Biology Unit 1 Study Guide

Scientific Method

A step-by-step process used by scientists to investigate questions, gather evidence, and draw conclusions based on experiments and obervations.

Independent Variable

The one factor that is changed/manipulated between groups (x-axis).

Dependent Variable

Factor that is measured/observed/affected by the IV (y-axis).

Hypotheis (Null vs Alternative)

Predictions that can be tested by recording more obervations and experiments.

Null: No Change

Alternative: A change is present

Control Group (negative vs positive)

Negative: Group NOT exposed to any treatment or exposed to treatment known to have NO effect.

Positive: Not exposed to Independent variable, but to a treatment KNOWN to have an expected effect.

Experimental Group

Recieves the Independent Variable to observe the outcome on the Dependent Variable.

Constants

Factors kept consistent for all groups to ensure only the IV affects the outcome.

Statistics

Mehtods used to collect, process, or interpret quantitative data. Summarizes observations and creates predictions.

Descriptive Statistics

Methods used to summarize or describe obervations/samples. Measure of central tendency (mean, median, & mode) and measure of variability (range, standard deviation, variance, skewness, quartiles).

Inferentail Statistics

Using obervations to make estimates or predictions; generlizing from a sample to a wider population. (standard error of the mean & hypotheses tests).

Central Tendencies

The tendency of the obervation to center around a particular value/category rather than spread evenly across the range/categoreis (mean, median, & mode).

Mean

The average of the data set.

Median

The middle number of a data set.

Mode

The most frequent value in a data set.

Variability

The measure of how spread out or dispersed the values in a set of data are.

Range

The difference between the largest and smallest values.

Standard Deviation

A measure of how spread out the data is from the mean.

Standard Error

Used to determine the precision of and confidence in the mean value or in other words how well does the mean of the sample respresent the true mean of the population.

Chi-Square

A form of statisitcal analysis used to compare the actual results (observed) with the expected results.

What are the 6 general steps of the scientific method?

1. Make an obervation

2. Ask a Question

3. Propose a Hypothesis

4. Design an Experiment

5. Collect Data

6. Draw a Conclusion

How are hypotheses formulated?

Turning a research question into a clear, testable statement that predicts a relationship between specific variables.

What is the difference between Null and alternative hypothesis? Do you always need both?

Null = no change

Alt = there is a change

YOU NEED BOTH

How do researchers determine their IV and DV? How are they often graphed?

IV (x-axis): noticing what they manipulate

DV (y-axis): noticing what they observe

Are constants the same as controls? Why or why not?

A constant is a factor that is kept the same, while a control is a baseline group.

When should a positive control be used? When should a negative control be used?

A positive control should be used to show that the experiment shows an effect, while a negative control should be used for proving a baseline.

Describe Central Tendencies. Identify when each type of central tendency should be used.

Central tendencies are values that capture the average, middle, or frequent value in a data set. Mean is used for normal distribution, median is used for data sets with skews or outliers, and mode is used to find common values.

What is used to measure variability?

Range, Interquartile Range (IQR), and Standard Deviation

Is data more reliable with a high or low STDEV? Why?

Data is more reliable with low STDEV since it means data points are close to the average. Ultimately, mean data is consistent and a true reflection.

Why do researchers use SEM?

To measure how close their sample represents the real world.

If standard error bars overlap, is the difference between the means significantly different? Why or why not?

No the difference between the means is not significantly different because the error bars represent where the true mean will fall according to the real population.

Matter

Anything that takes up space

Element

A substance that cannot be broken down into other substances by chemical reactions.

Electronegativity

The measure of an atom´s ability to attract electrons to itself.

Atomic Number

Number of protons

Atomic Mass

number of protons + neutrons averaged over all isotopes.

Octet Rule

Elements, will gain, lose, or share, electrons to complete their valence shell and become stable (like noble gasses)

Chemical Bonds

An attraction between two atoms, resulting from the sharing or transferring of valence electrons.

Compound

A substancce consisiting of two or more different elements combined in a fixed ratio.

Covalent Bonds

When two or more atoms share electrons usually between tow nonmentals

Nonpolar Covalent Bonds

Electrons are shared equally between two atoms.

Polar Covalent Bonds

Electrons are not shared equally between two atoms becoming slight + and -.

Ionic Bonds

The attractions between oppositely charged atoms (ions), usually between a metal and a nonmteal (metal tranfers electrons to nonmetal).

Adhesion

The attraction to other molecules that are polar or have charge (water spreading on table)

Cohesion

Attraction of molecules for other molecules of the same kind

Capillary Action

the upward movement of water due to the forces of cohesion, adhesion, and surface tension (occurs when adhesion is grater than cohesion).

Solvent

dissolving agent in a solution (universal solvent: water)

Solution

homogensous mix of 2+ substances.

Solute

the substance being dissolved

pH (acid vs base)

pH: measure of how acidic or basic a solution is

acid: substance that releases hydrogen ions when dissolved in water

base: a substance that accepts H+ or releases hydrogen ions (OH-)

Buffer

a solution that resisrs chnages in pH when an acid or base is added

Identify the elements that make up nearly all living matter.

C, H, N, O, P, & S

Differentiate between a solute, solvent, and solution.

Solute is the substance being dissolved, while the solvent is the doing the dissolving. A solution is a homogenous misture between 2+ substances.

Describe polar covalent bonds and give two examples.

A chemical link between 2 nonmetals that shair pairs of valence electrons to achieve a stable, outer shell. Two examples are H20 & CH4.

How are hydrogen bonds different than other types of bonds?

Hydrogen Bonds are different from other types of bonds because they are weak and pulls molecules together using partial charges.

Describe ionic bonds and give two examples.

