SBI3U Biology Exam Review

Kilocalorie (kcal) vs. Calorie (cal)

A kcal raises 1 kg of water by 1°C; a cal raises 1 g.

Three Macronutrients

Carbohydrates, fats/lipids, and proteins.

Two Micronutrients

Vitamins and minerals.

Necessary vs. Essential Nutrients

Necessary are needed to function; essential cannot be made by the body.

Vitamins

Organic compounds (C, H, O, N) that mostly act as coenzymes.

Minerals

Inorganic compounds forming structures, controlling water balance, and regulating cell pH.

Fat-Soluble vs. Water-Soluble Vitamins

Fat-soluble (A, D, E, K) are stored; water-soluble (B, C) are excreted.

Major Minerals vs Trace Minerals

Major minerals are required in large amounts, trace minerals are required in small amounts

LDL vs. HDL Cholesterol

LDL is "bad" cholesterol that clogs arteries; HDL is "good" and clears it.

Mechanical vs. Chemical Digestion

Mechanical physically breaks food down; chemical uses juices to create chyme.

What is the function of saliva?

helps in moistening food for easier swallowing, begins the digestion of carbohydrates with enzymes.

Peristalsis

Rhythmic, wavelike contractions of smooth muscle moving food down the GI tract.

Epiglottis

Flap of cartilage covering the trachea to prevent food entering the lungs.

Gastric Juice Composition

Made of acid, mucus, and enzymes.

Three Parts of the Small Intestine

Duodenum, jejunum, and ileum.

Small Intestine Surface Area

Increased by folds, villi, and microvilli to maximize nutrient absorption.

Functions of the pancreas?

Secretes enzymes for digestion, neutralizes stomach acid, and regulates hormones like insulin.

Bile Function and Storage

Emulsifies fats physically; produced by the liver and stored in the gallbladder.

How do enzymes work?

Substrates fit into the active site of enzymes. The enzyme induces a shape that facilitates the reaction. 

The reaction proceeds forming the product(s) for its release

The enzyme returns to its original configuration, ready to facilitate the next reaction.

Gastrin

stimulates gastric juice

secretin

stimulates bicarbonate

CCK

stimulates bile/pancreatic enzymes.

External vs. Internal Respiration

External is gas exchange in alveoli; internal is exchange at cells.

Inhalation Mechanics

Diaphragm/intercostals contract, chest volume increases, generating negative pressure to draw air in.

Exhalation Mechanics

Diaphragm/intercostals relax, chest volume decreases, pressure increases, forcing air out.

Where does gas exchange occur?

in the lungs/alveoli by diffusion

Tidal Volume vs. Vital Capacity

Tidal is normal involuntary breath; vital is maximum air inhaled/exhaled.

Primary Driver of Breathing Rate

Carbon dioxide (CO₂), which forms carbonic acid and lowers blood pH.

Plasma

Protein-rich liquid suspending blood cells and platelets; 90% water.

Three Cellular Elements of Blood

Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.

Erythrocytes (RBC) Function

Carry oxygen and carbon dioxide using iron-containing hemoglobin.

Leukocytes function

wbc immune defense

Platelets function

initiates blood clotting

Arteries vs. Veins

Arteries are thick, carry oxygen-rich blood away; veins are thin, return oxygen-poor blood.

Why Ventricle Walls Are Thicker

They pump blood long distances to the lungs or body, unlike atria.

Blood Flow Pathway Through Heart

Right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta.

What is the Rhesus factor?

Rh is an inherited protein found on the rbc surface.

What are the valves between the atria and the ventricles?

Atrioventricular (AV) valves

What are the valves between the arteries and the ventricles?

Semilunar valves

Systole vs. Diastole

Systole is cardiac contraction (emptying); diastole is relaxation (filling).

SA Node vs. AV Node

SA node is the pacemaker; AV node signals Purkinje fibers.

What Causes Heart Sounds?

"Lub" is ventricles contracting; "dub" is ventricles relaxing.

Angina vs. Heart Attack

Angina is chest pain from low blood supply; heart attack is muscle death due to oxygen deficiency

What is hypertension

Blood againsts your artery walls is always too high.

what is the normal blood pressure?

Less than 120 mmHg systolic on top and 80 mmHg diastolic on bottom.

Chromatin vs. Chromosome vs. Chromatid

Chromatin is loose DNA; chromosomes are condensed chromatin; chromatids are duplicated chromosomes.

