Biology Unit 1

What is the null hypothesis?

The idea that there is no relationship between two variables in an experiment

What is the alternative hypothesis?

The statement that suggests a relationship exists between two variables

What is an independent variable?

The variable that is manipulated by the experimenter

What is a dependent variable?

The variable that changes in response to the independent variable

What is a positive control?

A part of an experiment that is expected to produce a known result

What is a negative control?

A baseline condition that should produce no effect and is used for comparison

How should data be arranged in a bar graph?

Groups with similar data should be placed next to each other

What is the hydroxyl functional group?

-OH

What is the carbonyl functional group?

C=O

What is the carboxyl functional group?

-COOH

What is the amino functional group?

-NH2

What is the sulfhydryl functional group?

-SH

What is the phosphate functional group?

-PO4²-

What is the methyl functional group?

-CH3

What is cohesion in water?

The attraction between molecules of the same substance

What is adhesion in water?

The attraction between molecules of different substances

What is heat capacity?

The amount of heat needed to raise the temperature of a substance

Why does water have a high heat capacity?

Because hydrogen bonds absorb heat before breaking

Why does salt dissolve in water?

Water’s polarity separates sodium and chloride ions

Why is water polar?

Oxygen is more electronegative than hydrogen

What is evaporative cooling?

Cooling that occurs when water molecules with the highest energy evaporate

Why does ice float in water?

Ice is less dense because its molecules form stable hydrogen bonds

What is pH?

A scale that measures hydrogen ion concentration in a solution

What is surface tension?

The tightness of water’s surface caused by hydrogen bonding

What is temperature moderation?

Water’s ability to resist temperature change due to hydrogen bonding

What is standard deviation?

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

What does a small standard deviation indicate?

That the data points are close to the mean

What does a large standard deviation indicate?

That the data points are widely spread

What is the standard error of measurement?

An estimate of the variation between a sample mean and the population mean

What is the interquartile range (IQR)?

The range of values between the first quartile (25%) and the third quartile (75%)

What is a covalent bond?

A bond formed when atoms share electrons

What is a hydrogen bond?

A weak bond between a hydrogen atom and an electronegative atom like oxygen

What is an ionic bond?

A bond formed when electrons are transferred between atoms

What are proteins?

Macromolecules made of amino acids that perform many functions in the body

What are lipids?

Hydrophobic molecules such as fats

What are carbohydrates?

Macromolecules made of sugars that provide energy and structure

What are nucleic acids?

DNA and RNA

What are monomers?

The small subunits that build macromolecules

What are polymers?

Large molecules made up of repeating monomers

What are monosaccharides?

Simple sugars such as glucose and fructose

What is glycerol?

A three-carbon molecule that forms the backbone of many lipids

What are nucleotides?

The building blocks of nucleic acids

What are amino acids?

The building blocks of proteins

What are polysaccharides?

Long chains of monosaccharides

What elements make up carbohydrates?

C, H, O

What elements make up lipids?

C,H,O

What elements make up proteins?

C,H,O,N

What elements make up nucleic acids?

C,H,N,O,P

What is DNA?

A nucleic acid that stores genetic information in the form of a double helix

What is RNA?

A nucleic acid that helps make proteins by carrying instructions from DNA

What is the nucleus?

The organelle that stores DNA in eukaryotic cells

What are ribosomes?

The organelles that build proteins from amino acids

What are polypeptides?

Chains of amino acids linked by peptide bonds

What is protein folding?

The process where a polypeptide chain folds into a functional protein shape

How are proteins related to amino acids?

Proteins are made of one or more chains of amino acids

How are polypeptides related to proteins?

Proteins are folded polypeptides that perform biological functions

Why are proteins considered macromolecules?

They are large molecules built from repeating amino acid units

What is the function of carbohydrates?

To provide short-term energy and structural support

What is the function of lipids?

To store energy long-term

What is the function of proteins?

To catalyze reactions

What is the function of nucleic acids?

To store and transmit genetic information

What type of bond holds monomers together in polymers?

Covalent bonds

What type of bond holds base pairs together in DNA?

Hydrogen bonds

What happens if a protein folds incorrectly?

It may lose its function or cause disease

Why are controls important in experiments?

They allow scientists to compare experimental results against known conditions

What is the relationship between independent and dependent variables?

The dependent variable changes in response to the independent variable

What is the role of carbon in biological systems?

Backbone of macromolecules

forms stable covalent bonds

How do polar phospholipid parts interact when membranes fuse?

Hydrophilic heads interact with each other and water

How do nonpolar phospholipid parts interact when membranes fuse?

Hydrophobic tails cluster together

What is the immediate effect if fused B-cancer cells lack nitrogen?

Cells can’t make nucleotides or proteins → growth stops

Why does nitrogen deprivation halt growth?

Nitrogen is needed for amino acids and nucleotides

What process forms covalent peptide bonds?

Dehydration synthesis (condensation)

Why did the receptor protein change shape after substitutions?

Side chain properties changed (hydrophobic/hydrophilic/charge)

Which protein structure levels are altered by amino acid substitutions?

Primary

How is receptor function most likely affected by substitutions?

Shape change disrupts ligand binding and response

What is the primary structure of a protein?

The sequence of amino acids in a polypeptide chain

What is the secondary structure of a protein?

Local folding into alpha helices and beta sheets stabilized by hydrogen bonds

What is the tertiary structure of a protein?

The overall 3D shape formed by interactions between R groups

What is the quaternary structure of a protein?

The arrangement of multiple polypeptide chains into one functional protein

What is lactose?

A disaccharide sugar made of glucose and galactose.

What is lactase?

An enzyme that breaks down lactose into glucose and galactose.

How is biological information stored in DNA?

Through the specific sequence of nucleotides.

What happens when radiation damages DNA?

Damaged nucleotides can be removed and replaced with undamaged ones.

Which bond in DNA can be broken to replace a nucleotide without losing genetic information?

The bond between a nucleotide and the sugar-phosphate backbone.

How are starch and cellulose similar in structure?

Both are made of glucose

How is water transported upward in plants?

Through cohesion between water molecules and adhesion to xylem walls

What is the chemical composition of cell membrane macromolecules?

They all contain carbon and hydrogen

What can cause differences in leaf growth?

Environmental or genetic factors that affect photosynthesis and resource availability.

What must an amino acid have to join a polypeptide chain?

An amino group

How can changing one amino acid affect a protein?

A new side chain may alter folding and cause the protein to lose its proper function.