A chemical link where a metal transfers one or more electrons toa nonmetal to create stable chemical compounds. Two examples are NaCl & MgO.

How does electronegativity affect the interactions between water molecules?

Causes Oxygen to pull harder, creating a partial negative charge for Oxygen and a partial positive charge for Hydrogen.

Imagine O and H had the same electronegativity, what would that do to the properties of water?

Water would be come nonpolar, causing water to behave like a gas.

Describe the properties of water and give an example of each.

1. Cohesion (water sticking to itself)

2. Adhesion (water sticking to different molecules)

3. High surface tension (droplets on coins)

4. Universal solvent

5. High Specific Heat Capacity (ocean absorbing lots of heat, but not making the ocean hotter)

6. Low Density (Ice floating)

Describe two way in which water’s properties benefits organisms.

1. Universal Solvent (Being able to dissolve anything)

2. High Specific Heat Capcity (Keeping temperatures stable)

Funtional Groups

Chemical groups attached to the carbon skeleton that participate in chemical reactions

Organic Chemistry

The study of compounds with covalently bonded carbon

Organic Compounds

Compounds that contain carbon, hydrogen, and other elements

Hydrocarbons

Organic molecules consisting only of carbon and hydrogen

What makes carbonsuch a versatile element?

It has 4 valence electrons, so it can form many bonds.

How do functional groups affect the structure and behavior of organic molecules?

Functional groups affect the structure and behavior of organic molecules by determining chemical behavior and reactivity.

What is the difference between hydrocarbons and other organic molecules?

Hydrocarbons contain only H & O, while organic molecules control H, O, and additional elements.

Dehydration Reaction

A chemical process where small molecules called monomers join together to form larger chains called polymers, releasing a molecule of water as a byproduct

Hydrolysis

A chemical reaction where water breaks one or more chemical bonds in a molecule, splitting it into smaller parts

Polymers

A large molecule made of many smaller, repeating chemical units called monomers linked together in long chain

Monomers

A small, simple molecule that can chemically bind with other similar or identical molecules to form a larger, complex chain called a polymer

Differentaiate between a hydrolysis and a dehydration reaction.

Dehydration synthesis builds large biological molecules by removing water to link smaller pieces together. Hydrolysis does the exact opposite: it breaks big molecules apart by adding water back into the chemical bonds.

Disaccharide

A double sugar molecule formed when two simple sugars, or monosaccharides, join together through a covalent chemical bond.

Amino Acids

a small organic molecule that acts as the fundamental building block for proteins

Polypeptide

Many amino acids linked by peptide bonds

Cellulose

a tough, fibrous structural carbohydrate made of linked glucose units that forms the primary cell walls of plants

Monosaccharide

the simplest form of a carbohydrate, consisting of a single sugar unit that cannot be broken down into smaller sugars

Polysaccharide

a large, complex carbohydrate made of long chains of smaller simple sugar units—called monosaccharides—linked together by chemical bonds (glycosidic bonds)

Glycogen

a branched polysaccharide (a large carbohydrate made of many sugar molecules) that serves as the primary energy storage form of glucose in animals, fungi, and bacteria

Hydrophobic

"water-fearing"—it describes molecules or surfaces that repel water and do not dissolve in it.

Hydrophilic

water-loving" and describes molecules or parts of molecules that are attracted to and easily mix or dissolve in water

Glycosidic Linkage

a covalent chemical bond that joins a sugar (monosaccharide) molecule to another molecule

Starch

a soft, white, odorless complex carbohydrate made by green plants to store energy

How many monomers of proteins are there?

20 monomers (amino acids)

How do the R Groups of amino acids contribute to protein structure?

By forming different chemical bonds

Phospholipids play a major role in cells. Where can they be found in a cell, and what is their role?

Phospholipds can be found in the cell membranes, more specifically in organelles. Phospholipids form a lipid layer than prevent stuff from leaking out.

What are polysaccharides? What are their monomers?

Large, complex carbohydrates made of monosaccharides linked together.

What important roles do polysaccharides play in animals and plants?

In animals polysaccharides help store glycogen. In plants polysaccharides help store starch.

How does saturation affect fatty acid structure/funtion?

Saturation determines whether a fatty acid has a double or single carbon - carbon bond.

Saturated: Single Bonds

Unsaturated: 2+ Bonds

Saturated fats have higher melting points, are stable, and are solids at room temperature

Primary Structure

the specific, linear sequence of amino acids that makes up its polypeptide chain

Secondary Structure

the local, repeating 3D folding patterns of a protein's polypeptide backbone, held together by hydrogen bonds

Teritary Structure

the overall three-dimensional shape of a single protein molecule or polypeptide chain, forms through the interactions between R Groups and an amino acid

Quaternary Structure

The final, highest level of protein organization where two or more individual folded protein chains, called subunits, join together to form a single functional complex

Lipid

a diverse group of organic, hydrophobic (water-fearing) molecules that do not mix well with water

Fat

a specific type of lipid made of glycerol and fatty acids that usually stays solid at room temperature

Fatty Acid

a biological molecule made of a long hydrocarbon chain with a reactive carboxyl group (-COOH) at one end. They serve as the main building blocks of complex lipids like fats and cell membranes

Phospholipid

a type of fat molecule that contains a phosphate group and forms the main building block of cell membranes

Denature

a process where a biomolecule—such as a protein or nucleic acid—loses its natural three-dimensional structure and biological activity due to the disruption of weak chemical bonds

Protein

a large, complex molecule made of one or more long chains of amino acids linked together by peptide bonds.

Steroid

a type of lipid molecule defined by a core chemical structure of four fused carbon ring

What forms the backbone of DNA?

Alternating chains of deoxyribose and phosphate groups.