Diploid vs. Haploid

Diploid contains two sets of chromosomes (2n); haploid contains one set (n).

Four Stages of Mitosis (nuclear division)

Prophase (condenses), Metaphase (aligns), Anaphase (separates), Telophase (reforms nuclei).

Interphase

G1 recovers from previous division; just grows

S Phase duplicates copy of DNA

G2 double checks and undergoes a final period of growth

Meiosis Goal

To produce four genetically unique haploid gametes from one diploid cell.

Prophase I

chromosomes find matching partner and cross over

Metaphase I

pairs line up down the middle in 2 straight rows

anaphase I

spindle fibers pull replicated chromosomes to opposite sides

telophase I

original cell becomes 2 cells with replicated chromosomes

prophase II

starts with 2 haploid cells, nuclear membrane disintegrates and new spindle fibers attach

metaphase II

remaining chromosomes line up in a straight row down the center

anaphase II

chromosomes look like an X because it is made up of 2 identical copies, cell snaps x in half and pulls copies to opposite sides

telophase II

2 cells divide into 2 haploid daughter cells; total of 4

Synapsis vs. Crossing Over

Synapsis is homologous pairing; crossing over is homologous chromosomes intertwining and producing genetic recombination during Prophase I.

Spermatogenesis vs. Oogenesis Output

Spermatogenesis yields 4 functional sperm; oogenesis yields 1 functional egg.

Nondisjunction

Failure of chromosomes to separate properly during cell division.

Monosomy vs. Polysomy

Monosomy is missing one chromosome (45); polysomy is having extra chromosomes (47+).

Four Chromosome Structure Abnormalities

Deletion (fragment lost), duplication (extra copies), inversion (reversed), translocation (attached to non-homologous).

Three Types of Asexual Reproduction

Spore formation (bacteria/mold), budding (hydra/potatoes), and fragmentation (sea stars/worms).

Genotype vs. Phenotype

Genotype is genetic makeup (alleles); phenotype is observable physical traits.

Dominant vs Recessive

Dominant main trait expressed that masks the presence of another allele.

Recessive only expressed when you inherit 2 identical copies

Carrier

An individual carrying a recessive allele masked by a dominant allele.

Three Mutation Types

Harmful (disrupts proteins), neutral (no effect), and beneficial (improves traits).

Pedigree

A chart showing the inheritance of a specific trait across generations.

Law of Segregation

Alleles separate during gamete formation so each gamete carries one allele.

Law of Independent Assortment

Genes for different traits segregate independently during gamete formation.

Artificial Selection

Intentional human breeding of organisms for specific desired traits.

Stabilizing, Disruptive, and Directional Selection

Stabilizing favors average; disruptive favors both extremes; directional favors one extreme.

Homologous vs. Analogous Features

Homologous have similar structure/different function; analogous have similar function/different structure.

Vestigial Structures

features that are no longer useful (e.g., appendix).

Genetic Drift vs. Bottleneck Effect

Drift is random allele frequency change; bottleneck is random reduction from catastrophe.

Allopatric vs. Sympatric Speciation

Allopatric occurs via geographic separation; sympatric occurs within the same area.

Prezygotic vs. Postzygotic Barriers

Prezygotic prevents fertilization; postzygotic prevents hybrid survival or reproduction.

What are the prezygotic isolation mechanisms?

Behavioural isolation, temporal isolation, Ecological isolation, Mechanical isolation, Gametic isolation

What are the postzygotic isolation mechanisms?

Zygotic mortality, hybrid inviability

Abiogenesis

The theory that life originated from non-living matter.

Lamarck's Theory of Evolution

Inheritance of acquired traits and development via use and disuse.

Evolutionary Fitness vs. Adaptation

Fitness is reproductive success; adaptation is an inherited trait improving the chances of reproduction/survival.

What is survival of the fittest?

individuals that are best suited for survival; traits that help them survive and reproduce are more likely to pass those traits on to their offspring.

Six Kingdoms of Life

Animalia, Plantae, Fungi, Protista, Archaebacteria, Eubacteria.

Why Viruses are Non-Living

They lack cells, cannot reproduce independently, and require a host.

Lichen Symbiosis

Algae produce food via photosynthesis; fungi provide water, protection, and support.

Plant Adaptations to Land

Waxy cuticles, roots, vascular tissue, and waterless reproduction (seeds/pollen).