Bio Lab Flashcards
All science is ….
provisional
arranged or existing for the present, possibly to be changed later.
Null hypothesis
Just by chance
Theory stands the test of time it becomes
a law
Analysis
Reject or accept the hypothesis
Negative control group
Do not receive the manipulation of the experimental variable
Positive control group
Do not receive the manipulation either, but they do receive a different kind of manipulation one whose effects are known.
Confounding variables
Any variables that make the experimental and control groups dissimilar
Blind experiment
When patients do not know whether they are in the experimental or control group
Double blind experiment
When the person who administers the treatment doesn’t know which one contains actual medicine and which are placebo’s. It is a standard procedure for testing the efficacy of new drugs.
A graph which is used when the experiment of variable is a continuous range of numbers with no discreet lumping of the numbers into categories.
Line graph
A graph that is used when the experimental variable is composed of categories rather than a continuous range of number numbers.
Bar graph
The range of the pH scale
0 - 14
Equation of water dissociating
H20 ⇌ H+ +OH-
What is dissociating
when a molecule breaks apart into smaller components, like atoms or ions, usually happening when a substance dissolves in water; essentially, it’s the process of a compound splitting into its individual parts
What does it mean for an acid to be strong?
pH between 0 and 2
More Hydrogen Ions
What does it mean for an acid to be weak?
pH between 3 and 6.
Fewer Hydrogen Ions: Partially ionizes, resulting in a lower concentration of H+
What does it mean for a base to be strong?
Higher pH between 12 and 14
More OH- ions
Complete ionization, produces high concentration of hydroxide ions in water it is a
Strong Base
Strong Dissociation example
NaOH –> Na+ +OH-
What does it mean for a base to be weak?
pH around 8 to 11
Produces fewer OH−OH− ions compared to a strong base at the same concentration.
How does a buffer work?
any substance that picks up or releases hydrogen ions
Buffers rely on substances that can accept or donate hydrogen ions (H+) to maintain a stable pH.
A neutral substance of 50% H+ and 50% OH-
Water
Weak acids
dissociate slightly, most molecules stay together
Strong acids
have more dissociation of hydrogen ions
All acids, bases, salts are
ionic
When a strong acid reacts with a strong base, they
neutralize each other to form a salt and water:
Strong Acid+Strong Base→Salt+Water
If blood becomes too basic (alkaline), the body will
work to lower the pH back to normal (around 7.4) by releasing hydrogen ions (H+H+) to restore the balance.
if blood becomes too acidic (a condition called acidosis) the body will
works to raise the pH by removing excess hydrogen ions (H⁺) to restore the balance.
Blood contains chemical systems that resist changes in pH. Called
Buffers
How is pure water always neutral?
It is 50-50 hydrogen and hydroxide not favoring acidity or basicity
How does a solution become acidic
When there is an increase in H+
Explain how a solution can become basic
When there is an increase in hydroxide ions
The body always strives to maintain pH around-/——- to keep biological processes stable.
7.35–7.45
Reagent for lipids is
Sudan III
Sudan III tests for
Presence of lipids.
It is a fat-soluble dye that stains fat cells.
If fat cells are present the paper will turn dark orange
If Fat are present, the Sudan III will turn
Dark Orange. Orange colored spots
The color red in Sundan III indicates that
triglycerides or fats are not present
Benedicts solution tests for
the presence of reducing sugars such as monosaccharides, and dissaccahires
Why will polysacchirides not react to Benedict’s solution?
because they are not reducing sugars.
They have few free aldehyde or ketone groups to react with the reagent
“Benedict’s test detects reducing sugars, which have free aldehyde or ketone groups that can donate electrons to the reagent, causing a color change. Polysaccharides have few free groups available, so they do not react.”
Reducing sugars such as monosachharides or disacchirides will have a ______ that can be oxidized. Therefor, Benedict’s solution is used.
aldehyde group (-CHO)
If no reducing sugars are present Benedict’s solution stays
Blue
In the presence of reducing sugars, the Benedicts solution turns
Red-orange, orange, yellow, or green.
From Blue.
Lugol’s iodine test for
the presence of starch in carbohydrates
If starch is present, Lugol’s solution will turn from
yellow-orange to deep blue-black
The test for the presence of proteins and short peptides is
Biuret
In the presence of proteins the Biuret will turn from
blue to violet
A blue biuret indicates
negative results. No presence of proteins
Smallest molecule for each macromolecule:
Fats:
Carbohydrates:
Proteins:
Nucleic Acid:
Fats: fatty acids
Carbohydrates: monosacchires
Proteins: amino acids
Nucleic Acid: nucleotide
Proteins are considered polar molecules because they contain both polar and nonpolar regions within their structure, with the polar regions generally facing outward and the nonpolar regions usually tucked inside the protein’s core when folded in an aqueous environment; this is due to the different polarities of the amino acid side chains that make up the protein.
