DHS IB Biology HL 2025

CHEMISTRY OF LIFE UNIT

CHEMISTRY OF LIFE UNIT

Know how to draw and label a diagram showing the structure of 2 water molecules, including positive and negative charges

Water has a positive and negative charge, it is _________________

polar

Water binding to water

Cohesive

How is cohesive benefical to living things

surface tension, and helps water move up plants

What is adhesion?

Hydrogen bonds can form between water and other polar molecules

Why is adhesive beneficial to living things

keeps cell walls moist, allowing for substances to pass through

What is high specific heat capacity?

It restricts the motion of water molecules and increases temperature of water in a liquid state. Water doesn't want to boil because it is cohesive, the water sticks together and doesn't want to escape into the air.

How is high specific heat capacity beneficial to living things?

Stable habitat for aquatic organisms, they maintain the same temperature

What is buoyancy?

floating

What is the effect of buoyancy on living things?

some animals can float

What is viscosity?

a liquid's resistance to flow

What is the effect of viscosity on living things?

animals have to overcome viscosity in the air and water

What is a solvent?

Water forms hydrogen bonds with polar molecules. Water is the universal solvent.

How is a solvent beneficial to living things?

Absorption of complex mixtures and dissolves substances. Helps with digestion

What is hydrophilic?

Chemically attracted to water, water loving

What is an Example of hydrophilic substance?

Cellulose. Sugar. Salt.

What is hydrophobic?

Insoluble in water

What is an example of a hydrophobic substance?

Oil

Carbon atoms can form ____ covalent bonds (which allow a diversity of molecules to be formed)

carbon atoms can form 4 covalent bonds

List 3 examples of polysaccharides

starch, glycogen, and cellulose​

Be able to recognize a molecule of glucose (6 carbon ring, hexagon)

Be able to recognize a molecule of ribose (5 carbon ring, pentagon)

Differentiate between amylose and amylopectin

Amylose is a helix and amylopectin is branched

Describe the structure of beta-glucose monomers in cellulose

Glucose alternates up and down making it very strong

Glycoprotein

protein with glucose attached to it

Briefly describe the process of the condensation reaction for amino acids

The forming of a water molecule when 2 amino acids form together

Briefly describe a hydrolysis reaction for amino acids

A water molecule is added to split two amino acids apart. The H joins to one and the OH to the other. The picture here shows hydrolysis of a disaccharide into two monosaccharides

Monounsaturated lipid has how many double bonds?

one double bond

Polyunsaturated of an unsaturated fatty acid has how many double bonds?

many double bonds

What is a triglyceride?

A triglyceride is 3 fatty acids joined together with glycerol

State three functions of lipids

Long term energy storage, heat insulation, structural component (phospholipid bilayer)

Define Amphipathic

part hydrophilic and part hydrophobic. Phospholipids in the cell membrane are amphipathic. They have a polar head and non-polar lipid tails.

Be able to recognize a steroid molecule

Cholesterol is a steroid molecule, and is technically a lipid

2 Examples of steroid molecules

testosterone and oestradiol and cholesterol

Steroids can pass through the cell membrane because they are H________

Steroids can pass through the cell membrane because they are Hydrophobic

Know how to draw an amino acid

Draw a condensation reaction between 2 amino acids

Explain the difference between essential and non essential amino acids

Essential amino acids cannot be synthesized and must be obtained from food. Non-essential amino acids can be made from other amino acids.

There are _________ types of amino acids

There are 20 types of amino acids

What is a polypeptide?

Polypeptide means protein.

List 2 examples of polypeptides (proteins)

insulin regulates glucose, amylase breaks down starch

A protein that has been heated until it loses its natural shape has been

denatured (a denatured protein doesn't work any more because it isn't the right shape to fit with the substrate)

ENZYMES UNIT

ENZYMES UNIT

________ is the web of all the enzyme- catalyzed reactions in cell or organism

metabolism

Anabolism

two molecules being joined together

Catabolism

one molecule being split apart into two smaller molecules

Enzyme

A globular protein that performs a function

Substrate

The material that is altered by an enzyme

Active Site

The place on an enzyme where the substrate attaches

Denaturation

An enzyme's active site is damaged so it can no longer be used

Draw graph showing how enzyme activity is affected by temperature

Draw graph showing how enzyme activity is affected by pH

What do extreme temperatures or pH do to proteins?

