Lab 1 Flashcards
What is the scientific method
Is a process to explain natural phenomena and involves a series of
steps: the rational formulation of hypotheses, collection of data, and testing of hypotheses against
observations or experimental results.
Generally, this process begins with the observation of a phenomenon and is an attempt to explain its occurrence, and a hypothesis is the
proposed explanation of the phenomenon as a statement of cause and effect.
Hypothesis testing
starts with a clear description of the question or phenomenon
characteristics of a research hypothesis
1) It explains how or why: provides a mechanism.
2) It is compatible with and based upon the existing body of evidence.
3) It links an effect to a variable.
4) It is testable.
5) It has the potential to be refuted (must be falsifiable).
6) It has at least two possible outcomes.
what is a prediction?
the expected effect if the
hypothesis is supported.
it is used to establish a statistical
hypothesis when we evaluate the research hypothesis against the data collected.
Format of a hypothesis
the IF and THEN format of a hypothesis, where the “if” is linking an effect and a variable, and the “then” is providing the prediction of
what effect you expect to see in the system, based on evidence and research (variables).
Also add a BECAUSE to this, as the
“because” clearly outlines the mechanism that is behind your hypothesis.
- Think of mechanism as the silent partner in the hypo, it’s what you think is behind the relationship that we are not measuring or able to quantify directly (but is a potential cause)
- Variables are measured directly
- Mechanisms indirectly
biogeochemistry
study of distribution and movement of elements in a specific geographical location between biotic and abiotic pools.
The elements studied are usually those essential for life: carbon, nitrogen, phosphorus and sulfur.
cycling of these nutrients combined with other environmental variables can determine the fundamental niches of organisms.
Global warming is caused primarily through
the action of atmospheric carbon dioxide (CO2 ), water vapor, methane (CH4 ), and nitrous oxide (N2O); of these CO2 is considered the most important anthropogenic greenhouse gas.
increasing CO2 and location of CO2 in ecosystems
Increasing atmospheric concentrations of CO2 are correlated with higher temperatures in geological times and are thought to be increasing annual global temperatures currently.
CO2 is found in the ocean, freshwater, living or dead organisms, and the soil as well.
majority temporarily trapped in sedimentary rock, such as limestone.
the movement, or flux, of carbon between the biotic and abiotic components of the ecosystem
is cyclic, with the average residence time of carbon in organic molecules estimated to be between 20- 50 years and in the atmosphere to be between 3- 4 years.
CO2
CO2 dioxide is assimilated by plants during photosynthesis and is converted to organic compounds - simple sugars.
When plants are eaten, or die and decompose, t he carbohydrates are broken down again to CO2 and H2O by the process of respiration.
During respiration CO 2 is released either back to the atmosphere by of terrestrial organisms, or into the water by aquatic organisms, to continue the carbon cycle.
respiration
defined as the use of oxygen to break down organic compounds metabolically to release chemical energy.
Soil respiration
is the sum of autotrophic respiration from live plant roots and their partner mycorrhizae and of heterotrophic respiration by soil biota involved in decomposition, each contributing about 50% of the CO 2 emitted during the growing season
Decomposition of detritus
especially leaf litter on the soil surface and resulting heterotrophic respiration is a significant source of CO2.
leaching
Plant litter is decomposed in a sequential process that begins with leaching of water -soluble minerals and simple sugars, such as glucose, from the material.
fragmentation of the litter
after leaching, fragmentation occurs through both mechanical and biological means.
final stage of decomposition is mineralization
conversion of large organic compounds to simpler inorganic forms by organisms known as decomposers or detritivores.
The organisms involved in the process of decomposition function in a complex community with many trophic levels
Detritivores
organisms that feed on dead plant and animal matter, have variable impacts on decomposition rates, and are often separated by their physical size.
larger invertebrates (> 100 μm)
are classified as meso, macro, and megafauna.
The megafauna such as annelids (earthworms), arthropods ( e.g., springtails, mites and millipedes), and molluscs (e.g., snails and slugs) fragment dead vegetation into smaller pieces, mix litter into the soil, and excrete partially digested plant matter.
smaller organisms
(bacteria, fungi, nematodes, etc.) are classified as microflora/ fauna or more often microbes.
2013). The microbes specialize in the mineralization of organic matter either through aerobic or anaerobic respiration.
The interaction of the two groups of detritivores
results in increased overall decomposition rates, as the actions of the larger invertebrates facilitate the mineralization by microbes
The Experiment for this lab
Will conduct an experiment to determine the amount of CO2 given off during soil respiration.
20 incubation chambers will be set up containing the agreed treatment.
Which is Soil Type.
100 mL of soil in chamber
–> weigh the sample and record in table
–> Add 5.0 g of deciduous forest litter
–> Add 25.0 mL of distilled water
–> Add 25.0 mL of NaOH into small beaker
–> nestle beaker of NaOH into litter
–> Screw lid onto chamber tightly and incubate for 1 week.
