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Ecology Part 1
CP BIOLOGY
THE TRANSFER OF ENERGY
• Trophic levels –step in a food chain or webHerbivores – eat plantsCarnivores – eat meat
• Omnivores – eat both• Scavengers – eat dead things
Decomposers – release nutrients back into the cycle
• Food Webs – intertwined food chainsFood Chains –linear arrangement showing feeding relationships
• Ecological Pyramids – diagram that shows the relative amount of energy or matter within each trophic level (energy, biomass, numbers)Biomass –dry weight of organic matter at each trophic level
• 10% Rule – on average, only 10% of the energy from one trophic level makes it to the next
THE FLOW OF MATERIALS
• Biogeochemical Cycle – process in which materials are passed from 1 organism to another in an ecosystem
Water Cycle (hydrologic cycle)
http://earthguide.ucsd.edu/earthguide/diagrams/watercycle/
http://player.discoveryeducation.com/views/hhView.cfm?guidAssetId=087777c8-4ff0-45d2-878f-e7cd90f7ee19
• Precipitation – falling from the air (snow, rain, sleet)
• Runoff – drains water from the land• Evaporation – water vapor enters the air• Condensation – gas/vapor reduced to a liquid in
clouds• Transpiration – passage of water from the leaves
of plants to the atmosphere• Percolation – water seeps into the soil
Carbon/Oxygen Cycle (Atmospheric)• Photosynthesis/Cell Respiration
Nitrogen Cycle (Atmospheric) –
• Nitrogen fixation – bacteria in the roots of legumes trap nitrogen gas & convert it to ammonia
• Nitrification – ammonia is converted to nitrites & then to nitrates
• Assimilation – plant roots absorb nitrates & make DNA & proteins
• Ammonification –bacteria convert wastes into ammonia & ammonium Denitrification –bacteria convert this back into nitrogen gas
Sulfur Cycle (Sedimentary)
CELLS & ENERGY
• Some organisms are capable of using light energy to make their own food such as plants. They are called autotrophs. Others must get energy from the food they consume & are known as heterotrophs.
• Cells must have energy in order to work. Chemical energy is stored in the form of chemical bonds in food. In order for energy to be used, it must first be transferred to a molecule capable of providing energy where it’s needed. This energy is usually supplied by ATP. This molecule consists of a Nitrogen base (adenine), a sugar (ribose), & a chain of 3 phosphates. The bond that joins the 2nd & 3rd phosphates in ATP is easily broken. When there are only 2 phosphates present, it is known as ADP. When ATP is converted into ADP & a phosphate its stored energy is released.
• Photosynthesis & cell respiration form a cycle. The carbon atoms needed to make all of the organic molecules of living things come from a nonliving part of the environment (the CO2 in air). The hydrogen atoms needed to make carbohydrates comes from water. In photosynthesis, plants use the energy of sunlight to convert CO2 & H20 into glucose & oxygen.
• PHOTOSYNTHESIS3 Stages:1. Energy is captured from sunlight.
• 2. Light energy is converted to chemical energy.
• 3. Glucose is made from carbon dioxide.
• Equation for photosynthesis:
6CO2 + 6 H2O------------ C6H12O6 (glucose) + 6O2
• Photosynthesis occurs primarily within the leaves of plants. Cells inside leaves contain organelles called chloroplasts, which house chlorophyll (a green pigment). The interior of a chloroplast is filled with flattened membrane-bound sacs called thylakoids that are stacked like coins in columns called grana. The fluid inside of the chloroplast is called the stroma.
• Sunlight provides the energy for photosynthesis. Plants utilize components of the visible portion of the electromagnetic spectrum. Tiny packets of light energy are called photons. Plants absorb the greatest amount of energy from red, blue, & violet light. Plants reflect the green portion of the spectrum.
• Pigments are molecules that absorb light. Chlorophyll is the primary light-absorbing agent for photosynthesis. The 2 types of chlorophyll that plants contain are chlorophyll a & chlorophyll b. Plants also have xanthophylls (yellow pigments ) & carotenoids (orange pigments). These 2 are prevalent in autumn.
• Photosynthesis consists of 2 Phases:1. Light reaction – splits water
• 2. Calvin cycle – makes glucose
C4 Plants• These plants fix
Carbon 4 times faster than C3 plants – it binds CO2 to an intermediate – adapted to high temperature, dry conditions, & abundant light.
• Crabgrass• Corn• Sugarcane• sorghum
CAM plants
• Take in CO2 at night to minimize water loss – good in hot, dry climates.
• Cactus• Pineapple• Stone crops
• Factors That Affect Photosynthesis1. Amount of Water2. Temperature3. Light Intensity
CELLULAR RESPIRATION
• 2 Stages1. Glycolysis (glucose is broken down into pyruvic acid)2. Anaerobic respiration (fermentation) or
• 2. Aerobic respiration(the presence of oxygen determines which #2 it will do)
• The Calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 Celsius degree.
Cell respiration occurs in all cells. It involves breaking the chemical bonds of organic food molecules & releasing that energy to be used by the cells. This energy comes from photosynthesis.
• Equation for cell respiration:
6O2 + C6H12O6 (glucose)
6CO2 + 6H2O + energy (ATP)
• Metabolic processes that require oxygen are termed aerobic & those that do not require oxygen are termed anaerobic. The primary source of energy for the cells is glucose.
• STEP 1: Glycolysis- glucose is broken in half to form 2 three-carbon molecules of pyruvic acid - this step takes place in the cytoplasm of the cellThe presence or absence of oxygen determines what the next step in cell respiration will be – this step produces 4 ATP’s, but it took 2 to get started, so the net gain is 2 ATP’s.
IF THERE IS NO OXYGEN PRESENT,
• CELLS GO THROUGH anaerobic respiration.Pyruvic acid is broken down into ethyl alcohol (fungi & plants – CO2 is a byproduct – this is known as alcoholic fermentation) or lactic acid (animals – this is what makes you sore after an intense workout).
IF OXYGEN IS PRESENT, • CELLS GO THROUGH aerobic
respiration.STEP 1: Pyruvic acid conversion – pyruvic acid from glycolysis is broken into CO2, H, & a 2-carbon acetyl group – H combines with either NAD or FAD & the acetyl group combines with coenzyme A (niacin) & forms Acetyl CoA (carried to the next step)
Krebs Cycle STEP 2: Krebs Cycle – Acetyl CoA then enters the Krebs Cycle – one turn of the cycle produces 2 molecules of CO2, H combines with its acceptors to make NADH & FADH2, & ADP is converted into ATP.
• Occurs in the mitochondria of the cell
• The electron transport chain transfers energy from the NADH & FADH2 and makes ATP.
• Occurs in the mitochondria of the cell
http://www.youtube.com/watch?v=Ak17BWJ3bLg
The Yields of Cellular Respiration
• Glycolysis– 2 Molecules of ATP
• Krebs Cycle– 2 Molecules of ATP
• Electron Transport Chain– 32 Molecules of ATP
• TOTAL of 36 ATP molecules, per molecule of Glucose
Compare/Contrast Photosynthesis & Cell Respiration:
PS CR
Function Energy storage Energy release
Location in the Cell
Chloroplasts Mitochondria
PS CR
Reactants CO2 & H2O C6H12O6 & O2
Products C6H12O6 & O2 CO2 & H2O
Equation 6CO2 + 6H2O -> C6H12O6 + 6O2
6O2 + C6H12O6 -> 6CO2 + 6H2O
