Midterm Biological Sciences

What is a hypothesis?

A proposed explanation for a natural phenomenon, an educated guess based on previous observations or studies.

Give an example of a hypothesis.

"Maple trees drop their leaves in autumn because of the shortened amount of sunlight."

What are the rows of the periodic table called, and what do they represent?

Rows are called 'Periods,' and they correspond to the number of electron shells.

What do the columns of the periodic table indicate?

Columns are called 'Groups' and indicate the number of electrons in the outer shell.

What are isomers?

Molecules with the same molecular formula but different structures and characteristics.

Differentiate between structural isomers and stereoisomers.

Structural isomers have different bonding relationships, while stereoisomers have identical bonding relationships but different spatial positioning of atoms.

Why is water a polar molecule?

Electrons tend to be in the more electronegative oxygen atom, creating partial positive and negative charge regions.

Define hydrophilic and hydrophobic.

Hydrophilic substances dissolve in water; hydrophobic substances do not.

What defines an acid and a base?

Acids release hydrogen ions (H+) in solution, while bases lower H+ concentration by either releasing OH- or binding H+.

How does pH affect biological systems?

It influences molecule shape, reaction rates, molecule binding, and solubility.

What elements make up carbohydrates?

Carbon, hydrogen, and oxygen (C_n(H_2O)_n).

What are the monomers of carbohydrates?

Monosaccharides, the simplest sugars.

What are phospholipids made of?

Glycerol, two fatty acids, and a phosphate group.

Why are phospholipids amphipathic?

They have a polar, hydrophilic phosphate region and nonpolar, hydrophobic fatty acid chains.

Describe the four levels of protein structure.

• Primary: Amino acid sequence. - Secondary: Alpha-helices and beta-sheets formed by hydrogen bonding. - Tertiary: Three-dimensional folding from covalent and ionic bonds. - Quaternary: Multiple polypeptides forming a functional protein.

What are the three main components of cell theory?

1. All living things are composed of cells. 2. Cells are the smallest units of life. 3. New cells come from pre-existing cells.

What does the fluid-mosaic model describe?

The membrane as a dynamic structure with lipids, proteins, and carbohydrates moving relative to each other.

What happens to an animal cell in a hypertonic solution?

It undergoes crenation (shrinking).

What is the role of enzymes?

They act as catalysts that speed up chemical reactions without being consumed.

What is activation energy?

The initial energy input needed to start a reaction.

What are the two main types of metabolism?

• Anabolism: Building reactions. - Catabolism: Breakdown reactions.

What are oxidation and reduction?

Oxidation is the removal of electrons, and reduction is the addition of electrons.

How do producers and consumers obtain energy?

Producers use photosynthesis to convert solar energy into chemical energy, while consumers obtain energy by eating producers and using cellular respiration.

What is photosynthesis?

The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll.

What is the chemical equation for photosynthesis?

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.

What are the products of photosynthesis?

Glucose and oxygen.

What is cellular respiration?

The process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

What is the chemical equation for cellular respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP).

What is ATP?

Adenosine triphosphate, the primary energy carrier in living organisms.

What is the function of ribosomes?

To synthesize proteins by translating messenger RNA (mRNA).

What are the main components of the cell membrane?

Phospholipids, proteins, cholesterol, and carbohydrates.

What is diffusion?

The movement of molecules from an area of higher concentration to an area of lower concentration.

What is osmosis?

The diffusion of water across a selectively permeable membrane.