AP Biology Unit 2 – Cells: Ultimate Study Notes (CED aligned)

Why do cells remain small rather than growing indefinitely?

Surface area to volume ratio decreases as cells grow

If a cell’s surface area to volume ratio becomes too small, what is the most immediate problem?

Exchange of nutrients and waste becomes inefficient

Which cellular adaptation increases the efficiency of nutrient absorption in intestinal cells?

Microvilli increasing membrane surface area

Which statement best distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotes lack membrane-bound organelles

Which piece of evidence supports the endosymbiotic theory for mitochondria?

They contain circular DNA similar to bacteria

A protein that will be secreted outside the cell is most likely synthesized by ribosomes:

Bound to the rough endoplasmic reticulum

What would most likely happen if the Golgi apparatus stopped functioning?

Proteins would not be properly modified or transported

Which organelle is primarily responsible for detoxifying drugs and poisons in liver cells?

Smooth ER

Which cellular structure contains hydrolytic enzymes used to break down macromolecules?

Lysosome

Why do mitochondria have highly folded inner membranes (cristae)?

To increase surface area for ATP-producing reactions

Which structure in plant cells is responsible for maintaining turgor pressure?

Central vacuole

According to the fluid mosaic model, the plasma membrane is best described as:

A dynamic mixture of lipids, proteins, and carbohydrates

Which component of the cell membrane helps maintain membrane fluidity at different temperatures?

Cholesterol

Which membrane component is primarily responsible for cell recognition and immune responses?

Carbohydrate chains on glycoproteins or glycolipids

Which transport process requires energy and moves molecules against their concentration gradient?

Active transport

In the sodium-potassium pump, how are ions transported across the membrane?

3 Na⁺ out, 2 K⁺ in

When a red blood cell is placed in a hypotonic solution, what will most likely occur?

The cell swells and may lyse

Water moves across membranes during osmosis toward the area of:

Higher solute concentration

Which process allows cells to take in large particles such as bacteria?

Phagocytosis

Which form of endocytosis uses receptor proteins to selectively import molecules?

Receptor-mediated endocytosis

Why is compartmentalization beneficial in eukaryotic cells?

It allows different metabolic processes to occur simultaneously

Which cytoskeletal component is primarily responsible for intracellular transport and chromosome movement during cell division?

Microtubules

Which cell junction allows ions and small molecules to pass directly between adjacent animal cells?

Gap junction

Which plant cell structure allows direct cytoplasmic communication between adjacent cells?

Plasmodesmata

What is the first step in cell signaling?

Reception (ligand binds receptor)

During signal transduction, phosphorylation cascades primarily function to:

Amplify the signal inside the cell

Which molecule commonly acts as a second messenger in signal transduction pathways?

cAMP

What is a plasmid in a prokaryotic cell?

Small, circular DNA separate from the nucleoid

What is one important role of plasmids?

Carry antibiotic resistance genes

What is the main function of a prokaryotic flagellum?

Motility/movement toward nutrients

How is ATP produced in mitochondria?

Chemiosmosis: H⁺ flows through ATP synthase driven by a proton gradient

Where do light-dependent reactions occur in chloroplasts?

Thylakoid membranes

Where does the Calvin cycle occur?

Stroma

What is a key role of microtubules in eukaryotic cells?

Form spindle fibers during mitosis

Microfilaments are primarily involved in:

Cytokinesis and cell movement

Which molecules cross a cell membrane most easily?

Small hydrophobic molecules (O₂, CO₂)

What is the function of electrochemical gradients in cells?

Store potential energy for transport and secondary active transport

Water moves in plants from:

High water potential → low water potential

What does signal amplification in a cell do?

One ligand activates a cascade → larger cellular response

Why do cells divide when they grow too large?

Volume increases faster than surface area → diffusion insufficient