A sodium particle loses one electron and now carries a positive charge. What has it become?

Inside a water molecule, oxygen and hydrogen share electrons. What holds those atoms together?

Water droplets bead together because neighboring molecules attract each other weakly. What interaction causes that cohesion?

Blood proteins help resist dangerous shifts toward acid or base after metabolism releases extra hydrogen ions. What role are they playing?

Digestive enzymes break starch into glucose, and cells quickly use that fuel to make ATP. Which biomolecule class was digested?

Steroid hormones are made from cholesterol and pass easily through plasma membranes. Which biomolecule class do they belong to?

Hemoglobin carries oxygen because its amino acid chain folds into a specific three-dimensional shape. Which biomolecule class is it?

DNA and RNA store and transmit instructions used to build cell proteins. Which biomolecule class includes DNA and RNA?

A skeletal muscle fiber needs large amounts of ATP during contraction, so it contains many copies of which organelle?

A pancreatic cell makes digestive enzymes for export on a ribosome-studded membrane network. Which organelle is doing that work?

Cells of the adrenal cortex make steroid hormones from cholesterol. Which organelle is especially abundant in those cells?

After a secreted protein is made, a cell modifies, sorts, and packages it into vesicles. Which organelle performs that shipping step?

A macrophage breaks down an engulfed bacterium inside an enzyme-filled sac. Which organelle contains those digestive enzymes?

A cell protects its DNA and copies it before division inside which structure?

An mRNA strand is read to assemble a polypeptide one amino acid at a time. Which cell structure carries out that assembly?

The cell boundary controls entry and exit and carries receptors for many chemical signals. Which structure is this boundary?

Internal protein fibers maintain cell shape and help move organelles through the cytoplasm. Which structure has that role?

A dense body inside the nucleus assembles subunits that will later read mRNA in the cytoplasm. Which structure is it?

Oxygen moves from the alveoli into blood because its concentration is higher in the air sacs than in the capillaries. What transport process is this?

Water moves across a selectively permeable membrane toward the side with more dissolved solute. What process is occurring?

Glucose enters a cell through a carrier protein without ATP, moving from higher to lower concentration. What transport process is this?

The sodium-potassium pump uses ATP to move ions against their concentration gradients. What kind of transport is this?

A white blood cell surrounds a bacterium and brings it into the cytoplasm inside a vesicle. What transport process is this?

A gland cell releases hormone when vesicles fuse with the plasma membrane and empty outside the cell. What process is this?

A red blood cell placed in distilled water swells because water enters faster than it leaves. What is the surrounding solution?

A red blood cell placed in a very salty solution shrinks as water leaves the cell. What is the surrounding solution?

Before mitosis, a cell duplicates its DNA during which part of interphase?

During mitosis, sister chromatids line up across the cell's middle before they separate. Which phase is this?

During mitosis, sister chromatids are pulled toward opposite poles of the cell. Which phase is this?

After the nucleus has divided, the cytoplasm splits to form two daughter cells. What process finishes cell division?

In the nucleus, a gene's DNA sequence is copied into a complementary mRNA strand. What step of protein synthesis is this?

At a ribosome, mRNA codons are read and amino acids are linked into a growing chain. What step is this?

Alveoli need an extremely thin lining so gases can cross quickly between air and blood. Which tissue subtype best fits that job?

The epidermis protects against abrasion with many layers of flattened cells. Which tissue subtype forms that surface?

Kidney tubules use a single layer of cube-shaped cells for secretion and absorption. Which epithelial subtype is this?

Loose tissue under many epithelia holds capillaries and immune cells in a soft, gel-like matrix. Which subtype is it?

Under the skin, large lipid-filled cells store energy, cushion organs, and reduce heat loss. Which tissue subtype is this?

Rings in the trachea resist collapse because their cells sit in a firm but flexible matrix. Which connective tissue subtype is this?

The wall of the heart contracts with branching striated cells connected by intercalated discs. Which muscle tissue subtype is this?

The brain and spinal cord contain cells specialized to carry rapid electrical signals and support those signaling cells. What major tissue class is this?