Grade 12 Biology – Semester Review Vocabulary

Comprehensive vocabulary covering cell biology, circulatory and lymphatic systems, endocrine and reproductive regulation, respiratory anatomy and physiology, tissue types, digestion, biochemistry, genetics, excretion, and nervous system fundamentals.

Cytoplasm

Fluid portion of the cell in which organelles are suspended

Cell Membrane

Phospholipid-protein boundary that regulates passage of substances in and out of the cell

Nucleus

Control center of the cell that houses DNA

Chromatin

Uncondensed DNA–protein complex found in the nucleus

Ribosome

RNA-protein organelle where protein synthesis occurs

Rough Endoplasmic Reticulum

ER studded with ribosomes; modifies and transports proteins

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids and detoxifies substances

Golgi Apparatus

Stack of membranes that modifies, sorts, and packages proteins and lipids for transport

Vesicle

Small membrane-bound sac for transport or storage of materials

Peroxisome

Organelle that breaks down fatty acids and toxins, producing hydrogen peroxide

Vacuole

Membrane-bound storage sac for water, salts, proteins, or carbohydrates

Mitochondrion

Powerhouse of the cell; site of ATP, CO₂, and H₂O production

Lysosome

Organelle containing digestive enzymes for intracellular breakdown

Centrioles

Paired structures involved in spindle formation during cell division

Artery

Blood vessel with thick muscular walls that carries blood away from the heart at high pressure

Vein

Thin-walled blood vessel with valves that carries blood toward the heart

Capillary

One-cell-thick vessel connecting arteries and veins; site of diffusion

Pulmonary Circuit

Pathway that carries blood from the heart to the lungs and back

SA Node

Pacemaker in right atrium that initiates heartbeat

AV Node

Node that delays impulse before sending it to ventricles

Purkinje Fibres

Fibres that carry the impulse through ventricles, causing contraction

Systolic Pressure

Higher blood pressure measured when the heart contracts

Diastolic Pressure

Lower blood pressure measured when ventricles relax

Lymph

Fluid containing white blood cells, fats, and wastes returned to bloodstream

Lymph Node

Filter that traps pathogens; rich in lymphocytes

Lacteal

Lymph vessel in intestinal villus that absorbs fats

Spleen

Organ that filters blood, removes damaged RBCs, and stores WBCs

Right Lymphatic Duct

Drains lymph from right upper body into right subclavian vein

Thoracic Duct

Drains lymph from most of the body into left subclavian vein

Oval Opening (Foramen Ovale)

Fetal heart opening between right and left atria bypassing lungs

Arterial Duct (Ductus Arteriosus)

Fetal vessel connecting pulmonary artery to aorta

Umbilical Arteries

Fetal vessels that carry deoxygenated blood to placenta

Umbilical Vein

Fetal vessel returning oxygenated blood from placenta

Venous Duct (Ductus Venosus)

Fetal shunt allowing blood from umbilical vein to bypass liver

GnRH

Gonadotropin-releasing hormone from hypothalamus that stimulates FSH and LH release

LH

Luteinizing hormone that triggers ovulation and testosterone production

FSH

Follicle-stimulating hormone that promotes follicle growth and spermatogenesis

Estrogen

Ovarian hormone that develops the endometrium and provides feedback to hypothalamus

Progesterone

Hormone from corpus luteum that stabilizes uterine lining and inhibits new cycle

Negative Feedback

Hormonal control where rising levels inhibit further secretion

Positive Feedback

Control loop where rising levels stimulate further secretion

Corpus Luteum

Structure formed from ruptured follicle that secretes progesterone

Follicle

Ovarian structure where oocyte matures and estrogen is produced

Seminiferous Tubules

Testicular site of sperm production

Epididymis

Coiled tube where sperm mature and are stored

Vas Deferens

Duct that transports sperm from epididymis to ejaculatory duct

Seminal Vesicle

Gland adding fructose-rich fluid to semen

Prostate Gland

Gland adding alkaline fluid to semen

Cowper’s (Bulbourethral) Gland

Gland adding mucus-rich fluid that lubricates urethra

Trachea

Windpipe held open by cartilage rings and lined with cilia

Bronchus

Large airway branching from trachea into each lung

Bronchiole

Small airway branching within lungs leading to alveoli

Alveolus

Thin-walled air sac surrounded by capillaries; site of gas exchange

Diaphragm

Muscle that contracts downward during inhalation

Inhalation

Process where thoracic volume increases and air flows in

Exhalation

Process where thoracic volume decreases and air flows out

Medulla Oblongata (breathing)

Brain region that controls breathing rate

Hemoglobin

Protein in RBCs that transports O₂, CO₂, and H⁺ and buffers pH

Oxyhemoglobin

Hemoglobin bound to oxygen

Epithelial Tissue

Tissue covering body surfaces and lining cavities

Squamous Epithelium

Flat cells for protection, diffusion, or filtration

Cuboidal Epithelium

Cube-shaped cells for secretion, absorption, protection

Columnar Epithelium

Tall cells specialized for protection, secretion, absorption

Connective Tissue

Tissue that binds, supports, and stores materials

Cartilage

Flexible connective tissue with protein-rich matrix

Bone

Rigid connective tissue providing structural support

Blood

Fluid connective tissue whose matrix is plasma

Skeletal Muscle

Striated voluntary muscle attached to bones

Smooth Muscle

Non-striated involuntary muscle in organs and vessels

Cardiac Muscle

Striated involuntary muscle of the heart

Nervous Tissue

Tissue that responds to stimuli and transmits impulses

Mechanical Digestion

Physical breakdown of food by chewing and churning

Peristalsis

Wave-like muscular contractions that move food through digestive tract

Gastric Juice

Stomach secretion containing HCl and pepsin

Pepsin

Stomach enzyme that begins protein digestion

Duodenum

First section of small intestine where most chemical digestion occurs

Jejunum

Middle section of small intestine specialized for absorption

Ileum

Final section of small intestine continuing nutrient absorption

Villus

Finger-like projection that increases small-intestine surface area

Microvillus

Microscopic extension of villus cell membrane

Liver

Organ that makes bile, stores glycogen, detoxifies blood, and destroys old RBCs

Bile

Liver secretion that emulsifies fats

Pancreas

Gland that secretes digestive enzymes and bicarbonate into duodenum

Salivary Amylase

Enzyme that begins starch digestion in the mouth

Pancreatic Amylase

Pancreatic enzyme that continues starch digestion in small intestine

Trypsin

Pancreatic enzyme that digests peptides into amino acids

Lipase

Pancreatic enzyme that digests lipids into fatty acids and glycerol

Maltase

Intestinal enzyme converting maltose to glucose

Secretin

Hormone that stimulates pancreas to release bicarbonate

CCK

Cholecystokinin; hormone that triggers bile release and pancreatic enzyme secretion

GIP

Gastric inhibitory peptide; hormone that slows stomach activity

Dehydration Synthesis

Reaction forming polymers by removing water

Hydrolysis

Reaction breaking polymers by adding water

Protein

Polymer of amino acids with structural, enzymatic, and regulatory roles

Carbohydrate

Carbon-hydrogen-oxygen molecule used for energy and structure

Lipid

Water-insoluble molecule used for energy storage, insulation, and hormones

Nucleic Acid

DNA or RNA; polymers of nucleotides storing genetic information

Monosaccharide

Single sugar unit such as glucose

Disaccharide

Carbohydrate of two sugar units, e.g., maltose

Polysaccharide

Many sugar units linked together, e.g., starch