Proteins are considered polar molecules because they contain both polar and nonpolar regions within their structure, with the polar regions generally facing outward and the nonpolar regions usually tucked inside the protein’s core when folded in an aqueous environment; this is due to the different polarities of the amino acid side chains that make up the protein.
Are call carbohydrates polar?
Yes
Are all lipids are non-polar?
Yes. All lipids are non-polar
A molecule that has a nitrogenous base, a pentose sugar, and a phosphate would be?
A nucleotide
-Base Unit for DNA and RNA
Protein identifying features
Amino (NH3),Carboxyl (C=00), R Group, Hydrogen (H)
Carbohydrate identifying features:
Carbon, Oxygen, Hydrogen. Straight or Ringed.
Lipid features:
Hydrocarbon chain, Carboxyl group, Alcohol
How does Lugol’s iodine test for polysaccharides but not monosacahrides?
iodine binds to the helical structure of polysaccharides, not individual sugar molecules.
An easy test answer:
“Lugol’s iodine binds to the coiled structure of polysaccharides like starch, causing a color change. Monosaccharides lack this structure, so no reaction occurs.”
Why will polysaccharides not react wirh Sundan III?
Sudan III is specifically designed to detect lipids, which are nonpolar.
polysaccharides are polar carbohydrates.
Why is water often use as a control in scientific experiments
It provides a neutral baseline with minimal potential for interfering reactions, allowing for accurate comparison.
What happens to the field of view when switching from the scanning lens (4x) to the low-power lens(10x)?
A: The field of view shrinks (gets smaller).
Keep both eyes open when using an ocular lens microscope (10x)?
It reduces eye strain and helps with depth perception.
What is the magnification of the red scanning lens?
A: 4x
What is the function of the rheostat on a microscope?
It controls the light intensity.
Why should the coarse adjustment knob never be used with low, high, or oil immersion lenses?
It can damage the slide or objective lens due to large, sudden movements.
How do you calculate total magnification?
A: Multiply the ocular lens (usually 10x) by the objective lens
What is the total magnification for the scanning lens (4x)?
A: 40x (4x * 10x)
What is the total magnification for the low-power lens (10x)?
A: 100x (10x * 10x)
What is the total magnification for the high-power lens (40x)?
A: 400x (40x * 10x)
What do all cells have in common?
A: Plasma membrane, cytoplasm, ribosomes, and DNA.
What is the difference between animal and plant cells?
Animal cells have lysosomes and centrioles.
Plant cells have chloroplasts, a cell wall, and a central vacuole.
What is an organelle?
A specialized structure inside a cell that performs a specific function.
What are the three domains of life?
A: Bacteria, Archaea, and Eukarya.
What are the six kingdoms of life?
Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia.
Which kingdom contains unicellular organisms?
A: Bacteria, Archaea, and Protista.
Which kingdoms contain multicellular organisms?
Fungi, Plantae, and Animalia.
Part of the domain Eukarya
Which domains do prokaryotes belong to?
A: Bacteria and Archaea.
Which domain do eukaryotic organisms belong to?
A: Eukarya.
Why do humans belong to the domain Eukarya?
Because our cells have a nucleus and membrane-bound organelles.
What is the difference between a scanning electron microscope (SEM) and a transmission electron microscope (TEM)?
SEM creates a 3D surface image by scanning with electrons.
TEM provides detailed internal structures by passing electrons through the sample.
When would you use a compound microscope?
When viewing small, thin, transparent specimens like cells and tissues.
When would you use a dissecting microscope?
A: When viewing larger, 3D objects such as insects, plants, or small dissections.
What is the difference between a microscope’s magnification and field of view?
Magnification enlarges the image.
Field of view is the area visible through the lens and decreases as magnification increases.
Why is staining necessary when making a slide?
A: To increase contrast and make cell structures more visible.
Why is the iris diaphragm important on a microscope?
A: It controls how much light passes through the specimen, affecting contrast.
Why do scientists use microscopes?
A: To study structures too small to see with the naked eye.
Why is it important to understand depth of field in microscopy?
A: It allows you to focus on different layers of a specimen, especially when it is thick.
