Bio Unit 1 Grade 12 Test Review

What are the unique properties of water? In what ways do these properties contribute to water’s importance to living things?

Water is polar and forms hydrogen bonds. It has cohesion, adhesion, high specific heat, high heat of vaporization, and excellent solvent properties. These help regulate temperature, transport substances, and support chemical reactions.

Why are carbon-based molecules the foundation for life?

Carbon forms four covalent bonds, allowing it to build stable chains, rings, and complex molecules essential for living organisms.

Be able to identify all functional groups.

Hydroxyl (–OH), carbonyl (C=O), carboxyl (–COOH), amino (–NH₂), sulfhydryl (–SH), phosphate (–PO₄-containing group), and methyl (–CH₃).

What makes functional groups critical as accessories for macromolecules?

They determine a molecule’s chemical properties, including polarity, charge, acidity, solubility, and reactivity.

Know which functional groups you would find on each type of macromolecule.

Carbohydrates: hydroxyl and carbonyl. Lipids: carboxyl, hydroxyl, and phosphate in phospholipids. Proteins: amino, carboxyl, and sometimes sulfhydryl. Nucleic acids: phosphate and hydroxyl groups.

Where appropriate know the monomer and polymer names for each type of macromolecule and be able to recognize examples of each.

Carbohydrates: monosaccharides → polysaccharides (starch, glycogen, cellulose). Proteins: amino acids → polypeptides/proteins. Nucleic acids: nucleotides → DNA or RNA. Lipids are not true polymers; triglycerides contain glycerol and three fatty acids.

Know the names of the bonds that join monomers for the classes of macromolecules.

Carbohydrates: glycosidic bonds. Proteins: peptide bonds. Nucleic acids: phosphodiester bonds. Lipids: ester bonds join glycerol and fatty acids.

Be able to sketch the dehydration reactions that occur to join each type of monomer.

Carbohydrates: two sugar hydroxyl groups react, releasing H₂O and forming a glycosidic bond. Proteins: a carboxyl group and amino group react, releasing H₂O and forming a peptide bond. Lipids: glycerol hydroxyl groups react with fatty acid carboxyl groups, forming ester bonds and releasing H₂O. Nucleic acids: nucleotides join through phosphodiester bonds in condensation reactions.

Be able to relate structure to function.

A molecule’s shape and chemical properties determine how it interacts with other molecules and performs its biological role.

For all other macromolecules discussed, know their functions.

Carbohydrates provide energy, energy storage, and structural support. Lipids provide long-term energy storage, insulation, membranes, and signaling. Proteins function as enzymes, structural components, transporters, receptors, and more. Nucleic acids store and help express genetic information.

Know the differences between saturated and unsaturated fatty acids.

Saturated fatty acids have no carbon-carbon double bonds and pack tightly. Unsaturated fatty acids have one or more double bonds that often create bends, preventing tight packing and lowering melting points.

Understand each level of structure in proteins, how it’s formed and its significance.

Primary: amino acid sequence joined by peptide bonds. Secondary: alpha helices and beta sheets formed by backbone hydrogen bonds. Tertiary: overall 3D shape formed by interactions between R groups. Quaternary: association of multiple polypeptide subunits. Structure determines protein function.

Explain the fluid mosaic model of plasma membranes.

The membrane is a flexible phospholipid bilayer with hydrophilic heads facing water and hydrophobic tails facing inward. Proteins and other components are embedded in or associated with the bilayer and can move laterally.

What roles do proteins in the cell membrane fill?

Transport substances, receive signals, catalyze reactions, identify cells, help cells adhere, and anchor cellular structures.

What are the differences between passive and active transport?

Passive transport moves substances down their concentration or electrochemical gradient without direct energy input. Active transport requires energy to move substances, commonly against their gradient.

In general, know what types of materials can freely pass through the membrane and when active transport would be necessary.

Small nonpolar molecules such as O₂ and CO₂ cross the lipid bilayer easily. Ions and large or polar molecules generally need transport proteins. Active transport is necessary when substances must move against their electrochemical gradient.

What is the difference between a carrier protein and a channel protein?

A channel protein forms a passageway for specific substances. A carrier protein binds a substance and changes shape to move it across the membrane.

Be able to explain the direction of water flow during osmosis.

Water moves net from the side with lower effective solute concentration toward the side with higher effective solute concentration across a selectively permeable membrane.

Understand how endo and exocytosis work.

Endocytosis brings material into a cell by forming membrane vesicles. Exocytosis releases material when vesicles fuse with the plasma membrane.

Be familiar with the concept of osmoregulation.

Osmoregulation is the regulation of water balance and solute concentrations to maintain stable internal conditions.

Explain the factors that affect osmoregulation.

Water and salt intake, environmental salinity, water loss, hormones, kidney function, and the organism’s environment affect osmoregulation.

Label the structures of the kidney and nephron.

Kidney: renal cortex, renal medulla, renal pelvis, renal artery, renal vein, and ureter. Nephron: afferent arteriole, glomerulus, Bowman’s capsule, efferent arteriole, proximal convoluted tubule, descending loop of Henle, ascending loop of Henle, distal convoluted tubule, and collecting duct.

Explain the processes occurring at each section of the nephron: Glomerulus, Bowman’s capsule, proximal convoluted tubule, descending loop of Henle, ascending loop of Henle, distal convoluted tubule and the collecting duct.

Glomerulus: filters water and small solutes from blood. Bowman’s capsule: collects filtrate. Proximal convoluted tubule: reabsorbs most water and useful solutes, including nearly all glucose normally. Descending loop: water leaves by osmosis. Ascending loop: salts leave, but water cannot follow easily. Distal convoluted tubule: adjusts ions and pH through reabsorption and secretion. Collecting duct: adjusts water reabsorption, partly under ADH control, to regulate urine concentration.