intitial source of energy on earth?
Which would get more energy from what it eats? A rabbit or a hawk.
What is the 10% Law say?
What is an ecological pyramid?
Name three types of ecological pyramids.
Name and describe the processes involved in the carbon cycle.
Name and describe the process involved in the water cycle.
Why is nitrogen cycle important?
What is nitrogen fixation?
What is nitrification?
What is dinitrification?
What is a pigment?
Which light do you see? Reflected or absorbed?
Why is chlorophyll important in photosynthesis?
What is color(s) of light does chlorophyll absorb?
What color(s) of light does chlorophyll reflect?
Why are accessory pigments important?
What is the function of the cuticle and the epidermis of a leaf?
What are stomata? Name three functions of stomata.
What controls the opening of stomata?
In what cells of a leaf does most photosynthesis occur?
What two types of cells are found in a vein?
Why are the spongy cells surrounded by the air spaces?
What is transpiration?
What is biomass?
In your plant experiments, what is your independent variable for both experiments?
Why do some plants have lots of root nodules?