How are cells similar to bricks in a building?
A: Cells build up tissues and organisms just like bricks form a structure.
What is a cell?
A: The basic unit of life in all living organisms.
What influences the rate of diffusion?
Size, temperature, concentration gradient
iso:
hyper:
hypo:
equal
high
low
hypotonic solution: A solution with a ____ solute concentration compared to the inside of the cell, causing water to move___ the cell.
A solution with a lower solute concentration compared to the inside of the cell, causing water to move into the cell.
An animal cell in a hypotonic solution: The cell will ____ as water enters, and it may ___(burst) due to the lack of a cell wall.
The cell will swell as water enters, and it may lyse (burst) due to the lack of a cell wall.
Why doesn’t a plant cell burst in a hypotonic solution?
Plant cells have a rigid cell wall that prevents them from bursting. Instead, they become turgid (firm).
Plant cells have a rigid cell wall that prevents them from bursting. Instead, they become_____ (firm).
turgid
What is lysis?
The breaking or bursting of an animal cell membrane when too much water enters in a hypotonic solution.
What is turgidity?
The state of being swollen and firm due to water entering a plant cell, supported by the cell wall.
Best environment for plant cells is a ______ solution
hypotonic solution. The cell wall prevents it from bursting
An an isotonic solution an animal cell ______, a plant cell ______
normal
flacid
_______ occurs when a plant cell is placed in a ______ solution. Water leaves the cell, causing the cell membrane to pull away from the cell wall.
Plasmolysis occurs when a plant cell is placed in a hypertonic solution. Water leaves the cell, causing the cell membrane to pull away from the cell wall.
plasmolysis: happens in a ______ solution because water moves out of the cell by osmosis, leading to the shrinking of the cytoplasm and membrane.
hypertonic
Do animal cells experience plasmolysis?
No, animal cells do lack a cell wall. Instead, they undergo crenation in a hypertonic solution.
_____ is the shrinking of red blood cells when placed in a hypertonic solution as water moves out of the cell.
Crenation is the shrinking of red blood cells when placed in a hypertonic solution as water moves out of the cell.
______: Happens in plant cells due to water loss, causing the membrane to shrink away from the wall.
______: Happens in animal cells like red blood cells, causing them to shrivel without a cell wall.
Plasmolysis: Happens in plant cells due to water loss, causing the membrane to shrink away from the wall.
Crenation: Happens in animal cells like red blood cells, causing them to shrivel without a cell wall.
What does selectively permeable mean?
A membrane that allows certain molecules to pass while blocking others.
What are phospholipids?
Molecules with a polar (hydrophilic) head and nonpolar (hydrophobic) tails that make up the plasma membrane.
What is an integral protein?
: A protein embedded within the plasma membrane, involved in transport and signaling.
What three factors affect diffusion rate?
- Concentration gradient
- Molecular weight
- Temperature
How does temperature affect diffusion?
Higher temperature increases kinetic energy, leading to a faster diffusion rate.
How does molecular weight affect diffusion?
Heavier molecules diffuse more slowly than lighter ones.
How does concentration gradient affect diffusion?
A higher concentration gradient results in a faster diffusion rate.
What happens to a cell in a hypertonic solution?
It shrinks (crenation in animal cells, plasmolysis in plant cells) due to water loss.
What happens to a cell in a hypotonic solution?
It swells; animal cells may burst (lysis), while plant cells become turgid.
What is an isotonic solution?
A solution with equal solute concentration inside and outside the cell, causing no net water movement.
What is the best environment for a plant cell?
A hypotonic solution, as the cell wall prevents it from bursting while maintaining turgor pressure.
What is osmosis?
The diffusion of water across a selectively permeable membrane.
What are the expected results of diffusion experiments regarding molecular weight?
Smaller molecules diffuse faster than larger ones.
What happens when the concentration of a solute increases?
The rate of diffusion increases.
the solution becomes more hypertonic relative to the cell’s interior. This causes water to move out of the cell via osmosis, as water flows from an area of lower solute concentration (inside the cell) to higher solute concentration (outside the cell)
Animal cells: crenation (water loss)
Plant cells: plasmolysis (losing tugor-shrink away from cell wall )
Osmosis is diffusion of water across membranes through ____
aquaporin channel protein (transmembrane-intergral proteins)
An _____ _____ is where the enzyme binds to the _____
An active site is where the enzyme binds to the substrate
In the lab 8 experiment,
What was the substrate?
What was the enzyme?
What was the product?
