Biology: Life, Chemistry, and Organic Molecules (Chapters 1-3)

Comprehensive practice question-and-answer flashcards based on lecture slides covering evolution, the scientific method, chemistry, water properties, and organic macromolecules.

How does the lecture transcript define evolution?

Evolution is the process by which populations of organisms change over time by passing genes for traits from one generation to another.

Who proposed the theory of evolution by natural selection in 1859, and in what publication?

Charles Darwin proposed that present forms of life descended, with modifications, from existing forms in his 1859 book, On the Origin of Species by Natural Selection (alongside contributions from Alfred Wallace).

What are Charles Darwin's four observations regarding natural selection?

1. Individuals of a species vary from one another.
2. Organisms produce more offspring than will survive to reproduce.
3. Organisms must compete for resources.
4. Survivors pass their survival adaptations to their offspring, with the best adapted producing more offspring.

What ecological niche scenario in Madagascar illustrates evolutionary tinkering?

There are no woodpeckers in Madagascar, so lemurs fill that ecological niche.

What is the key difference between deductive and inductive scientific reasoning?

Deductive reasoning starts with supplied general information and draws specific conclusions (general to specific, e.g., predicting black holes from relativity). Inductive reasoning begins with specific observations and formulates a general principle (specific to general, e.g., Fleming discovering penicillin after observing mold kill bacteria in a petri dish).

What criteria must a scientific hypothesis fulfill?

A hypothesis must be a tentative explanation for observations that is consistent with well-established facts, capable of being tested, repeatable by independent observers, and falsifiable.

What experimental design is considered the gold standard to avoid researcher and patient bias?

A double-blind, randomized study with controls, where neither the patient nor the physician knows who receives the treatment or placebo.

How does a scientific theory differ from a simple hypothesis?

A scientific theory is an integrated explanation of an aspect of the natural world based on several hypotheses, each supported by consistent results from many observations or experiments.

What are the four primary elements that make up most living organisms?

Oxygen, carbon, hydrogen, and nitrogen.

What is the mass of a neutron or proton, and how does an electron's mass compare?

The mass of a neutron or proton is close to $1.66054 \times 10^{-24}\,g$, while an electron's mass is $\frac{1}{1800}$ of that mass.

What materials are needed to block alpha, beta, and gamma radioactive decay?

Alpha decay can be blocked by paper; beta decay can be blocked by skin or plastic; gamma decay requires thick lead or concrete to stop.

How do valence electrons influence the chemical behavior of an atom?

Valence electrons reside in the outermost shell (valence shell). Atoms with incomplete valence shells tend to lose, gain, or share electrons to achieve a full outer shell, driving chemical bonding and reactivity.

How are organic and inorganic compounds distinguished in the transcript?

Organic compounds always contain carbon (usually bonded to hydrogen) and typically come from living things. Inorganic compounds usually do not contain carbon and rarely come from living things.

What is the difference between nonpolar and polar covalent bonds?

Nonpolar covalent bonds share electrons equally between atoms. Polar covalent bonds share electrons unequally, creating partial positive and partial negative charges on opposite ends of the molecule.

What happens during oxidation and reduction in a redox reaction?

Oxidation is the loss of one or more electrons, while reduction is the gain of one or more electrons.

How do cations and anions form?

Cations form when atoms with 1, 2, or 3 valence electrons lose electrons and become positively charged. Anions form when atoms with 5, 6, or 7 valence electrons gain electrons and become negatively charged.

What is the difference between cohesion and adhesion regarding water?

Cohesion is the property of water molecules sticking to one another. Adhesion is the ability of water molecules to stick to other substances.

How are acids and bases defined by the ions they release in solution?

An acid dissociates in solution to yield hydrogen ions ($H^+$) and an anion (acting as a proton donor). A base dissociates to yield a hydroxide ion ($OH^-$) and a cation (acting as a proton acceptor).

What are the three main types of isomers?

1. Structural isomers: differ in the covalent arrangement of atoms.
2. Geometric isomers: have identical covalent bonds but differ in spatial arrangement.
3. Enantiomers: isomers that are mirror images of each other.

Which enantiomer shown in this image is effective against Parkinson's disease, and why?

L-DOPA is effective because the blood-brain barrier uses chiral transport proteins that selectively transport L-DOPA into the brain while ignoring D-DOPA, which faces the wrong way.

How do dehydration reactions and hydrolysis reactions synthesize and degrade polymers?

Dehydration reactions covalently link monomers into polymers by removing a water molecule ($H_2O$). Hydrolysis reactions degrade polymers into monomers by adding a water molecule.

What subunits make up maltose, and under what conditions is it produced?

Maltose is a disaccharide made of 2 covalently linked $\alpha$-glucose units. It is produced when larger starch chains break down, as well as in sprouting grains, starchy foods, and caramelized foods.

How does glycogen differ from plant starch?

Glycogen is a glucose storage polysaccharide in animal tissues (stored mainly in liver and muscle cells) that is similar in structure to plant starch, but is more extensively branched and more water-soluble.

What structural differences distinguish saturated fatty acids from unsaturated fatty acids?

Saturated fatty acids contain the maximum number of hydrogen atoms, have a straight shape, and are solid at room temperature. Unsaturated fatty acids contain carbon-carbon double bonds, have a kinked shape, and are liquid at room temperature.

What are the four levels of protein structure illustrated in this figure?

1. Primary structure: linear sequence of amino acids.
2. Secondary structure: shapes resulting from hydrogen bonding along the backbone (e.g., $\alpha$-helix, $\beta$-pleated sheet).
3. Tertiary structure: 3D shape formed by side chain interactions.
4. Quaternary structure: interactions among multiple polypeptide chains.

What nitrogenous bases are present in DNA versus RNA?

DNA contains purines adenine (A) and guanine (G), and pyrimidines cytosine (C) and thymine (T). RNA contains purines adenine (A) and guanine (G), and pyrimidines cytosine (C) and uracil (U).