science 8

Nutrition

The process of taking in food and converting it into energy and body materials.

Holozoic Nutrition

A type of nutrition involving ingestion, digestion, absorption, and elimination (typical in animals and humans).

Digestion

The breakdown of complex food substances into simpler, usable forms.

Ingestion

The process of taking food into the mouth.

Physical Digestion

Mechanical breakdown of food into smaller pieces (chewing, stomach churning).

Chemical Digestion

Breakdown of food using enzymes into simpler molecules.

Bolus

A soft mass of chewed food ready to be swallowed.

Peristalsis

Wave-like contractions that move food through the digestive tract.

Mouth

Site of physical and initial chemical digestion (teeth chew, saliva breaks down carbs and lipids).

Esophagus

Muscular tube that carries bolus to the stomach through peristalsis.

Cardiac Sphincter

Prevents backflow of stomach contents into the esophagus.

Stomach

J-shaped organ that churns food and secretes gastric juice (HCl + pepsin); begins protein digestion.

Chyme

Semi-liquid mixture of partially digested food and gastric juice.

Pyloric Sphincter

Controls the passage of chyme from stomach to small intestine.

Small Intestine

Main site of digestion and nutrient absorption; consists of duodenum, jejunum, ileum.

Villi

Fingerlike projections in the small intestine that absorb nutrients into the bloodstream.

Liver

Produces bile, detoxifies blood, stores iron, synthesizes proteins.

Bile

A substance that emulsifies fats (not an enzyme), stored in the gallbladder.

Gallbladder

Stores and releases bile into the small intestine.

Pancreas

Produces digestive enzymes (in pancreatic juice) and insulin to regulate blood sugar.

Large Intestine

Absorbs water and minerals; forms and stores feces.

Rectum

Temporarily stores feces before elimination.

Anus

Opening where feces are expelled.

Egestion/Defecation

Process of eliminating undigested food as feces.

Gut Microbiota

Helpful bacteria in the intestines that aid digestion and nutrient absorption.

Excretion

Removal of metabolic waste (not feces) from the body.

Excretory System

Organs that remove liquid, gaseous, and dissolved wastes (e.g., sweat, urine, CO₂).

Kidneys

Main excretory organs that filter blood, regulate water and electrolytes, and maintain pH.

Nephrons

Microscopic filtering units in the kidneys.

Bowman’s Capsule

Structure in the nephron where filtration starts.

Glomerulus

Capillary cluster in Bowman’s capsule where blood is filtered.

Filtrate

Fluid filtered from blood (contains water, urea, glucose, salts).

Reabsorption

Process where useful substances (water, nutrients) are reabsorbed into the blood.

Secretion

Movement of wastes from blood into the nephron to form urine.

Urine

Final waste fluid formed by kidneys; excreted via the ureters, bladder, and urethra.

Ureters

Tubes carrying urine from kidneys to bladder.

Urinary Bladder

Stores urine until it is ready to be excreted.

Urethra

Tube that carries urine out of the body.

Urination

Process of releasing urine from the bladder.

Xylem

Transports water and minerals from roots to other parts of the plant; supports the plant.

Phloem

Transports sugars and nutrients from leaves to the rest of the plant.

Transpiration

Loss of water vapor from leaf stomata; pulls water upward.

Cohesion-Tension Theory

Explains how water moves upward through xylem due to cohesion and negative pressure from transpiration.

Osmosis

Process by which roots absorb water from the soil.

Genetics

The study of heredity and variation in organisms.

Heredity

Transmission of traits from parents to offspring.

Traits

Characteristics passed from parents to offspring.

Variation

Differences in traits among individuals of the same species.

Gregor Mendel

Father of modern genetics; discovered the basic principles of heredity using pea plants.

Mendelian Genetics

Inheritance patterns involving dominant and recessive alleles.

Incomplete Dominance

Neither allele is dominant; offspring show a blend (e.g., wavy hair from straight + curly).

Codominance

Both alleles are fully expressed (e.g., AB blood type).

Multiple Alleles

A trait controlled by more than two alleles (e.g., blood type A, B, AB, O).

Polygenic Traits

Traits controlled by several genes (e.g., skin color, height, eye color).

Pedigree

A chart that shows how traits are passed through generations.

Carrier

An individual who has one copy of a recessive allele but does not express the trait.

Karyotype

A picture of all chromosomes in a cell, used to identify chromosomal abnormalities (e.g., Down syndrome, Turner syndrome).