Substrate: starch
Enzyme: Amylayse
Product: Glucose
A solution containing starch and an enzyme (such as amylase) gets lighter in color because the enzyme breaks down the starch into
simpler sugars.
What happens with the enzyme concentration?
Enzymes do not get used up in the reaction, but they can become less effective over time due to:
Denaturation (due to unfavorable conditions like heat or pH changes). Degradation (natural breakdown of the enzyme molecules over time).
If the solution is stored for a long time, the enzyme’s activity might gradually decline.
What happens with temperature?
Optimal Temperature (Usually 35–40°C): Enzyme activity is highest.
Too Low Temperature (<10°C): The reaction slows down significantly, but the enzyme remains intact.
Too High Temperature (>50°C): The enzyme denatures, losing its shape and function, stopping the reaction permanently.
What happens with pH?
If the enzyme produces acidic byproducts, the pH might decrease slightly.
If buffering agents are present, the pH may stay relatively stable.
Extreme pH shifts (too acidic or too basic) can denature the enzyme, stopping the reaction.
What happens over time?
The enzyme continues breaking down starch into simpler sugars (maltose, glucose).
The solution becomes clearer and lighter as starch disappears.
Once all the starch is broken down, the reaction slows down and eventually stops because there is no more substrate (starch) left.
If left for an extended time, microbial activity could start affecting the solution, possibly leading to contamination.
An enzyme serves as a ____ providing activation energy by _____ the activation energy needed for a chemical reaction to occur.
An enzyme serves as a catalyst providing activation energy by lowering the activation energy needed for a chemical reaction to occur.
What affects enzymes?
Concentration, Temperature, pH, Time
Adding an enzyme to Reactants(substrate)- creates ____
Reactants(substrate)—enzyme—–>
Products
Enzyme reaction process:
Substrate+Enzyme→Product+Enzyme
Starch+Amylase→Maltose (Product)
A substrate binds to an enzyme, which helps convert it into _____ through a chemical reaction. The enzyme itself is not consumed and can be reused.
A substrate binds to an enzyme, which helps convert it into products through a chemical reaction. The enzyme itself is not consumed and can be reused.
The starting materials of a reaction. The molecule that undergoes change (e.g., starch).
Reactants, Substrate (e.g., starch).
The biological catalyst that speeds up the reaction
Enzyme (e.g., amylase).
The end result after the reaction
Product (e.g., maltose, glucose).
What is the purpose of heat-fixing the smear?
What cells can you not apply heat?
Make them fix to the slide
Animal cells should not apply heat because they can lyse.
Why might fungal colonies be found growing on the Petri dish with the bacteria colonies?
Spores are all over, you can find it on damp surfaces.
How can Bacteria gain resistance to antibiotics?
Through mutation, and horizontal gene transfer
What is the name for spherical bacterial cells?
coccus
cocci
What is the name for rod-shaped bacterial cells?
bacillus
bacilli
What is the name for spiral-shaped bacterial cells?
pirillum
spirilla
spirochete
spirochetes
The prefix strepto means ‘occur in
chains
chain
The prefix staphylo means ‘occur in
bunches
bunch
clusters
cluster
groups
group
_____ happens when a bacterial cell takes in new DNA from the environment.
Transformation
_____ happens when DNA is transferred from a donor bacterial cell to a recipient bacterial cell.
Conjugation; donor, recipient
_____ happens when a bacterial cell receives new DNA from another organism or from the environment
Horizontal Gene Transfer
Bacteria reproduce via _____, which is a form of _____.
binary fission, vertical gene transfer
Bacterial cell walls are composed of
peptidoglycan
Bacteria are
unicellular, have a cell wall, are prokaryotes
The transfer of genetic material from parent to offspring during reproduction.
Vertical Gene transfer
Happens when bacteria replicate by binary fission.
The transfer of genes that happens when bacteria replicate by binary fission.
vertical gene transfer
The transfer of genetic material between organisms that are not parent and offspring. It often happens between different bacteria—even different species!
Horizontal gene Transfer
Occurs among living bacteria
Main ways _____ Gene Transfer happens:
*______ – DNA is transferred through direct contact (via a pilus).
*______ – Bacteria absorb DNA from the environment (usually from dead bacteria).
Main ways Horizontal Gene Transfer happens:
Conjugation – gDNA is transferred through direct contact (via a pilus). Transformation – Bacteria absorb DNA from the environment (usually from dead bacteria).
DNA is transferred through direct contact (via a pilus).
Conjugation
