Biology Final Exam

Ecosystem

Includes all living (biotic) and nonliving (abiotic) factors in an area.

Energy Flow

Energy flows through ecosystems, but matter cycles (water, carbon, nitrogen).

Carnivore

An organism that eats animals; secondary or tertiary consumers.

Herbivore

An organism that eats plants; primary consumers.

Omnivore

An organism that eats both plants and animals.

Scavenger

An organism that eats dead animals but does not break them down chemically.

Decomposer

An organism that breaks down dead organisms and returns nutrients to the soil (e.g., fungi, bacteria).

Mutualism

A symbiotic relationship where both organisms benefit (e.g., bee + flower).

Commensalism

A symbiotic relationship where one organism benefits and the other is unaffected (e.g., barnacles on whales).

Parasitism

A symbiotic relationship where one organism benefits and the other is harmed (e.g., ticks on dogs).

Trophic Levels

Levels of energy flow: Producers → Primary consumers → Secondary consumers → Tertiary consumers → Apex predators.

Energy Transfer Efficiency

Only about 10% of energy moves to the next trophic level.

Biome

Large regions with similar climate and organisms (e.g., Tundra, Taiga, Desert, Grassland).

Abiotic Factors

Nonliving components of an ecosystem, such as sunlight, temperature, water, soil.

Biotic Factors

Living components of an ecosystem, including plants, animals, fungi, bacteria.

Food Chain

A linear sequence showing one energy path in an ecosystem.

Food Web

A complex network showing many interconnected feeding relationships.

Hooke

The scientist who named 'cells'.

Leeuwenhoek

The scientist who observed living cells.

Schleiden

The scientist who stated that plants are made of cells.

Schwann

The scientist who stated that animals are made of cells.

Virchow

The scientist who concluded that cells come from other cells.

Nucleus

The organelle that stores DNA.

Mitochondria

The organelle that makes ATP through cellular respiration.

Ribosomes

Organelles that build proteins.

Rough ER

The endoplasmic reticulum that transports proteins.

Smooth ER

The endoplasmic reticulum that makes lipids.

Golgi Apparatus

The organelle that modifies and packages proteins.

Lysosomes

Organelles that break down waste.

Vacuoles

Storage organelles in cells.

Chloroplasts

Organelles involved in photosynthesis; found only in plants.

Cell Wall

Structure and protection found in plant cells.

Cell Membrane

Controls what enters and exits the cell; maintains homeostasis.

Plant Cells

Have cell walls, chloroplasts, and large central vacuoles.

Animal Cells

Have centrioles and smaller vacuoles.

Diffusion

Movement of molecules from high to low concentration until equilibrium is reached.

Osmosis

The diffusion of water across a membrane.

Hypertonic Solution

A solution where water leaves the cell, causing it to shrink.

Hypotonic Solution

A solution where water enters the cell, causing it to swell.

Isotonic Solution

A solution where there is equal movement of water, and the cell stays the same size.

Active Transport

Movement of molecules from low to high concentration using ATP.

Examples of Active Transport

Protein pumps, endocytosis, exocytosis.

Cell Cycle

Includes interphase (G1 growth, S DNA replication, G2 prep) and M phase (mitosis + cytokinesis).

Mitosis

Process that creates two identical diploid cells.

Phases of Mitosis

Prophase, Metaphase, Anaphase, Telophase.

Chromosomes

Humans have 46 chromosomes (23 pairs); formed by chromatids connected by a centromere.

Mendel

Discovered dominant and recessive traits using pea plants.

Monohybrid Cross

A genetic cross predicting one trait using a Punnett square.

Genotype Ratio Example

1:2:1.

Phenotype Ratio Example

3:1.

Sex-Linked Traits

Traits found on the X chromosome; males (XY) show recessive traits more often.

Incomplete Dominance

A situation where neither allele is fully dominant (e.g., red + white = pink).

Codominance

Occurs when both alleles show equally (e.g., AB blood type).

Meiosis I

Phase where homologous chromosomes separate.

Meiosis II

Phase where sister chromatids separate.

Crossing Over

Occurs in Prophase I of meiosis; increases genetic variation.

Gametes

Sex cells (sperm and egg) made through meiosis.

Diploid

A cell with 46 chromosomes.

Haploid

A cell with 23 chromosomes.

Fertilization

Process that restores the diploid number of chromosomes.

Franklin

Scientist who took X-ray images of DNA.

Watson and Crick

Built the double helix model of DNA.

Nucleotide

Basic unit of DNA, consisting of sugar (deoxyribose), phosphate, and nitrogen base (A, T, C, G).

Base Pairing Rules

A pairs with T; C pairs with G.

DNA Replication Process

1. DNA unzips, 2. Bases pair, 3. Two identical DNA molecules form.

S Phase

Phase of the cell cycle during which DNA replication occurs.

Enzymes in DNA Replication

Helicase unzips DNA; DNA polymerase adds new bases and proofreads.

Transcription

Process of converting DNA to mRNA that occurs in the nucleus.

Translation

Process of converting mRNA to protein that occurs at the ribosome.

RNA Polymerase

Enzyme that builds mRNA during transcription.

mRNA

Carries genetic code from DNA.

tRNA

Brings amino acids to the ribosome for protein synthesis.

Codons

Sequences of 3 bases that code for amino acids.

Darwin

Scientist who observed finches and proposed the theory of natural selection.

Theory of Evolution

States that populations change over time due to inherited traits that improve survival.

Evidence of Evolution

Includes fossils, DNA similarities, homologous structures, embryology, and vestigial organs.