Human Biology

What is the smallest unit of life?

The cell.

What is metabolism?

All biochemical processes within a cell or organism.

What is homeostasis?

Maintenance of a stable internal environment (e.g., pH, temperature).

Name the levels of biological organization.

Cell → Tissue → Organ → Organ system → Organism.

Give examples of stimuli.

Temperature change, hunger, danger.

What are the steps of the scientific method?

Observation → Hypothesis → Prediction → Experiment → Data/analysis → Conclusion.

Observational vs experimental studies?

Observational: no intervention; Experimental: controlled testing with variables.

What is biological evolution?

Change and adaptation of organisms over time via natural selection.

Key elements of natural selection?

Variation, competition, adaptation (differential survival/reproduction).

Evidence of evolution?

Fossils, biogeography, biochemical (DNA), anatomical similarities.

Key human evolution adaptation in hands?

Opposable thumbs (precision grip).

Major brain change in human evolution?

Larger, more complex brain.

What enabled cultural evolution in humans?

Language and social cooperation.

Difference between prokaryotic and eukaryotic cells?

Prokaryotic: no nucleus; Eukaryotic: nucleus + membrane-bound organelles.

What is the cell membrane?

A semi-permeable phospholipid bilayer (fluid mosaic).

What is diffusion?

Movement of molecules from high to low concentration.

What is osmosis?

Movement of water across a semi-permeable membrane.

What is active transport?

Movement against concentration gradient using energy (ATP).

Function of the nucleus?

Stores DNA and controls cell activities.

Function of ribosomes?

Protein synthesis.

Rough ER vs Smooth ER?

Rough ER: proteins; Smooth ER: lipids, detox, Ca²⁺ storage.

Function of Golgi apparatus?

Modifies, packages, and ships proteins/lipids.

Function of mitochondria?

ATP production via cellular respiration.

Function of lysosomes?

Digest waste and macromolecules with enzymes.

Function of cytoskeleton?

Maintains shape; supports intracellular transport and movement.

Three types of carbohydrates?

Monosaccharides, disaccharides, polysaccharides.

Example of a monosaccharide?

Glucose (also fructose, galactose).

Example of a disaccharide?

Sucrose or lactose.

Example of a polysaccharide?

Starch or glycogen (also cellulose/fiber).

Main function of carbohydrates?

Primary energy source; glucose fuels cells.

What are triglycerides?

Fats made of glycerol + three fatty acids.

Main functions of lipids?

Energy storage, insulation, membrane structure, signaling.

LDL vs HDL?

LDL delivers cholesterol (can deposit); HDL removes cholesterol to liver.

What are proteins made of?

Amino acids (including 9 essential amino acids).

Three functions of proteins?

Enzymes, structure (collagen/keratin), transport (hemoglobin).

Example of a transport protein?

Hemoglobin.

Four types of tissues?

Epithelial, connective, muscle, nervous.

Function of epithelial tissue?

Protection, secretion, absorption, lining surfaces.

Function of connective tissue?

Support, binding, protection (bone, blood, cartilage, fat).

Three types of muscle?

Skeletal, smooth, cardiac.

Which muscle is voluntary?

Skeletal muscle.

Which muscle is in the heart?

Cardiac muscle.

Structure of DNA?

Double helix.

DNA bases?

A, T, C, G.

RNA bases?

A, U, C, G.

Function of RNA?

Carries information and helps synthesize proteins.

What happens in S phase?

DNA replication.

What is mitosis?

Division into two identical diploid cells (growth/repair).

What is cytokinesis?

Division of the cytoplasm into two cells.

What does meiosis produce?

Four genetically different haploid cells.

Why is meiosis important?

Genetic variation and gamete formation.

What is an allele?

A variant form of a gene.

Homozygous vs heterozygous?

Same alleles vs different alleles.

What is codominance?

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

What is polygenic inheritance?

Trait controlled by many genes (e.g., height).

What is incomplete dominance?

Blended phenotype (e.g., red + white = pink).

How many pairs of ribs?

12 pairs.

Functions of the rib cage?

Protects heart/lungs; aids breathing.

Main muscle of breathing?

Diaphragm.

What happens during inhalation?

Diaphragm contracts, chest cavity expands, air enters.

Main parts of the cardiovascular system?

Heart, blood, blood vessels (arteries, veins, capillaries).

Pulmonary circuit?

Heart → lungs → heart (oxygenation).

Systemic circuit?

Heart → body → heart (delivery of O₂/nutrients).

Main function of urinary system?

Filters blood, forms urine, maintains homeostasis.

How much blood do kidneys filter daily?

About 150 liters.

Characteristics of living organisms

Made of cells, use energy (metabolism), maintain homeostasis, respond to stimuli, grow, reproduce, evolve

Homeostasis

Maintenance of stable internal conditions in the body

Metabolism

All chemical reactions in a cell or organism

Biological organization (inside organism)

Cell → Tissue → Organ → Organ system → Organism

Biological organization (outside organism)

Population → Community → Ecosystem → Biome → Biosphere

Scientific method

Observation → Hypothesis → Prediction → Experiment → Data → Conclusion

Hypothesis

A testable explanation or prediction