The Science of Biology
What are the main characteristics that define living organisms?
Made of cells, organized and complex, respond to the environment, grow and reproduce, use energy, maintain homeostasis, and adapt over time.
Explain the differences between the subatomic particles
Protons: positive charge, located in nucleus
Neutrons: neutral charge, located in nucleus
Electrons: negative charge, located in the surroundings of the nucleus
Why is carbon considered the backbone of biological molecules?
Carbon can form four covalent bonds, allowing it to create diverse and complex molecular structures.
Summarize the three main principles of cell theory.
All organisms are made of cells
Cells are the smallest living units
New cells come from pre-existing cells.
Describe the basic structure of the phospholipid bilayer.
Hydrophilic heads face outward toward water, while hydrophobic fatty acid tails face inward, forming a stable bilayer.
How do inductive and deductive reasoning differ in scientific investigations?
Deductive reasoning uses general principles to predict specific outcomes
Inductive reasoning builds general conclusions from specific observations.
What are the four elements that make up 96.3% of human body weight?
Carbon
Hydrogen
Oxygen
Nitrogen
How do dehydration synthesis and hydrolysis differ in macromolecule reactions?
Dehydration synthesis builds polymers by removing water, while hydrolysis breaks polymers into monomers by adding water.
Why are most cells small in size?
Smaller cells have a higher surface area-to-volume ratio, which allows more efficient diffusion of nutrients and wastes.
How does cholesterol help regulate membrane fluidity?
It prevents membranes from becoming too rigid at low temperatures and too fluid at high temperatures.
Explain the importance of control experiments when testing a hypothesis.
They provide a baseline to compare results, ensuring that observed changes are due to the independent variable and not other factors.
Explain the differences between the three types of bonds
Ionic bonds: gain or loss of electrons
Covalent bonds: sharing of electrons
Hydrogen bonds: bond between a slightly positive atom (H), and a slightly negative atom
Compare structural isomers and stereoisomers.
Structural isomers differ in carbon skeleton arrangement
Stereoisomers have the same skeleton but differ in spatial orientation.
What is one structural difference between prokaryotic and eukaryotic cells?
Prokaryotes lack a membrane-bound nucleus, while eukaryotes have one.
Differentiate between channel proteins and carrier proteins in facilitated diffusion.
Channel proteins form open pores for ions/molecules, while carrier proteins undergo conformational changes to transport specific molecules.
What role did Darwin’s observations of finches in the Galápagos play in forming the theory of natural selection?
He noticed that similar species varied slightly depending on their environment, leading him to propose “descent with modification” and natural selection as the mechanism.
Mention at least 2 of the 6 properties of water
1. water has high specific heat (hydrogen bonds absorb heat)
2. Water has a high heat of vaporization (liquid to gas)
3. Solid water is less dense than liquid water
4. Water is a good solvent
5. Water organizes nonpolar molecules
6. Water can form ions (self ionization)
What structural feature of cellulose makes it indigestible to humans?
Cellulose has β(1→4) glycosidic bonds, which human digestive enzymes cannot break down.
How does the endomembrane system ensure proteins like insulin are secreted properly?
DNA instructions in the nucleus → translation in rough ER → vesicle transport → modification in Golgi → secretory vesicles → exocytosis at the plasma membrane.
Why is the sodium-potassium pump considered active transport?
It moves Na⁺ out and K⁺ into the cell against their concentration gradients using ATP energy.
Name one of the five core concepts of biology.
1. Life is subject to chemical & physical laws.
2. Structure determines function.
3.Living systems transform energy & matter.
4.Living systems depend on information transactions.
5.Evolution explains unity & diversity of life.
Explain the concepts of acids, bases, and buffers
Acids: any substance that dissociates in water to increase the H+ and lowers the pH
Bases: any substance that combines with H+ dissolved in water, and rises the pH
Buffers: substance that resists changes in pH
Explain the role of the R group in amino acids.
The R group determines an amino acid’s chemical properties (e.g., polar, nonpolar, charged) and therefore influences protein shape and function.
Explain the endosymbiotic theory for the origin of mitochondria and chloroplasts.
These organelles likely originated as prokaryotes engulfed by larger cells, which became symbiotic and eventually permanent parts of eukaryotic cells.
Compare endocytosis and exocytosis
Endocytosis brings materials into the cell (via phagocytosis, pinocytosis, or receptor-mediated)
Exocytosis releases materials out of the cell (e.g., neurotransmitters, hormones).