biology semester one hardest questions

Steps of Cellular Respiration (in order)

Glycolysis → Krebs Cycle → Electron Transport Chain; Glycolysis occurs in cytoplasm, Krebs in mitochondrial matrix, ETC in inner mitochondrial membrane; ETC produces most ATP.

Where Glycolysis Happens

Cytoplasm of the cell; does not require oxygen (anaerobic); breaks glucose into 2 pyruvates.

Where Krebs Cycle Happens

Mitochondrial matrix; converts pyruvate into electron carriers (NADH, FADH2); produces 2 ATP, CO₂ released.

Where Electron Transport Chain Happens

Inner mitochondrial membrane; uses electrons from NADH/FADH2 to power ATP synthase; oxygen is final electron acceptor; produces 32–34 ATP.

First Molecule in Glycolysis

Glucose; a 6-carbon sugar that is broken into 2 molecules of 3-carbon pyruvate.

Total ATP from Cellular Respiration

About 36–38 ATP: 2 from glycolysis, 2 from Krebs, ~32–34 from ETC.

Most Common Element in Living Organisms

Carbon; forms backbone of carbohydrates, proteins, lipids, and nucleic acids.

Main Product of Glycolysis

2 Pyruvate, 2 ATP, and 2 NADH; pyruvate enters mitochondria for further respiration.

Function of ATP

Main energy currency of the cell; made from ADP + phosphate using energy from cellular respiration.

Blood Flow Through the Heart (in order)

Body → Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary veins → Left atrium → Left ventricle → Aorta → Body.

Right Atrium

Receives deoxygenated blood from the body via the vena cava.

Left Ventricle

Pumps oxygen-rich blood into the aorta to the rest of the body.

Alveoli

Tiny air sacs in lungs where oxygen enters blood and CO₂ exits; site of gas exchange.

Trachea

Windpipe; connects mouth/nose to bronchi; carries air to lungs.

Bronchi

Tubes branching from trachea into each lung.

Respiratory System Includes

Trachea, bronchi, lungs, alveoli.

Organ That Absorbs Nutrients

Small intestine; absorbs digested food into the bloodstream through villi.

Stomach

Uses acid and enzymes to break down proteins and food; churns food into chyme.

Liver

Makes bile, which helps digest fats.

Pancreas

Releases enzymes to break down carbs, fats, and proteins in the small intestine.

Esophagus

Muscular tube that pushes food from mouth to stomach.

Large Intestine

Absorbs water; compacts waste into feces.

Rectum

Stores feces until ready to be expelled.

Gland That Releases Adrenaline

Adrenal gland; located above kidneys; releases epinephrine during "fight or flight."

Function of Adrenaline

Increases heart rate, opens airways, increases energy during stress.

Passive Transport

Movement of molecules from high to low concentration; no energy required; includes diffusion, osmosis.

Active Transport

Movement from low to high concentration; requires energy (ATP); includes sodium-potassium pump, endocytosis, exocytosis.

Osmosis

Passive transport of water across a selectively permeable membrane; high to low water concentration.

Endocytosis

Active transport process; cell engulfs large molecules or particles by folding in membrane.

Exocytosis

Active transport; cell expels materials in vesicles that fuse with the membrane.

Diffusion

Passive transport of molecules (like oxygen or CO₂) from high to low concentration.

Sodium-Potassium Pump

Active transport that moves 3 Na⁺ out and 2 K⁺ in; important for nerve and muscle cells.

Active Energy

Energy currently being used (e.g., running, ATP powering reactions).

Potential Energy

Stored energy (e.g., food, glucose, stretched rubber band).

Mitosis

Cell division that produces 2 identical diploid body cells; used for growth and repair.

Meiosis

Cell division that produces 4 unique haploid sex cells (gametes); includes crossing over.

Haploid Cell

Contains one set of chromosomes (n); example: sperm and egg.

Diploid Cell

Contains two sets of chromosomes (2n); example: body cells.

Crossing Over

Happens in Prophase I of meiosis; homologous chromosomes exchange genetic material.

Homologous Chromosomes

Chromosome pairs (one from each parent) that are similar in size, shape, and gene location.

Purpose of Mitosis

Growth, repair, and replacement of cells.

Purpose of Meiosis

Production of gametes for sexual reproduction.