Atomic Structure, Isotopes, Radiation & Basic Chemistry for Biology

These flashcards cover atomic structure, isotopes, ion formation, chemical equations, buffer systems, radiation types, medical imaging, and their biological relevance, providing a comprehensive review for the upcoming exam.

Which sub-atomic particle determines an element’s atomic number and therefore its identity?

The proton (number of protons).

If you change the number of protons in an atom, what happens?

You change the element itself (e.g., lead → gold).

Which two sub-atomic particles are considered “negotiable” (can vary without changing the element)?

Neutrons and electrons.

Why are electrons considered negligible when calculating atomic mass?

Their combined mass is extremely small; even ~96 electrons weigh less than 1 atomic mass unit.

How is atomic mass calculated?

By adding the number of protons and neutrons (electrons are ignored).

Carbon has an atomic number of 6 and a mass number of 14. How many neutrons does it contain?

8 neutrons (14 – 6 = 8).

What does a –1 charge on a carbon atom (¹²C⁻¹) indicate about its electrons?

It has one extra electron compared to neutral carbon (7 electrons instead of 6).

What is an isotope?

An atom with the same number of protons but a different number of neutrons, making it unstable and often radioactive.

Why are isotopes generally radioactive?

Extra or missing neutrons destabilize the nucleus, leading to radioactive decay.

Which common fruit contains a measurable amount of radioactive potassium?

A banana.

What pH range must human blood stay within to avoid death?

Approximately 7.35–7.45; death occurs near 7.6 or 7.2.

Name the reversible buffer system that helps maintain blood pH.

CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻ (carbonic acid–bicarbonate buffer).

In a chemical equation, what does a coefficient represent?

The number of whole molecules or moles of a substance (e.g., 6CO₂ means six molecules of CO₂).

In the formula CO₂, what does the subscript ‘2’ mean?

There are two oxygen atoms bonded to one carbon atom.

Why is the simple photosynthesis equation (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂) considered highly oversimplified?

Actual photosynthesis involves dozens of enzymatic steps and intermediate reactions.

Most biological reactions can proceed in both directions. What term describes this property?

Reversible reactions (⇌).

Why is UV light effective for surface sterilization but poor for deep disinfection?

UV has very low penetration power; it can’t pass through fabrics or thick materials.

What protective device is typically placed on patients during dental X-rays to reduce exposure?

A lead (Pb) vest or apron.

Why must radiology and X-ray techs limit their exposure to ionizing radiation?

Cumulative doses can cause cellular damage and increase cancer risk.

What is the basic goal of chemotherapy that uses radioactive substances?

Kill cancer cells faster than it harms the patient’s healthy cells.

What metabolic preference of tumors does a PET scan exploit?

Tumors preferentially consume glucose (Warburg effect).

What radioactive substance is ingested for a PET scan, and why does it localize in tumors?

A radioactive glucose analog; tumors uptake it avidly for glycolysis.

Why can’t PET scans reliably detect bladder cancers?

The radioactive glucose is excreted through urine, flooding the bladder with signal.

How has precise imaging (e.g., PET/CT) improved surgical outcomes for cancer patients?

It shows exact tumor boundaries, allowing surgeons to remove tumor tissue precisely and spare healthy tissue (e.g., saving a limb).