sbi3u1 review

Peristalsis

Rhythmic contractions of smooth muscle that push food through the digestive tract (especially in the esophagus and intestines)

Amylase

Enzyme found in saliva and pancreas that breaks down starch into simple sugars

Pepsin

Enzyme in the stomach that begins the digestion of proteins; activated by gastric acid

Lipase

Enzyme that breaks down lipids into fatty acids and glycerol

Duodenum

First section of the small intestine; receives bile and pancreatic enzymes; primary site for digestion

Jejunum

Second section of the small intestine; responsible for most nutrient absorption

Ileum

Final section of the small intestine; absorbs vitamin B12, bile salts, and remaining nutrients

Villi and Microvilli

Finger-like projections lining the small intestine that increase surface area for absorption

Bile

Substance produced by the liver, stored in the gallbladder; emulsifies fats for digestion

Pancreas

Produces digestive enzymes (amylase, lipase, trypsin) and bicarbonate; also an endocrine organ

Liver

Detoxifies blood, produces bile, stores glycogen, metabolizes nutrients

Gallbladder

Stores and concentrates bile, releases it into the duodenum

Sphincter

Circular muscle that regulates the passage of substances (e.g., esophageal sphincter, pyloric sphincter)

Epiglottis

Flap of cartilage that prevents food from entering the trachea during swallowing

Gastrin

Hormone that stimulates gastric acid secretion in the stomach

Mucosa

Inner lining of the GI tract that secretes mucus and digestive enzymes

Mechanical digestion

Physical breakdown of food (chewing, churning in stomach)

Chemical digestion

Breakdown of food using enzymes and acids

Endoscopy

Medical imaging technique using a camera-tipped tube to view inside the digestive tract

Red blood cells (erythrocytes)

Transport oxygen via hemoglobin

White blood cells (leukocytes)

Fight infection and provide immunity

Platelets (thrombocytes)

Involved in blood clotting

Artery

Blood vessel that carries blood away from the heart (usually oxygenated)

Vein

Blood vessel that carries blood toward the heart (usually deoxygenated)

Capillaries

Smallest blood vessels; site of gas, nutrient, and waste exchange

Atria vs Ventricles

Atria receive blood into the heart; ventricles pump it out

Pulmonary circulation

Right side of heart → lungs → left side of heart

Systemic circulation

Left side of heart → body → right side of heart

Sinoatrial (SA) node

Heart’s natural pacemaker; initiates heartbeat

Systolic pressure

Pressure in arteries during heart contraction

Diastolic pressure

Pressure in arteries during heart relaxation

Hypertension

Chronic high blood pressure

Alveoli

Tiny air sacs in lungs with large surface area for gas exchange

Bronchi and Bronchioles

Branching airways that deliver air to alveoli

Diaphragm

Dome-shaped muscle under lungs that contracts during inhalation

Intercostal muscles

Assist diaphragm in breathing by expanding the ribcage

Gas exchange

Movement of O₂ into blood and CO₂ out at alveoli and tissues

Ventilation

Process of air moving into and out of lungs

Chemoreceptors

Detect changes in CO₂ and trigger respiratory rate changes

Cellular respiration

Converts glucose and oxygen into ATP, CO₂, and water

VO₂ max

Maximum rate of oxygen consumption during intense exercise

Hemoglobin

Iron-containing protein in RBCs that binds oxygen

Mitosis

Division of somatic cells producing two identical daughter cells (PMAT)

Meiosis

Division of sex cells producing four unique haploid gametes

Crossing over

Exchange of genetic material between homologous chromosomes during meiosis I

Independent assortment

Random alignment of chromosomes during meiosis I, increasing diversity

Nondisjunction

Failure of chromosomes to separate during meiosis; causes disorders (e.g., Down syndrome)

Gene

Segment of DNA that codes for a protein or trait

Allele

Different versions of the same gene

Genotype

The genetic makeup (e.g., Aa, BB)

Phenotype

The observable traits (e.g., blue eyes, tall)

Homozygous

Two of the same alleles (e.g., TT, aa)

Heterozygous

Two different alleles (e.g., Tt)

Dominant allele

Expressed trait when at least one is present

Recessive allele

Only expressed when both alleles are recessive

Punnett Square

Tool to predict genetic outcomes in offspring

Monohybrid cross

Cross examining one trait

Dihybrid cross

Cross examining two traits

Codominance

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

Incomplete dominance

Blending of traits (e.g., pink flowers from red and white)

Sex-linked trait

Trait carried on the X chromosome (e.g., colorblindness)

Artificial insemination

Sperm inserted into female reproductive tract

In vitro fertilization (IVF)

Egg and sperm combined in a lab, then implanted

Karyotype

Image of chromosomes arranged by size; used to diagnose chromosomal disorders

Cloning

Creating a genetically identical copy of an organism

Taxonomy

Science of classifying organisms

Binomial nomenclature

Two-part naming system (Genus species)

Prokaryote

Cell without a nucleus (e.g., bacteria)

Eukaryote

Cell with a nucleus and organelles

Virus

Non-living pathogen; requires host to reproduce

Lytic cycle

Virus replicates and lyses (bursts) host cell

Lysogenic cycle

Viral DNA integrates into host genome; remains dormant

Endosymbiosis theory

Explains origin of mitochondria and chloroplasts as former free-living bacteria

Protist

Diverse group of mostly unicellular eukaryotes (e.g., amoeba, paramecium)

Fungi

Eukaryotic decomposers that reproduce via spores

Hyphae

Thread-like structures of fungi

Mycelium

Mass of hyphae; main body of fungus

Xylem

Transports water and minerals from roots to leaves

Phloem

Transports sugars from leaves to rest of plant

Transpiration

Loss of water from leaves pulls water upward

Root hairs

Increase surface area for water/nutrient absorption

Monocot

Plant with one cotyledon, parallel veins, fibrous roots

Dicot (Eudicot)

Plant with two cotyledons, netted veins, taproot

Phototropism

Growth toward light

Gravitropism

Growth in response to gravity

Auxin

Plant hormone that promotes elongation and tropisms

Gibberellin

Plant hormone that stimulates stem elongation

Ethylene

Plant hormone involved in fruit ripening

Pollination

Transfer of pollen from anther to stigma

Angiosperm

Flowering plant with seeds enclosed in fruit

Gymnosperm

Seed plant without flowers; seeds often in cones

Natural selection

Organisms with advantageous traits reproduce more successfully

Mutation

A change in DNA that can be beneficial, neutral, or harmful

Gene flow

Movement of alleles between populations

Genetic drift

Random changes in allele frequencies; more impactful in small populations

Bottleneck effect

Drastic reduction in population size affects allele diversity

Founder effect

New population started by a few individuals, limiting genetic variation

Vestigial structure

Structure with no current function (e.g., human appendix)

Homologous structures

Same origin, different function (e.g., human arm, whale flipper)

Analogous structures

Different origin, same function (e.g., bird wing vs insect wing)