Extreme temperatures or pH will denature proteins

Draw graph showing how enzyme activity is affected by substrate concentration

Why does the enzyme graph level off for increasing substrate concentration?

The graph levels off because all the active sites are already preoccupied with substrates and can't do any more

Independent variable

variable the scientist changes (if testing the effect of coca cola on plant growth, the independent variable is the type of liquid given to the plant)

Dependent variable

variable the scientist measures (if testing the effect of coca cola on plant growth, the dependent variable is the height of the plant)

Control group

the normal group (if testing the effect of coca cola on plant growth, the control group is the plant given water)

Be able to draw a graph showing the effect of enzymes on activation energy

Name one enzyme and one substrate

amylase and starch, protease and amino acids, lipase and fatty acids

CELLS UNIT

CELLS UNIT

Name 3 aspects of cell theory

1. All living things are made of cells

2. The smallest unit of life is the cell

3. All cells come from other cells

be able to calculate magnification

magnification = observed value/labeled value The magnification should be a large number

know how to convert um to a decimal. 5 um = _______

5 um = .000005

What type of microscope has the highest resolution?

Electron microscope

Describe fluorescent stains in microscopy

Stains that glow and make it easier to see cell structures

Describe immunofluorescence in microscopy

antibody proteins stick to interesting molecules (antigens) and fluorescent stains then stick to the antibodies

Describe Freeze fracture electron microscopy

A cell is frozen, then split in two, and metal vapor makes an impression of it

Describe cryogenic electron microscopy

proteins are frozen under an electron microscope

Name three structures prokaryotic and eukaryotic cells share

DNA, Cell membrane, Cytoplasm

Are bacteria prokaryotes or eukaryotes?

Bacteria are prokaryotes (YOU are a eukaryote)

Draw a diagram of the ultrastucture of E. coli as an example of a prokaryote

Cell membrane

controls what goes in and out of the cell

Nucleus

Contains DNA

Chromosomes

DNA

Rough Endoplasmic Reticulum

transport of proteins within the cell (has ribosomes on it that make it look rough)

Golgi

modify, sort, and ship proteins and lipids outside the cell

Lysosome

break down food/organelles

Mitochondrion

ATP formation, krebs and the ETC occur here

80s Ribosomes

location of protein synthesis

Chloroplast

capture solar energy for photosynthesis. Contains thylakoids and stroma

Vacuole and Vesicles

absorb/digest food, expel excess water. Storage

What is a vesicle and what does it do?

A vesicle is a small vacuole/bubble that is used to transport things within a cell. Vesicles leave the E.R. and go within the cell, and they leave the golgi to go out of the cell

Microtubules and centrioles

move chromosomes in cell division, centrioles are organelles that make the microtubles (tubes that form the cytoskeleton)

Cilia and Flagella

used for cell locomotion, cilia are hairlike, flagella are larger corkscrew shaped

Name 3 things prokaryotes and eukaryotes have in common

dna, ribosomes, cell membrane

Define Homeostasis

keeping condition inside the organism within tolerable limits

Give an example of homeostasis

maintaining the correct temperature by shivering or sweating

Define Metabolism

chemical reactions inside the cell

Define Nutrition

obtaining food to provide energy for growth

Define Excretion

getting rid of waste products of metabolism

Define Growth

an irreversible increase in size

Define Response

the ability to react to changes in environment

Define Reproduction

producing offspring either sexually or asexually

Name two things plant cells have which animal cells do not

Cell wall, chloroplasts

Give one example of a cell that goes against cell theory

muscle cell with multiple nuclei

Draw a diagram of the ultrastructure of a liver cell as an example of an animal cell

Define Amphipathic

part hydrophilic and part hydrophobic. Phospholipids in the cell membrane are amphipathic. They have a polar head and non-polar lipid tails.

Define Hydrophilic

Attracted to water