BIO 101 Lab Midterm UNC

objective observation

observations can be verified, often involve counting or measuring

subjective observation

observer-specific observations, qualitative

hypothesis

tentative explanation of cause and effect based on underlying observed phenomena, must be testable

independent variable

the cause

dependent variable

the effect

control variable

all the factors are the same as the test group, except this one factor being tested is left in its normal, unmanipulated state

protocol

description of steps in a scientific investigation

occam's razor

if there are several explanations that might fit an observation, the simplest is most probable and therefore best

prokaryotes

unicellular organisms that lack membrane-bound organelles, including a nucleus; most abundant organisms in the world and found in virtually every known habitat; reproduce mostly asexually

eukaryotes

cells with true nuclei and membrane-bound organelles

domain Bacteria

bacteria and cyanobacteria/blue-green algae

nitrogen fixation

bacteria converts nitrogen into forms that can be used by plants

decomposers

bacteria break down dead plants and animals, and thereby return the organic materials to the system to be used by other organisms

photosynthetic bacteria

use light as their energy source in a process similar to photosynthesis in plants, however, they do not use water, pigments are different in structure, and lack chloroplasts

chemosynthetic bacteria

obtain their energy from the oxidation of inorganic substances

bacilli

rod-shaped bacteria

cocci

small spheres bacteria

spirilla

corkscrew-shaped bacteria

Lactobacillus

the bacterium that uses milk sugar (lactose) and converts milk to yogurt

cyanobacteria/blue-green algae

photosynthetic bacteria, possess the pigment chlorophyll a and use water in their photosynthetic process

gloeocapsa

unicellular form of cyanobacteria, gelatinous sheath surrounds the cell, clustered together, green color

oscillatoria

colonial form of cyanobacteria, may occur as filaments, plates, or spheres

staphylococcus

moist-looking colonies, gram-positive cocci

streptococcus

gram-positive coccus, common in nose and mouth, cause of "strep throat"

bacillus

waxy-looking, gram-positive bacillus, spores may be visible as poorly stained oval swellings, genera of decomposers

coliform

frequently foul-smelling colonies, wet-looking, gram-negative rods, common in intestines, and consequently in sewage and sewage-contaminated things, ability to ferment lactose

pseudomonas

diffuses into the medium, produce severe infections, especially in burn patients

yeasts

fungi that form very large colonies, strikingly white and glistening, very raised

molds

fungi is hairy-looking colonies, stains show hyphae (broken ends)

paramecium

animal-like protists, single-celled organism, cilia along cell membrane over body used for locomotion and food capture

Phylum Ciliophora

phylum contains the largest single-celled organisms and most complex protozoans, all members are heterotrophic and most live in freshwater environments

oral groove

in paramecium, rapid movement of cilia creates water currents outside the cell that force fluids and food particles into this, which appears as a fold on one long side of the cell

cytopharynx

region of lower end of the oral groove where food particles accumulate in paramecium

food vacuole

in paramecium, forms enveloping the food particles and migrates to an opening

anal pore

in paramecium, opening where food vacuole attaches and empties its contents, releasing indigestible food particles outside the cell

contractile vacuoles

paramecium has 2 of these and euglena has 1; removes excess fluids from the cell

macronucleus

large nuclei in ciliates that controls cell maintenance functions

micronucleus

small nuclei in ciliates that is responsible for genetic and reproductive functions, including producing the macronucleus

conjugation

reproduction in ciliates may be asexual or sexual, in this form, two cells exchange micronuclei and thus genetic material; each cell acts as both "donor" and "recipient"

euglena

unicellular organism with plant and animal characteristics; it is photosynthetic and contains chlorophyll a and b, yet not entirely autotrophic, Division Euglenophyta, freshwater organisms; reproduces asexually

phagocytosis

how euglena ingest food particles

pellicle

euglena does not have a cell wall, but retains rigid shape due to this, a layer of elastic proteins just inside the cell membrane

flagellum

how euglena moves, whiplike structure

stigma

eyespot, a light-sensitive structure containing carotenoids in euglena

pyrenoids

organelles in euglena that store sugars

pseudopodia

form of motility for amoeba where false feet extend from body and pull the rest of the cell along

plastids

the unique double membrane-bound organelles in plants

Endosymbiont Theory

implies chloroplasts and mitochondria were prokaryotic cells that were engulfed and developed a symbiotic relationship with their host cells

elodea

common pond weed found in NC, contains cell wall, chloroplasts, nucleus, vacuoles

cytoplasmic streaming

in elodea, chloroplasts are suspended in the cytoplasm and moving throughout the cell

volvox

belongs to the Division Chlorophyta, colony contains 500-50,000 cells, biflagellate, colony surrounded by a thin mucilaginous layer, reproduce sexually or asexually by reproductive cells produce daughter colonies inside the parent which are released when parent colony bursts

cytoplasmic strands

volvox outer cells are connected to one another by this

plasmolysis

cellular shrinkage occurring as a result of a cell being exposed to a hypertonic solution (examined in elodea)

human epithelial cells

consume food through ingestion rather than absorption, feature prominent nuclei, and form a protective layer so there is little extracellular material between cells (cells are tightly packed)

photoreceptors

pigments that trap light energy

chlorophyll a

blue-green pigment and occurs in all photosynthetic eukaryotes and cyanobacteria; essential photosynthetic pigment

chlorophyll b

olive-green pigment in most plants and is an accessory pigment (capture additional light energy which is then transferred to chlorophyll a)

chlorophyll c

pigment is found in certain kinds of algae

carotenoids

other class of yellow, orange, or red pigments; functions as accessory pigments and as coloring in reproductive parts to enhance pollination and fruit dispersal; can be divided in 2 groups: carotenes and xanthophylls

beta-carotene

yellow-orange pigment, essential dietary supplement in animals; chemically modified by splitting and adding water to form vitamin A

xanthophylls

yellow pigments

paper chromatography

method used to analyze pigments; pigments are separated at different rates (reference front value); polar molecules absorb to the polar chromatography paper and do not move whereas non polar molecules travel with the solvent

order from origin to solvent front

chlorophyll b, chlorophyll a, 2 xanthophylls, and beta-carotene

Hill Reaction

shows that chloroplasts in water can operate in the present of light and an electron acceptor to release oxygen (no CO2 was present so O2 came from water)

DPIP

replaced some of the NADP+ molecules to be reduced and change color from blue to colorless

parts of microscope

iris diaphragm

light passes through this before it goes through the slide which controls the amount of light passing through the slide

condenser

focuses all light on the specimen and should be close to the slide

objectives

first set of lenses; after light strikes the specimen, it goes up these which magnifies the image of the specimen

ocular lens

last set of lenses that the beam of light passes through

course and fine focus knobs

allow you to bring the specimen into focus by bringing the objectives as close to the stage as possible

gram stain

technique to identify bacteria; bacteria have strong cell walls that surround the cell membrane and provide protection made up of disaccharide sugars; gram-positive cell is thick and stain purple while gram-negative cell wall is thinner and partially dissolved so does not retain stain

gram stain procedure

crystal violet, gram's iodine, safranin